Multiple cropping management of corn and sorghum succeeding vegetables

MISSING IMAGE

Material Information

Title:
Multiple cropping management of corn and sorghum succeeding vegetables
Physical Description:
xvi, 146 leaves : graphs ; 28 cm.
Language:
English
Creator:
Mateo, Nicolás, 1945-
Publication Date:

Subjects

Subjects / Keywords:
Cropping systems -- Florida   ( lcsh )
Corn -- Florida   ( lcsh )
Sorghum -- Florida   ( lcsh )
Cabbage -- Florida   ( lcsh )
Potatoes -- Florida   ( lcsh )
Cabbage   ( fast )
Corn   ( fast )
Cropping systems   ( fast )
Potatoes   ( fast )
Sorghum   ( fast )
Florida   ( fast )
Agronomy thesis Ph. D
Dissertations, Academic -- Agronomy -- UF
Genre:
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis--University of Florida.
Bibliography:
Includes bibliographical references (leaves 140-145).
Additional Physical Form:
Also available online.
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by Nicolás Mateo.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. This item may be protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact the RDS coordinator (ufdissertations@uflib.ufl.edu) with any additional information they can provide.
Resource Identifier:
aleph - 020703275
oclc - 06014164
System ID:
AA00026367:00001


This item is only available as the following downloads:


Full Text











MULTIPLE CROPPING MANAGEMENT'OF CORN AND SORGHUM
SUCCEEDING VEGETABLES

















By
NICOLAS MATEO



















A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY



UNIVERSITY OF FLORIDA

1979
































To a couple of dreamers,
my grandfathers

Ladislao Mateo Esteban
and

Andres Valverde Amador















ACKNOWLEDGEMENTS


The author expresses his sincere gratitude to Dr. Raymond N. Gallaher, chairman of the supervisory committee, for his continuous support and encouragement in all phases of this study. He also thanks Dr. Dale R. Hensel, Director of the ARC at Hastings and member of the committee, for his support and for overseeing the field work. Special thanks are due to Dr. Victor E. Green, Jr. for his friendship and for serving on the committee and Dr. Elmo B. Whitty and Dr. Herman L. Breland, also members of the committee, for time and discussion devoted in correcting this manuscript.

Recognition is extended to Ms. Jan Ferguson, Ms. Ruth Schuman,

Mr. Ken Harkcom, Ms. Linda Osheroff, Mr. Rolland Weeks, and Mr. Jack Swing for their laboratory and field assistance and for providing many hours of country music. Thanks are also due to the personnel of the Analytical Research Laboratory of the Soil Science Department, and the personnel of the Agricultural Research Center at Hastings. The author is also indebted to Philip d'Almada for his guidance in the statistical analysis.

The author wishes to recognize the financial support provided by the Rockefeller Foundation during all his degree program. The author's deepest appreciation is extended to his family, Lorna, Elena, and Javier, for their love and support, and especially to Lorna for the typing and editing of the first draft. Finally, special thanks are due Ms. Maria I. Cruz for typing the final copy of this dissertation.



iii

















TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS. . . . . . iii

LIST OF TABLES........ . . .... ...... vi

LIST OF FIGURES ... . . .. ..... xiii

ABSTRACT. ................ . . . .. . xiv

INTRODUCTION. ... . ..... .. 1

LITERATURE REVIEW ......... ....... . .... 3

General . . . . . .. .. 3

Multiple Cropping. ......... . 3

Corn or Sorghum Following Vegetables . 3 Soil and Leaf Analysis .......... . 5

Fertility of Corn and Sorghum ...... . . 7

Drainage and Irrigation Beds. ...... . . 12

Cultivar Experiments. ..... .. .. . . 14

MATERIALS AND METHODS .................. 16

Fertility Experiments ................. 16

Bedding Experiments .................. 22

Cultivar Experiments ................. 25

RESULTS AND DISCUSSION .................. 27

Fertility Experiments in 1977 ............. 27

Corn . . . . . 27

Sorghum. . . . . . 37

Fertility Experiments in 1978 ............. 62

Corn ............. ........ 62

Sorghum. .. . . . . 81



iv









Page
Bedding Experiments. ...... ............ 100

Cultivar Experiments ................. .. 121

CONCLUSIONS. .......... ... . . . 136

Grain sorghum . . . . . 138

Corn . . . . . .. . 139

LITERATURE CITED .............. . 140

BIOGRAPHICAL SKETCH ................ ... 146




















































v














LIST OF TABLES

Table Page

1 Critical values for corn and sufficiency ranges for
corn and sorghum. ... ................ . 8

2 Basic information for all experiments during 1977 and 1978. . . . . . ..... 17

3 Pesticides used during 1977 and 1978. ........ 19

4 Treatments imposed on the bedding experiments, 1977
and 1978 .................. .... 23

5 Cultivars tested at Hastings during 1977 and 1978 26

6 Temperature and rainfall data for 1977 and 1978.
Hastings area, Florida. ............... 28

7 Soil Analysis before planting. Corn fertility
experiment No.1, 1977 ............... 29

8 Soil analysis before planting. Corn fertility
experiment No.2, 1977 ................ 29

9 Significant variables as determined by F test. Corn
experiment No.1, 1977 ................ 30

10 Significant variables as determined by F test. Corn experiment No.2, 1977. ................ 31

i11 Grain yield, pH, and nutrient concentration in the soil.
Corn experiment No.1, 1977. ............. 32

"12 Grain yield, pH, and nutrient concentration in the soil.
Corn experiment No.2, 1977. ............ 33

13 Nutrient concentration in the leaves. Corn experiment No.1, 1977 .. . ....... .... 34

14 Nutrient concentration in the leaves. Corn experiment No.2, 1977 . ..... ....... ... 35

15 Effect of N and K on concentration of Ca and In in the soil at 2 levels of P. Corn experiment No.1, 1977. 36





vi









Table Page

16 Effect of P and K (kg/ha) at different levels of N on the
concentration of K and Ca in the leaves. Corn
experiment No.2, 1977. . . . . 38

17 Effect of N levels on pH, K, and Mg Soil test and
the concentration of N, P, Mg, Cu, Mn, and Fe in the
leaves. Corn experiment No.2, 1977 ........ 38

18 Correlation coefficients for soil test and leaf
nutrient concentration. Corn experiment No.1, 1977. 39

19 Correlation coefficients for soil test and leaf
nutrient concentration. Corn experiment No.2, 1977. 40

\20 Grain yield, dry matter yield, and nutrient concentration in leaves. Sorghum experiment No.3, 1977 . 42

21 Significant variables as determined by F test. Sorghum
experiment No.3, 1977. ............ .. 43

22 Effect of K levels on grain yield at different levels
of N and P. Sorghum experiment No.3, 1977 ..... 44

23 Effect of N levels on the concentration of nutrients in the leaves and in dry matter yield. Sorghum experiment
No.3, 1977 . . . . . 44

24 Effect of P and K levels on the concentration of Ca and
Mg. Sorghum experiment No.3, 1977. ........ 45

25 Soil analysis before planting. Sorghum experiment
No.3 (tile drained). . . . ... 47

26 Grain yield, pH, and nutrient concentration in the soil.
Sorghum experiment No.4, 1977. ........... 48

27 Nutrient concentration in the leaves. Sorghum
experiment No.4, 1977. ............ 49

28 Significant variables as determined by the F test.
Sorghum experiment No.4, 1977. .......... 50

29 Significance of percent Ca and Mg in the leaves at 4
levels of N as determined by the F test. Sorghum
fertility experiment No.4, 1977. .......... 51

30 Effect of N levels on the concentration of Zn and Mn
in the soil. Sorghum experiment No.4, 1977. .... 52

31 Effect of K on Ca leaf concentration at 2 levels of P.
Sorghum experiment No.4, 1977 ........... 52


vii










Table Page

32 Correlation coefficients for soil and leaf nutrient
concentrations. Sorghum experiment No.4, 1977. 53

33 Grain yield, dry matter, pH, and nutrient
concentration in the soil. Sorghum experiment No.5,
1977. . . . . .......... 55

34 Nutrient concentration in the leaves. Sorghum experiment No.5, 1977 . . . . 56

35 Soil analysis before planting. Sorghum experiment No.4 (ditch drained), and No.5, 1977. ....... 57

36 Significant variables as determined by the F test sorghum experiment No.5, 1977 ........... 58

37 Effect of N levels on pH, grain, dry matter, K, and Mg in the soil. Sorghum experiment No.5, 1977. 59

38 Effect of N levels on concentration of several elements in the leaves. Sorghum experiment No.5, 1977 59

39 Effect of N levels on the concentration of K, Ca, and Fe in the soil at 2 levels of P and K. Sorghum
experiment No.5, 1977 . . . . 60

40 Effect of levels of K on soil test Ca at 2 levels of P.
Sorghum experiment No.5, 1977 ........... 60

41 Correlation coefficients for soil and leaf nutrient concentrations, grain and dry matter yields. Sorghum
experiment No.5, 1977 ............ ... 61

42 Grain and dry matter yield. Corn experiment No.8, 1978. ......................... 63

43 Soil analysis before planting, corn fertility experiment No.8, 1978 ........... . 64

44 Effect of N levels and percent lodging on grain, and dry matter yields. Corn experiment No.8, 1978. 65

45 Effect of N levels on grain and dry matter yields at
2 levels of P and K. Corn experiment No.8, 1978. .. 66

46 Significance of agronomic variables as determined by the F test. Corn experiment No.8, 1978 ...... 67

47 pH values, and nutrient concentration in the soil.
Corn experiment No. 8, 1978 .......... 73



viii











Table Page

48 Nutrient concentration in the leaves. Corn experiment
No.8, 1978 .. . .. .. .. ... 74

49 Significant variables as determined by the F test corn experiment No.8, 1978. ............. 75

50 Nutrient content and % IVOMD values for whole plant
samples. Corn experiment No.8, 1978. ....... 77

51 Correlation coefficients for soil and leaf nutrients Concentrations. Corn experiment No.8, 1978 ..... 78

52 Correlation coefficients for soil, whole plant nutrient concentration,and agronomic responses.
Corn experiment No.8, 1978. ............. 79

53 Correlation coefficients for leaf nutrient concentration, whole plant nutrient concentration,and agronomic
responses. Corn experiment No.8, 1978. ....... 80

54 Soil analysis before planting. Sorghum fertility experiment No. 9, 1978. ............... 82

55 Significant variables as determined by the F test.
Sorghum experiment No.9, 1978 ............ 83

- 56 Grain and dry matter yield, pH, and nutrient concentration in the soil. Sorghum experiment No.9, 1978 85

57 Nutrient concentration in the leaves. Sorghum experiment No.9, 1978 . . . . 86

58 Nutrient concentration in whole plant samples. Sorghum experiment No.9, 1978 . . . . 87

59 Effect of N and P levels on K, Mg,and Fe soil test at two levels of K. Sorghum experiment No.9, 1978 . 88

60 Effect of N and K levels on Mn soil test at 2 levels of P. Sorghum experiment No.9, 1978. ........ 88

61 Effect of N levels on p1l, Ca,and Mg soil test and grain yield. Sorghum experiment No.9, 1978 ..... 90

62 Effect of N levels on the concentration on several elements in the leaves. Sorghum experiment No.9, 1978. 90

63 Effect of K levels on the concentration of P, K, Ca, and Mg in the leaves. Sorghum experiment No.9, 1978. 90



ix











Table Page


64 Effect of N levels on N, P, Mg, and Mn concentration
in the leaves at 2 levels of K. Sorghum experiment
No.9, 1978............. . .. .... 91

65 Effect of N and K levels on P and Mn concentration
in the leaves at 2 levels of P. Sorghum experiment
No.9, 1978. ...... ............. ... 91

66 Effect of N levels on P concentration in the leaves at different combinations of P and K. Sorghum
experiment No.9, 1978 ................ 92

67 Effect of N levels on nutrient concentration of whole plant samples. Sorghum experiment No.9, 1978 ... 92

68 Effect of K levels on K, Ca, and Mg concentration in whole plant samples, and on percent IVOMD. Sorghum
experiment No.9, 1978. ................. 93

69 Effect of N and K levels on P, Mg, and Zn concentration of whole plant samples at two levels of P. Sorghum
experiment No.9, 1978 ............... 93

70 Correlation coefficients for soil and leaf nutrient concentrations, grain, and dry matter yield. Sorghum
experiment No.9, 1978. ............. ... 94

71 Nutrient content for sorghum fertility experiment No.9, 1978 . . . . . 95

72 Correlation coefficients for soil and whole plant nutrient concentrations, and nutrient content, grain, DM, and percent IVOMD. Sorghum fertility experiment
No.9, 1978. ... . . . . ... 97

73 Correlation coefficients for leaf and whole plant nutrient concentrations and nutrient content, grain, DM,
and percent IVOMD. Sorghum fertility experiment No.9,
1978. . . . . . ..... 98

74 Soil analysis before planting. Sorghum bedding experiment No.6, 1977 . . . . 101

75 Soil analysis before planting. Bedding experiment No.10, 1978. ................ . 102

76 Significant variables as determined by F test. Combined analysis 1977 and 1978. Bedding experiment No.6 and 10. 103




x










Table Page

77 Significant variables as determined by the F test in
1977 and 1978. Bedding experiments No.6, and 10 104

78 Grain yield in kg/ha. Bedding experiments No.6 and
10, 1977 and 1978 . . . . 105

79 Dry matter yield in kg/ha. Bedding experiments No.6
and 10, 1977 and 1978 . . . 107

80 Average plant population and plant height for 1977 and 1978. Bedding experiment No.6, and 10. ... 108

81 Significant variables as determined by the F test.
Combined analysis 1977 and 1978. Bedding experiments
No.6, and 10. .................. 109

82 Significant variables as determined by the F test.
Bedding experiments No.6, and 10. ....... 110

83 Nutrient concentration and percent IVOMD for whole plant samples. Bedding experiment No.6, 1977 ... 111

84 Nutrient concentration and percent IVOID for whole plant samples. Bedding experiment No. 10, 1978 112

85 Nutrient concentration and percent IVOND for whole plant samples. Combined analysis 1977, 1978.
Bedding experiments No.6 and 10 ........ . 113

86 Nutrient content of whole plant samples bedding experiments No.6 and 10, 1977 and 1978. ....... 115

87 Nutrient content of whole plant samples. Average of 1977 and 1978. Bedding experiments No.6 and 10. 117

88 Correlation coefficients for nutrient concentration and percent IVOMD, in whole plant samples, agronomic
variables and nutrient content. Bedding experiment
1977. ........... . ...... 118

89 Correlation coefficients for nutrient concentration and percent IVOMD in whole plant samples, agronomic variables,and nutrient content. Bedding experiment
1978. . . . . . .. 119

90 Correlation coefficients for nutrient concentration and percent IVOMD in whole plant samples, agronomic
variables,and nutrient content. Bedding experiments
1977-1978 ................... ..... 120



xi










Table Page

91 Soil analysis before planting. Sorghum cultivar
experiment No.6, 1977. .. .............. 122

92 Soil analysis before planting. Sorghum cultivar
experiment No.11, 1978 ............. 123

93 Nutrient concentration in whole plant samples and
agronomic variables for cultivars excluded from the
statistical analysis. Cultivar experiments No.7
and 11, 1977 and 1978. ....... ......... 124

94 Nutrient concentration in whole plant samples, and
agronomic variables for cultivars included in the
statistical analysis. Cultivar experiments No.7
and 10, 1977 and 1978. ............... 125

95 Significant variables as determined by F test.
Combined analysis 1977, 1978. Cultivar experiments
No.7 and 11. ..................... .. 126

96 Effect of year on nutrient concentration on whole plant samples. Cultivar experiments No.7 and 11,
1977 and 1978. ............. ....... 12 7

97 Nutrient concentration of whole plant samples.
Combined analysis. Cultivar experiment No.7 and 11,
1977 and 1978. .. .......... .......... 128

98 Nutrient concentration of whole plant samples.
Cultivar experiment, 1977. ............. 128

99 Nutrient concentration of whole plant samples.
Cultivar experiment, 1978. .... .......... 129

100 Percent IVOHD, dry matter, and grain yields.
Cultivar experiments No.7 and 11, 1977 and 1978. 1

101 Nutrient content of whole plant samples. Cultivar
experiments No.7 and 11, 1977 and 1978 ....... 132

102 Percentage of N removed in relation to N applied.
Cultivar experiment No.7 and 11, 1977 and 1978 . 133

103 Recycling of N, P, and K and digestible dry matter.
Forage sorghum cultivars. Cultivar experiments No.6
and 10, 1977 and 1978. . . . ... 134







xii















LIST OF FIGURES


Figures Page

1 Effect of N levels on grain yield. Corn experiment
No.8, 1978. .................. 68

2 Effect of N levels on grain yield at two levels of
P. Corn experiment No.8, 1978. .......... 68

3 Effect of N levels on grain yield at two levels
of K. Corn experiment No.8, 1978 ......... 69

4 Effect of N levels on dry matter yield. Corn
experiment No.8, 1978 ............ 69

5 Effect of N levels on dry matter yield at two levels
of P. Corn experiment No.8, 1978 .......... 70

6 Effect of N levels on dry matter yield at two levels
of K. Corn experiment No.8, 1978 ......... 70































xiii










Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy


MULTIPLE CROPPING MANAGEMENT OF CORN AND SORGHUM SUCCEDING VEGETABLES

By

Nicolas Mateo

August 1979

Chairman: Raymond N. Gallaher
Major Department: Agronomy

In the Hastings area of Florida, potato (Solanum tuberosum L.) and cabbage (Brassica oleraceae L.) are grown during late fall and winter. The rest of the year, available resources such as solar energy, irrigation water, residual fertilizer from the previous crops, and equipment are not fully utilized by farmers. The planting of a second crop could possibly make use of these resources. Corn (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) are alternative crops because Florida is a net grain importer and the ecological conditions are suitable for these crops. Several experiments dealing with production problems observed in the area (soil fertility, bed management, and cultivar evaluations) were conducted during 1977 and 1978, both in farmers' fields and at the Agricultural Research Center (ARC). The main objective of the research was to determine management needed for growing corn after cabbage, and sorghum after potato in succession cropping systems.

Experiments were planted on a Rutlege fine sand (Sandy, Siliceous,

thermic family of the Typic Humaquepts). Drainage beds lm apart were used to plant both crops. Factorial combinations of N(0, 100, 200, 300 kg/ha),



xiv











P(0,60 kg/ha), and K(0,60 kg/ha) were in a randomized complete block design. Soil and plant samples were collected before harvesting, and grain and total dry matter yields determined.

Nitrogen was the most important element affecting not only grain and dry matter yields but also nutrient relationships in all collected samples. In all cases the first N increment (100kg/ha) was sufficient to maximize yields. Phosphorus and K tended to decrease grain and dry matter yields in several cases, suggesting salinity problems and possibly nutrient toxicity. Nutrient content and correlations between soil and plant analyses are presented and discussed.

Use of the traditional 1.0 m potato bed resulted in an apparent

waste of space and yield reduction for the sorghum crop. Several modifications of the 1.0 m beds were made and compared to 1.5 and 2.0 m beds in which various numbers of rows and broadcast treatments were included in a split-split plot design. Highest grain yield was obtained from the

2.0 m beds. The highest yield was obtained from the 2.0 m bed four rows treatment, which showed a 40% yield increase over the control. Total sorghum plant dry matter was also higher in 1.5 and 2.0 m beds. Highest N content was 175 kg/ha in 1977 for the 1.5 m five rows treatment as opposed to 76 kg N/ha in 1978 for the 1.5 m five rows treatment. Nitrogen removal in relation to N applied was 233% and 101% respectively for the two above mentioned treatments.

Cultivar experiments included 6 grain sorghum and 2 forage sorghum hybrids. Grain yield was difficult to evaluate due to missing values. However, grain hybrids Dekalb BR-54 and Grower ML-135 would probably be



xv











the best choices for the area considering overall performance. There were no differences in the percent IVOMD in a combined 2 year analysis. The forage hybrids (Dekalb FS-25A and FS-24) showed the highest N, P, and K content values for both years. The importance of sorghum as a forage crop, probably needs to be stressed in this area. The percent N removed was very close to 100% by Dekalb FS-24. The total N, P, and K recycled by this forage sorghum was 74, 29, and 203 kg/ha, respectively.







































xvi














INTRODUCTION



Today's energy problems are being dealt with and understood differently by various countries and individuals. The challenge posed to agricultural systems based largely on the use of fossil fuels has prompted agronomists to come up with alternatives to help alleviate the energy problem.

The use of multiple-cropping systems and minimum tillage are probably the most dramatic and successful examples of a new approach to incorporate ancient practices in today's modern agriculture. The key is not necessarily to intensify agriculture but to combine intelligently the available resources of land, growing period, and solar energy to obtain a larger output of food, fiber, and forage.

Florida has a full year growing period and a subtropical climate to expand production through multiple cropping. If innovative cropping systems are designed to better utilize the exceptional characteristics of the state and if practices like irrigation, weed, and pest control are carefully considered, it would be possible to maintain successful cropping systems to go along with the times.

This research was initiated with the above guidelines in mind. In

the area near Hastings, Florida, potato (Solanum tuberosum L.) and cabbage (Brassica oleracea L.) are grown during late fall and winter. The rest of the year, available resources such as solar energy, irrigation water, residual fertilizer from the previous crops, and equipment are not fully utilized by the majority of the local farmers. The planting of a second




1













crop could possibly utilize available resources during this period of time. Grains like corn (Zea mays L.) and grain sorghum (Sorghum bicolor (L.) Moench) are good second crop alternatives, because Florida is a net grain importer and the climate and soil are suitable for these crops.

Several experiments dealing with the main problems observed in the Hastings area (soil fertility, bed and plant population management, and cultivar evaluations) were conducted during 1977 and 1978, both in farmers' fields and at the Agricultural Research Center (ARC) at Hastings, Florida. The main objective of the research was to determine management needed for growing corn and grain sorghum after the cabbage and potato harvest.















LITERATURE REVIEW


General


Multiple Cropping

The recent emphasis on multiple cropping as a useful tool in food production, could probably be attributed to Bradfield(6, 7). His work has spread to Asia, Africa, the USA, and Latin America. The advantages and possibilities of multiple cropping systems (intercropping, relay cropping, succession cropping, etc.) are well known and have been practiced for generations by subsistence farmers. Extensive reviews and detailed research reports on modern multiple cropping studies are abundant in the literature (13, 26, 45, 52), and therefore will not be considered here.


Corn or Sorghum Following Vegetables

In order to sustain its cattle industry, Florida must import grain. The area planted to corn in Florida was 204,120 ha and the total produc1/
tion was 769,745 metric tons (12) in 1977. Gallaher- has estimated that an additional 162,000 and 24,300 ha could be double cropped with corn and sorghum respectively by 1985.

As early as 1959, Kretschmer and Hayslip (32) recognized the advantages of growing field corn following tomatoes and other highly



/ Gallaher, R. N. 1976. Potential for Multiple Cropping Growth. Mimeo
report 9/1/76. Agronomy Department. University of Florida. 3 p.


3









fertilized vegetables in south Florida. The authors pointed out that no P, K, or micronutrients need to be applied to the corn crop. In a later report Kretschmer, Hayslip, and Forsee (33) proposed that both corn and sorghum were good alternatives to follow winter vegetables and suggested that cattlemen who lease ranch land to tomato growers each year, can reap additional benefits by planting a grain or silage "catch" crop between fall tomatoes and summer pastures. In this way within 12 months the same field can produce tomatoes, field corn, and good quality pasture.

Soybean (Glycine max. L.) peanut (Arachis hypogaea L.), and southern pea (Vigna unguiculata (L.) Walp) were grown successfully as relay cropping after an initial crop of corn or sorghum in Florida (20). In this study it was concluded that irrigation would be indispensable for this particular cropping system. Akhanda et al. (2) also studied relay intercropping systems. Peanut, soybean, pigeonpea (Ca.anus cajan (L.) Druce), and sweepotato (Ipomoea batatas (L.) Lam) were interplanted in middles between rows of early, medium and late-maturity hybrid corn for two years. Interplanted crops did not affect corn grain yield in either year. Control of weeds and ease of harvest were more difficult than in sole planting, so the authors recommended double cropping where the growing season is long enough for successive cropping.

Hipp and Gerard (25) indicated that in the lower Rio Grande Valley of Texas and northeastern Mexico two or more cash crops may be grown on the same location per year. They worked successfully with grain sorghum and cotton planted immediately after cabbage.

In Georgia, Gallaher (14) explored possibilities of triple cropping systems in which sweet and field corn as well as grain sorghum were









interplanted in winter barley before it was mature. Third crops after corn and sorghum included, among others snapbean (Phaseolus vulgaris L.), and English pea (Pisum sativum L.). However, the most impressive system was one of barley followed by relay field corn and by a crop of soybean planted by the first week of July.


Soil and Leaf Analyses

The possibilities, advantages, and limitations of soil and plant analyses as tools for studying and predicting crop response are topics widely found in the literature. Different methods have been used in order to obtain meaningful correlations between soil and plant analyses values and crop responses. The most popular approach has been the critical level or the concentration of an element below which the crop yield or performance is decreased below optimum (62). Jones and Eck have criticized this method on the basis that it designates only the lower end of the analysis spectrum. Instead they have proposed the use of sufficiency ranges, the optimum element concentration range below which deficiency occurs and above which toxicity or unbalances occur (29, 30). This system of plant evaluation is in use in the University of Georgia Plant Analysis Laboratory.

Plant growth and yields are functions of many variables beyond the

single nutrient under consideration. Sanchez (52) quoting an earlier work by Fitts, points out that actual yields are functions of over a hundred variables, which can be grouped into soil, crop, climate, and management categories. The same author affirms that soil test correlations cannot predict yields or even absolute yield responses because of the many









variables involved. However, he considers that a major breakthrough in soil test correlations occurred with the development of the CateNelson method. This is a graphic method which consists of plotting relative yields (percents of maximum) as a function of soil test values under a plastic overlay sheet divided into quadrants. The quadrants separate critical levels and soil with high and low response to nutrients.

The "nutrient intensity and balance" is a soil testing procedure, developed by Geraldson (18), that measures the ionic equilibrium in the soil solution. The electrical conductivity of the saturation extract is used as an indicator of nutrient concentrations or intensity which can range from deficient to optimum to excessive for crop production. Specific cations or anions contained in the saturation extract are calculated as percent of the total salt concentratrion and used as an indicator of nutrient balance. From 1955 to 1963 recommendations to establish a more favorable nutrient intensity and balance were associated with a 50% increase in tomato yield in Florida (18).

Probably the latest approach to foliar analysis is the Diagnosis and Recommendation Integrated System (DRIS). According to Summer (57), the critical value and the sufficiency range methods are not able to deal adequately with the variation in nutrient concentration on a dry matter basis with age. The DRIS method, on the contrary, overcomes this difficulty because it is an holistic approach in which as many yield determining factors as are capable of quantitative or qualitative expression are considered simultaneously in making diagnosis. The yield-determining factors are characterized in terms of indices which are derived as comparable functions of yield.










Most authors agree, independently of the methods used, that plant

and soil analysis are definitely valuable tools and that their use should be extended. Engelstad and Parks (11) consider soil and tissue testing as being more important in the present age than ever before. The authors emphasize that these are the only ways in which soil fertility levels can be monitored and application practices adjusted, and finally state that the credibility of soil and plant testing must be maintained and protected.


Fertility of Corn and Sorghum


Fertility evaluations of corn and sorghum grown as monocrops have

received considerable attention from agronomists (27, 28). An example of critical values for corn and nutrient sufficiency ranges for both corn

(30) and sorghum (36), derived from many research studies, are presented in Table 1.

However, when double cropping is involved, and if the previous crop is a well fertilized vegetable crop, the situation could be drastically different. The buil-up of P and K in soils is a relevant topic in this time of energy shortage. Engelstad and Parks (11) suggest a reevaluation of fertilization programs to make certain they mesh with soil fertility levels and crop needs. It is estimated that the recovery of applied P by crops during the year is between 5 and 20% and for K the value is from 30 to 60%. This leaves substantial quantities of fertilizer P and K in the soil (significant leaching losses occur only in sandy soils of low cation exchange capacity). The same authors quoting a 1940 report by Terman and Wyman point out that an estimate of 20% N, 30% P, and 35% K applied remained in the soil after removal of a potato crop.



















J-SI


I I
I I



M I C O IO O ) In o I cm I o I I N H 0


En 4 I I N c 0






(o C (V t I I










-
I w C: r::I O


S u I I I I I I I I I I I I U4 I H 0e I if o ,- H S 1(d 0 N o o I0C ocI 0 NN O O I
u) 0 M I I


SI I
I I : I O- t I I
0 M 4 14
0 H I o I r e j I ) a .
0 o 1 0 I Co t I
0 p I 1 0 0 O 4 S H OO ) N0 U) LOmc I I I Im mN t*

0 v i o a L L0 c C IOO 0 HN )d o c I I
M O H I
o 0 I I OOL 0 N- I 00

U O to I I Hr( 0 W C) C C C C I 0 CH 4 H HI Lt -r ) C D I O O i) i* I* I if) iLO O O C) 4 4M 1 4I O N Ol C I HN c-: Cn 00 ) (l I I I I I I I I I I I 1) 1I'0 A f) rH O C -I O O C 0 C)

C: 1l C) H C )
$4~


0 0 I I

I I mU) O 4-4 I 00 p 0 0 I dI C:
Iu td 0.

> 0:3 I e a
H r:-co I I 0 0
> 1 N 0 4 N I4-I H 0 I * I Lf Lf Lf Lf Lf I ,fl(* H C WHIC)O C I HH H H U


Cd >Q C4 n)

U 4J Ca 0



4- 1 U l- H
*H H 0 00C/O






H 4 H aW4-











Engelstad and Parks (11) quoting a study by Cummings reported that North Carolina farmers in 1943 added to the soil by fertilization about 60% as much N, 430% as much P, and 158% as much K as was removed by the potato crop. In 1957 Terman (58) emphasized the increasing difficulty in finding sites sufficiently responsive to P to permit a meaningful comparison of P sources. Another possible cause of P and K accumulation is the habitual application of certain grades at the same rate over time, without regard for fertility levels. While some of this repeated application of certain ratios may reflect farmer reluctance to change, farmers simply may not have alternative choices in some states (11). Very recently McCollum

(38) reported significant increases in total and extractable soil-P reserves when high rates of P were applied to potatoes over many years. While fertilization practices for other crops grown in rotation with potato reflect both plant demand and soil-test P, many producers continue to fertilize potatoes with little regard to crop requirements nor to existing soil P levels. If neither potato nor crops grown in rotation with them require such high rates of directly applied P, a considerable saving in fertilizer costs could be realized (11).

Large initial applications of P to high-P-fixing soils had a marked residual effect on maize yields 7 to 9 years after applications (31). Even when P was added in the row, maize yields were 50% higher where high rates had been applied 9 years before. No further increase in maize yields, reports Kamprath (31), was obtained when available soil P (0.05 N HC1 + 0.025 N H 2SO4 extractant) was > 8 ppm. A field study conducted by Powell (47) in Iowa showed that corn yields responded largely to applied N, with applied P and K having smaller and less consistent effects. Maximum






I0


yields were obtained with the first or second increment of applied N, P, and K in all years. Higher fertilizer rates had little additional effect on yields the first 2 years but caused' some decrease the third year. Cope

(8) showed negative response of corn yield to high amounts of P applied during an ll-year period. Rates used were 22.4, 44.8, and 67.8 kg P per ha.

In a Malaysian Tropofluvent, Lim, and Shen (35) found that corn grain yield responded significantly to 100 kg/ha P and continued to provide enough P through the sixth corn crop. Grain yield, available P, and leaf P concentration relationships showed critical available soil test P at 25 ppm and P concentrations of the leaf at 0.27%.

The influence of the previous crop and N application on yield of sorghum was studied by Hipp and Gerard (25). There was a sharp increase in grain sorghum yield with 67 kg/ha of N if sorghum followed cabbage, but application of the same rate of N to grain sorghum grown on soil that had been fallow from August until March did not significantly influence grain sorghum yields. Increasing N rates to 134 kg/ha resulted in only a slight additional increase in yield. Apparently fall and winter temperatures are warm enough that N mineralization allows accumulation of NO3-N in the soil profile and may preclude a response from application of N.

Double cropping corn or sorghum planted after other cereals are also popular cropping systems in the United States. The resulting nutrient relationships are found in several reports. Murdock and Wells (40) investigated yields, nutrient removal, and nutrient concentrations when corn was planted after barley (Hordeum vulgare L.) and oat (Avena sativa L.). Corn grown after barley, harvested in soft dough averaged 25% more yield than






I1



that grown after oat, harvested at heading, Fertility rates above 280-89-232 kg/ha of N-P-K did not significantly increase the yield. The average nutrient removal at the foregoing rate of fertility was 241-54260 kg/ha of N-P-K. One fact in this study was that the small grain accounted for 47% of the total K removed. Nelson et al. (43) planted corn and grain sorghum with or without tillage following winter wheat (Triticum aestivum L.) or barley. Yields did not differ significantly for conventional tillage and no tillage plantings made on the same date. An application of 28 kg P and 168 kg K per ha each fall was sufficient to meet the needs of P and K for both crops. Nitrogen was supplied to either corn or sorghum at a rate of 224 kg/ha when the plants were 25 to 35 cm tall. In Georgia, Gallaher and Nelson (15) studied the soil fertility management of several double cropping systems. Wheat and barley were used as winter crops followed by soybean, corn, or grain sorghum. Results showed that effective fertilization should include lime, P, and K in the fall with incorporation to satisfy needs of both winter and summer crops. The authors also found that systems having small grain forage followed by the summer crops tended to reduce the soil pH, P, and K levels more than systems having small grain for grain. In general the double cropping systems were fertilized with less N and about equal or slightly more P and K than the sum of what would be recommended for the winter and summer crops if grown separately as monocrops. This last concept reflects an important aspect of a cropping system, the components are not additive but instead form a new unit with definable characteristics.






L2


Drainage and Irrigation Beds


It is estimated that 90% of the world's farming area receives too little rain during the growing season'. Of the other 10% some places get too much rain. Almost nowhere is rainfall ideal (55).

In the Hastings area, annual rain of nearly 1,270 mm has a pattern that is not sufficient for the potato and cabbage crops. The reason is that half of the year's rain falls in June, July, and August (55), while potato and cabbage are grown from December to Hay. Local farmers have traditionally used a system of bedding and water furrows for drainage and irrigation. Each water furrow is slightly deeper than the alley between row beds which are crosscut to allow surface water to move to the water furrow. Drop pipes at the ends of the water furrow convey run off water to boundary ditches (49). Under this system irrigation water is supplied during dry periods to the water furrows to maintain the water table at 12 to 25 cm below the alley height at the midpoint between water furrows (22). In 1973 corrugated plastic tile drains were installed on the ARC on a trial basis. The drain tiles were used both for irrigation and drainage. One end of the tile was raised to ground surface to facilitate irrigation and the other end discharged into an open ditch. Reports by Rogers, Hensel, and Campbell (49) and Hensel (23) showed the advantages of this system. Potato yield increased by 56% (12% of this increase was due to increase in number of rows, since water furrows were eliminated, the number of beds increased from 16 to 18), plants emerged about one week earlier over the drains, there was an improvement on water control, there were no water furrows to maintain, and potentially less water was used. A later report by Hensel (24) points out other important






13



aspects of the tile drainage system: 1) yield increases up to 50% can be achieved during wet seasons; 2) the tile systems removed internal soil water in 12 hours as compared to 2 1/2 days by a conventional system; 3) planting or harvesting operations could be performed satisfactorily soon after a rain on tiled land.

In a report by Bishop et al. (4) the authors reviewed several aspects that have been related to the shape of the potato soil bed, like incidence of greening of potato tubers, differences in tuber-set and yield, soil temperature, drainage and infiltration of water, equipment design for application of chemicals, and cultivation and harvesting of the crops. The authors developed a profilometer to measure changes occurring in the potato soil bed profile during growth of a potato crop. Changes in bed cross sectional area were found to be closely related to changes in soil bulk density and air permeability on the Hesperia sandy loam from California.

Allen and Musick (3) tested a wide bed-furrow system for irrigation of winter wheat and grain sorghum on a slowly permeable clay loam in the Southern High Plains (Texas). The system consisted of 152 cm spaced furrows separating relatively broad flat beds about 100 cm wide compared with conventional 100 cm bed furrows where wheel traffic occurs in irrigation furrows. Yields were not different. Water intake during irrigation of wide bed-furrows averaged 23% less during three spring irrigations, and 19% less during two seasonal irrigations of grain sorghum. In an earlier study, Musick and Dusek (41) reported a 15% yield increase when growing grain sorghum and winter wheat in alternating 203 cm field beds with adequate irrigation. The increased yields on strip-planting plots







14



was believed to be associated with increased light interception, although increased soil water availability may have been a factor also.

In Arkansas, growing cotton in narrow rows on permanent wide beds

is a very common procedure. However, it is understood from the beginning that a farmer could not be expected to adopt permanent wide beds for his cotton acreage unless the same cultural system could be used for his other crops. Parish and Mermond (46) reported successful crops of soybeans, grain sorghum, and corn planted in the wide beds. There was no loss of yield; indeed, yield was increased in some years.

Good results were also obtained by Nolte (44) in Ohio. Corn yield planted in beds was 4778, 6048, and 6411 kg/ha when the drainage system was by surface only, tile only, and surface + tile respectively.

The effect of mulches and bed configuration was studied by Adams

(1) in Texas during 2 years. Bed configuration had a significant effect on sorghum growth when used with mulches and caused a significant increase in grain sorghum during the first year but not during the second.


Cultivar Experiments


Cultivar experiments are one of the most popular and useful research tool available to agronomists. The Agricultural Experiment Stations in Florida do cultivar evaluations on a continuous basis for all major crops planted in the state. The Florida Field and Forage Crop Variety Report (64) is publ ished for reference use only, while Agronomy Facts

(65) sheets provide specific recommendations for use of cultivars. In the case of corn, the hybrids recommended have been evaluated in station trials for at least two years. In addition to yield, standability, ear







15



quality, husk cover, ear height, and insect resistance are also evaluated. Sorghum trials include yield performance, bird resistance, plant height, and number of days to bloom. Sorghum and field corn production guides (27, 28) are also published and include cultivar suggestions. Cultivar experiments are also conducted for specific purposes. Green (19) gave a detailed report on yield and digestibility of 41 grain-sorghum birdresistant and non-bird-resistant hybrids.

Comparative trials using both corn and sorghum varieties were reported by Dunavin (10) and Lutrick (37). Sometimes sorghum outyields corn and vice-versa depending on conditions and purposes of the studies.















MATERIALS AND METHODS


The area near Hastings, Florida (290 43' N 810 30' W) includes farm land in St. Johns, Flagler, and Putnam counties. Most of this land is about 3.0 m above sea level and from 16 to 32 km from the coast. The annual rainfall is nearly 1,250 mm and usually half of this amount falls during the summer months.

This area normally produce an estimated 9,300 ha of potato and

5,300 ha of cabbage. This full area is potentially suitable for growing corn and grain sorghum in double cropping systems. Potato is grown from January to May. Cabbage is grown over a much wider season; however, most of the cabbage crop is produced for harvest in March.

Three different types of experiments were conducted: fertility, bedding, and cultivar experiments as described below.


Fertility Experiments

Two corn and three sorghum fertility experiments were planted in 1977; one corn and one sorghum fertility experiment was planted in 1978. Location, planting and harvest dates, hybrid used, row spacing, number of replications, and type of drainage are given in Table 2 for each of the studies. In all locations experiments were planted in Rutlege fine sand (Sandy, Siliceous, Thermic family of the Typic Ilumaquepts) which had previously been either in cabbage (the corn experiments) or in potato (the sorghum experiments) production.





16








17










S -1 4-1 -4 4J -4 -1 r-4 41 -4 r-4 H H H H H H H H H H
*H *H *H *M H *H *M *


C, 41 44 a 4 14 ) 4 4-1





O n
CL a 03 03 03 -z < T OOI
0 a)






*H
0 o o o o o o 0 o
0-H 0 O 0 0 0 t 0 0 c o M U H- H- > > HO4 > >
U)

Co 00 I 4
C: 4 Ln pq pq 7) 00 (13 CO 03 Cl rt I--4 r- 4 >- cl p ca c o wQ) o
c ~ ca WFc zC~ O a' 0 I I Cf -H M

rCO u I a. Q *H)

C0 0 0 4 4 0


r-0 0 H 0 4- 0 ID U) H 0c 0 0
a' U) a) -4 -4 C14 44 -4T r -4 a -4 -4 f
a --)
-H 0 ) a a a


t o oa a a








oQ) ca4Cdic



9 H H H H









0
r- -q a) '.W '.a- cc COca O N- 1 4a 4 ,-4 C'4 4 4 *4 a 0





0 E-4
-4 Q)a4 1

-H 060 u ) u 0 u u u





0 0&0 O ra M \ ~
U, 4-4J -I '0 Cl C 0 CO Cl ,- C




a) aa N- '0 N- N- N a)4



*H *0*5H.







0 0 o a)44a 44 C ~C










4a 0 a) 4 H
C-) -S P~'d0 a)
















Ca 0 H a- 1-HiHO *H
0 1-4 p -4 4-1I 4 a) rA

















Q) O O4 O4 O4 O 0 S0 0 0 0 a 0 0 j
o











a) u u 44 uU 4 Q4 r( l (aa







*H *H) *H0 *H 00 -H
~- -4 -4 -X4~Ct, 44 -H a a a)*H a



a) Sr ~ 1-4Y

X 03 0 CI 0 )'0 )7




Hr rHl Cl( C' 4 03 '0 N-C '
h~~~ 'H -I C (






18




A 4 x 2 factorial in a randomized complete block design was used in all fertility studies, with 4 replications at the ARC and 5 replications in farmer's fields. Four N rates (0, 100, 200, and 300 kg/ha), 2 P rates (0, 60 kg/ha), and 2 K rates (0, 60 kg/ha) were used in all combinations. Plots (10 m x 5 m) had 6 rows in all cases but only the 4 middle ones were used to collect samples or to determine yield.

The land was listed and disk harrowed before the 1 m drainage beds

were built using a conventional "bedder." Planting was done with a double hopper tractor. Fertilizer was applied by hand on top of each row. Nitrogen was applied in two equal amounts, at planting and 4 weeks later, P and K were applied all at planting time.

Farmers performed normal cultural practices like bed formation,

planting, and cultivation; however, weed control and irrigation were not satisfactory during 1977 and affected crop yield potential. At the ARC all operations were better controlled and monitored by field personnel.

Insect pests were particularly serious in 1977; this made it necessary to replant experiments No. 3 and 5, and prompted the application of insecticides. A list of pesticides used during both years is presented in Table 3.

In all fertility studies soil samples were taken from each replication before planting and from each experimental plot before harvesting. Ten cores were collected from a depth of 0 to 18 cm, the samples were air dried, and passed through a 2 mm stainless steel sieve. Soil extraction was done by means of the double acid procedure or North Carolina extract

(51). Five grams of soil were weighed and extracted with 20 ml of












Table 3. Pesticides used and dates applied during 1977 and 1978

Experiment No. 1/
3 4 5 6 7 8 9 10 11 Pesticide 2/ 1977 1978

Paraquat (a) 7/5

Paraphos(b) 7/27

Methamidophos(c) 7/7 7/11 7/11 7/11

Methomyl (d) 7/28 7/21

Carbaryl (e) 9/22 9/21 9/22

Atrazine (f)+
propachlor(g) 6/20 6/19 6/22

Carbofuran (h) 7/27 7/7 7/5 3/8 6/20 6/20 6/20

Evik (i)+ 2, 4D(j) 5/25

1/ Experiments No.1 and 2 did not have pesticide application. 2/ Rates were used according to the label.
(a) 1, l'-Dimethyl-4, 4'-by pyridinium ion (post directed)
(b) 0, 0-Diethyl 0-p nitrophenyl phosphorothioate
(c) 0, S-Dimethyl phosphoramidothionate
(d) S-Methil-N-((methylcarbamoyl)oxy) thioacetimidate
(e) l-Naphthyl N-methylcarbamate
(f) 2-Chloro-4-ethylamino-6-isopropylamino-s-triazine (at planting)
(g) 2-Chloro-N-isopropylacetanilide (at planting)
(h) 2, 3-Dihydro-2,2-dimethyl-7-benzofuranyl-lethylcarbamate (at planting)
(i) 2-(ethylamino)-4-isopropyl amino-6-methylthio-s-triazine(post directed)
(j) 2,4-Dichlorophenoxyacetic acid. (post directed)







20



0.05 N HCI + 0.025 N H2SO4 for five minutes in an Eberbach mechanical reciprocating shaker (160 oscillations/minute). The extracts were filtered through Whatman No. 6 filter paper and stored in 25-ml vials under refrigeration until analyzed for P, K, Ca, Mg, Cu, Zn, Mn, and Fe. Phosphorus was determined colorimetrically using a Technicon Auto Analyzer. Potassium was determined by flame emission photometry and the rest of the elements were determined by atomic absorption spectrophotometry.

Soil pH was measured for each sample using a Corning glass electrode potentiometer and a 1:2 soil to water ratio. The 50 ml mixture was stirred, left standing for one half hour, and stirred again prior to reading (51).

Corn leaf samples were collected during the early silk stage, the

complete earleaf was taken from the lowest ear on 10 plants per plot. The same procedure was followed in the sorghum experiments with the difference being the type of leaf collected, in this case 10 to 15 leaves were taken per plot, usually corresponding to the third leaf from the top. Forage samples were taken at harvest from each plot during 1978. Two 8 m long rows of corn or sorghum were cut at the base and the total fresh weight recorded. A smaller sample, 4 or 5 plants, was also weighed in the field, then dried in forced-air forage dryers at 650 C for a minimum of 48 hours, and then weighed again in order to determine dry matter content in each plot.

Leaf samples were ground (pulverized) in a Cristy Norris Mill to less than 1 mm particle size, then mixed thoroughly after grinding and kept in airtight sample bags. Forage samples were chopped in a mulching machine, 'Mighty Mac' (Amerind MacKissic), and subsampled before they could be ground in the mill.










Nitrogen analyses were done following accepted procedures described by Gallaher (16). A 100 mg sample of the ground plant tissue was placed into a 75 mm pyrex test tube along with 3.4 g of prepared catalyst (90% anhydrous K2SO4 + 10% anhydrous CuS04), two or three Alundum boiling chips, and 10 ml of concentrated H2SO 4 The contents were mixed and a total of 2 ml of 30% H202 was added immediately in 1 ml increments. Small funnels were placed on top to recondense liquids into the test tube. Samples were digested at 3850 C in a 126 sample capacity aluminum block (17). After cooling, samples were stirred in an automatic mixer and the solution was then diluted to 75 ml with distilled water and analyzed with a Technicon Auto Analyzer.

Phosphorus, K, Ca, Mg, Cu, Zn, Mn, and Fe were analyzed by routine methods (63). One gram of plant sample was placed into a 50 ml pyrex beaker and ashed at 4800 C for a minimum of 6 hours. A small amount of distilled water and 2 ml of concentrated HC1 were added to the ash and this mixture was gently heated on a hotplate until dry. Following this, another 2 ml of concentrated HICI were added with about 15 ml of distilled water. This mixture was covered with a watchglass and digested for onehalf hour before being diluted to 100 ml and stored in a plastic vial. The stored digestate was approximately .1 N HC1. Phosphorus was determined colorimetrically, K by flame emission photometry, and Ca, Mg, Cu, Zn, Mn, and Fe by atomic absorption spectrophotometry.

The revised two-state in vitro organic matter digestion (IVOMD)

procedure was done on all forage samples (39). The technique involves a 48 hour fermentation by rumen microorganisms followed by a HCl-pepsin digestion. Separate aliquots were analyzed for organic matter content in the sample and for residual organic matter after the fermentation-digestion.






22


The amount of organic matter disappearing was considered to have been 'digested."

The statistical analysis included an analysis of variance for all responses, analysis at different levels of one factor when significance was found, Duncan's multiple range tests to compare means, and correlations between nutrient concentration and content in the soil and in the plant. The statistical model was: YijkZ = Py+ pt + ai + Bj + Tk + (ac)ij + (y)jk + (ca)ik + (ada)ijk + cijkZ where Yijkk = response

P = th block effect
ai = ith nitrogen effect
Sj = jth phosphorus effect
k kth potassium effect
( (~a)ik = ik nitrogen-potassium interaction effect
(at3)ijk =ijk nitrogen-phosphorus-potassium interaction effect
Eijkk = error term

Bedding Experiments

Initial observations indicated that the use of the 1.0 m previous

potato beds caused an apparent waste of space and yield reduction for the sorghum crops. To test this hypothesis two bedding experiments, one in 1977 and one in 1978, were designed and conducted at the ARC. The 1.0 m beds were modified and 1.5 m and 2.0 m beds were built and a total of 16 treatments were imposed on them (Table 4).

Land was prepared in strips to facilitate the use of machinery.

Each one of the four replications had a strip of land that included the

3 bed widths and thus the 16 treatments. Building the 2.0 m beds was relatively easy and it was accomplished by removing every other 1.0 m
















Table 4. Treatments imposed on the bedding experiments, 1977 and 1978.


Treatment No. Bed width (m) Arrangement

1 1.0 One row (control)

2 1.0 Double row narrow (15 cm)

3 1.0 Double row wide (25 cm)

4 1.0 Broadcast

5 1.0 Single row in flattened bed

6 1.0 Double row in flattened bed(25 cm)

7 1.0 Broadcast in flattened bed

8 1.5 Three rows

9 1.5 Four rows

10 1.5 Five rows 11 1.5 Broadcast

12 2.0 Three rows

13 2.0 Four rows

14 2.0 Five rows 15 2.0 Six rows 16 2.0 Broadcast






24


bedder. The 1.5 m beds required a narrower tractor with a wheel spacing. In order to plant 2 rows in the normal 1.0 m beds they had to be knocked down slightly on the top. Sorghum planters were offset 7.5 and 12.5 cm from the center of each bed and planted twice in order to achieve the 2 narrow and wide rows.

Soil samples were taken from each replication. They were prepared

and analyzed in the same way as the samples of the soil fertility experiments. A total of 222 kg NH4NO3/ha was applied to all treatments 4 weeks after planting.

Specific information on planting and harvest dates, cultivar, drainage, herbicides, and insecticides used is presented in Tables 2 and 3. During 1977 handweeding was done on the 1.5 and 2.0 m beds; in 1978 weed control was satisfactorily accomplished by the use of herbicides (Table 3).

Whole plant samples were collected at harvest time and dry matter,

IVOMD and nutrient analysis was done as previously described for the fertility experiments. Grain yield, plant height and plant population was also recorded and included in the statistical analysis. Due to a severe sorghum "midge" (Cantarinia sorghicola (Coquillet)) damage, an insect that affects grain formation, grain yield in 1977 was estimated by running a correlation between grainless heads weight and heads with grain from a healthy field of the same cultivar.

The experiment was a nested split-split-plot arrangement of treatments in a randomized complete block design with 4 blocks. Arrangements within beds were nested and correspond to the first split; years make the second split. The statistical model was: Yijkt = py + pk + oci + cai + Bj (oi) + Ebj (i) + 3k +c-ik + B jk(i) + Eck(m) where Yijkl = response





25



m = 1,... ji = 16 ji = 7, j2 = 4, J3 = 5

th
ai = i bed effect
Bj(i) = jth arrangement within ith bed effect
Dk = kth year effect
cEai = (pa) Ri
cbZj(i) = (pP) j(Wi) Eck(m) = p3Rk((a)m)

Cultivar Experiments

Considering the potential of the area not only as a grain but also as a forage producer, two cultivar experiments, one in 1977 and one in 1978, were conducted at the ARC. A list of the cultivars tested for both grain and forage, is shown in Table 5.

Cultivars were planted using a composite split-plot in a randomized complete block design with 4 replications, the split corresponds to years. Planting was done on the usual 1.0 m beds and treatments were fertilized with a total of 222 kg NH14NO3/ha 4 weeks after planting. Planting and harvest dates as well as drainage, herbicides, and insecticides used are shown in Tables 2 and 3. Soil samples were taken from each replication before planting and whole plant samples were collected at harvest time.

Crain yield (when applicable), and dry matter yield, were recorded for most varieties. A combined (2 year) statistical analysis as well as separate analysis per year was conducted using the following models:

Yijk = + p. + cti + Eaai + Bj + aij + Ebjk(i); 2 years
Yi = 1 +PZ1 + li+ Eli ; 1 year where YijZ and Yi = responses
cait = apit
obji(i) = 6pjZ(ai)
ai = ith variety effect, i=1,...,5
Bj = jth year effect, j = 1, 2






26





Table 5. Cultivars tested at Hastings during 1977 and 1978.

Brand and hybrid Brand and hybrid Number 1977 1978

1 Dekalb FS-25A Dekalb FS-25A

2 Northrup King NK-121 Northrup King NK-121

3 Dekalb C-42Y Dekalb C-42Y 4 Dekalb BR-54 Dekalb BR-54

5 Dekalb D-60 Dekalb D-60 6 Dekalb FS-24 Dekalb FS-24

7 Dekalb A-26 Dekalb A-26

8 Dekalb E-59 Grower ML-135















RESULTS AND DISCUSSION


Precipitation and temperature data for the area during 1977 and

1978 are shown in Table 6, There was a marked difference in precipitation, 1977 being considered a very dry year (58).


Fertility Experiments in 1977


Corn

Experiments No. 1 and No. 2 had low yields (Tables 11 and 12). This was the result of poor weed control and water management by farmer cooperators. Soil analysis data before planting showed low pH values, and high P and Ca concentrations which provided an insight on the natural fertility of these soils and the previous vegetable fertilizer practices (Tables 7, 8).

Significance of variables according to the F test and nutrient concentrations in the soil and leaves are presented in Tables 9 to 14. Increasing rates of N caused a drop in pH values. This was likely due to the release of hydrogen ions (H+) when ammoniacal and most organic N fertilizers were converted to nitrates (65). Higher rates of N and P applied to the soil lowered the concentration of Ca in experiment No. 1 and increased that of Mn (Table 15). A K defficiency was observed in the leaves reflecting the low soil K test. The addition of K fertilizer increased significantly soil test K, but not K concentration in the leaves. Higher N rates also increased N and Cu concentration and decreased Mg concentration in the leaves. In experiment No. 2 the higher rate of K (60




: 7








28




cc cc

cI
00 00I

o o oo
r-4





U
l Lf r




O ON
-r

-HT I' cc C) ~
0 CO l q




0 *0 I'D 0" r Z *c o a
o
9 H O rHC


LO


a, i 1 ; C1 4 Q) r-



* O O 00



U)

(n cc m w





(r t r- C r- 01 C l
C- r- *,
- r- in 0







cc C-4 0 l (N 0cc -4
r-4

0 Q C0 0 0 co 0* C
CO N 4 E 01 N CO c CI *H


N N)







0 m 0 %0 "1 00 (a
C o N.~~h c- u




0 O cc cc c




.H I*00



** U




<(N I- raI u a 0 o
fa








ca m 01 4
(N N- (N -4 0 Ch






-M N LO CO Cr cc 0u u7 0' (N 4J





c (Nv a 4


0
Na P CO C N N. n cc0
1 (N -4 01. 0rU CUU






C) rOH

0 0 C -4





) C) A
0O 00
Uo 44 U


*.0 0 C E w
Scalc
a4 P-, r-' I ai ccj w 0 w N J H : HV H rl o -4






29








Table 7. Soil analysis before planting. Corn fertility
experiment No.1, 1977

Rep pH P K Ca Mg Cu Zn Mn Fe
----------------------- ppm -------------------------I 5.3 416 76 1254 72 4.9 12.3 6.1 83 II 5.2 460 103 1406 92 5.9 9.3 6.9 88 III 5.2 484 159 2000 164 6.5 10.5 8.6 100 IV 5.3 498 113 1432 76 5.6 10.0 6.4 85 V 5.4 488 113 1334 100 5.3 9.6 6.2 94


X 469 113 1485 101 5.6 10.3 6.8 90












Table 8. Soil analysis before planting. Corn fertility
experiment No.2, 1977

Rep pH P K Ca Mg Cu Zn Mn Fe
----------------------- ppm ----------------------------I 4.7 297 71 858 35 1.6 5.8 5.6 50 II 5.1 194 70 490 27 0.8 3.7 4.7 37 III 5.0 570 157 1678 148 2.4 8.8 9.4 69 IV 5.0 418 88 1176 73 2.0 7.3 6.7 60 V 5.4 238 124 642 40 1.0 4.2 4.9 58

X 343 102 969 65 1.6 6.0 6.3 55









30









C'oo

4














r-C

r-( "

0





4. m
0 C O d0



x I

0 cH U o 0 C ,O 4-i



c 0 N
O O






O o4 0 (U












i
*) 0 U

















0)
. H 0 0
O0






a
41 0,















Q)
CO4






















- 3 a CO~~ 0, 0) z H ~Z~~ C/) WHH-4Z










31










rH

0



W, 0
FLI 0
00
*CH





0
0 0 h0

N 0 C



(NJ(

* N
LO
oO
zO







S4
O0O



U 0
N




44
a) P: 0 0 u
0 H r Hr




4 0 0% Co t UI 0 -t t o aT S0 0

o a)


4 0 N0 00 m CD a D CD



) cU 0 00 a) C 0 0 00



44 C) 0 C r C C





'H 0 01) C1
0 0 F*H > b 4






4O 0 0
- 0 0 0 0




co Q.
0 0 OOO


. *H




44
*H OU)00 0 H) c.

OO0 '-O



0) 0-. *I' 00








CCD
*00

a O U)
4- 44I 0
( U) 0 ~o a
O 44N0





H uI CO '-O




O 0








44i 0. 0. :!: 0O
0






C/)
9 0



X X


a u
r( kX X X X X X CO 0 a
H~~~~" to HH HH~ 0~HH H









32
















cO o 0. N ...t .. . 0 i 0 'O co

w r4c o mso oo -4 N Hf -)r r- o -, T f m n c Z>

O O 01 00 01 CO CO CO 01 0O 01 0- -1 00 0- N, 0 O 4-4


a) a










0

0c
a) 0




O m m' o -* * *. . oo 0 .0 0 ( Co o o O- 0 01 0 0 0 a C 0 C6



00
*C 0




a O C 0- 0 C lo 00 c 1 0 o 0o o r- c o C
U





0 0












,-O 01 01 to < < u e-4 m co o "I 4H HO
41 V

4 4-4 '. C ) IT I' 0 or0 (N ifn r ( N -' ol Z



0 0

o-N
** O








r: 0 ( o co 0 mO D NO- 'N : .00 cus e m o te co ) (d U O rO o (N o ( c o o 44 U U) \D N- Ln -Zr U) tt o N- Lw U( '. U) D U tC Z aO 0





















c o uo) O O -- r- -T -I m- -Zom Il r o .0 Z 0 a (U











tz Cf) '.D C) C) 1-1 I) '.0 1) i) m 0t 0 (U(







r H- 4 -i CI Z N N Z t -r C) 0 '0 -r 00
'-H '.0 N- o n ~ C-- '0 0. c~-) '. c') i) C (








,- a) 0 0 0 HN ?









33















o o o 0 -,1 o o r -C t -r o -LT w L o
4J p, 1LA -r Ho _; r Cr o o 0 0 so C L r Cr 0o















cO
0 0
o










0 -" 0 ry oo or O0 oo cc -o 0 o 0 00 to 00 00
o
0 0 C ) CO Cr -t C CO CO -i C4 0 4 0 C O S- -T r IT -I '-1 i) LI Tr- -T -Z CO O r*H 0
0




F.1 -o Om- -. 0 a- 0 cc -- 0 -0r- I' 0o C C




S ~ 0 I if) L Lr L L L 0 L L 0 0 T L )




1 0
4
Q

r. U H 0r L1) ID H H I) C- -S -tr l i) L) V) m N t r) 0 a r-- 0 c a O 0 Cm C O' 00 00 n 0 c c a 4cI 00
o >

l 00 r-O r- ) H \ 0 L 0 CO r- r- O- 0 0 oC O :d V) i) L H t C r- C- r-f L- N a 0 a' LI) c wI




ra f) O C-- 1 O0 -M c O- Cl T o Cl Ln Cl
P C H i)n T C m I r- -1 O C' C f )
:C
0

SCD o H o w ow r- o- orP:1 a)




U c M I IH Cl H HH Cl H 0


Z C4 H M H 0 ~d 0
Cl JJ


0 1-i(
H HZ 00~0~~ ~ ~ H H C l lC C)C' C) H









34















a) I C0 Cl 'H cn C') - Zr C
o O Co4 4 m o o 00 oo -t






C4 0 Cl4 CO Cl _q CA -" co 'A '. Cl Cl -! -4
4 I O O O N 0 Cl 'H a CN -Zr < a Cl Nl 00 CN H- Cl l l H l Cl Cl l Cn l l r- E

i- l
4-4 1 O O ". O -." O Co Cl O C l Cl O '0 O 'Hm c) -Zr -Zt -Zr n Z -Zr -Z Ln tn In Ul) 00
0) )
Z '




C



m O Im m m C1 h 'h ('1 m C--l 'H m ') Cl Cl 00 0 -1 oD c o D o o o o4)-iD 0)






4.J
- 0
X O
a
4- 0 Il a' C n a' N a zr T m '. C l Z N 0




u 0

S- 0) 1 O 4 O O O O U o 0 N 00000 0 000 0 0 00 O0



























U I inm o O, 00 m cO a o Oo OD O O- O O I O O
, 0 I



u I- 4
0 U I'H 0000000000 0 'HO








0 I I *H I . . . .













> 0 10O








H ICD 0- C' C ') a' 0 -q 0 M M M-M o G***-* 0 IC
U I


-Zr a'CoC a O G O 0 H a H 1100









35















a) 1i0 0 0 N ) O N O 0 -" -T 0 I r- a r-. a a' C -i al O O O O O





m 00 O ,-- -01 r-- N O OO0, O I 00- C OT0 0 T '



r .*H- o V) C n D r

0 I
ZM 5

- t I I 10 N < N NWO 0 -0 0 O -0 4 0




Z 1 I
0 I
0 H 0 0 00 ID -' 0 'T w O O


4 1






S0 0 0 0 0 0 0 0 O < c
> I




m C) 1r- C.t0 0 0 0O 0 0 0 0D 0 0 0 0 ) 0l (a
i 00 0 00 D O D 00000a





p 0 C o o C o o o o o N N o 4 No O C

0 I

00 c I u.o 00 C r- C o cc 1 4





wId rd o d m m m 0 m m d -T C) -:T o 0 S CU ICac















0 I I 0 p 0 I a) 0 I ca
1 i c 0 -40 c4 '--t 1 0 4 r4 Cl '0 0 H Z 10 e Cl C Cl Cl Cl C 0 o









0
(D l d C") Cl CD 1 -4 '0(0 C- -q CD 0 -q Cl Cl

















E- 0 0 D CD o o-4 -4 r- Cm-o o Mo o -.r C> 0) 4CO r






36








Table 15. Effect of N and K on concentration of Ca and Mn in the
soil at 2 levels of P. Corn experiment No.1, 1977.

Ca Mn N P = 0 P = 60 P = 0 P = 60 kg/ha ------ kg/ha -------- ------ kg/ha ----------------------------- ppm ---------------------0 1691 a 1623 a 7.25 ab 6.54 b 100 1539 b 1633 a 6.78 b 7.77 a 200 1553 ab 1621 a 7.42 ab 7.57 a 300 1573 ab 1427 b 7.70 a 7.24 ab

K

0 1611 a 1580 a 7.42 a 7.44 a 60 1568 a 1572 a 7.15 a 7.11 a


Means within each column for N or K treatments followed by different letters are significantly different according to Duncan's multiple range test.





37



(60 kg/ha) increased the K concentration in the leaves at 0 level of N but not at the 100, 200 or 300 kg/ha levels (Table 16). However, K concentration in the soil decreased when going from 0 to 300 kg N/ha. Higher N rates increased N, P, Cu, Mn and Fe concentration in the leaves, however an opposite effect was observed for Mg concentration (Table 17). The 60 Kg/ K/ha rate caused a decrease in Mg concentration in the leaves accentuating the Mg deficiency observed in this experiment. Possibly most of these changes could be attributed to changes in balance of nutrients, since it has been shown that plants under uniform environmental conditions tend to take in a constant number of cations and anions (62).

Correlation coefficients for soil test and leaf nutrient concentrations were not consistent for the corn experiments in 1977. In experiment No. 1 (Table 18) Mg and Mn in the soil were positively correlated with Mg and Mn in the leaves, the R values were 0.32 and 0.37 respectively. Manganese in the soil was also positively correlated to the concentration of Ca in the leaves. However, the R value of 0.23 was also very low. In experiment No. 2 Mg in the leaves could be a good predictor of P, Ca, Mg, Cu, Zn, Mn, and Fe in the soil, positive correlations and R values ranging from

0.48 to 0.68 are presented in Table 19. Some of these results differ from those of Dingus and Keefer (9) who found that Mg, Mn, and Cu accumulation in plants was reduced by the presence of Zn in the soil. Phosphorus in the leaves was also positively correlated with Cu, Zn, and Mn in the soil (Table 19). There is disagreement again with several authors (50, 53, 54, 56) who report Zn deficiencies being accentuated by P. Sorghum

Sorghum experiments No. 3 and No. 4 were also located on Farmers fields and were planted on tile and ditch (subfurrow) drained land,







38












oi co do Co Cd .. M I0) I 0. Mo 0 I -I *H
Ir-I 0 ci O\ I I CO r0 0 4 4II I 4 -z c I I 1-4 4 0 I I I
ZI oD 0 o I I E
0 I Z I I O I
*m I I I I I 0.c .C Cd 0 $4 0 1 Cd o D r-C d
4-I o' IO 0 S r I 0 0 I I r r 4


0 Cd I t I 10 4 ) I I O I ,* 0) I I C L) I I I o o o 0 I 1 0 0 I I 0
0 0 1 Ho 0 11 0 o.0 U I co co t O- N
01 604 Cd Cd In 0 ca -c I 1 0 4-1 o

0o I r O O Or-4-M o Od

0o I o O a d 0 -4 oci o -4, To
I c r cI r-4 I r- r-4 r-) 0 .) 0r > 0
I 0 1C * 0




I 0 0 d 0 I I IO 0 0 0
I I
0) 1 0)- C 4
I) C D d 4mo P 1 0 10000 4 0 1 0)0 r to I I (a)
II i m 0 ) 44 o I I4 rn- I * H4j 4-J I I ,ir-o Io o 00 'w Mto i I I' 0 .0 0)5 I 14 C d
0r I L4 iCO 0 -1 I C-4 Ig4 0-Tm 4J mNa Oo 0ca *H I I * 0 r0 m I U0 toeW I I 00( wz I 0 0 0 N *H u I IrA 1- II I N N N4 CI 400 I I a)I 0p I Ir 44 z IC N C Cl 0 I I 4)ca Cd 0f 44 I 60 toC) I I to y4
*H I H. 0 I I (N M r- -4 -H 0I q Cd I Z t i LI-a h a 4I I I 4J0) 01 co D I IN N N N 0 Cd0. 01 I M co Cd t4 94

\ Li O N N- Cd "Cd cd II I 0 i M y |l ) o
1 ZI I N NN C 0) I o C4 Cd 0) 4 0O I o0 0) I I
SI 00 4- I I *S4- I to I c ( 4.
to O )I d d d ,g 0) I 4 '00 U) 04) Ir) 1.0 Sr) -4 I0 1 N 0 0 00 I 0. 0 0 r tCd II ON CN r- r- 4A cd Cd Q) k0 0) I ** 0)0 r-4 0)
-4 Z IC- C-N N C-4 -4 Z I *- 1 0 0 O .0 4Q
4- O 10 O I 140 I *H ) 4-4Cd M I 00 r-l r- r ..4


O00 Cdd OE I
0 1 0 0 I ,D 0V O0C 144C Ia CO 0)C L 0 I0 u II am rH I 0- 4 N




)C C r- v 00 4) CO 0O ) 0Cd U 44 3 CW

4)'- O O c ,0 0 Cd0 ~ H a, oo r- 0 Cd () '0 O W0 dd 0 000 0 cd 4A 4-AH E r- r-INm 4-







39











f- -C ?0 OP N 0 e C Vr 0* 0. 0* 0. -. -e 0. -, 0 C0 *C e .0



z C o m7 Co we a o
DE~ ON Ne Op, 2- c





0 0 0 0 0~
ON 'N CO L0' O NN !o oe -* 0. N*~ -4 C* -e No 0.
*0 *D *0 *D0 *0 so a0


L4 0 0 C 0 o 0 0

0 L0 -0 '0 >* 2; C' < 0' Ng
04 0 0* 0. 0 e O* e O*.
o.0 *0 '0 so 40 *C *D a 0 C 0 0

0




41





r- C0 90 *~0 '\ 0 0 ~ 0 0- On NC CO CL: C, C
C -, C' *. 0o --4 So 0O
*0 *C .0 .C 4c .0 .
0 0 0 0 C



** *





.- -q e 0. D *0e *. -. 0.

S 0 0 0 0 0
I I


L'. N -L NW -S 25 v- 0o 'S. OO W A 9 yg 4
*0 4O *0 D .0 *0




0 0 a 0 0. 0 a o


o o
O* O* '* we 0, ,?









0 0 o 0 0. 0 0 0
ri~ x o C 3









2:
EX 4 rY e 00 02 L -=
3 3 o3 '? 0 L M* 3r 0. 0. -* -. C\. 0.



H ~ 0 t IO C wI
Hu
.0 ''
a)~~~~~~ -l ~ C~t O 0 h Ij~CO ~







40













L C ,- 0 '~'. z CSL,
Co 0 Co C C C C C



0 ~ 3 C *O *3 *Z 0L



c 4 *) 0 0




























4



C C, o C- cL^ C Z O N OL CO C, C< .
0 .


















I I
u -c c 00 O Le d t N ,N e -a -s o e K *


II



C$ O' 0$' O 0 $ 0. -OC *0 *0 *0 *C *O *O so
L 0 C C.
L0L IN O N3 L4C1





.0 C 0 .3 C .0 r3 0 3 0 0 N 0 0













-l ) O c O O ,
m~ C)=C~
ri O ) '-I






41



respectively. Management problems such as weed and water control plus a heavy infestation of sorghum midge caused grain yields to be low (Tables 20 and 26). In experiment No. 3, N was an important factor responsible for differences in the concentration of N, Ca, Mg, Zn, and Mn in the leaves as well as for differences in dry matter yield. Other significant effects and interactions are presented in Table 21.

Further analysis showed that when no K was added to the soil the different levels of N or P caused no differences in grain yield; however, when 60 kg/ K/ha was included in the fertilizer program, the addition of P caused a significant yield decrease (Table 22). This finding has been reported in the literature before (59) and possibly could be attributed to salinity problems. The effect of N levels on the concentrations of N, Ca, Mg, Zn, Mn in the leaves and dry matter yield is presented in Table 23. In all cases higher levels of N increased the concentration of the element and the dry matter yield. Terman and Noggle (61) found similar results when working with corn, in this case N caused an increase of P, Ca, and Mg concentrations in the leaves and a decrease in K concentration. The authors point out that these opposite trends indicate the reciprocal relationship between concentrations of K and Ca + Mg in plants. Differences caused by levels of P and K on Ca and Mg concentrations are shown in Table 24. Additions of P increased Ca concentrations and addition of K decreased Mg concentration. This latter relationship has been discussed before by Terman, Allen, and Bradford (59) who found marked reciprocal relationships between K-Mg, K-N, K-P, and K-Ca, and attributed them to ion antagonism. The K-Mg effect, the authors report, was most pronounced at higher K rates, no additional yield response occurred and resulted in







42











I N 0 -00 0 C) w D 0 O -: w CN S I r- -. O CO O0 (- aO 0 W 0 0 O O 0





:I O 1c c0 '. O -- a- -T 0 G l r- O -j 0 a 0 r- cl Cl N c C Cl m m Cl m

1 0H
oI

V)


u-) r- r- -4 oD I- 0O o 7 % 0 ".D 0 -Z


0 I
1el '0 0 0 00 CO 0 O0 o C o -- 0 O.D '.0 1.0 .0D O 4
o I




U
O 4


O. I
O )




o I- IV) n c cn w ) 0 w r- r- ma ll ra' -i t Cl r










I & 0 N N N N N c N N i m 0 N 2 0 S100 0 0 0 00 0 0 0 0 0 0 0 0 0





I IC C CD Cl C C C Cl Cl Cl C; Cl Cl C; Cl Cl
0 I
Irl 0 l 4 a 0 C


M ( Io 00) C) Co r- (T C_ Cl 0f 0 0 -- 0 00
UIO 0 0 0 0 0 0 0 0 0 0 00 0( 0 0 O I -O










0 >
S-4 I ) 0 O












r4 P ( N M Ln W (O -T 0 wO m" r r- O) 00 '- )) SZ I '.D0 O Cf M C 0 0 O 4 m0 a' CO O U 4 I I .-. 0 .- 4 -I .-- C C 0


S00 D
1 C 0 0 -4 a' C 1 CO O -1 O 0 -I \ P \@. S H C a N O ,-Z4 O -0 a -Z O CO a 'M M ) 0



*H Q -4 i '0 0 f If) if H 0 Cl If C N- 0 0o 011100 1



E 4 -01 C.)D 0-40O H -40 O4 "0o oC -M s >









43








e-I
90



0
C) ca

o








o "








O 2 0 c COO







:; cc UU O
0 0 CO










ca D O 1 N M o o1



4O Ci 0 > O -0v S(1 0 4- 0 a



Z 4 CD



Eco











MAA
0) 0












0)
0 0 04







H t o E
*H 0 U u o E o0 0 -t ,- 4- -I c 121 0 C/) '-Hr




(d pX .07
0 H Cl






44











Table 22. Effect of K levels on grain yield at different levels of N and P. Sorghum experiment No.3, 1977



N K = 0 kg/ha K = 60 kg/ha

kg/ha -------------kg/ha--------------O 319.1 a 301.2 a 100 286.5 a 273.5 a 200 336.0 a 360.4 a
300 346.2 a 346.2 a
P
0 313.0 a 357.7 a 60 330.8 a 282.9 b
Means within each column for N or P treatments
followed by different letters are significantly
different according to Duncan's multiple range
test.





Table 23. Effect of N levels on the concentration of nutrients in the
leaves and in dry matter yield. Sorghum experiment No.3, 1977



N N Ca Mg Zn Mn Dry matter kg/ha ----------------% ----------- -------ppm------- kg/ha
0 1.61 c 0.26 b 0.21 c 37.8 b 20.6 c 3867 b 100 1.82 b 0.28 b 0.25 b 42.3 b 25.1 b 4102 b 200 1.95 b 0.28 b 0.25 b 55.5 a 28.5 b 4789 a 300 2.12 a 0.32 a 0.29 a 54.2 a 30.4 a 4890 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.






45












Table 24. Effect of P and K levels on the
concentration of Ca and Mg.
Sorghum experiment No.3, 1977



P Ca K Mg

kg/ha % kg/ha %
0 0.27 b 0 0.26 a 60 0.30 a 60 0.24 b
Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.






46



decreased Ca, Mg, or P uptake. Soil test before planting (Table 25) may also help to explain some of the above mentioned relationships.

Experiment No. 4 grain yield, pH, soil test, and leaf nutrient concentrations are presented in Tables 26 and 27. Statistical results are shown in Table 28; N, and P to a lesser extent caused significant changes in several elements. Further analysis indicates that P increased Mg concentration at the higher level of N (Table 29), and that the addition of K fertilizer decreased Ca concentration in the leaves when no P was added (Table 31).

In the soil only Zn and Mn were significantly affected by levels of N. The 200 kg N/ha rate increased the concentrations of Zn and Mn in the soil. However, the lower and the higher levels produced the opposite effect (Table 30). A similar relationship was reported by Soltanpour (54) who found that Zn increased protein and nitrate N as a percentage of total N when applied together with N.

The correlation coefficients for soil test versus leaf nutrient concentrations (Table 32) differ from the previous corn experiments. In this case Ca in the leaves was closely correlated to the concentration of P, Ca, Mg, Cu, Zn, and Mn in the soil. Magnesium in the leaves was negatively correlated with K, Ca, Mg, and Zn in the soil. Copper and Zn were also negatively correlated. This last antagonistic effect has been reported before (34).

Sorghum experiment No. 5 had good overall management. However, a severe infestation by sorghum "midge" precluded getting higher grain yields. Total dry matter showed that marked differences occurred among the N levels. Yields, pH, soil test, and nutrient concentrations in the






47









Table 25. Soil analysis before planting. Sorghum experiment
No.3 (tile drained), 1977


Rep pH P K Ca Mg Cu Zn Mn Fe

------------------- ppm---------------------------I 5.5 100 153 818 116 0.36 2.6 2.3 69 II 5.3 142 149 820 100 0.28 2.6 2.6 54 III 5.3 124 156 740 92 0.20 2.7 2.2 56 IV 5.5 97 149 598 84 0.20 2.1 1.9 54 V 5.2 101 186 740 116 0.20 2.7 2.7 66

X 113 159 743 102 0.25 2.5 2.3 60








48










N






z aa C ) O 0 W ,T ) oZ C ." c o




0 000o


S ~ O
a) N * '...o ". L. -.

N o 00 N N Co CO' N Cob / Co N (N Co ( 0 00 0 Co It 00 C' C 000 T 0 0 0 0 C r 1- 00 LO -7 0 0 C0 H N CO 0 00 \.D O







n 0
U) )
* a
'( aN Co -i N- Co r- c' L) r- r- mI Co m' o 'H I








O 0H









4 O
-H
S 41 .0 L) m 0 C0 V1 00 m Co C C' 0 'H 'o H co a4 '0 o (N -4 H H o o' o o C0


.4 0 ci m -..m "0 t m 00 -, U) m C 0 D m 0
0



4 4n 0 z en Co ) t -- -4 ) 0 0 r- (N Co z 0 CU a\ -q k. -4 L a' C o 0r Ci ( ( a m' C aD (m t m





o 1-4
M (D 0






)O 'H 'HoC H 'H 'H -1 C a






Ir( OHc i di CU SI ( N CI) -A -1 N 1 1 -( A( 'H H -4 -N 'HA D













SC' C C' 'H 'H (N N (N (N C'4 ")m n m cn -









49















Q ICN 030 'D N 0 : m IN Cl O 1 IN C. N OC 0 I r-I' r- O0 00 r- 0 0 0O0 0" h- O% O0 o, C'

Ir










- 0 -,1 L0 ) 'C 0 o- C. .4 "Dr ..T -T -.7
0 N I\ m ) 0 C o 'H Ill -z '0 In -O ) .1r -Z O I) 'C z I


O -'T 01 0D 3 'C -0 ( 3 -T 4 0 ( 03 'C 0 S O u I -r 'C s r Ir- m 'H (3 ( -q m" 0o O IH N H H N 'H N N N H 'H 'H N N 'H '


x 0
O I z


o I



S 1 r L r ooo o o o O L oo

I

S O((I ( 0 0 ( 0 3(30 3 ( (3 (3 (- "CO 'H 4-J I 0





U I)
1 I 0 Z I 4









o--
.0 1 I o O










-C) 00 OI C 0 C) (3 Cl (3 0 r- 00 m r 0 1 'C 0 -. D m I 0 0 03 -. 0. .4 0 'C0
O I
I O 11)









0 OI 0 0 0 0 -4 0 0 0 o 0r 0 o ( 4I- V 4J I C A ) P4 D 4 0 ) -4 -1 C) r4 C) ( 1 4 O I MM4CO



OIN N I1 H N N N N N N N N N N N N m W


C) I11 II >


FO H c C ClCO Cl Cl ClO Cl C Cl C Cl C') mO C 0 0 'H ( 'H (3 'H C) 'H C 'H H





H H Z (3 (3 (3 (3 'H 'H 'H 'H Cl C C Cl C') C) CI C' H









50












trq



C O


O D0
















o4 r-. oo 0
z

0 C0
0

-C O O





S co a a





SC O 4 0 N 0 0 (f O 0C

0 0 U O





J0 0







*o 0 0 *H 4) O0 00 c 0 0 I 0




0






0 Q



















00
CO 8 8













&, & E E88 B M






51





















Table 29. Significance of percent Ca and Mg in the leaves at 4 levels
of N as determined by the F test. Sorghum fertility experiment No.4, 1977



N = 0 kg/ha N = 100 kg/ha N = 200 kg/ha N = 300 kg/ha Source D.F Ca Mg Ca Mg Ca Mg Ca Mg
Rep 4
TP 1 0.0225 TK 1
TP x TK 1 0.00019






52






Table 30. Effect of N levels on the concentration
of Zn and Mn in the soil. Sorghum
experiment No.4, 1977



N Zn Mn kg/ha -----------ppm-------------------0 4.10 b 3.72 b 100 4.04 b 3.77 b 200 4.72 a 4.30 a 300 3.93 b 3.63 b
Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.











Table 31. Effect of K on Ca leaf concentration at 2
levels of P. Sorghum experiment No.4, 1977



K P = 0 kg/ha P = 60 kg/ha kg/ha ---------------Ca %------------------0 0.596 a 0.505 a 60 0.454 b 0.566 a
Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.







53











; r-)< Ca'- cC @ or
0-- JC -- rC C 0 L.-- c -" C. c'

C *,C C C r O I)c C :I r


N c C cc -I o C 0 c
-0 C0 0- -n
O C *0 *0 .0 *0 0 .0 .0
C C c 0 0 0 0 c < 0 MO 0 go CO to we

0 0 NCJr- CO N c4 O0


- -0 ~- '- ,R IO ,-- ,-O ? <. C\ o *J0 0 0 _0
O O 0O C O O C C



I I I i





*-4C 0 0 C 0 O
or-, ~C C'- r-~' CO LN 0v Oo




'~) 0-c C"; o 0c- -03 0 -o
( 0) 0 RI 0) 00 -z c a








0-r-" *0 a 0 x C a0 0 0 0 O C-OC 0 *0 *C *0 so ( I II o .= O O C0 OZ" '1 27 eq












Or CC O0n L OC 0 0 t4 U. 0 0 '
*C O* *0 .0 C





















o A .- c 0 0 0 o o o
C. 0 C u r x a
















Wu- 00 00





54



leaves are presented in Tables 33 and 34, Soil analysis before planting appear in Table 35. Nitrogen accounted for the majority of the significant effects (Table 36) both in the soil and the leaves. These results are in complete agreement with a report by Terman (60). The author reviewed over 100 reports of experiments with maize and cotton which indicated that the frequency and magnitude of crop responses to N were generally greater than those to P and K in representative cropping areas of the USA, Higher levels of N decreased pH in the soil; an effect previously noted in the literature (62), as well as K and Mg concentrations. On the other hand, it also increased grain and dry matter yield (Table 37). The effect of N levels on nutrient concentration in the leaves appears in Table 38 and it is clear that N, P, K, Ca, Mg, Mn, and Fe concentrations were increased by the higher rates of applied N. Reports on these kind of relationships vary depending upon conditions of a study. Larssen (34) found that high rates up to 500 kg N/ha did not appreciably influenced Ca and P. However, K was increased and Mg was decreased by N fertilizer.

Further analysis revealed that only at the 0 level of N did fertilizer P increase Ca and Fe concentrations in the soil, while at the 200 kg N/ha rate the addition of fertilizer K reduced extractable K in the soil (Table 39). Soil test Ca fertilizer remained the same at both levels of P and K (Table 40).

Correlation coefficients for soil and leaf nutrient concentration

as well as for pH, grain, and dry matter values appear in Table 41. Grain yield showed a high positive correlation with Ca, Mn, and Fe concentrations in the leaves and with dry matter yield but was not correlated with any particular element in the soil. Dry matter yield was positively correlated








55










t 0 0 0 r L 0 L n




-C
(U 4 1 CO 0 0 4 H Ol N.




Cd CO O V) C- O O 0 a' O '0 Cl 0 b m

O

n 0 N 4 N 00 0 ra 4 0 C C1 .-I
o


*H
O OO OU C 0 CO O 0 N ~ CO C) a n 40 d C.)

C 0






S Co


C .0 O 0 Cl 4O 4 o 0 -m NC Co 0 co C : l C Cl or C) C C C C Cl Cl 0 rn In




OZT Ln O ,.O ,-t 17 cV 7O O T m -1 (n (-1 4J C




S 00






Cd m n r 0 0 0 a r C) m C m c









( if)oN N-. -. .- N N CO 0 -N. 0 $ O0 If ) OO 4 o




S. .
O O' 0 n CO 0 O O O a -- m m C 0






O 0 'n a l a 0 0N a C 'a T N c Oi r





-- ,---- m a > 0 : S p H Cl -T C -.7 -1 r- ClO7 Cl ON











IH Cd H H C N CD I D m0 Cd C









Cda)
(U 4- P-i 00- i- 0 0 -4 o 0 0 -4 -4 0 0 hi- -l9 Cd~~~0~9 ~ ~ b (U~~~~mm~~y ( Cd H 0 0 '4 .4 aCl C l C '








56
























t I T L

-4










H I3
I I





0 0



-1 r -q r-4 -q --I -I_ -A i -I -1 -_ __ _1
0)





S u I
0 I 0 o- -O O 00





C)I \. (. n N- w N- w 0 H 1 H 0 0 -I -.T X .0







C *H H 0 0 00 0 0 0 0 a O 0 I 4-1 O I




.0 I
I








aZ a ? a c
0 H I 0 e C J I 0


Ci I
HI z <, o m m
0 I 000 00000 00000 000 O 0a a) O\\@ o .I
I O N nC N N U U n H Cl



000 a






57








Table 35. Soil analysis before planting. Sorghum experiments
No.4 (ditch drained), and No.5, 1977

Experiment No.4
Rep pH1 P K Ca Mg Cu Zn Mn Fe
----------------------------- ppm --------------------------I 5.6 446 164 1842 180 0.92 6.3 5.4 38 II 5.2 228 190 1402 212 1.46 4.1 3.6 48 III 5.2 199 189 1326 180 0.32 4.1 3.5 38 IV 5.3 207 186 1544 180 0.52 4.0 4.1 36 V 5.3 197 161 1204 132 0.28 4.1 4.3 32 X 255 178 1464 177 0.70 4.5 4.2 38 Experiment No.5
I 5.4 371 142 936 73 4.12 9.3 6.4 61 II 5.3 317 116 746 45 3.40 6.8 4.8 59 III 5.4 350 103 836 58 3.80 7.6 5.1 60 IV 5.5 329 98 748 45 3.24 6.7 4.9 59 X 341 115 816 55 3.64 7.6 5.3 60









58








'


Cd
EO


CO CD







40 CD
0









-$4
*H

0)
0 0 C) oo O

COO








444
COO

Q) C)


.C) 900






C: C- 41 l O C



a) ca 0 :1 C U) C




*H 0 O



C: CD CD0 C o *
O C O




NC ci
UO 01 9 -I o N O
C ~ 0 0 O


O O 0







*OO CO m Z 0 C- O








> 1 ( O4 I O 0) 4 0 C 00








0)0

O O- ONrC: CD 4















rn C H rl) r-q m c Qa CO 0 0 C4) U, U- C C C) C

















O S4


4-4 (n C O 0




C0 QZ 44 0









OCf)
0) I -I 0

44 -H 44 C 0) 0 I C)












oM
0 0




0 M a 8 Cdr Z 44 ci IC))
0) C) C)4 ,~( m r CO 44





C)C
'44-eICO* ur4 C' ,4 C)C1 ~ ~ CCXXX X U) 3 a x- xp"" "^F~~~~






59






Table 37. Effect of N levels on soil pH, grain, dry matter and K and
Mg soil test. Sorghum experiment No.5, 1977



N pH grain Dry matter K Mg

kg/ha kg/ha -----ppm------0 5.40 a 423 c 3625 d 50 a 30 a
100 5.25 b 605 b 4210 c 46 a 30 a 200 5.41 a 627 b 4774 b 39 b 26 b
300 5.26 b 860 a 5823 a 39 b 27 ab Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.








Table 38. Effect of N levels on concentration of several elements in
the leaves. Sorghum experiment No.5, 1977



N N P K Ca Mg Mn Fe kg/ha ------------------------% ------------------------ -----ppm-----0 1.23 b 0.36 b 1.97 b 0.26 c 0.13 d 41 c 68 b 100 1.38 b 0.38 ab 2.11 a 0.29 b 0.15 c 49 b 77 ab 200 1.55 a 0.39 ab 2.07 ab 0.30 b 0.16 b 50 b 79 a 300 1.67 a 0.41 a 2.11 a 0.33 a 0.18 a 56 a 86 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.








60










I 0 0 0
c I T0
I CDH (N H
iJI O I 0 try


O CO I D '
i I UcI




m ca a H I CO CO CO C 4 I c o OC 1 4 0 m y0 O W 00 II *-z -z Co in4II
CO I
0H I H C (i (C

U) 4-4 rI CO CO CO CO1
(3) U) 41 ) .J4- Q




0 I 0 J-J I H.
> I'O LO) 00 Nr r- -1r 1
I~r- :o 1r H g
cli m M al G,

1 0 CI. I CO L* CO Ir
c O I '.0 0 -0 I4J :



0C 1CON I C
CN00 I LO (O O L II I 1 0
t- (N( I= 001 C (d V) m (3) (nc


I I 0 H
11s As



CO 0 ro m a H O()0 4r U 1 4 C4 I C ca ca
I CO < 1 0 O Ca OH 0. 0OH 0.'
4.I ) 'O. ir m 002 at I




C: Ca) Q') 0.' WZ \ IO
C0I H4- 0H u I a) H o O I4 CO 0 OOa )
J0 I r NC I 0 a 4 4.I O0 1 01 01 0 W O I CO H 43I ir to 0 U Ni E3 '0 '0 StoC 0C)H II I m





0 I 1 00 -I 00 U) w
-T I 44a4 I
UZ 1 & gec ,





OC I C O OW rOM ca M M o r
C H 1 CO CO CO LD OL3


4J II



w 4A I i) r- < 0 :3 Ho H H w I o. a' 0 O 02 r2)
U) 4- JH -Zr LR 4-/-4)


O II I co co





41COa) 0 O4
I t C H '. 0u


0 CI -Z -10 -Z cua O ~ r6 m rdco co 4 -1 Ci) C




O CICO UC 0/1 i H H ~I .0 *H ZC/ 0 I N 0 OO
S I u y 4-a I I .O O O O C O


4- .0-H
0c0 I (N Ou C' C











C C 4 I C Co a )n O






'4C O M O OX ? I CO CO CO CO4-JI J~y g 2~I 0a I J -HCPI



0 (/2W

CO OO- C ~ 0 0
H, CO '.0'0 (









61
















i -0 NC -e N o- -* 0 'r on M 0; "' NC O 0 0 OC -0 OC
00 3 0 CO CC Ul f, ,
CC c 40 CC rj 0 NO CC OC


o z Z e .0- .0 -' *.0 0 *0 -On C 0- co a C 0 so co U)
o Z ~~ 0 I(320 -'1 ;- Q2 0-
2 .31 1! C cC C o C L'. C' 00 CC 0 o < 00 Nc Ns O C' ( o C 0 c 00 ,
-d C. '3- -C 00 00 N27 Cc 00? 010 DC
a N. e o C C C. .
0 0 0 0, 0 *0 C0 co o
Z- C L C C C C C C Cq r

0
, z C- aC 3C '-o, ?.- 0.? 00' NC' .30



0H N- n C,-eNc ao 0N
4.1 C 00 C' 0' 10 C' -Z 0 '02 0- Q O 10C ,19 NM. NC -- C N N -0


H ., 0 1 o '. 3 o 0 Ca N Nre me o e CC am -. 0 0. -. r. r -. K. N. C.
'o 'o o .0 .0 a0 .O .0 .o *0 a 41 5 c C r C C 0 C C C C C :


S*



00
C : 2 N-

coi 0- 0 m Nc 0'0 3 o N C 00 ( C ax "N 100 00 NC 1 "- 0I CN 0r 3- =I



2- 00 00 3- "- %C CN N C Cc, 0 0 N. .. C. -- '. c N. C : "!
*Z *o *C .0 .0 .0 .0 .C '0 .0 .



O 0 0 0 C O 0 0 in C



00 C- O- No o 'N 3o o- CO CS C N) N- Co 0- cl' s NN 00 Hrl "a 1 Cme N a- -e C o CC Z_ L'' NC ON C- C -0 CC 0 CN 0
0 0 C C C C 0 C C 0 0







<4 0 L o






Sa e 0- o e c 0 c
- 2 C'- 0- OF- OC NO 00 00 0- 00
Cl or .. cO O 10. 0 Cc '. C. i). C
e. -C O N CC '- D' 1." oC C
0 2 C 0 0 .3 C c 0 0 N O N C C
-. .. .. .. N.





o e C 0 0 C. 0 C c C

) e co 0 C In as C l) 04



U) 0 0$ 0 NC o0 0?- 0 e -3 00 0, O 4.) '. $0 CO0 30 0~. a'o 0.3 ? '.21l

'.0 N- "o 00 'o e 0 C'4










o a) = o a
4o c e c o



orr -0l s- o 5
4.J C, n D N 3 (VN m U) 3 N m0 00 NN
r0 Cq C" C.6 "0 X0 0 -0 L' c a
0 0 00 0.0 U)
r t. O N co o jI I C C C 0
N0 C C N 0 C C' t

C c 0 OC ." 0 C' CO 0 0 oa t C 0 C O 0 0 0 ? 0 0 10 C-. N$ C', 0 '20 -2 00 -0 0 -O NC
.0 .0 .0 .0 '0 *o *0 *0 .0 .0
0~ ~ 0 0 C' 0 0 0 0 010 z
4-i 0 0 ON N CU) Or" N-, 0- 00 40 t-F

0)-C -~ O' '3 3.. CC 1.1 '30 0 0 0 '
~r -. -. N. C- N. -. C'

U CO


CCC' -' OC C. I' OC 0 N.. OC N
-1* ~ ~ ~ ~ ~ ~ ~ ~ c -. ,. 2. -






62


with N, P, Ca, and Mn concentrations in the leaves as well as with grain yield and with Cu and Fe in the soil.


Fertility Experiments in 1978


Corn

Adequate water, weed and insect management allowed good responses to treatments imposed in the 1978 study (Table 42). Soil test before planting is shown in Table 43. Nitrogen was responsible for increased grain and dry matter yields (Tables 44, and 45). The first increment of N(100 kg/ha) was sufficient to maximize grain and dry matter yields; higher rates were not statistically different. The 100 kg N/ha seemed to be a consistent figure to obtain highest yields for both corn and sorghum in this area. This result differes from an earlier report by Cuzman et al. (21) that recommended 179 kg N/ha for top yields on Florida's sandy soils. Rhoads (48) proposed applying N in North Florida soils according to corn plant population. For 29,640, 59,280, and 88,920 plants/ha the amounts of N should be 89, 178, and 267 kg N/ha respectively for yields up to 12,500 kg/ha.

Further analysis were conducted, due to significance of the triple

interaction NxPxK (Table 46), to determine the effect of N levels at different levels of P and K. Even though no significant differences were found in this case (Table 45), as they were in experiment No. 3, it appeared to be a clear tendency for P and K to diminish grain and dry matter yields. These effects are depicted in Figure 1 to 6 and are found in several literature reports (8, 11, 47).






63








Table 42 Grain and dry matter yield. Corn experiment
No. 8, 1978

Treatments 1/ Grain yield Dry matter N P K kg/ha kg/ha 0 0 0 4287 11227 0 0 1 4137 11353 0 1 1 4845 11438 0 1 1 2982 9535 1 0 0 6089 14123 1 0 1 5316 14389 1 1 0 5525 16039 1 1 1 5712 14252 2 0 0 6689 14194 2 0 1 5231 14630 2 1 0 4795 14177 2 1 1 6028 17726 3 0 0 5996 13313 3 0 1 5956 14485 3 1 0 5642 14940 3 1 1 4258 13952 1/
- N 0, 1, 2, 3 = 0, 100, 200, 300 kg/ha
P 0, 1 = 0, 60 kg/ha K 0, 1 0, 60 kg/ha
Values are an average of five replications







64







Table 43 Soil analysis before planting, Corn fertility
experiment No.8, 1978

Rep pH P K Ca Mg Cu Zn Mn Fe

----------------------- ppm --------------------------I 5.6 394 120 1208 92 2.2 7.6 3.1 32 II 5.5 334 188 1312 104 2.2 6.8 3.2 24
III 5.6 398 172 1508 120 3.5 7.2 3.9 40 IV 5.6 274 136 1040 92 1.8 4.8 2.3 26


X 354 149 1269 103 2.4 6.6 3.1 29






65














Table 44. Effect of N levels and percent
lodging on grain, and dry matter
yields. Corn experiment No.8, 1978



Grain Dry matter Lodging N yield yield percent

kg/ha -------kg/ha-------0 4063 b 10888 b 8 100 5660 a 14700 a 20 200 5686 a 15180 a 35 300 5463 a 14172 a 41
Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made withing columns.








66













I ca ca --I
4- I
m %10 r- c0 r,
C I ON -O Cl C a 0 t I 0 -- -4 Uo I ) --I -7-H u --. I -4l4-4
O 4 I 0< -H

00
0 \ I --4H H
C I
cn I c C

co 1 I 00* 0 Il CO CO 0
I o C I f-- n ca
94 I 0 O CO
S I t -- to in -n
44
3 I 9a 00
4-i
ci I 4-i
0, I Nd 0 (C cd O
-~ 0 I CO N CD COW co I C
ca cc wU~c
4J I C4 C 1 10 00
0) C", I c Ln 00 r-

Cl I -4 0I 4 41I
4-) L"0 I -H< 0
ca L 4

CI C I

I O O CO O 0) o I 0 l Cl
I 0 H

Z LA to t ln a
.H I 1
z I co ce t U

) (0 I 0 to 0




(04-i I NH OMCCI) 1C I z to Ln n QJ



0 I )rH
-4 I






-H 4i I CO II ( I CO CO CO CO 4-.ib
$ I 0 *

00 Z H I L' 00 4 40 W
Fo I 4 o C:






0 0 I 0 0 -10-i
I I '0 00 t w m Cl C-I ca a)


-4 1-CO
0 I 00 w CO I C 0 00 r, -7o




CO0 I H Cl-Z ) -P0
00 I C 0 4 0 -4440 r, L-4 '4 '-40


ow I 0 0 0 4
I O 0 OMM 4I H-i H O
0 u >00 40-4





rHI 0 1 C0 O 0 c


-H I Cl 01 ~ '.0 0-HC CO I 4 m 00 m '.






c o I 0 o m -H0 ) C --4


4J -H 0 r 0 00)-H u '.oCD u 10


cz r-q %o .

ca (n Q)

co C ) Z C) C) -r






67









Table 46. Significance of agronomic variables as determined by the
F test. Corn experiment No.8, 1978

Grain Dry matter Source D.F yield yield

Rep 4

N 3 0.0003 0.0001
P 1 Nx P 3 K 1 NxK 3
PxK 1
N x P x K 3 0.0276






68








KG/HA
6,000

5,000 4,000

3,000.
I I I
0 100 200 300 N KG/HA

Figure 1. Effect of N levels on grain yield. Corn experiment
No.8, 1978















KG/HA
6,000 ap


4,0 0

3,000

0 100 200 300 N KG/HA Figure 2. Effect of N levels on grain yield at two levels of P.
Corn experiment No.8, 1978






69











KG/HA
6,OO~ -------Ko
5,000- / ..... K,

4,000

3,000

O 100 2OO 300 N KG/HA

Figure 3. Effect of N levels on grain yield at two levels of
K. Corn experiment No.8, 1978















KG/HA
16,000 14,000 12,000 10,000

0 100 200 300

N KG/HA
Figure 4. Effect of N levels on dry matter yield. Corn
experiment No.8, 1978






70









KG/HA
16,000 P
14,000 -Po
12,000 10,000


0 100 200 300 N KG/ HA

Figure 5. Effect of N levels on dry matter yield at two levels
of P. Corn experiment No.8, 1978















K G/HA
16,000

14,000- K Ko
12,000

10,000

0 100 200 300 N KG/HA

Figure No.6. Effect of N levels on dry matter yield at two
levels of K. Corn experiment No.8, 1978






71



Regression analysis was conducted in order to find suitable prediction equations. However, the results came far short from this objective.

A highly significant linear N effect and a significant quadratic N effect were detected on dry matter yield. A stepwise regression analysis was run in order to find the individual contribution of the variables in the model. When the variable N was entered the prediction equation was


Yi = 4,584.3 + 4.22 N where

Yi = dry matter and N = fertilizer N


However, the R2 = 0.078 was very low and most of the variability remains unaccounted for. When N and N2 were entered, the prediction equation became


Yi = 4,129 + 17.87 N 0.045N2 where

Yi = dry matter and N = fertilizer N

The R2 = 0.151 was still very low. When all other possible variables were entered, the maximum R2 obtained was only R2 = 0.218.

Highly significant linear and quadratic N effects were also detected on grain yield. When N was entered, the equation was:


Yi = 12,186.0 + 10.33 N

where Yi = grain and N = fertilizer N

The R2 = 0.114 did not help again to explain much variability.

When N and N2 were entered, the prediction equation became


Yi = 10,980 + 46.49 N 0.12 N2 where

Yi = grain and N = fertilizer N


Again the R2 = 0.239 was very low. When all other possible variables were
2 2
considered, the maximum R2 possible was R = 0.278, indicating that the above equations did not account for most of the variability.







72


Nutrient concentration values and statistical analysis for soil test and leaf samples are presented in Tables 47, 48, and 49. Nitrogen fertilizer again was responsible for most differences, especially in leaf analysis where it increased the concentration of N, P, Ca, Zn, and Mn, and decreased K.

Nutrient content (dry matter x nutrient concentration) values are shown in Table 50 and correspond to the amount of nutrients removed by each treatment. Nitrogen removal ranged from 100 to 248 kg/ha, P from 30 to 52 kg/ha, and K from 145 to 227 kg/ha, Ca and Mg were also removed in large amounts. It was not surprising to find that N caused most differences in nutrient content (Table 49). It was found to increase the content of N, P, K, Ca, Mg, Cu, Zn, Mn, and Fe in whole plant samples. The percent IVOMD values are included in Table 50 and were only decreased by K fertilizer (Table 49).

Correlation coefficients for soil and leaf nutrient concentrations (Table 51) show several significant effects. Manganese in the leaves was positively correlated with a few elements in the soil, namely Ca, Mg, Zn, and Mn. Soil versus whole plant nutrient content correlations (Table 52) show N content in whole plants to be negatively correlated with K in the soil and positively with grain and dry matter yield as well as with percent lodging. Also grain yield and dry matter showed a positive correlation, the R value being equal to 0.60.

Table 53 contains the correlation coefficients for leaf nutrient concentrations and whole plant nutrients content. Nitrogen content in whole plants was positively correlated with several elements but especially with N in the leaf samples (R = 0.68). At the same time, N in









73














0:1 00 00 C C r- 0o 0 co (n Cn 0 ,-i r- ,. CO 0 n m n 0cc" n cncn m c) (n n




oc (4 o a 0 a c : 2c o m


c cc

E
.-H c" C C 0 C C4 -.T CO So Cl O 00 oc0 o0 o p 0a'% O Un "l Cl ,-4 C 00 '0 cc '00 0 0 A 0CONNoo co o r-. coc o. r o o-. -oo- o c o r r c X
a) a


o .I I c00 cO ', -Z C Cl O 0 cc 0 .t D 3 O CO O) U O 0. ;r 0 to a 4 Lo 4 m toa N H CO S0 Z ,ND L N (') N f -N N NZT MN O 0 N 00



*4


.I-- I'o Dtar-o o oicc


4- 0 q 1 -4 ,-4 OA 0 r-OA o -o '4 01 O 0O




ci a


I 0 rON o o 0 ry a0C a o M H co 0 to c c o o co to to to to c 0 0 O-i C 4 0 0 4 ci) OU 0 .4 ) ca --- m cc Cl Sr cc 0 cc \D c n m So n a\ 0 4J u




C co l O4 'o o Ca)De.d r 4








m 8 cl c








7 t














I O 0 -zr N J "N1 0 D 0
w I 0 O H (D N H a M H 4 0 C M
0 'H HH nH H H H H H H
4I















o I
O I
aI
0 C-4 00 C O-4 CO 00 0 0 Wi I r. -. r- r- .H r- 1. .- 0
F I ON OH r -4 H c o




0 M





I u 1 -,T m ONN- 0 m m (' m i r- m00 > o
di ao








SI 0) 0 0 0 0 o C I
a I v




Ia rH U




I oo 0 m o o 0 O 0 H Uo 1 ,- 0 o I. ,. 0 H
A I 0 0000 G0 0000000000 O




SI *






-0 0c m c0 00 r00 00 0 0 0 a



S o lo 4 >






4Z I :r -4 o O 'o o H o-i o 0 0 o i t C o I
















CI0 0 0 04 0 0 0 0 0 00 0 di I o o -om- O 'H~~ ~ 14 ~ ~ ~~~~~ JJ (NJ 14Oh ~ O~O O







75










C)
u 0

Q)1





cO

OH 1 O r- CC 4 o o o o








aa u
0 c J
U
_- ZO O



O

OO Q C OC





Q)C 0



4OO
00




Oco






O I O 2- C o
00

0 0 Co C )U) C) a) C) CC I I co

C, 5 0 5 an








C C








0f z 0. tn 2








7b








44 co
0 00 u 0

'H
(














c 0
00










S









O 0

O O
0













o 0






c ) CD
O










CD
4 4
















O
0 OO




I O


















O
F4
O) u





W 24 F-









7.7






















o" I O r-. D O O C14 ,-0 IT _zT ". m .,1 m -7 ,o CI 0 Om




0 m r- ,"N f o1 C) a i rA M m A 00 r- r- -1- 0 r-* H

S) '. ao m C 4H C D -I m '.0 m" m0 r. n M O C, C) Cl n ,.D C) L(N r-a' l Lf a' r-., r-C) "> ommo ooo momNo
o, o ma





C)C CD C0o 0 C) C C) C) C) C) C) C) C aC -- T0000000000000000






> ca 0




4 -- C p C-4 u' 0 LI Cl C) la 0 o -.. 0 a' ) CO Cl. l ( -H" C)r CO ro a- a a C LI m L ) C l L




> o Co 1 06 .. C; 1 d o -4
CU C O OON ., C O O ,-.C lO ',O H ." '0 LI CO oO r-) O- O ,-0






M O r.-. C T o 0 O O O)
r-' cN r- -.. ... O 00 -- oM." .O...... . . o
S H Cl m C L 0 o w











r 'CD o (N CD r- a' aL ) Cl C C H CO, m


CD Cl 0 00 r ', LC) UN CD LI -T Cl a' (N a' C)C

_q1 H Cl o) 0)0) oq ',4 C H '0 (- ,- .
,.-O



O C H C. CI H ar 0 Cl c ) oo a C L H -c 0 C C C C
P C) C C) 0 N C- a a a.
4-'H N H N N H N N Cl w 4 R M 0 ---a
4

00 c o s 0


IOm
H- H Z ) C ) C l l C l C l C l H



















0*0U *C'.

C' = C 0 C *0 .
=>e



.c C
4I 1

ar




x cn 14- e- o a) )c V- 0 h-0 e )0 CC





a o. 0 e *0 aC C .0 .0 o




I
C 3 a a a3~ ~=
....0 0 P'. .0 'o- ?r? N. rC 3h )3 OC' t



'-o me *- -0 co







00 0 0






















o 0 a 0 C -o
0- In















C)
ca
4.. .- .' e )" .c .0* 0 -o S 0 0. 0. 0. 0-. .. -, -4 -.

. *0 a0 .0 a 8 4.o
-1 1 I
-4 -33 0 L'C V.'-- -'



Ca C' C 0' 0 0 0 0 0'





-- 0' 0' -~ .7 0'. 0h ?

('> C.O .*e -- *r C'l 0 0 0 C C 5-'


'.4-hrI~4)?~1 3 ?
J? -- ..,0 C'2 C '

d C' 0 0 0 0I C C 0 0 4.1i I


*i ., 0'0 22 r'i C hy h LII y



- "'- 0 'C -- b ~3 0-4. ~C
-U '0' .0 'C~ '0h *'rr -o, .
C' C> 0L 0' 0 0 0' C 0



Ca u iZo m P, ap=! P )
4-~uu *








79






















ca
L .- *.. -. -. .










c cI
C.0 .= .o .C .e .e







7r C






o a 0
a -- --0






























4-4
-. C-0 CV C eC e. cC 00 c













cl c- = e a.- 0-3 = =C





j o rv. C .
C; : = = o r -oo= r, 5




































oa. 0 c





0 or
8,- J J ~ e ~ ~ 0




































c0 *0 0 0 c 0
UU
-: C 0T C 7 0 C -; -3 C






o e. I e e -.


0 0- .- e : :o mc -: =L 'e -e ee -0 e




a 0 -- *- e e .=
0P I C c

SI _. -- .-,- ~



'C ~~= 0'-' C-f 'C 4

I c -. C. 3. 0* 0* 0L -, ~ = s



a, -.-C ~ r OIC

C 5 C C C 03 3



~,"~ -~ ?- c'r- --' ~IIc- o.., -o ~ -o o> r?



"I Ce o'- Cv0 ~f ?e I'- ." a -- -0 Or. C. -- 0"

I C. 0. 3- :. 3 -;~ p P. -.





0 *C .0 .0' .0 .0 .0' .0 *o *o *e *



0~-- '~" -o 00' .-.- .0".*) -I -c -t 7 r. i:o -~. '< C* *.* =*. -. .0 C




r -- : N.- "- ,r '0 00 "40 C JC O O'
~ -. C. C. C. C. ". N. N- CC 0 0 0 3 0 0 0 C IC 0r 0: 0
O~ II I I I
a, 0. .... C C 3 C .Z C- 3 c =

-;E 5 i. I -:- I-C ti ^ Ca3 3 h '








80











CN



002C
.7- --, -- -., -c -- ~- 0




C)
i ---P
m '-, %















S *,



0) 4 C J ~
4-4C
















0 0





4
C) -n -,
-,3 -c C
-; '' ~ 2 -" C' -c *- -4-4 LO 1 ~ ~
C C -*




*0 0
C)~~~ C-W0
- -- .p-A
-e -- -- A. S























tt wC
-- -- k-- C-- .-- C -~a) cc t,: c ~ .7-4 C C* 0*
























L) car)
E
-u *" -h *h 32 .r .- -7 h C u~ ~ 0 C' -- ^ ( w1Z *- 031"





i ~ C; --A' --A I44rcA-e* C r
-d C 0 *' 0 0 0 0)0 -. ^ -A' -= -2 -, C






A- > .0 .0 *' '


'- 7 4." ~: -, --- Ua ) '--i "'4- ~C 00 00 Cr -C -C -- ? 4QJQ


wCa *V1-* -A-- -.1 -h 3 A L~ 'A C = __ j
-k --: N. I '
7'- 0'~ h O rct
A--
U; 0 -V *u -.S *S 0) ( C' C c







81



in the leaf was positively correlated with Ca, Mg, Zn, and Mn in the whole plant samples, as well as with dry matter and grain yield. Sorghum

This fertility experiment planted at the ARC also had good overall management in 1978. Soil analysis before planting is presented in Table 54. Soil, leaf, and whole plant analysis, grain and dry matter yield, and percent IVOMD appear in Table 55. Both N and K fertilizer affected elements in leaf and whole plant while N mostly affected responses in soil samples. Even though this was the trend for most fertility experiments reported before, it appeared that K had a more definite role in this particular case. Values for nutrient concentration among the samples are shown in Tables 56, 57, and 58. Grain and dry matter yields appear also in Table 56 and followed a similar pattern to the 1977 previous experiments in which the first N increment (100 kg/ha) was enough to obtain maximum yields.

Further statistical analysis was conducted taking into account significant factors from the ANOVA tables. In the soil, high rates of N caused a decrease in K and Mg concentration at both 0 and 60 kg K/ha, but Fe concentration remained unchanged (Table 59). In the same table is shown that the 60 kg P/ha only decreased Mg concentration at the 0 level of K. On the other hand, Mn concentration increased with increasing rates of N at the 0 level of P (Table 60). Changes in pH, Ca, and Mg in the soil as affected by N levels appear in Table 61, and follow the same pattern already discussed in the 1977 data and found in several literature reports (5, 34, 62).







82








Table 54. Soil analysis before planting. Sorghum fertility
experiment No.9, 1978


Rep pH P K Ca Mg Cu Zn Mn Fe

--------------------- ppm --------------------------I 5.3 100 84 736 100 3.9 8.8 3.7 40 II 5.1 260 76 556 68 3.7 8.0 3.5 40 111 5.5 264 76 664 76 4.2 8.0 3.0 44 IV 5.5 270 96 592 80 3.6 6.8 3.4 84

X 223 83 637 81 3.8 7.9 3.4 52











83




















41


>
aG,











41 r
C
IL C P I Cc






0





E:




ca I
0' -1 "







C ; !















Q) C C Cli


C C
4 C
C C









44
O 0
0), I C C

-, C:r- C /3) C t\



Cl C


'C
~D C, 2 C

II C


Ki C C C0



(/3 C i0 U Crc3





Ki C
-t4 (L C~- r





C XC O(X ~
rl L

































































Icc
























.r-
4-1

0C 'U



x x-




Full Text

PAGE 1

MULTIPLE CROPPING MANAGEMENT OF CORN AND SORGHUM SUCCEEDING VEGETABLES By NICOLAS MATEO A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY. UNIVERSITY OF FLORIDA 1979

PAGE 2

To a couple of dreamers, my grandfathers Ladislao Mateo Esteban and Andres Valverde Amador

PAGE 3

ACKNOWLEDGEMENTS The author expresses his sincere gratitude to Dr. Raymond N. Gallaher, chairman of the supervisory committee, for his continuous support and encouragement in all phases of this study. He also thanks Dr. Dale R. Hensel, Director of the ARC at Hastings and member of the committee, for his support and for overseeing the field work. Special thanks are due to Dr. Victor E. Green, Jr. for his friendship and for serving on the committee and Dr. Elmo B. Whitty and Dr. Herman L. Breland, also members of the committee, for time and discussion devoted in correcting this manuscript. Recognition is extended to Ms. Jan Ferguson, Ms. Ruth Schuman, Mr. Ken Harkcom, Ms. Linda Osheroff, Mr. Rolland Weeks, and Mr. Jack Swing for their laboratory and field assistance and for providing many hours of country music. Thanks are also due to the personnel of the Analytical Research Laboratory of the Soil Science Department, and the personnel of the Agricultural Research Center at Hastings. The author is also indebted to Philip d'Almada for his guidance in the statistical analysis. The author wishes to recognize the financial support provided by the Rockefeller Foundation during all his degree program. The author's deepest appreciation is extended to his family, Lorna, Elena, and Javier, for their love and support, and especially to Lorna for the typing and editing of the first draft. Finally, special thanks are due Ms. Maria I. Cruz for typing the final copy of this dissertation. ill

PAGE 4

TABLE OF CONTENTS Page ACKNOl>rLEDGEMENTS iii LIST OF TABLES vi LIST OF FIGURES xiii ABSTRACT xiv INTRODUCTION 1 LITERATURE REVIEW 3 General 3 Multiple Cropping 3 Corn or Sorghum Following Vegetables 3 Soil and Leaf Analysis 5 Fertility of Corn and Sorghum 7 Drainage and Irrigation Beds 12 Cultivar Experiments 14 MATERIALS AND METHODS 16 Fertility Experiments 16 Bedding Experiments 22 Cultivar Experiments 25 RESULTS AND DISCUSSION 27 Fertility Experiments in 1977 27 Corn 27 Sorghum 37 Fertility Experiments in 1978 62 Corn 62 Sorghum 81 iv

PAGE 5

Page Bedding Experiments 100 Cultlvar Experiments 121 CONCLUSIONS 136 Grain sorghum 138 Corn 139 LITERATURE CITED 140 BIOGRAPHICAL SKETCH 146 V

PAGE 6

LIST OF TABLES Table Page 1 Critical values for corn and sufficiency ranges for corn and sorghum 8 2 Basic information for all experiments during 1977 and 1978 17 3 Pesticides used during 1977 and 1978 19 4 Treatments imposed on the bedding experiments, 1977 and 1978 23 \ 5 Cultivars tested at Hastings during 1977 and 1978 ... 26 6 Temperature and rainfall data for 1977 and 1978. Hastings area, Florida 28 7 Soil Analysis before planting. Corn fertility experiment No.l, 1977 29 8 Soil analysis before planting. Corn fertility experiment No. 2, 1977 29 9 Significant variables as determined by F test. Corn experiment No.l, 1977 30 10 Significant variables as determined by F test. Corn experiment No. 2, 1977 ^ 11 Grain yield, pH, and nutrient concentration in the soil. Corn experiment No.l, 1977 32 •^12 Grain yield, pH, and nutrient concentration in the soil. Corn experiment No. 2, 1977 33 13 Nutrient concentration in the leaves. Corn experiment No.l, 1977 34 14 Nutrient concentration in the leaves. Corn experiment No. 2, 1977 35 15 Effect of N and K on concentration of Ca and Iln in the soil at 2 levels of P. Corn experiment No.l, 1977. 36 vi

PAGE 7

Table Page 16 Effect of P and K (kg/ha) at different levels of N on the concentration of K and Ca in the leaves. Corn experiment No. 2, 1977. .• 38 17 Effect of N levels on pH, K, and Mg Soil test and the concentration of N, P, Mg, Cu, Mn, and Fe in the leaves. Corn experiment No. 2, 1977 38 18 Correlation coefficients for soil test and leaf nutrient concentration. Corn experiment No.l, 1977. 39 19 Correlation coefficients for soil test and leaf nutrient concentration. Corn experiment No. 2, 1977. 40 ^20 Grain yield, dry matter yield, and nutrient concentration in leaves. Sorghum experiment No. 3, 1977 .... 42 21 Significant variables as determined by F test. Sorghum experiment No. 3, 1977 43 22 Effect of K levels on grain yield at different levels of N and P. Sorghum experiment No. 3, 1977 44 23 Effect of N levels on the concentration of nutrients in the leaves and in dry matter yield. Sorghum experiment No. 3, 1977 44 24 Effect of P and K levels on the concentration of Ca and Mg. Sorghum experiment No. 3, 1977 45 25 Soil analysis before planting. Sorghum experiment No. 3 (tile drained) 47 ^ 26 Grain yield, pH, and nutrient concentration in the soil Sorghum experiment No. 4, 1977 48 27 Nutrient concentration in the leaves. Sorghum experiment No. 4, 1977 49 28 Significant variables as determined by the F test. Sorghum experiment No. 4, 1977 50 29 Significance of percent Ca and Mg in the leaves at 4 levels of N as determined by the F test. Sorghum fertility experiment No.4, 1977 51 30 Effect of N levels on the concentration of Zn and Mn in the soil. Sorghum experiment No.4, 1977 52 31 Effect of K on Ca leaf concentration at 2 levels of P. Sorghum experiment No.4, 1977 52 vii

PAGE 8

Table P^g^ 32 Correlation coefficients for soil and leaf nutrient concentrations. Sorghum experiment No. 4, 1977. ... 53 ^ 33 Grain yield, dry matter, pH, and nutrient concentration in the soil. Sorghum experiment No. 5, 1977 55 34 Nutrient concentration in the leaves. Sorghum experiment No. 5, 1977 56 35 Soil analysis before planting. Sorghum experiment No. 4 (ditch drained), and No. 5, 1977 57 36 Significant variables as determined by the F test sorghum experiment No. 5, 1977 58 37 Effect of N levels on pH, grain, dry matter, K, and Mg in the soil. Sorghum experiment No. 5, 1977 ... 59 38 Effect of N levels on concentration of several elements in the leaves. Sorghum experiment No. 5, 1977 59 39 Effect of N levels on the concentration of K, Ca, and Fe in the soil at 2 levels of P and K. Sorghum experiment No. 5, 1977 ^0 40 Effect of levels of K on soil test Ca at 2 levels of P. Sorghum experiment No. 5, 1977 ^0 41 Correlation coefficients for soil and leaf nutrient concentrations, grain and dry matter yields. Sorghum experiment No. 5, 1977 \ 42 Grain and dry matter yield. Corn experiment No. 8, 1978 63 43 Soil analysis before planting, corn fertility experiment No. 8, 1978 64 44 Effect of N levels and percent lodging on grain, and dry matter yields. Corn experiment No. 8, 1978. ... 65 45 Effect of N levels on grain and dry matter yields at 2 levels of P and K. Corn experiment No. 8, 1978. 66 46 Significance of agronomic variables as determined by the F test. Corn experiment No. 8, 1978 67 47 pH values, and nutrient concentration in the soil. Corn experiment No. 8, 1978 ^3 viii

PAGE 9

Nutrient concentration in the leaves. Corn experiment No. 8, 1978 Significant variables as determined by the F test corn experiment No. 8, 1978 Nutrient content and % IVOMD values for whole plant samples. Corn experiment No. 8, 1978 Correlation coefficients for soil and leaf nutrients Concentrations. Corn experiment No. 8, 1978 Correlation coefficients for soil, whole plant nutrient concentration and agronomic responses. Corn experiment No. 8, 1978 Correlation coefficients for leaf nutrient concentration, whole plant nutrient concentration and agronomic responses. Corn experiment No. 8, 1978 Soil analysis before planting. Sorghum fertility experiment No. 9, 1978 Significant variables as determined by the F test Sorghum experiment No. 9, 1978 Grain and dry matter yield, pH, and nutrient concentration in the soil. Sorghum experiment No. 9, 1978 Nutrient concentration in the leaves. Sorghum experiment No. 9, 1978 Nutrient concentration in whole plant samples. Sorghum experiment No. 9, 1978 Effect of N and P levels on K, Mg,and Fe soil test at two levels of K. Sorghum experiment No. 9, 1978 . Effect of N and K levels on Mn soil test at 2 levels of P. Sorghum experiment No. 9, 1978 Effect of N levels on pH, Ca,and Mg soil test and grain yield. Sorghum experiment No. 9, 1978 Effect of N levels on the concentration on several elements in the leaves. Sorghum experiment No. 9, 1978. Effect of K levels on the concentration of P, K, Ca, and Mg in the leaves. Sorghum experiment No. 9, 1978. ix

PAGE 10

Table Page 64 Effect of N levels on N, P, Mg, and Mn concentration in the leaves at 2 levels of K. Sorghum experiment No, 9, 1978 91 65 Effect of N and K levels on P and Ita concentration in the leaves at 2 levels of P. Sorghum experiment No. 9, 1978 91 66 Effect of N levels on P concentration in the leaves at different combinations of P and K. Sorghum experiment No. 9, 1978 92 67 Effect of N levels on nutrient concentration of whole plant samples. Sorghum experiment No. 9, 1978 92 68 Effect of K levels on K, Ca, and Mg concentration in whole plant samples, and on percent IVOMD. Sorghum experiment No. 9, 1978 93 69 Effect of N and K levels on P, Mg, and Zn concentration of whole plant samples at two levels of P. Sorghum experiment No. 9, 1978 93 70 Correlation coefficients for soil and leaf nutrient concentrations, grain, and dry matter yield. Sorghum experiment No. 9, 1978 94 71 Nutrient content for sorghum fertility experiment No. 9, 1978 95 72 Correlation coefficients for soil and whole plant nutrient concentrations, and nutrient content, grain, DM, and percent IVOMD. Sorghum fertility experiment No. 9, 1978 97 73 Correlation coefficients for leaf and whole plant nutrient concentrations and nutrient content, grain, DM, and percent IVOMD. Sorghum fertility experiment No. 9, 1978 98 74 Soil analysis before planting. Sorghum bedding experiment No. 6, 1977 101 75 Soil analysis before planting. Bedding experiment No. 10, 1978 102 76 Significant variables as determined by F test. Combined analysis 1977 and 1978. Bedding experiment No. 6 and 10 103 X

PAGE 11

Table Page 77 Significant variables as determined by the F test in 1977 and 1978. Bedding experiments No. 6, and 10 104 ^ 78 Grain yield in kg/ha. Bedding experiments No. 6 and 10, 1977 and 1978 105 79 Dry matter yield in kg/ha. Bedding experiments No. 6 and 10, 1977 and 1978 107 80 Average plant population and plant height for 1977 and 1978. Bedding experiment No. 6, and 10 108 81 Significant variables as determined by the F test. Combined analysis 1977 and 1978. Bedding experiments No. 6, and 10 109 82 Significant variables as determined by the F testBedding experiments No. 6, and 10 110 83 Nutrient concentration and percent IVOMD for whole plant samples. Bedding experiment No. 6, 1977 .... HI 84 Nutrient concentration and percent IVOMD for whole plant samples. Bedding experiment No. 10, 1978 112 85 Nutrient concentration and percent IVOMD for whole plant samples. Combined analysis 1977, 1978. Bedding experiments No 6 and 10 113 86 Nutrient content of whole plant samples bedding experiments No. 6 and 10, 1977 and 1978 115 87 Nutrient content of whole plant samples. Average of 1977 and 1978. Bedding experiments No. 6 and 10, 117 88 Correlation coefficients for nutrient concentration and percent IVOMD, in whole plant samples, agronomic variables and nutrient content. Bedding experiment 1977 118 89 Correlation coefficients for nutrient concentration and percent IVOMD in whole plant samples, agronomic variables, and nutrient content. Bedding experiment 1978 119 90 Correlation coefficients for nutrient concentration and percent IVOMD in whole plant samples, agronomic variables, and nutrient content. Bedding experiments 1977-1978 120 xi

PAGE 12

Table Page 91 Soil analysis before planting. Sorghum cultivar experiment No. 6, 1977 122 92 Soil analysis before planting. Sorghum cultivar experiment No. 11, 1978 123 93 Nutrient concentration in whole plant samples and agronomic variables for cultivars excluded from the statistical analysis. Cultivar experiments No. 7 and 11, 1977 and 1978 124 94 Nutrient concentration in whole plant samples, and agronomic variables for cultivars included in the statistical analysis. Cultivar experiments No. 7 and 10, 1977 and 1978 125 95 Significant variables as determined by F test. Combined analysis 1977, 1978. Cultivar experiments No. 7 and 11 126 96 Effect of year on nutrient concentration on whole plant samples. Cultivar experiments No. 7 and 11, 1977 and 1978 12-7 97 Nutrient concentration of whole plant samples. Combined analysis. Cultivar experiment No. 7 and 11, 1977 and 1978 128 98 Nutrient concentration of whole plant samples. Cultivar experiment, 1977 128 99 Nutrient concentration of whole plant samples. Cultivar experiment, 1978 129 100 Percent IVOMD, dry matter, and grain yields. Cultivar experiments No. 7 and 11, 1977 and 1978. 130 101 Nutrient content of whole plant samples. Cultivar experiments No 7 and 11, 1977 and 1978 132 102 Percentage of N removed in relation to N applied. Cultivar experiment No. 7 and 11, 1977 and 1978 .... 133 103 Recycling of N, P, and K and digestible dry matter Forage sorghum cultivars. Cultivar experiments No. 6 and 10, 1977 and 1978 134 xii

PAGE 13

LIST OF FIGURES Figures Page V 1 Effect of N levels on grain yield. Corn experiment No. 8, 1978 68 2 Effect of N levels on grain yield at two levels of P. Corn experiment No. 8, 1978 68 3 Effect of N levels on grain yield at two levels of K. Corn experiment No. 8, 1978 69 4 Effect of N levels on dry matter yield. Corn experiment No. 8, 1978 69 5 Effect of N levels on dry matter yield at two levels of P. Corn experiment No. 8, 1978 70 6 Effect of N levels on dry matter yield at two levels of K. Corn experiment No. 8, 1978 70 xiii

PAGE 14

Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy MULTIPLE CROPPING MANAGEMENT OF CORN AND SORGHUM SUCCEDING VEGETABLES By Nicolas Mateo August 1979 Chairman: Raymond N. Gallaher Major Department: Agronomy In the Hastings area of Florida, potato (Solanum tuberosum L.) and cabbage ( Brassica oleraceae L.) are grown during late fall and winter. The rest of the year, available resources such as solar energy, irrigation water, residual fertilizer from the previous crops, and equipment are not fully utilized by farmers. The planting of a second crop could possibly make use of these resources. Corn (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) are alternative crops because Florida is a net grain importer and the ecological conditions are suitable for these crops. Several experiments dealing with production problems observed in the area (soil fertility, bed management, and cultivar evaluations) were conducted during 1977 and 1978, both in farmers' fields and at the Agricultural Research Center (ARC). The main objective of the research was to determine management needed for growing corn after cabbage, and sorghum after potato in succession cropping systems. Experiments were planted on a Rutlege fine sand (Sandy, Siliceous, thermic family of the Typic Humaquepts) • Drainage beds Im apart were used to plant both crops. Factorial combinations of N(0, 100, 200, 300 kg/ha) xiv

PAGE 15

P(0,60 kg/ha), and K(0,60 kg/ha) were in a randomized complete block design. Soil and plant samples were collected before harvesting, and grain and total dry matter yields determined. Nitrogen was the most important element affecting not only grain and dry matter yields but also nutrient relationships in all collected samples. In all cases the first N increment (lOOkg/ha) was sufficient to maximize yields. Phosphorus and K tended to decrease grain and dry matter yields in several cases, suggesting salinity problems and possibly nutrient toxicity. Nutrient content and correlations between soil and plant analyses are presented and discussed. Use of the traditional 1.0 m potato bed resulted in an apparent waste of space and yield reduction for the sorghxim crop. Several modifications of the 1.0 m beds were made and compared to 1.5 and 2.0 m beds in which various numbers of rows and broadcast treatments were included in a split-split plot design. Highest grain yield was obtained from the 2,0 m beds. The highest yield was obtained from the 2.0 m bed four rows treatment, which showed a 40% yield increase over the control. Total sorghum plant dry matter was also higher in 1.5 and 2.0 m beds. Highest N content was 175 kg/ha in 1977 for the 1.5 m five rows treatment as opposed to 76 kg N/ha in 1978 for the 1.5 m five rows treatment. Nitrogen removal in relation to N applied was 233% and 101% respectively for the two above mentioned treatments. Cultivar experiments included 6 grain sorghum and 2 forage sorghum hybrids. Grain yield was difficult to evaluate due to missing values. However, grain hybrids Dekalb BR-54 and Grower ML135 would probably be XV

PAGE 16

the best choices for the area considering overall performance. There were no differences in the percent IVOMD in a combined 2 year analysis. The forage hybrids (Dekalb FS-25A and FS-24) showed the highest N, P, and K content values for both years. The importance of sorghum as a forage crop, probably needs to be stressed in this area. The percent N removed was very close to 100% by Dekalb FS-24. The total N, P, and K recycled by this forage sorghum was 74, 29, and 203 kg/ha, respectively. xvi

PAGE 17

INTRODUCTION Today's energy problems are being dealt with and understood differently by various countries and individuals. The challenge posed to agricultural systems based largely on the use of fossil fuels has prompted agronomists to come up with alternatives to help alleviate the energy problem. The use of multiple-cropping systems and minimum tillage are probably the most dramatic and successful examples of a new approach to incorporate ancient practices in today's modern agriculture. The key is not necessarily to intensify agriculture but to combine intelligently the available resources of land, growing period, and solar energy to obtain a larger output of food, fiber, and forage. Florida has a full year growing period and a subtropical climate to expand production through multiple cropping. If innovative cropping systems are designed to better utilize the exceptional characteristics of the state and if practices like irrigation, weed, and pest control are carefully considered, it would be possible to maintain successful cropping systems to go along with the times. This research was initiated with the above guidelines in mind. In the area near Hastings, Florida, potato ( Solanum tuberosum L. ) and cabbage (Brassica oleracea L.) are grown during late fall and winter. The rest of the year, available resources such as solar energy, irrigation water, residual fertilizer from the previous crops, and equipment are not fully utilized by the majority of the local farmers. The planting of a second 1

PAGE 18

2 crop could possibly utilize available resources during this period of time. Grains like corn ( Zea mays L.) and grain sorghum ( Sorghum bicolor (L.) Moench) are good second crop alternatives, because Florida is a net grain importer and the climate and soil are suitable for these crops. Several experiments dealing with the main problems observed in the Hastings area (soil fertility, bed and plant population management, and cultivar evaluations) were conducted during 1977 and 1978, both in farmers' fields and at the Agricultural Research Center (ARC) at Hastings, Florida. The main objective of the research was to determine management needed for growing corn and grain sorghum after the cabbage and potato harvest.

PAGE 19

LITERATURE REVIEW General Multiple Cropping The recent emphasis on multiple cropping as a useful tool in food production, could probably be attributed to Bradfield(6, 7). His work has spread to Asia, Africa, the USA, and Latin America. The advantages and possibilities of multiple cropping systems (intercropping, relay cropping, succession cropping, etc.) are well known and have been practiced for generations by subsistence farmers. Extensive reviews and detailed research reports on modern multiple cropping studies are abundant in the literature (13, 26, 45, 52), and therefore will not be considered here. Corn or Sorghum Following Vegetables In order to sustain its cattle industry, Florida must import grain. The area planted to corn in Florida was 204,120 ha and the total production was 769,745 metric tons (12) in 1977. Gallaher^'' has estimated that an additional 162,000 and 24,300 ha could be double cropped with corn and sorghum respectively by 1985. As early as 1959, Kretschmer and Hayslip (32) recognized the advantages of growing field corn following tomatoes and other highly — Gallaher, R. N. 1976. Potential for Multiple Cropping Growth. Mimeo report 9/1/76. Agronomy Department. University of Florida. 3 p. 3

PAGE 20

4 fertilized vegetables in south Florida. The authors pointed out that no P, K, or micronutrients need to be applied to the corn crop. In a later report Kretschmer, Hayslip, and Forsee (33) proposed that both corn and sorghum were good alternatives to follow winter vegetables and suggested that cattlemen who lease ranch land to tomato growers each year, can reap additional benefits by planting a grain or silage "catch" crop between fall tomatoes and summer pastures. In this way within 12 months the same field can produce tomatoes, field corn, and good quality pasture. Soybean ( Glycine max L.) peanut ( Arachis hypogaea L.), and southern pea (Vigna unguiculata (L.) Walp) were grown successfully as relay cropping after an initial crop of corn or sorghum in Florida (20) In this study it was concluded that irrigation would be indispensable for this particular cropping system. Akhanda et al (2) also studied relay intercropping systems. Peanut, soybean, pigeonpea ( Cajanus cajan (L.) Druce) and sweepotato ( Ipomoea batatas (L.) Lam) were interplanted in middles between rows of early, medium and late-maturity hybrid corn for two years. Interplanted crops did not affect corn grain yield in either year. Control of weeds and ease of harvest were more difficult than in sole planting, so the authors recommended double cropping where the growing season is long enough for successive cropping. Hipp and Gerard (25) indicated that in the lower Rio Grande Valley of Texas and northeastern Mexico two or more cash crops may be grown on the same location per year. They worked successfully with grain sorghum and cotton planted immediately after cabbage. In Georgia, Gallaher (lA) explored possibilities of triple cropping systems in which sweet and field corn as well as grain sorghum were

PAGE 21

interplanted in winter barley before it was mature. Third crops after corn and sorghuni included, among others snapbean ( Phaseolus vulgaris L.), and English pea ( Pisum sativu m L.). However, the most impressive system was one of barley followed by relay field corn and by a crop of soybean planted by the first week of July. Soil and Leaf Analyses The possibilities, advantages, and limitations of soil and plant analyses as tools for studying and predicting crop response are topics widely found in the literature. Different methods have been used in order to obtain meaningful correlations between soil and plant analyses values and crop responses. The most popular approach has been the critical level or the concentration of an element below which the crop yield or performance is decreased below optimum (62) Jones and Eck have criticized this method on the basis that it designates only the lower end of the analysis spectrum. Instead they have proposed the use of sufficiency ranges, the optimum element concentration range below which deficiency occurs and above which toxicity or unbalances occur (29, 30). This system of plant evaluation is in use in the University of Georgia Plant Analysis Laboratory. Plant growth and yields are functions of many variables beyond the single nutrient under consideration. Sanchez (52) quoting an earlier work by Pitts, points out that actual yields are functions of over a hundred variables, which can be grouped into soil, crop, climate, and management categories. The same author affirms that soil test correlations cannot predict yields or even absolute yield responses because of the many

PAGE 22

6 variables involved. However, he considers that a major breakthrough in soil test correlations occurred with the development of the CateNelson method. This is a graphic method which consists of plotting relative yields (percents of maximum) as a function of soil test values under a plastic overlay sheet divided into quadrants. The quadrants separate critical levels and soil with high and low response to nutrients. The "nutrient intensity and balance" is a soil testing procedure, developed by Geraldson (18) that measures the ionic equilibrium in the soil solution. The electrical conductivity of the saturation extract is used as an indicator of nutrient concentrations or intensity which can range from deficient to optimum to excessive for crop production. Specific cations or anions contained in the saturation extract are calculated as percent of the total salt concentratrlon and used as an indicator of nutrient balance. From 1955 to 1963 recommendations to establish a more favorable nutrient intensity and balance were associated with a 50% increase in tomato yield in Florida (18) Probably the latest approach to foliar analysis is the Diagnosis and Recommendation Integrated System (DRIS) According to Summer (57), the critical value and the sufficiency range methods are not able to deal adequately with the variation in nutrient concentration on a dry matter basis with age. The DRIS method, on the contrary, overcomes this difficulty because it is an holistic approach in which as many yield determining factors as are capable of quantitative or qualitative expression are considered simultaneously in making diagnosis. The yield-determining factors are characterized in terms of indices which are derived as comparable functions of yield.

PAGE 23

/ Most authors agree, independently of the methods used, that plant and soil analysis are definitely valuable tools and that their use should be extended. Engelstad and Parks (11) consider soil and tissue testing as being more important in the present age than ever before. The authors emphasize that these are the only ways in which soil fertility levels can be monitored and application practices adjusted, and finally state that the credibility of soil and plant testing must be maintained and protected. Fertility of Corn and Sorghum Fertility evaluations of corn and sorghum grown as monocrops have received considerable attention from agronomists (27, 28). An example of critical values for corn and nutrient sufficiency ranges for both corn (30) and sorghum (36), derived from many research studies, are presented in Table 1. However, when double cropping is involved, and if the previous crop is a well fertilized vegetable crop, the situation could be drastically different. The buil-up of P and K in soils is a relevant topic in this time of energy shortage. Engelstad and Parks (11) suggest a reevaluation of fertilization programs to make certain they mesh with soil fertility levels and crop needs. It is estimated that the recovery of applied P by crops during the year is between 5 and 20% and for K the value is from 30 to 60%. This leaves substantial quantities of fertilizer P and K in the soil (significant leaching losses occur only in sandy soils of low cation exchange capacity). The same authors quoting a 1940 report by Terman and Wyman point out that an estimate of 20% N, 30% P, and 35% K applied remained in the soil after removal of a potato crop.

PAGE 24

8 ^ 1 >-. 4-1 H B C Vj D •H 3 x: CC] 4-1 bE M 60 S O CO 4-1 CO / — s 4-1 n3 O *H 60 3 60 CO 4J U c 0) CO O u c e CO o o u 4J CO C CO 14-1 o 0) CO o 60 cu c rH ca O (-4 X) M-l ^ >-l CO a CO cu c ^ s tu 3 •H d ^ cfl O CO 6£ •i-t y-i >. U-l u w u D O C CO dl CM| •r-l 4-1 U-l O c CO •H o 0) M-( •H rH u 4-1 ^1 CO 3 CO CU c u C o 1-1 o o C u 1-1 o o o <4-l u CO o M-l O 4-1 d CO CO CO s-^ a) cd 0) iH > 3 CO .-1 0) (J CO S CO rt > O W u •H rH 4J cfl •H O M •H U 4-1 •H u i-H 4-1 c 0) OJ H E (U .H H w O CNI CO CM tH O rH CNl o o O o CO en o o CO I in o I o CO o iH I in I o CO in O o O <^ o o o cri o o o 1 1 1 1 B rH rH CO CO CNI o o 1 1 1 1 CO CNI oCO 00 in vD in rH in O CO o o O o in o O in o (NJ C3^ CNI in in in in CO o iH O o iH iH rH rH o O o O O •H in
PAGE 25

9 Engelstad and Parks (11) quoting a study by Cummings reported that North Carolina farmers in 1943 added to the soil by fertilization about 60% as much N, 430% as much P, and 158% as much K as was removed by the potato crop. In 1957 Terman (58) emphasized the increasing difficulty in finding sites sufficiently responsive to P to permit a meaningful comparison of P sources. Another possible cause of P and K accumulation is the habitual application of certain grades at the same rate over time, without regard for fertility levels. While some of this repeated application of certain ratios may reflect farmer reluctance to change, farmers simply may not have alternative choices in some states (11). Very recently McCollum (38) reported significant increases in total and extractable soil-P reserves when high rates of P were applied to potatoes over many years. While fertilization practices for other crops grown in rotation with potato reflect both plant demand and soil-test P, many producers continue to fertilize potatoes with little regard to crop requirements nor to existing soil P levels. If neither potato nor crops grown in rotation with them require such high rates of directly applied P, a considerable saving in fertilizer costs could be realized (11) Large initial applications of P to high-P-f ixing soils had a marked residual effect on maize yields 7 to 9 years after applications (31) Even when P was added in the row, maize yields were 50% higher where high rates had been applied 9 years before. No further increase in maize yields, reports Kamprath (31), was obtained when available soil P (0.05 N HCl + 0.025 N H^SO^ extractant) was > 8 ppm. A field study conducted by Powell (47) in Iowa showed that corn yields responded largely to applied N, with applied P and K having smaller and less consistent effects. Maximum

PAGE 26

10 yields were obtained with the first or second increment of applied N, P, and K in all years. Higher fertilizer rates had little additional effect on yields the first 2 years but caused' some decrease the third year. Cope (8) showed negative response of corn yield to high amounts of P applied during an 11-year period. Rates used were 22.4, 44.8, and 67.8 kg P per ha. In a Malaysian Tropof luvent Lim, and Shen (35) found that corn grain yield responded significantly to 100 kg/ha P and continued to provide enough P through the sixth corn crop. Grain yield, available P, and leaf P concentration relationships showed critical available soil test P at 25 ppm and P concentrations of the leaf at 0.27%. The influence of the previous crop and N application on yield of sorghum was studied by Hipp and Gerard (25) Tliere was a sharp increase in grain sorghum yield with 67 kg/ha of N if sorghum followed cabbage, but application of the same rate of N to grain sorghum grown on soil that had been fallow from August until March did not significantly influence grain sorghum yields. Increasing N rates to 134 kg/ha resulted in only a slight additional increase in yield. Apparently fall and winter temperatures are warm enough that N mineralization allows accumulation of NO^-N in the soil profile and may preclude a response from application of N. Double cropping corn or sorghum planted after other cereals are also popular cropping systems in the United States. The resulting nutrient relationships are found in several reports. Murdock and Wells (40) investigated yields, nutrient removal, and nutrient concentrations when corn was planted after barley ( Hordeum vulgare L.) and oat ( Avena sativa L.). Corn grown after barley, harvested in soft dough averaged 25% more yield than

PAGE 27

11 that grown after oat, harvested at heading. Fertility rates above 280-89-232 kg/ha of N-P-K did not significantly increase the yield. The average nutrient removal at the foregoing rate of fertility was 241-54260 kg/ha of N-P-K. One fact in this study was that the small grain accounted for 47% of the total K removed. Nelson et al. (43) planted corn and grain sorghum with or without tillage following winter wheat ( Triticum aestivum L .) or barley. Yields did not differ significantly for conventional tillage and no tillage plantings made on the same date. An application of 28 kg P and 168 kg K per ha each fall was sufficient to meet the needs of P and K for both crops. Nitrogen was supplied to either corn or sorghum at a rate of 224 kg/ha when the plants were 25 to 35 cm tall. In Georgia, Gallaher and Nelson (15) studied the soil fertility management of several double cropping systems. Wheat and barley were used as winter crops followed by soybean, corn, or grain sorghum. Results showed that effective fertilization should include lime, P, and K in the fall with incorporation to satisfy needs of both winter and summer crops. The authors also found that systems having small grain forage followed by the summer crops tended to reduce the soil pH, P, and K levels more than systems having small grain for grain. In general the double cropping systems were fertilized with less N and about equal or slightly more P and K than the sum of what would be recommended for the winter and summer crops if grown separately as monocrops. This last concept reflects an important aspect of a cropping system, the components are not additive but instead form a new unit with definable characteristics.

PAGE 28

12 Drainage and Irrigation Beds It is estimated that 90% of the world's farming area receives too little rain during the growing season. Of the other 10% some places get too much rain. Almost nowhere is rainfall ideal (55), In the Hastings area, annual rain of nearly 1,270 mm has a pattern that is not sufficient for the potato and cabbage crops. The reason is that half of the year's rain falls in June, July, and August (55), while potato and cabbage are grown from December to Hay. Local farmers have traditionally used a system of bedding and water furrows for drainage and irrigation. Each water furrow is slightly deeper than the alley between row beds which are crosscut to allow surface water to move to the water furrow. Drop pipes at the ends of the water furrow convey run off water to boundary ditches (49). Under this system irrigation water is supplied during dry periods to the water furrows to maintain the water table at 12 to 25 cm below the alley height at the midpoint between water furrows (22). In 1973 corrugated plastic tile drains were installed on the ARC on a trial basis. The drain tiles were used both for irrigation and drainage. One end of the tile was raised to ground surface to facilitate irrigation and the other end discharged into an open ditch. Reports by Rogers, Hensel, and Campbell (49) and Hensel (23) showed the advantages of this system. Potato yield increased by 56% (12% of this increase was due to increase in number of rows, since water furrows were eliminated, the number of beds Increased from 16 to 18), plants emerged about one week earlier over the drains, there was an improvement on water control, there were no water furrows to maintain, and potentially less water was used. A later report by Hensel (24) points out other important

PAGE 29

13 aspects of the tile drainage system: 1) yield increases up to 50% can be achieved during wet seasons; 2) the tile systems removed internal soil water in 12 hours as compared to 2 1/2 days by a conventional system; 3) planting or harvesting operations could be performed satisfactorily soon after a rain on tiled land. In a report by Bishop et al (4) the authors reviewed several aspects that have been related to the shape of the potato soil bed, like incidence of greening of potato tubers, differences in tuber-set and yield, soil temperature, drainage and infiltration of water, equipment design for application of chemicals, and cultivation and harvesting of the crops. The authors developed a profilometer to measure changes occurring in the potato soil bed profile during growth of a potato crop. Changes in bed cross sectional area were found to be closely related to changes in soil bulk density and air permeability on the Hesperia sandy loam from California. Allen and Musick (3) tested a wide bed-furrow system for irrigation of winter wheat and grain sorghum on a slowly permeable clay loam in the Southern High Plains (Texas) The system consisted of 152 cm spaced furrows separating relatively broad flat beds about 100 cm wide compared with conventional 100 cm bed furrows where wheel traffic occurs in irrigation furrows. Yields were not different. Water intake during irrigation of wide bed-furrows averaged 23% less during three spring irrigations, and 19% less during two seasonal irrigations of grain sorghum. In an earlier study, Musick and Dusek (41) reported a 15% yield increase when growing grain sorghum and winter wheat in alternating 203 cm field beds with adequate irrigation. The increased yields on strip-planting plots

PAGE 30

14 was believed to be associated with increased light interception, although increased soil water availability may have been a factor also. In Arkansas, growing cotton in narrow rows on permanent wide beds is a very common procedure. However, it is understood from the beginning that a farmer could not be expected to adopt permanent wide beds for his cotton acreage unless the same cultural system could be used for his other crops. Parish and Mermond (46) reported successful crops of soybeans, grain sorghum, and corn planted in the wide beds. There was no loss of yield; indeed, yield was increased in some years. Good results were also obtained by Nolte (44) in Ohio. Corn yield planted in beds was 4778, 6048, and 6411 kg/ha when the drainage system was by surface only, tile only, and surface + tile respectively. The effect of mulches and bed configuration was studied by Adams (1) in Texas during 2 years. Bed configuration had a significant effect on sorghum growth when used with mulches and caused a significant increase in grain sorghum during the first year but not during the second. Cultivar Experiments Cultivar experiments are one of the most popular and useful research tool available to agronomists. The Agricultural Experiment Stations in Florida do cultivar evaluations on a continuous basis for all major crops planted in the state. The Florida Field and Forage Crop Variety Report (64) is publislied for reference use only, while Agronomy Facts (65) sheets provide specific recommendations for use of cultivars. In the case of corn, the hybrids recommended have been evaluated in station trials for at least two years. In addition to yield, standability ear

PAGE 31

15 quality, husk cover, ear height, and insect resistance are also evaluated. Sorghum trials include yield performance, bird resistance, plant height, and number of days to bloom. Sorghum and field corn production guides (27, 28) are also published and include cultivar suggestions. Cultivar experiments are also conducted for specific purposes. Green (19) gave a detailed report on yield and digestibility of 41 grain-sorghum birdresistant and non-bird-resistant hybrids. Comparative trials using both corn and sorghum varieties were reported by Dunavin (10) and Lutrick (37). Sometimes sorghum outyields corn and vice-versa depending on conditions and purposes of the studies.

PAGE 32

MATERIALS AND METHODS The area near Hastings, Florida (29 43' N 81 30' W) includes farm land in St. Johns, Flagler, and Putnam counties. Most of this land is about 3.0 m above sea level and from 16 to 32 km from the coast. The annual rainfall is nearly 1,250 mm and usually half of this amount falls during the summer months. This area normally produce an estimated 9,300 ha of potato and 5,300 ha of cabbage. This full area is potentially suitable for growing corn and grain sorghum in double cropping systems. Potato is grown from January to May. Cabbage is grown over a much wider season; however, most of the cabbage crop is produced for harvest in March. Three different types of experiments were conducted: fertility, bedding, and cultivar experiments as described below. Fertility Experiments Two corn and three sorghum fertility experiments were planted in 1977; one corn and one sorghum fertility experiment was planted in 1978. Location, planting and harvest dates, hybrid used, row spacing, number of replications, and type of drainage are given in Table 2 for each of the studies. In all locations experiments were planted in Rutlege fine sand (Sandy, Siliceous, Thermic family of the Typic Humaquepts) which had previously been either in cabbage (the corn experiments) or in potato (the sorghum experiments) production. 16

PAGE 33

17 00 T3 C 60 •H ^1 3 13 W U C Q) a •H (J 01 a. y, 01 o c o •H 4-1 B o 1/1 PQ CM CU r-l nJ H OJ 60 (13 •r4 tfl O 01 Z ^1 s u 601 S C O -H Od O P. C (J 4-1 to 0) 60 c H 0) 4-1 4-1 K x: x; u 0) o 0) 0) 0) 4-1 t-( 4J iH rH •H •H •H •H •H •H •H 4J 13 4-1 13 4-1 4-1 W o o 00 in o o o o o o o o in CM XI CO arm c >4-l 0 o M •H 4-1 cfl 4-1 IM c 4-1 CO o O 13 CM 13 13 O •r^ •H •H iJ 0) 0) 1-1 o o o in ^ >^ >s 4-1 4J 4-1 •iH •H •rl rH rH rH o 4-1 4-1 •H •H •r( 4-1 •iH H 4-1 •u 4-) •H iH rH M )-l H rH 4-1 •H •H 0) OJ 0) •H c iJ U iw 14H iw 4-t U M B Q) 0) B 0 00 Cfl CU •H U-l 14-1 J 3 c > 14H U j=; H rl CU C c 60 60 60 13 4J c a U (J )H >-l 13 rH X O o O O o OJ 3 o w U CJ CO r} •H o U O O cfl O rH > rH <}• -Jin in 1 Pi 1 oi CO PQ 13 •rl 2 0) o C_) 4-1 •H 4-1 IJ CU 14H § 60 U O CO Cfl Q 00 00 00 rH rH rH CJ^ C3^ 00 c •H 13 13 CU CQ 00 rH as o CM CM rH CM \0 vO C_) > •rl 4J rH 3 U

PAGE 34

18 A A X 2 factorial in a randomized complete block design was used in all fertility studies, with 4 replications at the ARC and 5 replications in farmer's fields. Four N rates (0, 100, 200, and 300 kg/ha), 2 P rates (0, 60 kg/ha), and 2 K rates (0, 60 kg/ha) were used in all combinations. Plots (10 m X 5 m) had 6 rows in all cases but only the 4 middle ones were used to collect samples or to determine yield. The land was listed and disk harrowed before the 1 m drainage beds were built using a conventional "bedder." Planting was done with a double hopper tractor. Fertilizer was applied by hand on top of each row. Nitrogen was applied in two equal amounts, at planting and 4 weeks later, P and K were applied all at planting time. Farmers performed normal cultural practices like bed formation, planting, and cultivation; however, weed control and irrigation were not satisfactory during 1977 and affected crop yield potential. At the ARC all operations were better controlled and monitored by field personnel. Insect pests were particularly serious in 1977; this made it necessary to replant experiments No. 3 and 5, and prompted the application of insecticides. A list of pesticides used during both years is presented in Table 3. In all fertility studies soil samples were taken from each replication before planting and from each experimental plot before harvesting. Ten cores were collected from a depth of 0 to 18 cm, the samples were air dried, and passed through a 2 mm stainless steel sieve. Soil extraction was done by means of the double acid procedure or North Carolina extract (51). Five grams of soil were weighed and extracted with 20 ml of

PAGE 35

19 Table 3. Pesticides used and dates applied during 1977 and 1978 Experiment No. J^/ 3 4 5 6 7 8 9 10 11 Pesticide y 1977 1978 Paraquat 7/5 Paraphos^^^ 7/27 Methamidophos^'^'* 7/7 7/11 7/11 7/11 Methomyl HI'S, 7/21 Carbaryl 9/22 9/21 9/22 Atrazine ^^^+ propachlor (g) 6/20 6/19 6/22 Carbofuran
PAGE 36

20 0 05 N HCl + 0.025 N H^SO, for five minutes in an Eberbach mechanical — — 2 4 reciprocating shaker (160 oscillations/minute). The extracts were filtered through Whatman No. 6 filter paper and stored in 25-ml vials under refrigeration until analyzed for P, K, Ca, Mg, Cu, Zn, Mn, and Fe. Phosphorus was determined colorimetrically using a Technicon Auto Analyzer. Potassium was determined by flame emission photometry and the rest of the elements were determined by atomic absorption spectrophotometry. Soil pH was measured for each sample using a Corning glass electrode potentiometer and a 1:2 soil to water ratio. The 50 ml mixture was stirred, left standing for one half hour, and stirred again prior to reading (51) Corn leaf samples were collected during the early silk stage, the complete earleaf was taken from the lowest ear on 10 plants per plot. The same procedure was followed in the sorghum experiments with the difference being the type of leaf collected, in this case 10 to 15 leaves were taken per plot, usually corresponding to the third leaf from the top. Forage samples were taken at harvest from each plot during 1978. Two 8 m long rows of corn or sorghum were cut at the base and the total fresh weight recorded. A smaller sample, 4 or 5 plants, was also weighed in the field, then dried in forced-air forage dryers at 65 C for a minimum of 48 hours, and then weighed again in order to determine dry matter content in each plot. Leaf samples were ground (pulverized) in a Cristy Norris Mill to less than 1 mm particle size, then mixed thoroughly after grinding and kept in airtight sample bags. Forage samples were chopped in a mulching machine, 'Mighty Mac' (Amerind MacKissic) and subsampled before they could be ground in the mill.

PAGE 37

Nitrogen analyses were done following accepted procedures described by Gallaher (16). A 100 mg sample of the ground plant tissue was placed into a 75 mm pyrex test tube along with 3.4 g of prepared catalyst (90% anhydrous K^SO^ + 10% anhydrous CuSO^), two or three Alundum boiling chips, and 10 ml of concentrated H^SO, The contents were mixed and a total of z 4 2 ml of 30% H2O2 was added immediately in 1 ml increments. Small funnels were placed on top to recondense liquids into the test tube. Samples were digested at 385 C in a 126 sample capacity aluminum block (17). After cooling, samples were stirred in an automatic mixer and the solution was then diluted to 75 ml with distilled water and analyzed with a Technicon Auto Analyzer. Phosphorus, K, Ca, Mg, Cu, Zn, Mn, and Fe were analyzed by routine methods (63) One gram of plant sample was placed into a 50 ml pyrex beaker and ashed at 480 C for a minimum of 6 hours. A small amount of distilled water and 2 ml of concentrated HCl were added to the ash and this mixture was gently heated on a hotplate until dry. Following this, another 2 ml of concentrated HCl were added with about 15 ml of distilled water. This mixture was covered with a watchglass and digested for onehalf hour before being diluted to 100 ml and stored in a plastic vial. The stored dlgestate was approximately .1 N HCl. Phosphorus was determined color imetrically, K by flame emission photometry, and Ca, Mg, Cu, Zn, Mn, and Fe by atomic absorption spectrophotometry. The revised two-state in vitro organic matter digestion (IVOMD) procedure was done on all forage samples (39) The technique involves a 48 hour fermentation by rumen microorganisms followed by a HCl-pepsin digestion. Separate aliquots were analyzed for organic matter content in the sample and for residual organic matter after the fermentation-digestion.

PAGE 38

22 The amount of organic matter disappearing was considered to have been "digested." The statistical analysis included an analysis of variance for all responses, analysis at different levels of one factor when significance was found, Duncan's multiple range tests to compare means, and correlations between nutrient concentration and content in the soil and in the plant. The statistical model was: YijU = )jy+ p£ + ai + 6j + 8k + (a3)ij + (6y)jk + (a9)ik + (a83)ijk + eijkJl where YijkJl = response pi = l^^ block effect ai = i^h nitrogen effect 3j = j*"*^ phosphorus effect 9k = k'''^ potassium effect (a6)ij = ij nitrogen-phosphorus interaction effect (a8)ik = ik nitrogen-potassium interaction effect (a69)ijk = ijk nitrogen-phosphorus-potassium interaction effect eijk£ = error term Bedding Experiments Initial observations indicated that the use of the 1.0 m previous potato beds caused an apparent waste of space and yield reduction for the sorghum crops. To test this hypothesis two bedding experiments, one in 1977 and one in 1978, were designed and conducted at the ARC. The 1.0 m beds were modified and 1.5 m and 2.0 m beds were built and a total of 16 treatments were imposed on them (Table 4) Land was prepared In strips to facilitate tlie use of machinery. Each one of the four replications had a strip of land that included the 3 bed widths and thus the 16 treatments. Building the 2.0 m beds was relatively easy and it was accomplished by removing every other 1.0 m

PAGE 39

Table 4. Treatments imposed on the bedding experiments, 1977 and 1978. Treatment No. Bed width (m) Arrangement 1 1.0 One row (control) 2 1.0 Double row narrow (15 cm) 3 1.0 Double row wide (25 cm) 4 1.0 Broadcast 5 1.0 Single row in flattened bed 6 1.0 Double row in flattened bed (25 7 1.0 Broadcast in flattened bed 8 1.5 Three rows 9 1.5 Four rows 10 1.5 Five rows 11 1.5 Broadcast 12 2.0 Three rows 13 2.0 Four rows 14 2.0 Five rows 15 2.0 Six rows 16 2.0 Broadcast

PAGE 40

24 bedder. The 1.5 m beds required a narrower tractor with a wheel spacing. In order to plant 2 rows in the normal 1.0 m beds they had to be knocked down slightly on the top. Sorghum planters were offset 7.5 and 12.5 cm from the center of each bed and planted twice in order to achieve the 2 narrow and wide rows. Soil samples were taken from each replication. They were prepared and analyzed in the same way as the samples of the soil fertility experiments. A total of 222 kg NH^NO^/ha was applied to all treatments 4 v;eeks after planting. Specific information on planting and harvest dates, cultivar, drainage, herbicides, and insecticides used is presented in Tables 2 and 3. During 1977 handweeding was done on the 1.5 and 2.0 m beds; in 1978 weed control was satisfactorily accomplished by the use of herbicides (Table 3). Whole plant samples were collected at harvest time and dry matter, IVOMD and nutrient analysis was done as previously described for the fertility experiments. Grain yield, plant height and plant population was also recorded and included in the statistical analysis. Due to a severe sorghum "midge" ( Cantarinia sorghicola (Coquillet)) damage, an insect that affects grain formation, grain yield in 1977 was estimated by running a correlation between grainless heads weight and heads with grain from a healthy field of the same cultivar. The experiment was a nested split-split-plot arrangement of treatments in a randomized complete block design v/ith 4 blocks. Arrangements within beds were nested and correspond to the first split; years make the second split. The statistical model was: Yijk£ = uy + p£ + ai + ea£i + 3j (ai) + ebJij(i) + 3k -kxdik + 68jk(ai) + Ec£k(m) where Yijkl = response

PAGE 41

25 m=l,...,^eiji =16 ji = 7, 22 = ^^ j3-5 ai =1 bed effect 0j(ai) = j^^ arrangement within 1^^ bed effect 9k = k^^ year effect ea£i = (pa) £1 ebS,j(i) = (P3)iij(al) ec£k(m) = p3£k((3a)m) Cultlvar Experiments Considering the potential of the area not only as a grain but also as a forage producer, two cultlvar experiments, one in 1977 and one in 1978, were conducted at the ARC. A list of the cultivars tested for both grain and forage, is shown in Table 5. Cultivars were planted using a composite split-plot in a randomized complete block design with 4 replications, the split corresponds to years. Planting was done on the usual 1.0 m beds and treatments were fertilized with a total of 222 kg NH^NO^/ha 4 weeks after planting. Planting and harvest dates as well as drainage, herbicides, and insecticides used are shown in Tables 2 and 3. Soil samples were taken from each replication before planting and whole plant samples were collected at harvest time. Grain yield (when applicable), and dry matter yield, were recorded for most varieties. A combined (2 year) statistical analysis as well as separate analysis per year was conducted using the following models: Yij£ = y + p£ + ai + eaai + 3j+a3ij + ebj£(i); 2 years Yi = yi +pJJ.i + aii + Ciii; 1 year where Yij£ and Yi = responses cai£ = apifc abj£(i) = 3pj!i(ai) ai = ith variety effect, i=l,...,5 3j = j"^^ year effect, j = 1, 2

PAGE 42

26 Table 5. Cultivars tested at Hastings during 1977 and 1978. Brand and hybrid Brand and hybrid Number 1977 1978 1 Dekalb FS-25A Dekalb FS-25A 2 Northrup King NK-121 Northrup King NK-121 3 Dekalb C-42Y Dekalb C-42Y 4 Dekalb BR-54 Dekalb BR-54 5 Dekalb D-60 Dekalb D-60 6 Dekalb FS-24 Dekalb FS-24 7 Dekalb A-26 Dekalb A-26 8 Dekalb E-59 Grower ML-135

PAGE 43

RESULTS AND DISCUSSION Precipitation and temperature data for the area during 1977 and 1978 are show in Table 6, There was a marked difference In precipitation, 1977 being considered a very dry year (58). Fertility Experiments in 1977 Corn Experiments No. 1 and No. 2 had low yields (Tables 11 and 12). This was the result of poor weed control and water management by farmer cooperators. Soil analysis data before planting showed low pH values, and high P and Ca concentrations which provided an insight on the natural fertility of these soils and the previous vegetable fertilizer practices (Tables 7, Significance of variables according to the F test and nutrient concentrations in the soil and leaves are presented in Tables 9 to 14. Increasing rates of N caused a drop in pH values. This was likely due to the release of hydrogen ions (H+) when ammoniacal and most organic N fertilizers were converted to nitrates (65) Higher rates of N and P applied to the soil lowered the concentration of Ca in experiment No. 1 and increased that of Mn (Table 15). A K defficiency was observed in the leaves reflecting the low soil K test. The addition of K fertilizer Increased significantly soil test K, but not K concentration in the leaves Higher N rates also increased N and Cu concentration and decreased Mg concentration In the leaves. In experiment No. 2 the higher rate of K (60

PAGE 44

28 •a o OJ u CO w 60 C •H 4-1 W TO 00 ON c TO l-i O TO -a c o o. •H O Q) t-l a p 4-) TO i-i a) a e OJ H o H U OJ Q > o o o CO 00 < 0) c TO TO C TO On 00 O CN CO CN 00 CO CN 00 00 CN -3CN TO H CO O CN CN o CJN o a e 01 H CO CM 00 o o c^ O CN 00 ^1 OO r-. cjN rH 00 0\ CO CM I — CN CN o X3 CTv C 01
PAGE 45

29 Table 7. Soil analysis before planting. Com fertility experiment No.l, 1977 Rep pH P K Ca Mg Cu Zn Mn Fe ppm I 5.3 416 76 1254 72 4.9 12.3 6.1 83 II 5.2 460 103 1406 92 5.9 9.3 6.9 88 III 5.2 484 159 2000 164 6.5 10.5 8.6 100 IV 5.3 498 113 1432 76 5.6 10.0 6.4 85 V 5. A 488 113 1334 100 5.3 9.6 6.2 94 X 469 113 1485 101 5.6 10.3 6.8 90 Table 8. Soil analysis before planting. Corn fertility experiment No. 2, 19 77 Rep pH P K Ca Mg Cu Zn Mn Fe ppm I 4.7 297 71 858 35 1.6 5.8 5.6 50 II 5.1 194 70 490 27 0.8 3. 7 4.7 37 III 5.0 570 157 1678 148 2.4 8.8 9.4 69 IV 5.0 418 88 1176 73 2.0 7.3 6.7 60 V 5.4 238 124 642 40 1.0 4.2 4.9 58 X 343 102 969 65 1.6 6.0 6.3 55

PAGE 46

30

PAGE 48

32 u (U > u 6 a o cn o •H 4-1 u c QJ o c o a c •H M 4J D 2 H 1^ PL, c xi w C u to dj ^( 00 CD CN CN O 00 00 O CN o vD CO r-l vD CO
PAGE 49

33 ON o c e •H U 0) tx X o o •H O W OJ x: c •H c o •H 4-1 Cfl U 4-1 C 0) a c o o c 3 C •a c re a rH •H c •H e p. 0) 4-1 c O C O O C OJ •H 4J D C T3 ct! •H -H jz: CO OJ h -H t)0 ^1 4J iH c OJ B 01 4-1 rH ra ,o n) i-i H H 00 i^ o CM 00 CM CM in 00 CO CM 00 CM CM o rH O rH in rH rH m 00 00 00 00 CNI 00 in rH vO 00 x> r-~ rH 00 CM 00 rH rC\l rH a\ in
PAGE 50

34 •H 4-1 tfl CO 01 > cu c o ca 4-1 (1) a d o o 2; PL, 4-1 CO C iH 0) B PL, QJ 4-1 r-l ro J3 Cfl H H tN a. o -JI vO I CN O O 00 ON o o o CM o n CN CN o CN CNI CM 00 CN CN o CN 00 CN in 00 00 O o II c 0) -, ta o o a pu rH cn 0) D O rH <0 t>i >

PAGE 51

35 0) 1 1 00 o 00 o tN O CN O CN O CN O << 1 nj 0) 1 iH 1 00 vD o

PAGE 52

36 Table 15. Effect of N and K on concentration of Ca and Mn in the soil at 2 levels of P. Corn experiment No.], 1977. Ca Mn N P = 0 P=60 P = 0 P = 60 kg/ha kg/ha kg/ha ppm 0 1691 a 1623 a 7.25 ab 6,54 b 100 1539 b 1633 a 6.78 b 7.77 a 200 1553 ab 1621 a 7.42 ab 7.57 a 300 1573 ab 1427 b 7.70 a 7 24 ab K 0 1611 a 1580 a 7.42 a 7.44 a 60 1568 a 1572 a 7.15 a 7.11 a Means within each column for N or K treatments followed by different letters are significantly different according to Duncan's multiple range test.

PAGE 53

37 (60 kg/ha) increased the K concentration in the leaves at 0 level of N but not at the 100, 200 or 300 kg/ha levels (Table 16). However, K concentration in the soil decreased when going from 0 to 300 kg N/ha. Higher N rates increased N, P, Cu, Mn and Fe concentration in the leaves, however an opposite effect was observed for Mg concentration (Table 17). The 60 Kg/ K/ha rate caused a decrease in Mg concentration in the leaves accentuating the Mg deficiency observed in this experiment. Possibly most of these changes could be attributed to changes in balance of nutrients, since it has been shown that plants under uniform environmental conditions tend to take in a constant number of cations and anions (62) Correlation coefficients for soil test and leaf nutrient concentrations were not consistent for the corn experiments in 1977. In experiment No. 1 (Table 18) Mg and Mn in the soil were positively correlated with Mg and Mn in the leaves, the R values were 0,32 and 0.37 respectively. Manganese in the soil was also positively correlated to the concentration of Ca in the leaves. However, the R value of 0.23 was also very low. In experiment No. 2 Mg in the leaves could be a good predictor of P, Ca, Mg, Cu, Zn, Mn, and Fe in the soil, positive correlations and R values ranging from 0.48 to 0.68 are presented in Table 19. Some of these results differ from those of Dingus and Keefer (9) who found that Mg, Mn, and Cu accumulation in plants was reduced by the presence of Zn in the soil. Phosphorus in the leaves was also positively correlated with Cu, Zn, and Mn in the soil (Table 19). There is disagreement again with several authors (50, 53, 54, 56) who report Zn deficiencies being accentuated by P. Sorghum Sorghum experiments No. 3 and No. 4 were also located on Farmers fields and were planted on tile and ditch (subfurrow) drained land,

PAGE 54

38 T3 C H-i O c o •H U n) ^1 4-1 c dJ o c o o c o 00 OJ ON > rH H eg 4-1 • C (U 0) o is •H c e •H >-l 0) a c n O O X) c Pi tH o x: o c (1) -H W U O H j (11 o j oO o to Co rr( Co Oh j *H 0^ ** It j CO rH P-4 j p 1^ j o I—' R j CO I j PJ O rrt I'O ] ni rri TO r" 1-1 Q j O Cn R 11 j CO f— 1 I \ j Cfl j o O O O O 1-4 j 4-J • CO I-! I /II C 4-J U o •H ct3 o j rrt rri TO Co CJ 1 — 1 j >-i O j 1 — t O O tj^J II [ CO CJ QJ r*** [ ACT^ <-* O -M 1—1 { 4-* } •H CM d) [ lu TO rrt TO ^ fi O j ni n\ j 0^ OO LO *-M QJ ClJ II CO CO CO O o o o (U CO CJ QJ E CO — c t— i CJ o j s ^ •H o [ TO rH TO Co rrt TO Co I— j u ?s CO [ r 1 /-X y o CO QJ Oi Oi vO CN 'H CJ 11 1 CN| CM CO r^ M 1 [ rvi CN ro CN o j tiO si j n 4_i (-• M [ CO .H rrt Co [ QJ ^ TO r* CO ci3 rrt 10 CN] j 00 frt m 10 XJ lO CM •> C^ 11 II CN CO CO B •T^ flj 1 CM pH i~H [ CN CM CJ Q) [ tl CJ O j j CO o 1 rH C o 1 Cj Co Co Co CJ 'H I— 1 > [ 0^ CO QJ II I— 1 CNI CM 1— 1 iH 1 OJ (0 2: 1 -l ill o o cd CJ Qj rrt 10 rrt 10 X cd 1 1 1 1 CO 4-1 1 1 ,_j rH 1 r-1 c 1 1 (1) 1 1 U 1 cu j 1 1 1 j 1 •H 1 X) 1 J r\ cd cd CO 1 >, 1 &^ LO 00 o j t\ CO CO CO 4-1 C rH I j 1 1 CTJ O 1 U o •H 4H c 1 H •H 1 (J cd cd J3 j 00 4-1 1 1 CM CO 1 •iH •H Z 1 1 O CO :s j 1 CM CM CM CM Q) (U U XI CO CO CO a 1-'-' 1 t-Q Cd cd cd 01 1 1 4J 1 1 Mn 1 1 uo CM 4J 0) Id 1 1 uo in m tH =) j o j 4J j B C CO 1 X5 CJ cu P-> Co cd XI o V4 to rH (U c •H 1 00 o o UH o O 1 • • • U-l CO CO 1 00 rH I — 1 •H •H 1 XI u j CO a cd o XI o T3 XI OJ u o < rH CM rH 00 o a. iH 4-1 UO
PAGE 55

39 CO c o •H 4J CO U 4J d 0) u c o u c 1-! U *J 3 C CO 0) O to U O W CO 4J c •H rO CJ^ •H .H >4-l M-l (U iH O • C3 O 4J •H C to e OJ l-i u o; O X U 0) 00 H II -Z (I C^ • — :^ "ST L' • w cc •r C O Cf' r-j L' — o o c c o 2 N C CTj — c L-C OCT o .• o w — n r o-n o — • c o o o I -< c o • o o c c • • o c I c rv c .. c I — • • c o -< IL CN.' ^ T O r a U.' c O ro .' n < O c o cr -c L': o • z. o • c • o O r^ rw 0 in ar, t>. L', K Z L'! O OD • '0 • o • O • z> o w 1 => rr-.
PAGE 56

40 o c o M u s o o a; 3 C CO XI c t5 o 03 o CO c •H r•H r-l QJ CM O • u o z c O -U •H C 4J Q) CO E M G CC H rv C X C. 7*^ — f 2 ~ ^ -cr 3 ^ Cv X w • **. • r* e • o • o ^ O ^ • T" 1 1 1 1 z r\ CC' o w f\; !\: C c ^ *" — r L'. — J — ^ r c • c • ^ • D a O f c • ~T • o • c • o o • O • o • o ~ o o o o o I 1 ( o r.' r; ro tV IT cr; c c o ih o IT. in o (V — u. ro o — r\j o li ^ fr L O O L'^ . ^ o — o c ^ Ir^ ^ • o • CM • c — ^ • ^ 0 O 9 o • • o • o o • o • c • O • o • o o o o o o o c u 1 1 CC ca c c Cu,

PAGE 57

41 respectively. Management problems such as weed and water control plus a heavy infestation of sorghum midge caused grain yields to be low (Tables 20 and 26). In experiment No. 3, N was an important factor responsible for differences in the concentration of N, Ca, Mg, Zn, and Mn in the leaves as well as for differences in dry matter yield. Other significant effects and interactions are presented in Table 21. Further analysis showed that when no K was added to the soil the different levels of N or P caused no differences in grain yield; however, when 60 kg/ K/ha was included in the fertilizer program, the addition of P caused a significant yield decrease (Table 22). This finding has been reported in the literature before (59) and possibly could be attributed to salinity problems. The effect of N levels on the concentrations of N, Ca, Mg, Zn, Mn in the leaves and dry matter yield is presented in Table 23. In all cases higher levels of N increased the concentration of the element and the dry matter yield. Terman and Noggle (61) found similar results when working with corn, in this case N caused an increase of P, Ca, and Mg concentrations in the leaves and a decrease in K concentration. The authors point out that these opposite trends indicate the reciprocal relationship between concentrations of K and Ca + Mg in plants. Differences caused by levels of P and K on Ca and Mg concentrations are shown in Table 24. Additions of P increased Ca concentrations and addition of K decreased Mg concentration. This latter relationship has been discussed before by Terman, Allen, and Bradford (59) who found marked reciprocal relationships between K-Mg, K-N, K-P, and K-Ca, and attributed them to ion antagonism. The K-Mg effect, the authors report, was most pronounced at higher K rates, no additional yield response occurred and resulted in

PAGE 58

42 0) P 1 CO 00 CN o o CO CM O vD 00 CN 1 CX3 CO 00 o> 00 00 00 O o 00 O [ j rH rH rH rH e j j o 1 O rH O o o O (N H i C^J CO tH o CO id erj I 1 CNI Ml 0^ iH o VD LO o 4J 1 CO CO Cm CO CO lO LO lO LO v£) C C O 01 *H o 4-i c I — 1 1—1 0^ tH 0^ LO vT lO LO rH LO CO O cd o W 1 CNl CN CNJ iH CM CM CN CM CN CN CN CM CO CN CM CO H o 1 O o C_J O O o O o O O o O O O o o c 4-1 c u 0) c •H o -l 1 00 CO CO o 00 CTn H f CM u 4J nJ 1 CN CN CN CN CN CM CO CN CM CM CN CM CO CN CO CO 3 O Z 1 o O o O O O o O o o O o O o O O c (!) j •H 1 1 1 CN 00 o CM CM o O s I CO CN CO CO CN CO CO ^ 1 1 0) 1 c^ UO O CO CO CO CTn LO lO •W 2: 1 'vD Ln 00 CT o 00 tH o CTn CM -t-J (13 On u 1 iH iH iH iH H iH rH r-i rH rH CNl rH CN CN rH CM e 1 — 1 0) 4-t >, 4J "O CO n n3 iH T3 E 0) iH C7\ iH C7N 00 o \0 r-. o CO CO o •H to CN CJN CO •^ 6 C C U n) 0) CN 00 -cT LO CO CN

PAGE 59

43 OJ r-l H U U P nJ B C t3 •r-l iH rd QJ O o u 3 o CO o o o o < o o o o 00 n o o o o o in o o o in m n o 00 rH rH o o o o o o H ^ ^ ^ Dc; H H ?S PL, H H H

PAGE 60

44 Table 22. Effect of K levels on grain yield at different levels of N and P. Sorghum experiment No. 3, 1977 N K = 0 kg/ha K = 60 kg/ha kg/ha kg/ha 0 319.1 a 301.2 a 100 286.5 a 273.5 a 200 336.0 a 360.4 a 300 346.2 a 346.2 a P 0 313.0 a 357.7 a 60 330.8 a 282.9 b Means within each column for N or P treatments followed by different letters are significantly different according to Duncan's multiple range test Table 23. Effect of N levels on the concentration of nutrients in the leaves and in dry matter yield. Sorghum experiment No. 3, 1977 Ca Mg Zn Mn Dry matter kg/ha % ppm kg/ha 0 1.61 c 0.26 b 0.21 c 37.8 b 20.6 c 3867 b 100 1.82 b 0.28 b 0.25 b 42.3 b 25.1 b 4102 b 200 1.95 b 0.28 b 0.25 b 55.5 a 28.5 b 4789 a 300 2.12 a 0.32 a 0.29 a 54.2 a 30.4 a 4890 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 61

45 Table 24. Effect of P and K levels on the concentration of Ca and Mg. Sorghum experiment No. 3, 1977 p Ca K Mg kg/ha % kg/ha % 0 0.27 b 0 0.26 a 60 0.30 a 60 0.24 b Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 62

A6 decreased Ca, Mg, or P uptake. Soil test before planting (Table 25) may also help to explain some of the above mentioned relationships. Experiment No. 4 grain yield, pH, soil test, and leaf nutrient concentrations are presented in Tables 26 and 27. Statistical results are shown in Table 28; N, and P to a lesser extent caused significant changes in several elements. Further analysis indicates that P increased Mg concentration at the higher level of N (Table 29) and that the addition of K fertilizer decreased Ca concentration in the leaves when no P was added (Table 31). In the soil only Zn and Mn were significantly affected by levels of N. The 200 kg N/ha rate increased the concentrations of Zn and Mn in the soil. However, the lower and the higher levels produced the opposite effect (Table 30) A similar relationship was reported by Soltanpour (54) who found that Zn increased protein and nitrate N as a percentage of total N when applied together with N. The correlation coefficients for soil test versus leaf nutrient concentrations (Table 32) differ from the previous corn experiments. In this case Ca in the leaves was closely correlated to the concentration of P, Ca, Mg, Cu, Zn, and Mn in the soil. Magnesium in the leaves was negatively correlated with K, Ca, Mg, and Zn in the soil. Copper and Zn were also negatively correlated. This last antagonistic effect has been reported before (34) Sorghum experiment No. 5 had good overall management. However, a severe Infestation by sorghum "midge" precluded getting higher grain yields. Total dry matter showed that marked differences occurred among the N levels. Yields, pH, soil test, and nutrient concentrations in the

PAGE 63

47 Table 25. Soil analysis before planting. Sorghum experiment No. 3 (tile drained) 1977 Rep pH P K Ca Mg Cu Zn Mn Fe ppm I 5.5 100 153 818 116 0.36 2.6 2.3 69 II 5.3 142 149 820 100 0.28 2.6 2.6 54 III 5.3 124 156 740 92 0.20 2.7 2.2 56 IV 5.5 97 149 598 84 0.20 2.1 1.9 54 V 5.2 101 186 740 116 0.20 2.7 2.7 66 X 113 159 743 102 0.25 2.5 2.3 60

PAGE 64

48 •V iH QJ •H C •H n) w > u OJ •H U 3 2: C -O CO •H 1-1 rt at u C CN 00 00 CN vO CM tH o a\ iH in 00 o C^J o o On 00 ^ CO iH o o o o o O o O o o o o o o o o m CO CN in 00 in CN CM CO O ON CN eg ro ^ CN CO CN CO CM iH CN CM Csl rH rH rH CN rH LO in m in in in in m in m in in in in in H 00 CO in CN o o rH rH CJN CO in o
PAGE 65

49 CNI 00 CM 00 00 00 00 Csl o 00 O Csl a^ 00 CN O 0^ in o 00 00 00 00 1^ ON 00 o o O 0^ ON 00 O e a a.
PAGE 66

50 c "a in o o CNI V0 O o c 3 CO o PL, T3 1 o iH QJ I— 1 pH o CNI o c O o •H • nj o o M o •H 4J ro CO CM n) >-l O 4-1 c o C o o •H c CN 4-1 o cd a o o 4-1 0) c 4-1 o
PAGE 67

51 Table 29. Significance of percent Ca and Mg in the leaves at 4 levels of N as determined by the F test. Sorghum fertility experiment No. 4, 1977 N = 0 kg/ha N = 100 kg/ha N = 200 kg/ha N = 300 kg/ha Source D.F Ca Mg Ca Mg Ca Mg Ca Mg Rep 4 TP 1 0.0225 TK 1 TP X TK 1 0.00019

PAGE 68

52 Table 30. Effect of N levels on the concentration of Zn and Mn in the soil. Sorghum experiment No. 4, 1977 N Zn Mn kg/ha ppm 0 4.10 b 3.72 b 100 4.04 b 3.77 b 200 4.72 a 4.30 a 300 3.93 b 3.63 b Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns Table 31. Effect of K on Ca leaf concentration at 2 levels of P. Sorghum experiment No. 4, 1977 K P = 0 kg/ha P = 60 kg/ha kg/ha Ca % 0 0.596 a 0.505 a 60 0.454 b 0.566 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 69

53 B 3 u o to cn II c o •ri 1 1 M \ 1 t r" QJ o (J #-< o (-1 U — 4J l-i QJ ^ 3 C <4-l — s 01 rH CI c — A •H O tn o cn 4-1 C tOJ 1 — H o -H Q) o — o o— o o — • • c • r.' • • 'J • • c • o • o • o • o • o • c • c 1 c 1 c o 1 o \ 1 1 niD oi*; o K-J o o r>jn o — o -c rvjc on u1 O < o N C .'vj • o • • <• • c • O • • ^ • o • o • o • o • o • c o 1 1 c o 1 o 1 c 1 o 1 c ^ c :oo c:> fvi C nn OJ — ojn O n c — iT) LIO (\J o ^ — LOO o o n — • o • rj — C\' o oo C' -? Co O — n'S, o n o CO ^ 'Si O mm* O <*o c o "0 N. I'v • .'J • OJ • n • <* • C' • • o • o • o • o • O • c • o • o c i 1 c 1 1 c 1 o 1 1 rj S N C> cr c — CO OO O O — n C OJ n n r: r*" ^ On o "O n o o ioc •e-N n "J t\i • • o • OJ • b • o • — • c • • o • o • o o • o • o • o • o o c c O o o o o H CO c ^ XI — o IT X C'CJ N-O O OO <3O ^ c N O
PAGE 70

54 leaves are presented in Tables 33 and 34, Soil analysis before planting appear in Table 35. Nitrogen accounted for the majority of the significant effects (Table 36) both in the soil and the leaves. These results are in complete agreement with a report by Terman (60) The author reviewed over 100 reports of experiments with maize and cotton which indicated that the frequency and magnitude of crop responses to N were generally greater tlian those to P and K in representative cropping areas of the USA, Higher levels of N decreased pH in the soil; an effect previously noted in the literature (62), as well as K and Mg concentrations. On the other hand, it also increased grain and dry matter yield (Table 37) The effect of N levels on nutrient concentration in the leaves appears in Table 38 and it is clear that N, P, K, Ca, Mg, Mn, and Fe concentrations were increased by the higher rates of applied N. Reports on these kind of relationships vary depending upon conditions of a study. Larssen (34) found that high rates up to 500 kg N/ha did not appreciably influenced Ca and P. However, K was increased and Mg was decreased by N fertilizer. Further analysis revealed that only at the 0 level of N did fertilizer P increase Ca and Fe concentrations in the soil, while at the 200 kg N/ha rate the addition of fertilizer K reduced extractable K in the soil (Table 39) Soil test Ca fertilizer remained the same at both levels of P and K (Table 40) Correlation coefficients for soil and leaf nutrient concentrations as well as for pH, grain, and dry matter values appear in Table 41. Grain yield showed a high positive correlation with Ca, Mn, and Fe concentrations in the leaves and with dry matter yield but was not correlated with any particular element in the soil. Dry matter yield was positively correlated

PAGE 71

55 4J (3 CN uO in m in in in CN CO QJ 0 1 in H > lPi •n in in uO CN CN in CM (3 00 1 — 5 CO 00 CN iH CM 0 CO CO CO CO CO CO CO a bO CX V-i o CO r— j 0 uO CN CN tn CN in Q CN CM ,— 1 CN CO CN CO CO ,—1 CM Q U) p^ \0 ,—1 *H d) o (/] 4_) vD CO CO CN CO CO CO 00 lO 1 — t 00 00 CO vO in CO 00 CO CO CO CO CO CO CO CO *H •H C cd Q &C 00 CN *— J CN 00 0 c*n 00 CO CO 'H CN CO CO CO CM CN CN CO CSl eg CN rsi CN CN 4- c 0) 4-t CJ CO ^sD 1 in \0 CM 00 00 CN 00 OD — 1 CN CO 1 — ( CN CO o c \£> vD a 4J u QJ f— 4 r— i 00 (3 in in uO CO CO CO 'O f2 nj 1 ro 00 CO 0^ CO CN CN 0^ 0 (~H 0 0 0^ CJ "<3" ro CO "4 o> CO in in 00 CN CO WJ *o • 6 -H 60 0 0 vD I — 1 -, CN in CN H CNj 00 >, on CO CO ^ B •H tH J= •H n) 0) ^ ^ ro ro 00 CO ci. M X 0 CJ 0 1— t 0 (H 0 0 i-H 0 fH iH 0 iH 0 iH c ro 0) B QJ 0 0 r-l iH 0 0 rH rH 0 0 iH fH 0 iH iH iH CO OJ i-i H H 0 0 0 0 iH fH fH CN CN CM CN CO CO CO CO

PAGE 72

56 3 s o o ,n -U •rl B u a c o •iH u CO c 0) O c O O c 0) H Z I I I I o CNI in rsi in in CM o O o in VD CO 00 00 00 CJ^ OS 00 0^ ro vD 00 00 iH ro 00 CM C3^ a\ CTv O H CO ^ >

PAGE 73

57 Table 35. Soil analysis before planting. Sorghum experiments No. 4 (ditch drained), and No. 5, 1977 Experiment No. 4 Rep pH P K Ca Mg Cu Zn Mn Fe I 5.6 446 164 II 5.2 228 190 III 5.2 199 189 IV 5.3 207 186 V 5.3 197 161 X 255 178 I 5.4 371 142 II 5.3 317 116 III 5.4 350 103 IV 5.5 329 98 X 341 115 ppm 1842 180 0.92 1402 212 1.46 1326 180 0.32 1544 180 0.52 1204 132 0.28 1464 177 0.70 Experiment No. 5 936 73 4.12 746 45 3.40 836 58 3.80 748 45 3.24 816 55 3.64 6.3 5.4 38 4.1 3.6 48 4.1 3.5 38 4.0 4.1 36 4.1 4.3 32 4.5 4.2 38 9.3 6.4 61 6.8 4.8 59 7.6 5.1 60 6.7 4.9 59 7.6 5.3 60

PAGE 74

58 c Ml cn (-1 4J 03 B C T3 •H iH
PAGE 75

59 Table 37. Effect of N levels on soil pH, grain, dry matter and K and Mg soil test. Sorghum experiment No. 5, 1977 N pH grain Dry matter K Mg kg/ha kg/ha ppm 0 5.40 a 423 c 3625 d 50 a 30 a 100 5.25 b 605 b 4210 c 46 a 30 a 200 5.41 a 627 b 4774 b 39 b 26 b 300 5.26 b 860 a 5823 a 39 b 27 ab Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns. Table 38. Effect of N levels on concentration of several elements in the leaves. Sorghum experiment No. 5, 1977 N N P K Ca Mg Mn Fe kg/ha ppm 0 1.23 b 0.36 b 1.97 b 0.26 c 0.13 d 41 c 68 b 100 1.38 b 0. 38 ab 2.11 a 0.29 b 0.15 c 49 b 77 ab 200 1.55 a 0.39 ab 2.07 ab 0.30 b 0.16 b 50 b 79 a 300 1.67 a 0.41 a 2.11 a 0.33 a 0.18 a 56 a 86 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns

PAGE 76

60 o to u o CO 1^ iH UO :5 0) CO O • iH > o ,c -H 4-1 OJ :s i-H cn H cd Cd cd O OJ O j-j CN O a\ o> u OJ o tn uo uo W 0) o *-l e Cd II c c u cd Cd OJ n3 cd Cd Cd 6 M W u u O o o o Cd OJ in CJ iH vD U (X O U -H CO CO CN CO 00 CO I-H u-1 O CO CO CO CO in D o rH u O o 00 CO CO c X! •H cn 00 u TD CO M OJ O O d O •H CO j:: CO CO 4-1 H C OJ
PAGE 77

61 nJ u 00 o •H 4J (0 >-l 4-1 O c o o JJ c 01 •H V-l 4-1 3 o c >4-l 4-1 nj C 0) tu iH E •H t3 >-l c 0) 03 a iH at •H O B cn P x: M O 14-1 0 c dJ tn •H o O .H •H 01 14-1 •H y-j 0) o t-i o cu 4-1 C 4-1 o •H e 4-J m >^ iH )-4 XI ^4 M TD o C u CO a oronr,. no oc C^K oo tvx coo oo o — n — nr. o K-O O £ <• o nmo Of cn n — -o no Orj *o n — — NC o — Oo no o c • rv • rv. c • • o • o tO • o •o • o • o o c c c o o o nn orv*DO nN an -0 c n -o o? on n aiM >(> nrv On 3-0 oc CDC on n o "^n OO o • C^' • — c • o • • o • ^ • O • o • o •o • c c c c o c oo o o o ?• cnM c O irn O N Oc oc no nj o co CV. • ^; f M • M • • o • o • O • O o o C O o o o MC OM o o — KM Csjfg OO CM -c nr; n r J c • — • c • — • • o • c • c • O o o 1 T -c N-O cc on o — C N — O X n n — o c^ o MC n • M • O • • 3 • O • o • c c o t>on c o KN on K o c n O nrg no (DO Oc 30 o— o CK c • •c • o • c o o o O 1 -o org n o — c M3 ^ K c o CO c — O^C K — o o MC o • M • o • o • O o o o 1 c ~" 1 c 0/ rt r u. tQ

PAGE 78

62 with N, P, Ca, and Mn concentrations in the leaves as well as with grain yield and with Cu and Fe in the soil. Fertility Experiments in 1978 Corn Adequate water, weed and insect management allowed good responses to treatments imposed in the 1978 study (Table A2) Soil test before planting is shown in Table 43. Nitrogen was responsible for increased grain and dry matter yields (Tables 44, and 45). The first increment of N(100 kg/ha) was sufficient to maximize grain and dry matter yields; higher rates were not statistically different. The 100 kg N/ha seemed to be a consistent figure to obtain highest yields for both corn and sorghum in this area. This result dif feres from an earlier report by Guzman et al. (21) that recommended 179 kg N/ha for top yields on Florida's sandy soils. Rhoads (48) proposed applying N in North Florida soils according to corn plant population. For 29,640, 59,280, and 88,920 plants/ha the amounts of N should be 89, 178, and 267 kg N/ha respectively for yields up to 12,500 kg/ha. Further analysis were conducted, due to significance of the triple interaction NxPxK (Table 46), to determine the effect of N levels at different levels of P and K. Even though no significant differences were found in this case (Table 45), as they were in experiment No. 3, it appeared to be a clear tendency for P and K to diminish grain and dry matter yields. These effects are depicted in Figure 1 to 6 and are found in several literature reports (8, 11, 47).

PAGE 79

63 Table 42 Grain and dry matter yield. Com experiment No. 8, 1978 Treatments Grain yield Dry matter N P K kg/ha kg/ha 0 0 0 4287 11227 0 0 1 A137 11353 0 1 1 4845 11438 0 1 1 2982 9535 1 0 0 6089 14123 1 0 1 5316 14389 1 1 0 5525 16039 1 1 1 5712 14252 2 0 0 6689 2 0 1 5231 14630 2 1 0 4795 1 / 1 7 7 2 1 1 6028 17726 3 0 0 5996 13313 3 0 1 5956 14485 3 1 0 5642 14940 3 1 1 4258 13952 1/ N 0, 1, 2, 3 = 0, 100, 200, 300 kg/ha P 0, 1 = 0, 60 kg/h a K 0, 1 0, 60 kg/h a Values are an average of five r eplications

PAGE 80

64 Table 43 Soil analysis before planting. Com fertility experiment No. 8, 1978 Rep pH P K Ca Mg Cu Zn Mn Fe ppm I 5.6 394 120 1208 92 2.2 7.6 3.1 32 II 5.5 334 188 1312 104 2.2 6.8 3.2 24 III 5.6 398 172 1508 120 3.5 7.2 3.9 40 IV 5.6 274 136 1040 92 1.8 4.8 2.3 26 X 354 149 1269 103 2.4 6.6 3.1 29

PAGE 81

65 Table 44. Effect of N levels and percent lodging on grain, and dry matter yields. Corn experiment No. 8, 1978 Grain Dry matter Lodging N yield yield percent kg/ha -kg/ha 0 4063 b 10888 b 8 100 5660 a 14700 a 20 200 5686 a 15180 a 35 300 5463 a 14172 a 41 Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made withing columns

PAGE 82

66 1 I tu lU u 1 i-i 1 as SO c n3 1 u 1 ro CN m TO j in ,—1 g as ( in 1 iH H u 1 J-l Q I to o 1 o 1 cn 1 T3 1 TO TO iH II C I Q) •H I o CM •H nj j vO -H >s U TO as O x: lO in >-i OJ CO 4J -U 1 (rt 1 QJ 1 TO TO u 1 1 U TO I in T) B 1 (N 1 in •a a: >. 1 a M to o O 1 o I a j •H j II 1 TO TO C 1 M •H 1 m 00 TO 1 o tH C 00 l-i 1 O O j m 0^ j W iH j .H 1 (U M 1 > CO i I-I iH O 01 E Q W -H o , CN O C~l so in in O • rH 4-1 iH to o tu TO TO IM 4-) iH O tfl tu 00 CN •U CO o cn C C in tu TO iH iH g u 4J TO tu (U rH Lj n r^ l-l4 4-1 -H TO TO 4-1 rH so D o iH E 00 in o in in m (U c TO O U TO TO 14-1 q 3 C Q ro 1 ro 3 O iH o H 4-1 iH rH O O CO c x: -H O T3 TO V-i tU O TO TO o c o o •H TO x; in in 4-1 4-1
PAGE 83

67 Table 46. Significance of agronomic variables as determined by the F test. Corn experiment No. 8, 1978 Grain Dry matter Source D.F yield yield Rep 4 N 3 0.0003 0.0001 P 1 N X P 3 K 1 N X K 3 P X K 1 N X P X K 3 0.0276

PAGE 84

68 4,000 3,0OOJ: 00 200 N KG/HA 300 Figure 1. Effect of N levels on grain yield. Com experiment No. 8, 1978 KG/HA 6,000 5,000 4,000 3,000 x^*— • 100 200 N KG/HA 300 Figure 2. Effect of N levels on grain yield at two levels of P. Com experiment No. 8, 1978

PAGE 85

69 KG/HA 6,ooor 5,000-^-^^* *~~ •K, 4,000 r-'' 3,000\ 1 1_ 0 100 zoo 300 N KG/HA Figure 3. Effect of N levels on grain yield at two levels of K. Com experiment No. 8, 1978 100 200 N KG/HA 300 Figure 4. Effect of N levels on dry matter yield, experiment No, 8, 1978 Com

PAGE 86

70 KG/HA 16,000 14,000 12,000 10,000 h 100 200 N KG/ HA 300 Figure 5. Effect of N levels on dry matter yield at two levels of P. Com experiment No. 8, 1978 KG/HA 16,000 100 200 N KG/HA 300 Figure No. 6. Effect of N levels on dry matter yield at two levels of K. Com experiment No. 8, 19 78

PAGE 87

71 Regression analysis was conducted in order to find suitable prediction equations. However, the results came far short from this objective, A highly significant linear N effect and a significant quadratic N effect were detected on dry matter yield, A stepwise regression analysis was run in order to find the individual contribution of the variables in the model. \^en the variable N was entered the prediction equation was Yi = A,)84.3 + 4.22 N where Yi = dry matter and N = fertilizer N 2 However, the R = 0.078 was very low and most of the variability remains 2 unaccounted for. l-Jhen N and N were entered, the prediction equation became Yi = 4,129 + 17.87 N 0.045N^ where Yi = dry matter and N = fertilizer N 2 The R = 0.151 was still very lov;. 1/nen all other possible variables v;ere 2 2 entered, the maximum R obtained was only R = 0.218. Highly significant linear and quadratic N effects were also detected on grain yield. V'Jhen N was entered, the equation was: Yi = 12,186,0 + 10.33 N where Yi = grain and N = fertilizer N 2 The R = 0.114 did not help again to explain much variability. 2 When N and N were entered, the prediction equation became 2 Yi = 10,980 + 46,49 N 0.12 N where Yi = grain and N = fertilizer N 2 Again the R = 0.239 was very low. When all other possible variables were 2 • 2 considered, the maximum R possible was R = 0.278, indicating that the above equations did not account for most of the variability.

PAGE 88

Nutrient concentration values and statistical analysis for soil test and leaf samples are presented in Tables 47, A8, and 49. Nitrogen fertilizer again was responsible for most differences, especially in leaf analysis where it increased the concentration of N, P, Ca, Zn, and Mn, and decreased K. Nutrient content (dry matter x nutrient concentration) values are shown in Table 50 and correspond to the amount of nutrients removed by each treatment. Nitrogen removal ranged from 100 to 248 kg/ha, P from 30 to 52 kg/ha, and K from 145 to 227 kg/ha, Ca and Mg were also removed In large amounts. It was not surprising to find that N caused most differences in nutrient content (Table 49). It was found to increase the content of N, P, K, Ca, Mg, Cu, Zn, Mn and Fe in whole plant samples. The percent IVOMD values are included in Table 50 and were only decreased by K fertilizer (Table 49). Correlation coefficients for soil and leaf nutrient concentrations (Table 51) show several significant effects. Manganese in the leaves was positively correlated with a few elements In the soil, namely Ca, Mg, Zn, and Mn. Soil versus whole plant nutrient content correlations (Table 52) show N content in whole plants to be negatively correlated with K in the soil and positively with grain and dry matter yield as well as with percent lodging. Also grain yield and dry matter showed a positive correlation, the R value being equal to 0.60. Table 53 contains the correlation coefficients for leaf nutrient concentrations and whole plant nutrients content. Nitrogen content in whole plants was positively correlated with several elements but especially with N in the leaf samples (R = 0.68). At the same time, N in

PAGE 89

73 to > u •H o w c OJ •H u u 3 '^1 •u C v£) O vD H o O o O ,-1 rH rH rH CN CM Csl CN CO CO CO CO 00 o o CO CO c o CO u OJ U O ^ O cc nj O \ \ M -H CL, ti M n) O ^ so B OO o ^ II o sD CO O O O Z Ph u II CO i4 >

PAGE 90

7 A 00 OS 00 d c OJ 6 •H t-l 0) a 0) o u 01 (1) 4= o 1-1 c 0) c o 1-1 *j c Ci c o o c QJ •H U M D 2: D 1^ 4-1 C e 4-1 n) H tH iH rH rH rH rH rH rH rH rH o o CO iH (N in CO O 00 00 CJv 00 O 00 CN o CN n n < ro ro CO ro CO CO X1 O O rH ON o O o II CM CM cs CSI CM CN CM CO CO CO CN CN CN CO CO CN O rH o iH o iH O iH o rH o rH o iH O rH rH O o O I-H i-t o O iH iH o o rH rH o O rH rH o o O O rH iH H rH CN CN CN CN CO CO CO CO ^1 cn C o •H J-i cfl o in HH o ™ 2i^ PH ii ™ CO o \0 c oo o vO ,o 2 II I rH W ^ 3 O (0 >

PAGE 91

75 4J c P 01 ^ O C u t> QJ H P-i QJ 00 rH c CO o > q p M QJ N g 4J •H q 1 tn JO 4-1 q T) QJ QJ •H t-l •H 4-1 g q q QJ 4-1 iH QJ •H T3 Q p ) W CO W CX QJ 1 — 1 rQ •H 4-) U CO m QJ > 4J 1 Tt 1-t CO •^^ •H C to Q •H C/1
PAGE 92

76 c u o 0) Pi 00 o CM o o o o o o o 4J C OJ rH u o c o o o 4-1 iH c O 0) O •H O (-1 4-1 O D C 1-1 O 4-1 O c O 03 i-H O O0) iH O x; c o cn n 4-1 r-i w o on QJ o o 4J 1 o o fl4 o o o u o CO a. Pi H H H X X

PAGE 93

77 o in H o o > w QJ > M 4= CO 3 c E 0) u vD o 00 CNI 00 1^ CN CO 00 o o o vO CO CO o in o C^J 00 o o rH o CN rH rH rH CN rH CN rH iH 0^ rH r~r~. r~ r-^ rH oCO in CO CO 00 o CM o OS in o in in ON rH CO CO CJN ON CO C3N o O < rH 00 rH
PAGE 94

7.8 c a; E U 0) a o CO c o •H rt M 4-) c 0) u s c 4J 3 C 0) o CO u o m u c 01 •H U •rt <-l IH V O U c • 0 00 •H CB tH 01 ^ M 00 M o o u z m 0) rH nl H c • c r o c c I • c O I I." 'T n> PI' — V d c I o • • o T 'si'?c • c OC • C* t • o • • -• ^ • c o c c o ts. — o •c o • • o I I — ~ O— < s. ~ • Tv w C o C' o I c o rvi or. c O o c -o o >^ f *) o b o • c • • • o •o • ^ • O o o • C • o o I o c I o o -• o • I • o 3fv LI — 1 — b • rv.' • o orv r: • • o ^ ~ •O 5 ?. c • -. o o — • o 1 o 1 o o 1 O c o c o c n— o • • c o • • c c I • o o 2 00r • r • O t • ^ • o • c c 1 o 1 o 1 ::>:: o O 1 • O o -b I -" ? c no — ri o • c o -•c • o o c o c

PAGE 95

79 u •H o g u c o u o u e 3 4J P. 0) 1-1 o 00 riH •H o 0 u o jj y-i c o rc E c dJ •H a O •H M-l u — s. -r ^ •5 be OlT CJC ^ c £^ C c ^ *• £ • c • — • C • o c I o c *^ >^ c • c K— *o c C *^ Id c < <* c c • o • a • c • o • c • c • c • o • C 1 o c 1 1 — 1 "^^ r r. < < ^ n r 1 On i c c c • o\ c • c • j • c • c 1 1 c 1 c J o o "~ 1 1 1 O 2 <" T rvjK [ ."I — ^ "* 1 N o— ^ c >: i.^ r— o o • o • o • o • c • • • c • c • o • c ~ — c ^ ^ o [ c 1 — t — — ^ r *^ t '* rrr <7 — C ^— r — • c *^ c r 0 • ^ • c • C" • o c 1 ) c <* ON J" <* ^ r Tv — r; — no < C a c • r-s' • • ^ C • c • T c T 1 r -(* T ?^ <*<^ <" o ^ "* o*T — o ^ o cr O — • r • • c • -•c • c • c ^ • C" • c c o O c c c o — Co c = r. ; c r • c • c -JO — /7^ in c • c c c -0 c c c *^ c •-"0 •^J — n f— t^ O TT "I" rjr. • c • c> • o • • c • c • c • c r~ c 1 c c o c c I." <• 1.1 ^ o *^ c — • o — ^ o — c Ok. -''O 2•cC oo e ^c — D f-jo c O c • • C" • r: • r• • • o •o • c • o • c • c • O • c • C • O c c o o o c c c o O

PAGE 96

80 c o •H C6 >-i u C 0) u c o u c a> •H *-l 4J 3 C (U o c o ft ti u 00 c a; a c •> 0 00 u o u c CD u •H c 0/ U E a •H c !-i 0) U-l C (C t< 01 0) iH !-i E O o M-i u 0) m C 0) 0) cn •H c O o •H a U-l to 4-1 0) 01 )^ O V o •H c e o o •H c l-l o CO u iH 00 0) ffi u u •o o c u CO J3 (0 H c o I' K, L • ^ • • • • • t • • • c • • C • • • • ll.> T • • • • • • ^-^ C* • • • • • • — N ; c 7 — \ • • • c • • • • • • o • ^ • • 1 1 1 I 1 c • • — • • • • • • • • • • C o — — \ X ^ m — • • • o 1 /• V. w *^ 0 S r •T" MM X MM • • c* '-^ c <~" — r L" ^ _^ w c r — \ ^ 0 c ^ • "^p t —J ^. c • • C' ^ I *-, L' *^ 0 c • c • • o • 0 • c • c *> 0 < • • • • • • • • • • 0 0 C C I 0 0 c 0 • • • • • • • • • • c • C • • • /—I 0 ,* <^ 0 '^"^ -L 0 • T 0 — c> 0 • • c 0 • 0 £
PAGE 97

81 in the leaf was positively correlated with Ca, Mg Zn, and Mn in the whole plant samples, as well as with dry matter and grain yield. Sorghum This fertility experiment planted at the ARC also had good overall management in 1978, Soil analysis before planting is presented in Table 54. Soil, leaf, and whole plant analysis, grain and dry matter yield, and percent IVOMD appear in Table 55. Both N and K fertilizer affected elements in leaf and whole plant while N mostly affected responses in soil samples. Even though this was the trend for most fertility experiments reported before, it appeared that K had a more definite role in this particular case. Values for nutrient concentration among the samples are shown in Tables 56, 57, and 58, Grain and dry matter yields appear also in Table 56 and followed a similar pattern to the 1977 previous experiments in which the first N increment (100 kg/ha) was enough to obtain maximum yields. Further statistical analysis was conducted taking into account significant factors from the ANOVA tables. In the soil, high rates of N caused a decrease in K and Mg concentration at both 0 and 60 kg K/ha but Fe concentration remained unchanged (Table 59) In the same table is shown that the 60 kg P/ha only decreased Mg concentration at the 0 level of K. On the other hand, Mn concentration increased with increasing rates of N at the 0 level of P (Table 60). Changes in pH, Ca and Mg in the soil as affected by N levels appear in Table 61, and follow the same pattern already discussed in the 1977 data and found in several literature reports (5, 3A 62).

PAGE 98

82 Table 5A Soil analysis before planting. Sorghum fertility experiment No. 9, 1978 Rep PH P K Ca Mg Cu Zn Mn Fe I 5.3 100 84 736 100 3.9 8.8 3.7 40 II 5.1 260 76 556 68 3.7 8.0 3.5 40 III 5.5 264 76 664 76 4.2 8.0 3.0 44 IV 5.5 270 96 592 80 3.6 6.8 3.4 84 X 223 83 637 81 3.8 7.9 3.4 52

PAGE 99

83

PAGE 101

85

PAGE 102

86 00 ON o 2: B •H M 0) 60 o C/2 CO c c o CD u 4-1 a o d o u c 4-1 c in 0) 0) *j c •H C O 3 OJ i O CM in CM o in CM o CM r-j 1 QO rH o rH rH OJ o o rsl i i rH rH rH rH rH rH rH rH j o < 00 in CO CN CN CM 00 in in in CM o<• — 1 O ro in - ,—1 vO 00 CNI CO CO 00 CO r-H in o\ 1 1-1 i-H CM CO CN ro CM CO CN ro CN CO CO CO CM u j O O O o o O O O O O O O O O o O CO 1 Z^ 00 CM CO in CO CO m rH rH ro rH in in O LO vO vD 0\ 00 vD OO vO r~ o 1 iH I-H iH iH iH rH rH rH rH rH rH rH rH rH rH rH o j CO o j o m in m CTN in in i-H O CN o CN PL, i r~i CO CO m in in in in vO vD O O o O o o o o o o O o O O O o o o rH to in vD CO 00 o CN
PAGE 103

87 00 oo (0 H C 0) o (-1 0) CM > M nj 4-1 cn 0) iH e ts] p. 1-1 o 3 3 c o H u n3 U 4J C 0) O c o o c 0) •H u D 2; 60 2 05 C a e u CO 0) H e a p. CX) 00 00 o rH o 00 in m tN in CO o o o ^ c CO O OJ u II CO rH CO 3 O rH CO >

PAGE 104

88 Table 59. Effect of N and P levels on K, Mg and Fe soil test at two levels of K. Sorghum experiment No. 8, 1978 K = 0 kg/ha K = 60 kg/ha N K Mg Fe K Mg Fe kg/ha ppm0 33 a 68 a 44 a 53 a 70 a 45 a 100 28 ab 64 ab 45 a 32 b 65 ab 44 a 200 23 b 60 b 44 a 31 b 59 be 44 a 300 23 b 51 c 43 a 28 b 51 c 42 a P 0 27 a 64 a 45 a 34 a 60 a 43 a 60 27 a 58 b 43 a 38 a 63 a 45 a Means within each column for N or P treatments followed by different letters are significantly different according to Duncan's multiple range test. Table 60. Effect of N and K levels on Mn soil test levels of P. Sorghum experiment No. 9, 1978 P = 0 kg/ha P = 60 kg/ha N Mn Mn kg/ha ppm 0 2.70 c 2.95 a 100 2.85 be 3.11 a 200 3.16 ab 2.75 a 300 3.32 a 2.92 a K 0 3.07 a 2.86 a 60 2.94 a 3.01 a Means within each column for N or K treatments followed by different letters are significantly different according to Duncan's multiple range test.

PAGE 105

89 Leaf nutrient concentrations response to levels of N, P, and K and their combinations are found in Tables 62 to 66. As expected addition of K fertilizer decreased P, Ca, and Mg concentration in the leaves but increased K concentration. Also, high N rates increased concentration of N, P, Mg and Mn at both 0 and 60 kg K/ha. At different combinations of P and K, the P concentration in the leaves increased going from the 0 to the 300 kg N/ha level. Tables 67 and 69 present various NPK relationships for whole plant samples. It is evident that both N and K played an important role though their individual effects were almost opposite. Nitrogen increased N, P, and Mg concentrations and K decreased K, Ca and Mg concentrations. Potassium increased the percent IVOl'ID (Table 68), contrary to what was found in experiment No. 6. Correlation coefficients for soil and leaf nutrient concentrations as well as for grain and dry matter yields are presented in Table 70. Grain yield was positively correlated with N, P, Ca, and Mg concentration in the leaves; the R values were 0.85, 0.83, 0.73, and 0.73 respectively. Dry matter yield followed a similar pattern though R values were smaller. Table 71 shows the nutrient content for all treatments. The amounts removed are smaller than those previously reported for a corn crop (Experiment No. 8). Nitrogen removal ranged from 18 to 55 kg/ha, P from 8 to 19 kg/ha, and K from 43 to 81 kg/ha. Assuming a N concentration in the grain of 1% (30), knowing that the amount of N removed in the whole plant was 55 kg N/ha, and the grain yield 3,958 kg/ha (treatment 300 N, OP, 60 K in Table 56) it is possible to calculate the amount of N recycled by this treatment.

PAGE 106

90 Table 61. Effect of N levels on pll, Ca and Mg soil test and grain yield. Sorghum experiment No. 9, 1978 N pH Ca Mg Grain yield ppm kg/ha 0 5.74 a 672 a 69 a 1604 b 100 5.55 b 677 a 64 ab 3753 a 200 5.49 b 652 a 60 b 3858 a 300 5.23 c 605 b 51 c 3949 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns. Table 62, Effect of N levels on the concentration of several elements in the leaves. Sorghum experiment No. 9, 1978 N N P Ca Mg Cu Zn Mn Fe kg/ha % ppm 0 1. 38 c 0. 36 d 0.19 b 0.18 b 11.69 b 124 b 44 c 72 b 100 2. 45 b 0. 56 c 0.30 a 0.39 a 14.31 a 132 b 56 ab 102 a 200 2. 80 a 0. 62 b 0.31 a 0.39 a 13.69 a 136 ab 52 b 111 a 300 2. 91 a 0. 67 a 0.32 a 0.40 a 14.75 a 146 a 60 a 106 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns. Table 63. Effect of K levels on the concentration of P, K, Ca, and Mg in the leaves. Sorghum experiment No. 9, 1978 K P K Ca Mg % 0 0.56 a 1.63 b 0.30 a 0.38 a 60 0,53 b 1,79 a 0.26 b 0.30 b Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 107

91 Table 64. Effect of N levels on N, P, Mg, and Mn concentration in the leaves at 2 levels of K. Sorghum experiment No. 9, 1978 N K = 0 kg/ha K = 60 kg/ha N p Mg Mn N P Mg Mn kc/ha — "a ppm ppm -%0 1.35 c 0. 36 d 0.19 b 43 b 1.41 d 0.35 c 0.17 b 45 b 100 2.47 b 0. 57 c 0.43 a 60 a 2.42 c 0.54 b 0.34 a 51 ab 200 2.80 a 0. 63 b 0.45 a 53 a 2.80 b 0.61 a 0.34 a 51 ab 300 2.84 a 0. 69 a 0.45 a 61 a 2.97 a 0.64 a 0.35 a 59 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns. Table 65. Effect of N and K levels on P and Mn concentration in the leaves at 2 levels of P. Sorghum experiment No. 9, 1978 N P 0 kg/ha P 60 kg/ha P Mn P Mn kg/ha % ppm % ppm 0 0.35 c 43 c 0.37 c 45 b 100 0.54 b 52 b 0.57 b 59 a 200 0.64 a 53 ab 0.60 b 50 ab 300 0.67 a 61 a 0.66 a 59 a K 0 0.56 a 51 a 0.57 a 57 a 60 0.54 a 53 a 0.53 b 50 b Means within each column for N or K treatments followed by different letters are significantly different according to Duncan's multiple range test.

PAGE 108

92 Table 66. Effect of N levels on P concentration in the leaves at different combinations of P and K. Sorghum experiment No. 9, 1978 kg/ha 'O'^O ^0^60 ^60-^0 ^60 '^60 kg/ha %p 0 0.36 c 0.33 d 0.35 c 0.37 b 100 0.55 b 0.53 c 0.59 b 0.56 a 200 0.65 a 0.62 b 0.60 b 0.59 a 300 0.66 a 0.67 a 0.72 a 0.61 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns. Table 67. Effect of N levels on nutrient concentration of whole plant samples. Sorghum experiment No. 9, 1978 N N P Mg Zn Mn Fe kg/ha % 0 0.63 d 0.31 b 0.17 c 473 a 71 a 208 a 100 0.81 c 0.29 c 0.21 b 471 a 49 b 84 b 200 1.05 b 0.33 ab 0.26 a 474 a 49 b 89 b 300 1.20 a 0.35 a 0.24 a 417 b 48 b 81 b Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 109

93 Table 68. Effect of K levels on K, Ca, and Mg concentration in whole plant samples, and on percent IVOMD. Sorghum experiment No. 9, 1978 K K Ca Mg IVOMD kg/ha %— 0 1.46 b 0.19 a 0.24 a 55.87 b 60 1.59 a 0.16 b 0.20 b 57.36 a Means followed by different letters are significantly different according to Duncan's multiple range test. Comparisons should be made within columns. Table 69. Effect of N and K levels on P, Mg, and Zn concentration of whole plant samples at two levels of P. Sorghum experiment No. 9, 1978 P = 0 kg/ha P = 60 kg/ha N P Mg Zn P Mg Zn kg/ha —'/. / ppm ppm 0 0.32 a 0.19 c 470 ab 0.31 be 0.16 c 476 a 100 0.30 a 0.20 be 461 b 0.29 c 0.22 b 480 a 200 0.32 a 0.25 a 480 a 0.38 ab 0.26 a 469 a 300 0.31 a 0.22 ab 467 ab 0.38 a 0.27 a 367 b K 0 0.33 a 0.23 a 471 a 0.33 a 0.24 a 459 a 60 0.30 a 0.19 b 468 a 0.33 a 0.21 a 437 a Means within each column for N or K treatments followed by different letters are significantly different according to Duncan's multiple range test.

PAGE 110

94 c •H 00 c^ p. e>f>. — r r\;n oc — c oo_ c mc Cm o o — r, c oc oo — o o — c uoo cj e^ IC o <\J o ••c in o oo o o Oo e c c f*> c >Cei o O'O no Oo e • • • • n • n • • • c • • C! • O t eO • o • c • o • o o • o • o • o • o O o o c c o o c o o n c| o •H 4J 18 t-i 4J C 0) o c o 00 o tH c 0) •H ON u u o z c ca u cfl c Ql rH e •H •o )-i c U cC X 1—1 01 o e 0! 3 j: u M o U ^-i o CD CO 4-1 c K •r-i o iH •H 14-1 •H rii IflO oo oo t ino no iC n o n o no ajo no in o oo no c • c • ^> • • f\.• • r. • o • V • • c • o • o • o • o • o o • o • o c c o o o c o o c o — c n Oc o <• — .n ~c 1. >^ — c tr._ • ln^ CK c^n c K in m o — n (T 0 CU o Lin c a K O o-n c ^ 0-e nr. on < r ^ <• c c c r. — >' c fvir. vD o cir> oo oo — n no o a c •* f • O t (V n • o • a • o • a • • o c • c • o • o • o • o • o • c • o • o c 1 t o o 1 o 1 o o 1 o o o o — o n a CO' nor (\.^ ino n c O T -5 I" f^. n c r ^ — K T — r> c n n coc on — (V S!K tr n CV X n'' *£>C • O ->o OlTi MC Nn o • O e O o • c • tvj nj • rv, • c • O • -* e • o • c c • c • o •C • o • o c O • o O c o o o o D o o o o o o c c — n c OS l— 0 K — . Om c c t\i — t> ^ n c — rv. e LV c — w o
PAGE 111

95 <} O en O in ro en in ON CN in >^ CN cn o O O i-i O o o o o O O O o o O O c-l o CN CNJ in r 1 CN CNJ I-H CNJ CN o CNJ ON ro m C-i CN I-I .H o c^ ON r-l O o o o o O o o o o O o o o o o m CO in in TO' CN I-H 00 CJN o CO rH O CN O rH CO CM CO CO CJN CS o o LO I-H rH CN (N rH CN CN CM CN CM rH iH CN rH O CO o 00 o o CN II II o o (0

PAGE 112

96 3,958 X 0.01 = 39,58 kg N/ha in the grain 55.00 39.58 = 15.i*2 kg N/ha returned to the soil Likewise since out of 300 kg N/ ha applied to the soil only 55 kg/ha was removed by the wliole plant (forage and grain) this represents an 18% removal of N in relation to N applied, a low figure indeed. Correlation coefficients for soil test and whole plant nutrient concentration, nutrient content, grain, and dry matter yields are presented in Table 72. Nitrogen concentration in whole plant samples was negatively correlated with K and Mg in the soil but positively correlated with grain (R = 0.69) and dry matter yield (R = 0.29). However, nutrient content in whole plant samples was positively correlated only with grain and dry matter yields (R = 0.71 and R = 0.79, respectively). The high R values in this latter case suggest that N content in whole plant samples could be a good indicator of yield potential for sorghum. Table 73 shows the same kind of relationships using nutrient concentration values in the leaves (instead of nutrient concentration in the soil) In this case N in whole plant samples was positively correlated with N, P, Ca, Mg, Ca, Zn, Mn, and Fe in the leaves as well as with grain yield and dry matter. Very high R values up to 0.83 indicate that leaf concentration could aslo be a good indicator of the sorghum fertility status and yield. Nitrogen content in whole plant samples showed, except for Fe, the sane positive correlation found in the leaf samples, suggesting that they could be used interchangeably. Despite differences due to management, crop and location, there appears to be some general trends derived from all fertility experiments during 1977 and 1978. Nitrogen was definitely the most important element

PAGE 113

97 c (U 3 C 00 C O CO r-i C • o o •H 2: u n) 4-1 C (U iJ •H -H U -H c D 4-1 „ C (-1 = 0) •U U-l c •• CO e ? iH 3 a jz MI 0) M -I o r o w CO o A > M •H O 4J 03 en V U o O IM < a. to 4-1 T3 c c a; CO •H (J •H 0) o C o •H CO < C -i o 00 •H 4-1 CO 4-i tH C CU OJ )-l i-i -l C o O u O 43 H IT -• ^ .\ 1 3 r •? IT .") T .1 — ^ *. J' r J • 0 C = o •3 ^ IT r. O c o *C •"; o c <• o o • 3 o • O • o O o 3 o O O C^J CJ — o CO "^r OO OO —CM -. O OO -J o — 1^ — r— — — 1."— — — — E—
o y o — tl o n-3 o o 3 o o o o c • o "> o o — — o c o < o r\; t> c o < X c o • o fl^ rj o o :<3 -O O O (V O C "4 5' Oh. z — 3 o o o o -ji^ 1? .1 o o o 0 • O •o oO o •o o o o o o .o • o • o • o • o • o • o o o o t O o 0f^. — c r (\j nc 03 O 3n n rr o M C r -1 — o o — t 7 OC • o o c ? o ? o > c o o ;7 o T r, — o O o -* ^ r o — fj o • • o o o o -Mir D — • o • o o — c 3 LO • o o o o (\ • • o o • • c o ^' o — 2 ^o O ru rj C r e • O • o o .c • o .c o o o o c -lO 3 -c o •o 03 C •n ^ c ^ o c iT, — o c w~ ^ u' o o — 9 a a : o n 0 T t\JLc •o ^ c c #^ O O O o 1, c o c d • o • O 1 r, • cy • o o • o • c • o o • o • o • c o • o • o 0 c • o • O • o t o o • o • o o w o c o 3 o o o o O o o o 3 o O V 3(v m o O 1.'. K — r. l/i r "M IM C•T ,0 a *i -\ i o c — -r rj 3 rg C IT ^ — 1 (V. 41 r. 3 3 ~ 3 • 3 9 O • O I o • — • O • o • — • 3 ~i • o • C a • O • 3 • o • o • 3 • o c • o •O o 3 • o • o ) c • O 3 3 3 O o 3 3 o T sT — ^* K (M c •0 T 43 — y £: .1 1/1 r e 1 T u'. 3 m OCM 3 3 ^ r> O -T o ^ 'M o J — ._n(M .%( — o M ^ O CM — T C O • o ino ?• C 3 K c in c 0 — O rr e •n (\J 17 -JO o c K o 3 = J in 3 r c — 0 3 • O 0 O • 3 f\ • • o • c • c • o • o • o • O • o •O • O • o o • O • o • O • o • o • c o o o 3 3 o O 3 I o o I o o 3 o o 5>C•Vj o o -" .M-1 3 M — — T ^ o n X i^. 3 ri ^ 3 — o o c OO ? o n ^* L" y o r\i n O 3 3 -'1 o n • 3 "t V • .M • • o • 5 ~ 04 h % o o O • CM • 1 M • 3 "^o • o • O • O • O o • o .O • o • o • o • o • o • o • o • o • o • O • o • o o 3 o 1 3 o c o o o 1 t o o o 1 o o 3 o > IM -jC — o O f ^ r" O OO OO o*y 1/1 43 IT o — x>c 43 U1 r, c ?^J O *o o Or, O 1^ r OlT. /) c e C C4 r X rj •M K — r ) CM o < o i. c ?4 r r IT 3 — •ff >; iT Jin M' C c <* .~ f. C ."^ K O rj — o X T D o O-C ^ — K — ^ C c

PAGE 114

98 a •H l-l p C 00 O ON c c o •H 21 M 4-1 c 0) o c o U X (U 4-1 C >^ 0) 4-) •H -H ^1 r-l 4-1 -H 3 4J C M 4-1 H-l C ra E H 3 a. 4= 00 QJ )-l .H O o to ^ • •a p c is CO o > 4-1 M 0) 4-1 H C u o O V4 >4-t 0) w 4.) T3 c c •H o H S >4-l O in o o c o •H 4J C •H CO 00 4-1 -( c 0) 01 ^4 4-1 u c o o u u C iT 0 c K c — o — o — r\' o Cv — a. — ^ K_ J" r c — c Oc c r, c MO c o — O Li ^< c r. ^ ^ c o C o C o r c L' r o ? C C f ^ n c •r r, ^ r\ • f • r. \ c • c • o c • • If • c • o • c c • o • o • o • c • o c o o o c o c o o c c o c c .% T ^ c < c c> — c o o c c l" • 0 o — c o • or L-. o •J" c — a O I" o r. L'.f f. •/ o *— t'' r. c c r. iI-'. C C— < c ^ • •— o C c c • e • c • o • O • o • c • o "C • c o • c • c e C • c t c c. O t 1 c o c c c _*C L"/ — o o ^ O — crj — • ~ c co 1.'' n r r c o c v o c r. e o r. r" • C f\j • c L" • ^ • V • • c • c • • c o • c 0 O c o c o c c c c c c LI O c I r. K. -* Lc c o t. O -V L"' ^ c inf. c — rin o c n Lo c rj nif n — o — (Mlv O 0 lf). n c N. — L". C o z Or ruK IT. C n c o n o > nc or. C f o Cc >^ c rj C r rjc ^ — o n — ^ • cfc<" LI c — o f\J "J o Cy o <• fj ff L-. S iC — n 0.' O fv' ^ ic c — f> i>LM r O L-. 1". o • r • rj tv • c • o • c • — • r. • rv< • o o • o • o • c • o • c • o • c • o • o • o • o • o o o • o • o • o • o • c • D c .o < c o c c c o c o o c c o o o t c 1 o 1 o c ^ • o r c K. X ^^. <• Lo r c c r. c L* r — c c c ^ r o n cL-iC c rc K O L->c — • N, c w n n c •"c o c a' c c w c o r c no <" O L- C er. o c o fV O — c ~c — c LI c c• f^. < c • L' • o • c rr • r c • <• • c • ^ • • c • (\ c • c o r C • o • c • C • c • c o • C • c • o • c • c c c c C C o c c o o c o c c c c o c ~ c a. c or et — c-c c ILo c o u — c o < ir, ^ C o o — r\. o c o >^ c p no oc *\/r— n, Ol o Cwc. O p cr • r • — • ^ • o • o • c • ^ • o • o o o o c o H c u — c c r r\j — — o LT O C • • O o — iTi, c to o — o <• C I' L" r ro c • ^ • o • • t r a L'. • rv • r. • c • f. • •o • e o • c c• C • o • o o • o o o c c cc c c tr t; r c c > c z u cr c re X & u.

PAGE 115

99 affecting not only grain and dry matter yields but also nutrient relationships in all collected samples. In all cases the first N increment was sufficient to maximize yields, higher rates causing either a slight decrease or no increase at all. However, this conclusion is especially valid for the management level presently used by local farmers. Improvements in irrigation, weed control, and plant population management would likely result in a need for higher N rates in order to obtain higher yields. This is confirmed by other research (48). Economic considerations would certainly play an important role in decision making. For 1977 conditions, Dilbeck-'' estimated a net income of $223.8 and $98.5/ha for corn and sorghum respectively following cabbage and potato crops. These figures seem attractive considering that land, equipment, and solar energy are plentiful in the area during the summer months. The fertility research reported here showed that high N rates caused a drop in pH and extractable nutrients in the soil, and an increase in N, Ca, Mg, Zn, and Mn in the leaves, and whole plant samples. Phosphorus and K tended to decrease grain and dry matter yields in several cases, suggesting salinity problems and possibly nutrient toxicity. The previous well fertilized vegetable crop would certainly contribute to the problem. Potassium showed ion antagonism and reciprocal relationships normally found in these type of studies (47). In several cases fertilizer K decreased Mg concentration and content in plant samples, similar results occurred with N, P, and Ca. Potassium was the only nutrient affecting percent IVOMD. However, the trend was not clear since in one study it increased percent IVOMD, and in another it caused a Dilbeck, J. 1977. Annual Grain Meeting, St. Johns Country Fairgrounds, Feb. 28, 1977.

PAGE 116

100 significant decrease. Magnesium and Mn shovijed good correlation with other elements. For instance it was found that Mg in the leaves was negatively correlated with K, Ca, Mg, and Zn concentrations in the soil in several cases. In general it was observed that plant samples showed more significant differences than soil samples and that the use of correlations provided a good insight in nutrient balance and relationships. Bedding Experiments The main idea behind modifications of the traditional 1 m wide potato beds was to provide better use of space for the sorghum crop. The objectives of the bedding experiments were met fully because of good overall management during both years. Soil test were made prior to planting each year. Data are presented in Tables 74 and 75. Differences in agronomic variables as determined by the F test are shown in Tables 76 and 77. The type of bed and the modifications imposed on them influenced yield. All treatments that provided narrower rows (except broadcast) than the 1 m bed single row check resulted in increased grain yield (Table 78). Highest yield was from the 2.0 m bed three or four row treatments. Grain yield for these treatments were 3,323 and 3,335 kg/ha respectively, a 40% yield advantage over the control. This would be a relatively easy treatment for which present equipment could be adapted. One meter bedding equipment could be converted to 2.0 m bedding equipment with relative ease by removing every other bedder. The highest yielding 2.0 m beds three row treatment would be difficult to cultivate without modifying existing equipment. On the other hand narrow rows helped to suppress weed growth by competition and shadening, provided the weeds could be controlled during early sorghum growth with herbicides.

PAGE 117

101 Table 74. Soil analysis before planting. Sorghum bedding experiment No. 6, 1977 Rep PH P K Ca Mg Cu Zn Mn Fe ppm I 5.1 280 96 758 57 4.60 9.1 5.8 67 II 5.0 383 112 906 60 5.64 11.3 6.8 70 III 4.9 312 109 858 60 5.36 9.6 5.7 69 IV 4.9 351 98 796 55 4.12 8.4 5.7 60 X 331 104 829 58 4.93 9.6 6.0 66

PAGE 118

102 Table 75. Soil analysis before planting. Bedding experiment No. 10, 1978 Rep pH P K Ca Mg Cu Zn Mn Fe — ppin I 5.5 248 94 724 96 4.8 11 4.4 56 II 5.4 274 84 716 92 6.8 13 4.8 52 III 5.2 293 76 752 84 6.0 12 4.4 48 IV 5.2 300 92 688 88 4.4 10 4.0 44 X 279 86 720 90 5.5 11 4.4 50

PAGE 119

103 Table 76, Significant variables as determined by F test. Combined analysis 1977 and 1978. Bedding experiment No 6 and 10 Source Dry matter yield Grain yield Plant population Plant height Rep Bed 0.0377 Rep c Bed Arr (bed) 0.0001 Rep X Arr (bed) Year 0.0001 Bed X Year 0.0001 Arr X Year (bed) 0.0031 0.0001 0.0001 0.0001 0.0001 0.0270 0.0001 0.0001 0.0025 0.0001 0.0097

PAGE 120

104 p cu e •H t-i (U a y, 0) bO c •H 73 T) 0) PQ C M O O o iH iH • 00 O O 00 o O C ON o O On O iH • • iH •H o o S 4-1 o nj 03 c .H iH ca a 00 iH r-o O a. o O ON ON o O t-i • • o o w 0) r-H 00 ro o O o ON O O 0) • • O o c T) •H r-l CO 01 )-i •H > cn 0) o c ON o •H i-H o H CJ 4J ON O o u o o o c U T3 •H C iM n3 H C vD OO • •H O CO 13 ^ — N OJ 'O m 0) cu u X iH U o a P. o 0) 0) l-l PS PQ <:

PAGE 121

105 Table 78. Grain yield in kg/ha. Bedding experiments No. 6 and 10, 1977 and 1978. Treatment 1977 1978 Average kg/ha I 1 2389 be 2443 bed 2416 b 2 2436 be 3125 a 2781 a •J 3. JUUO ao onoi „ 4 2433 be 2188 d 2311 b 5 2046 c 2201 d 2123 b 6 2832 ab 2824 abc 2833 a 7 2139 c 2352 cd 2246 b II 8 3300 a 2983 a 3142 a 9 3062 a 2572 ab 2817 a 10 3092 a 2032 b 2562 a 11 3195 a 2352 b 2768 a III 12 2713 a 3934 a 3323 a 13 2793 a 3877 a 3335 a 14 2714 a 3156 b 2935 ab 15 2622 a 2700 c 2661 b 16 2482 a 3159 b 2821 b I, II, III = 1.0, 1.5 and 2.0 m beds respectively. Means followed by different letters within each bed group are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 122

106 The 1.5 m beds showed a slight advantage over 1.0 m beds planted to twin double wide rows per bed. However, it would be harder to adapt 1.0 m bedding equipment for 1.5 m beds. Running very close to the 2,0m bed three or four row treatments was the 1.0m bed double wide two rows per bed. This treatment gave 29% higher grain yield than the 1.0 m bed one row check. Existing 25 cm cultivator weed control equipment could easily be used with the 1.0 m bed double wide row treatment. The increased plant population from double rows would make better use of available space, water, and fertilizer and provide better shading of weeds. In all cases broadcast treatment had inferior yields within each type of bed. Dry matter yields (Table 79) followed a similar pattern to grain yield, 2.0 m and 1.5 m beds in general outyielded 1.0 m beds except for the double narrow and double wide two rows treatments. The best treatment was the 2.0 m five rows with 12,518 kg/ha, this represents a 44% increase over the 1.0 m bed one row treatment. The resulting plant population according to the bed modifications imposed appear in Table 80. There is a close association between the highest yielding treatments and their plant population. The 1.5 and 2.0 m beds with the largest number of rows also had the largest populations. Plant height did not change appreciably. Significant effects on whole plant analysis appear in Tables 81 and 82 for both years and for each year separately. The percent IVOMD was not different from either bed type or for arrangements within beds. Nutrient concentrations and percent IVOMD for 1977, 1978 and the average for both years are shown in Tables 83, 84, and 85. The differences

PAGE 123

107 Table 79. Dry matter yield in kg/ha. Bedding experiments No. 6 and 10, 1977 and 1978. Treatment 1977 1978 Average — kg/ha I 1 9342 d 8021 b 8681 e 2 11706 be 9962 a 10834 abc 3 13046 ab 9349 ab 11197 ab 4 10568 cd 7903 b 9236 de 5 11222 be 7807 b 9514 cde 6 14314 a 9805 a 12060 a 7 12077 be 8473 ab 10275 bed II 8 14552 a 9045 a 11798 a 9 13277 a 9263 a 11270 a 10 15569 a 9052 a 12310 a 11 13621 a 7265 b 10443 a III 12 11351 a 10193 a 10772 a 13 13438 a 10136 a 11787 a 14 14548 a 10488 a 12518 a 15 13422 a 9756 a 11589 a 16 11904 a 8057 b 9980 a I, II, III = 1.0, 1.5 and 2.0 m beds. respectively. Means followed by different letters within each bed group are significantly different according to Duncan's multiple range test. Comparisons should be made within columns.

PAGE 124

108 Table 80. Average plant population and plant height for 1977 and 1978. Bedding experiment No. 6 and 10. Pt. Pop. Pt. Ht. Treatment pts/ha cm 1000 T 1 I 1 llz c 1 c:Q i JO a 1 230 a 158 a 3 230 a 156 a 4 135 c 146 b 5 115 c 159 a 6 247 a 159 a 7 200 b 157 a II 8 300 ab 157 c 9 367 ab 156 b 10 417 a 162 a 11 217 b 151 d III 12 288 b 156 a 13 364 a 157 a 14 406 a 158 a 15 408 a 157 a 16 244 b 155 a I, II, III = 1.0, 1.5 and 2.0 m beds respectively. Means followed by different letters within each bed group are significantly different according to Duncan's multiple range test.

PAGE 125

109 00 CO •H CO 0) D 1 1 r 1 4-J (0 c lU QJ u U C o o 0) M x: 4-1 c QJ •H ^1 U -a 0) TO C fi a •H e o w G QJ TO i-H OJ c a XI TO !^ QJ to ^ 1-1 TO O O W Z (U iH W c ^ tJ o TO C Ph •H QJ 4-1 E w TO -H 0) > t-l 4-1 1 c TO QJ O •H 60 >+-< C •H -H C Xl ao XI Q •H 0) W M iH 00 QJ QJ O i-l 1-1 ^ TO O H to o > c QJ U M QJ o. XI c TO C O •H u-i o o o o o o o o o o o o o o o o • o o o o o o o o o o o o o CM ro rH t-l ro <

PAGE 126

110 o O XI t> c O 01 U) O 4-1 > C M (U 6 4-1 •H c c u 0) o a. X OJ 01 p00 c XI c c •H M CO •r) Xl c 0) o PQ •H 4J CO • CO t-i 4-1 U 4J cn c QJ 4-1 O C O U 0) 00 x; 4-1 4J c OJ •H (-1 4J o CO C c u •H 4-1 e C CO r-t 4J O. 01 0) t-l CO o CO CO QJ ro ft, 4J CO Q) CD 4-J > 1 Ph 4-1 C CO 2: O •H ^4-1 •H c 60 Q •r-l Crt CM 00 01 0) O iH U 3 to H ON o CM O 00 O CM O O CO O 00 fo o CNI (X CO CN vD XI 0) a QJ X) OJ PQ XJ u 01 >-l PQ
PAGE 127

Ill • o c e •H U u cd CO w x: 4J 4-1 c to CO to a. 0) o. iH o to CO 4-1 I-I c o to iH Q o. 0) o ,-1 > o M 4-1 c c 01 •H o c 0) o (X H T3 to c J^ nj 4_) c p OJ o u 4-) 0 nl (J J-I 4J 1 1 c c a; o •H c 1-1 Q o 3 ] t c 01 B u to OJ u H 1 x> -P rP rP r4-J iJ-i 1 cO to to to to rP to to CO to t\J to lU vO rH tN CO ON 1 1 in VP in vP B P. P. o in 1^ in r~ 1 o O O 1 CM CM CM in 1 4 1 r-^ CM in O 1 CN in cn in 1 in CO 1 CO CO CO 1 rH 1 1 1 1 i_i 1 1 ,—1 1 in in in I — f — % I — j 1
PAGE 128

112 o > M U c o u a -a c c 00 o •H iH O c iH a> u O c o u 4-J c 4-1 c e •H •H c DQJ O (X, C e u 03 QJ 1-1 H I I O H rH iH ON £1 in in in m o ON O rH O 1 o o o 1 in CN CO rH in in in 1 ^ in in 1 CO in in CO 00 o1 ON 00 ON 1 CJN vO CJN o CJN ON ON 00 CO OO ON 1 00 00 CTn 00 1 00 On ON o rH rH in r~ o o o 1 o in CM CM 1 o CN in m m o i-H o rH o rH o 1 o o rH o 1 rH rH o o rH rH rH rH rH rH rH rH 1 rH rH rH rH 1 rH rH rH rH rH rO XI X3 nJ to XI nJ nJ -O CD CO (0 to ON rH 00 vD 00 00 o ro o ON CN ON CM fH CM rH rH rH rH 1 rH tN CM CM rH rH CM rH CM O o O O O o O o O o o O O o O O vD 00 00 vD 00 VO rH 00 rH 00 ON rH rH rH rH rH rH rH CN rH rH rH CN rH rH O o O o o o o d o o o O O o o O 00 ro CM ON 00 rH 00 ON o CN CM r~ 00
PAGE 129

113 CO CO o c M • o O •H •u Z 4-J c CO 0) CO 1-1 O 4-) 4-) C c 01 0) Q) a e O •H C •n 1-1 0 c C ^4 CO -H 4-1 i-i 13 3 4-1 13 C! 0) 0) pq o c o • U 00 4-1 OS cu in 00 CO H 1 1 iH ro CNI 00 in 1 in 00 00 00 in 00
PAGE 130

114 in nutrient concentration between years are striking and could possibly be attributed to a number of causes, namely nutrient dilution and environmental conditions affecting the state of the tissue at sampling time. As expected, difference in concentration would also affect nutrient content values. In Tables 86 and 87 it is observed that 1978 presented much lower nutrient content values than 1977. Highest N content was 175 kg/ha in 1977 for the 1.5m broadcast treatment as opposed to 76 kg N/ha in 1978 for 1.5 m five rows treatment. Phosphorus content ranged from 32 to 55 kg/ha in 1977 and from 21 to 28 kg/ha in 1978. Potassium content also showed appreciable differences ranging from 163 t.> 284 kg K/ha in 1977 and from 110 to 174 kg K/ha in 1978. Since only 75 kg N/ha were added to the crop, N depletion from the soil was very high in 1977. In other words 233% N was removed in relation to N applied in the 1.5m bed broadcast treatment as compared to 101% for the 1,5 m five rows treatment in 1978. Correlation coefficients for nutrient samples, agronomic variables, and nutrient content in whole plant samples are presented in Tables 88 and 89 for 1977 and 1978, respectively. Percent IVOMD was negatively correlated with plant population, dry matter yield, and P, K, Ca, Mg, Cu, and Zn content in whole plant samples during 1977. However, the R values were low ranging from 0.29 to 0.43, indicating a weak correlation. In 1978 the percent IVOMD was also negatively correlated with P and Ca content in whole plant samples. Grain yield, plant population and plant height did not show any correlations with nutrient concentration in whole plant samples. As could be expected, nutrient concentration and nutrient content of N, P, K, Ca, and Mg presented a close degree of correlation for both years. This is also shown in Table 90 when a combined analysis was conducted.

PAGE 131

115 w iH a e nj w c rH a. u 0) w rH O > ^ l4-( O C3N 00 ON .H rH rH rH rH CM CN CN CN (N rH j rH r-i rH rH rH O O o O o o O o O o oj O O O O O m 00 o vO in CN in cn o\ cn tN rH rH rH CN rH rH CN rH j CN CN CN CN( rH CM CN rsi CN in rH CO H 4-1 O OJ D. [0
PAGE 132

116 T3 C C o u QJ a 3 00 r. CO u c 00 B 0) 4-1 l-i to H 00 00 0^ 0^ O in o 00 1 C7N 1 o O O CN in ON in 1^ vD 1 vD 00 00 in 1 r~00 00 o O o o o o O 1 O o O o 1 O O o o O o o m ro 1 CO m 1 in CN in o m uo in o\ o 1 rH rH o o a\ ^ 1 1 t — 1 1 1 — 1 1 I — 1 — 1 rH rH 1 — 1 o o 1 Q o O O O o • o CN o CM in 00 f— 1 CO CNJ [ CN 1 — t 1 — 1 CN rH ,—1 QJ *> •H 4_i O QJ a 00 rsi m in as rH CO
PAGE 133

117 00 c •H -a • CO r~ ON iH •o c cd o> t-H <4-l O < • cn >H o. • B 4J CO U) cn 0) > n) s iH a 4-1
PAGE 134

118 c r-i c O X) > 0) C • 0) 4-1 o c a c o •a c cd c o •H t-i c O CO C o w O 0) iH C CO 0) -H •H M CO 4-1 > D C O u o "4-1 to c (1) 6 o c o u M CO O cn fi le I.*" C — s. O fVI 3O C If O o o ^ > o o — • Q fj O K o 7 ^ r. t o • C^ • r \ r • t ; • D • o • o • c o • O • o ^, r m c 1 c i o 1 o 1 o 1 o o O I o c 1 1 1 1 C 0 o n '•>K nc -JC, .1 — C c o c c a Cl c 7 ^ lo a L-. c; r. r-. 3 C^ o o U1 !!•• >£ C ''1 '/ t c. (V' L'*i :^ < o r> c^ <* c\; o in ^ > o o ? L'-.O 3 • c> • l-c • ^• • f. • n. • o • o • • • • ^ • o • c • o • o • o • o • o • o • o • o o J o r o co o o 1 o o O t\. r. <^ (O rv m in ij o r, o O o -C^ • O • o t c• ^ • 3 • o • C: o c o o o c o o c O c X a o r-, in ru in n 0" < f\.' o o c* c* rj — K mm — r., r^ — — 'n Oc — ^ < LT O — o r^ rj o !? Zl •v, — :^ n >^ o o M O c; O -|>^ n n f\JC\i — o cc — *. C O fj o o — c o CD o no — 1 • • • — • n • C\J • • • • o • o • o o o O O C o o ~ o o o o < in ? r, c — o — o — 0' ry c>o n in lt O r— c IT O in o c. O n o o ino 0 o c rj 7o o L. o CJo 0 w o -* ri 0'" L cr 0 00 r-o CJ • 3 • 0 • V t K. • iT. • r, • in • C • n • • 0 • 0 • 0 • 0 • 0 • 0 • 0 • 0 • 3 • 0 •3 C r 0 c 0 0 c 0 c 0 0 0 0 00 00 IT 0: ir N cr r', — or CC' ftj
PAGE 135

119 •H 60 c o -o > 0) C • u. o <• 1/;inn a !\, — a. n u. w o o c c '1 <. n ^ t o uiO > r <• c: — — o IT rri '0 >~ *^ o J-, c. — •> ; ry o • '^ • o • c • c • o • n n • rvi • c C • c • n • 3 • o o O o o ^1 c ^ o C o Or a c o n c r-, ? r^, — Of f o 3 A C o •H j-i e o o 4-1 c o U) u 4-1 00 C CO 01 •i-l t u o Cfl •H (U 14-1 i-H 14-1 a. L. 0) e CX) o to r-^ O a\ i-( c 4-1 o c 4J •H CO c 4-1 iH cfl a e *? tH •H OJ 1-1 01 o a. O X u 5 QJ o ty X ir. L'. air. o> o o inw o — N O a? o n C' oC • o • o • o o o o o c o o o c in ^ •--1 o O J eg o r. an •CO IT *f N. — ^ O • O • • • c • o • o O O c o • c o • c C f, L'' o o ir O o • • o c I • o c O It L" C \ o o — c c o O <7 tn o • c D — o .^J o r — 1\ • C o D — ;^ O c o I c h. • • c o o n cno (MX fy o — O c o ^ • i^• c • <• • ^ • • _) • o • n • c • o o o o o c o c — c (L — in — 0o t o >c o — N. c c K o oo E D o o h-O — IT no S) o K O OO 3 o ttj o L-IC oL' O OC r. • c • O t o O o o o o co o fU c • K M • o • o • r\. o • • o • O • o • c • O • -J O 1 o 1 o 1 o o 1 o C . in r o (MCC M — C^ ^o n-•0 o CO c^i m tj — be no o • n. • n • c • — • r-. • • o O • o • c • O • o o o o o 1 O 1 O o f\JO \r c C c
PAGE 136

120 00 o> r— 1 ,_j o c rH •H Q > 14-1 o w •H B c o 01 c •H o o u •H 60 U-l U-l OJ o CO o QJ iH c o 6 •H CO tn rH CU 4-) u u o Cu o CO H < o O f ^ • o C O IT C IT y ftrj K. ^ "t •> CN; • O • o o V c. c • • c • c o ~ i< c c cv u • • c • o c o — — t> IT, — C ^ NO L' — r. D t C • • o • c • O • c • o • o • 1 c 1 o 1 o o O ^ o > CI n"j U ^ *f o • c • C • • o • :> • o o C c c o — K — IT. — rv.' ^ f> o If c w W N — r\j — M O O G IT' w o \ ~ o c r> C T ^ r, ^ ^ n c '^1 o O -C ."^ ^ •e • L' • r • o • o • O • O • c ^ *-) > o c ~ C o o =C mm cr— !rl r* fVi — [2 IT O N o rj T D n ^ f >. O o o o o C r"] rr r ^ o c o o ^ o c c ru o ^ O ^ • ^ • • ^ C? • • 1 c o O o C O O c c> — tr< >-< !^ ^ rn c '1* ^ o ^ cc o o o o c O r • o IP Q ^ o — O C c • • iT • ~ • o • -* • o • o • C 1 o o c c o O c o — n If? (M iT T C* t> CO o ^ — o X o o K c Xo o O 'v f', • C> • \f) • f\ CI • o o O ^ O • o • o • o • C o o 1 c o o If 1 — r> — £/ — o C D c o N T. Vi' — rs. ^ Ci.' L" U oc ~> O on Co Ifi o > Co u C' n r> o l'>0 0 o "-o CD O ^ o c o r". • • • CM f\J • (V • r-i • • • o • o • r> • o • o • O • o o o o o o o ^ '0 — o — rj — o m o n c o c c o c o LIO o f, c rj o o r*) • C • • t* • L'; • • ip • ''i • • C • o o • c •o • o • o o • o 1 o c o o o o o O — o — L' — >f — n — ^ — r' — o — c — c r-' o rj c C — o 7 O rb oc r.'C c o c o K o o o •C O c <• o IT C o T • c • L • L' • •c • 5 e n • C e C • o • O • c • C • o c t c O c O o Cm Cu .5 c Mn

PAGE 137

121 These studies agree with literature sources (41, 46) that point out that bed and plant population modifications are adequate alternatives. The yield increase and the low cost of the new operations involved could justify the change from the traditional 1 m bed. If farmers do not wish to change bed width, the inclusion of double rows in the traditional 1.0 m beds would bring an important Improvement. Cultivar Experiments These experiments included 6 grain sorghum and 2 forage sorghum hybrids. Soil test were made prior to planting each year. Data are shown in Tables 91 and 92. Means for agronomic variables and nutrient concentration of whole plant samples are presented in Tables 93 and 94. Hybrids No. 3 and 7 (Dekalb D-60 and Dekalb A-26) did very poorly and were excluded from the combined statistical analysis. Hybrid No. 8 (Dekalb E-59 in 1977 and Grower ML-135) were also excluded. Significant variables as determined by the F test appear in Table 95. There were only differences due to cultivar and to the year (Table 96). Dif ferences in nutrient concentration of whole plant samples, percent IVOMD, dry matter, and grain yields (when applicable) are shown in Tables 97, 98, 99, and 100. From the combined analysis, it is clear that hybrids No. 2, 4, and 5 had the highest N and P concentrations. Cultivars No. 1 and 6 (forage sorghum) had the highest dry matter yields, 10,816 and 11,243 kg/ha respectively. Grain yield was difficult to evaluate due to missing values. However, hybrid No. 4 (Dekalb BR-54) and No. 8 in 1978 (Grower ML-135) would probably be the best choices for the area considering overall performance. There were no differences in percent

PAGE 138

1 22 Table 91. Soil analysis before planting. Sorghum cultivars experiment No. 6, 1977 Rep. pH P K Ca Mg Cu Zn Mn Fe ppm I 4.9 344 90 836 65 3.64 6.5 4.8 66 II 5.1 368 73 810 52 3.64 6.8 4.9 64 III 5.1 351 76 750 45 3.68 6.4 4.7 62 IV 4.9 357 94 914 56 4.04 7.9 5.6 66 X 355 83 827 54 3.75 6.9 5.0 64

PAGE 139

123 Table 92 Soil analysis before planting. Sorghum cultivars experiment No. 11, 1978 Rep pH P K Ca Mg Cu Zn Mn Fe I 5.4 300 112 672 76 3.8 7.6 3.2 52 II 5.3 264 52 608 68 3.7 7.6 3.1 48 III 5.6 274 72 600 76 3.0 6.4 3.0 44 IV 5.4 274 60 640 72 3.2 6.4 3.2 40 X 278 74 630 73 3.4 7.0 3.1 46

PAGE 140

12 4 c -O CO •H rH x: E CO CN CO 1-1 n) )-l H 01 D r-. .H •H 4-1 ^ Q iH H CT\ oo 01 l-H m in in o U S 0) 4-1 0) 4J "O CO iH CO — i C ^ A— in o rJ2 CU — ^ vC iH vo ro o CO o H (31 00 vO iH vD •H Z iH H n CN M n! w c U 0) 1 CN o in O in •H B d) 1 a^ 00 CM e -H Tt 1 rH O 1-1 j C (U 1 O D. 1 U t< 1 60 Q) 1 00 CM o H o nj 4J 1^ 1 00 tH o in Cfl rH iH X) l-l 0) B c a. cd > CO D. •H w U-) in CN in M 00 o vO m CN CO CN p. CO 1 B 1 CO c o 1 to 1 CM CN , .-( iH 4-J CJ\ CX CO t-H rH s 11 vO
PAGE 141

125 to C t3 TO u •H H ^ as TO cu \ > c ^1 • H 60 •H TO O >^ ^ 4-1 iH M O O a^ c 0) O M o > O t-l M TO o f> H U 03 •H 4-1 e c 03 o [•r 1 C e o •H I-l )-l M 4_J nj a 03 !< r-* •a dJ > c TO TO s: TO CO > 4J 0) •H TO P tH 4-1 PI-l e 3 O TO U •H [fi 4-1 TO 4-1 • ^1 3 C 03 4-1 U TO •H c rH 03 01 a u rH c TO o iH C u 60 o TO 4-1 3 iH TO 0) c U •H •H •H I-l 4J 4J c 03 3 TO o •H O •H 4J 4J TO TO 4-* U 03 4-1 c 0) o 4-1 c 0 o •H 4-1 c 0) TD •H 3 iH 00 4J U r-D C CT^ C •H I-l • St Z (Ti 01 I-l 4J r-l to 3 H e D. ON 00 vO CJN vO o -aCO CN rH rH i-H CnI in ro t3N 00 \0 in rH O o CN 00 00 o to in in <} in in in 00 ON <
PAGE 142

12 ;6 C E "-I c c c o o o o c o rH u iH m 0) -T3 c >^ o z T3 (U CO C •H c Cl) e OJ •H U (U 0) o pX m cn M > •H 4J •H iH M U > 4-1 c 00 o On •H iH y-l •H C to •H a^ CO rH • O O o c vT c o o d c c o c c c o £ d c o c o c d .£3 CO H

PAGE 143

127 a (U u Hi o. X V4 > •H U H 3 U CO H CO a A o -§ o C3 O •H 4-1 nt a 0) u o o 4J 00 C 0) 0^ •H U U 3 C C n) >^ rH rH O TD IM O W 2 C 0) u u u Pa a t-i e >^ u Q •H CO CO OJ rH (X to 4-1 n 60 n) H 00 00 CO 00 CM CO in ON O (0 in in in o o o CNI in to ON CO o CM U3 m o 60 c •iH TD u o o u CO C (U V4 OJ 4-( 14-1 •H -a 4-1 g CO o 60 4J -^ -H w 5
PAGE 144

128 to I-H (Tj 00 u c r-H i-i •o a C CO 0) iH o j= o •H c o XI •H C 4-1 (0 t-l u G 0) d o z c o to u c 01 c B (1) •H •H M 4-1 a S z 01 60 i4 > •rH 4-1 r-l u 6-S be nj ab ab O vO rH ON l CO CM iH CM iH CM o o o o IT) to CO CO ri vD CO 00 in VO iH I-H rH XI m (0 CO ja 00 00 CO CO o o o O O CO CO XI OS o O o m o^ O r-^ O o O iH CN UO cn 60 o w x; CO 4J cn ^ Oi 0) ^ X) *-> CO OJ B OJ OJ -3 O x; CO o cfi -a -H 01 (-1 CO B o cS U-l cn C 4-t CO cn 0) OJ ON C Q) 6 •H >-l 01 (X X 0) M CO > 3 C_3 cn OJ rH a B CO cn CO o x; u 4H O c o •H iJ CO 4-1 c 01 o c o o OJ 2 00 X CO H 60 ft, CO > CJ be X u CO •a CM CO Csl in a CO abe ab be 00 vO 001 so OS CM X CO X CO CO X CO in
PAGE 145

129 01 tn 0) > x; 4-1 CO d o 3 to u C 0) o C o u c •H •U D CO U CO > •H P XI CO CO CO XI o r^v CM o CO iH lO O i-H CN 4H to >^ S H g *-> rH C O CO a o •H C •H X C U •H S cn at
PAGE 146

130 •a c o c (U 6 •H U 0) X (1) cd > •H 3 CO T3 iH (U •H ^( 00 C 01 CO 6 M T) 00 Q Is o. O r-l > M u C 0^ 0) tH O U 0) iH fin r-i o o H iH 0) •H 00 >> c •H CO (-1 O Q 00 > < OS o Csl H O ct! tH CO m 00 1 vO CO < 1 LO in in in in 1 u 1 XI X o 1 cfl cfl o cfl X oo 1 in CO o •H u CNI CO in VO 0) oo c CO •H rH e CO c cfl o c Q 00 a H O O O CO d CO • o w H C bb o H u CO Is 0) 0 OJ u X ^ n-l >^
PAGE 147

131 IVOMD in the combined analysis. However, on the separate analysis hybrid No. A in 1977 and hybrid No. 2 in 1978 presented the higher IVOMD values. Nutrient content values are presented in Table 101. Cultivars No. 1 and 6 (forage sorghum) showed the highest N, P, and K content values for both years. Grain hybrids No, 4, 5, and 8 presented intermediate values, while hybrids No, 2, 3 and 7 had the lowest content, The importance of sorghum, especially as a forage crop, probably needs to be stressed in this area. The N removed in relation to N applied was almost 100% for the forage sorghum (cultivar No. 1 and 6) as shown in Table 102. If the crop was chopped and returned to the soil, it would mean an enhancement to the soil fertility, and a benefit for the next crops If used as forage, it represents a valuable source of feed as illustrated by the recycling of nutrients, and the digestible dry matter yield presented in Table 103.

PAGE 148

132 OJ CM ir, in iH r-t ol CO ON 00 iH CM in in o m o CSI CN CN 00 00 O CN o CTN -4m ON iH CN tH iH C^J CSl m iH iH nD tH 00
PAGE 149

133 Table 102. Percentage of N removed in relation to N applied. Cultivar experiment No. 7 and 11, 1977 and 1978 Cultivars Year 1 23 45678 percent N removed 1977 97 33 30 60 47 99 28 59 1978 90 65 71 99 37 82

PAGE 150

134 B X. 60 U O W (U 60 CO U 00 O r-as c to a o i-H ^ c •H nj 4-1 0) vO OJ 00 o •H 2 0) -a 4J c c B -H X) (-1 0) X • u o u 00 C •H cn •H -a o -H U ,C1 0) 03 X. CO o fsll r-t ^ >^ •H 4J U 0) 4-J to 4-1 O o u CO B >^ l-l U > 3 O CO 60 I I I I I I I I I I I I CO 60 in nH -aeg 00 tX3 00 CN ON CM 00 00 o 00 CO X. 60 00 00 00 O O v£> O CM 0\ CM 00 CM CM o CN o O i-l in 00 cn ro c O •H 4J CO U u C QJ O C O O C Q) •H 4-1 3 C U 0) CO B QJ .H U U 03 U OJ 4.) 4-1 CO B u X) 4J CO 00

PAGE 151

The pages in this thesis have been misnumbered and there is no page ^35^

PAGE 152

CONCLUSIONS Studies on fertility, bedding and cultivar management of sorghum and fertility of corn were conducted for two years In the Hastings area of Florida. These experiments were grown In Rutlege fine sand (Sandy, Siliceous, Thermic family of the Typic Humaquepts) Data from these studies provided Information on plant nutrient element relationships in soil and plant samples, as well as on alternative management over traditional farm practices to improve yield. In the fertility experiments N affected grain and dry matter yields as well as nutrient relationships in all collected samples. In all cases the first N increment was sufficient to maximize yields under the management levels of these studies. Improvements in irrigation, weed, pest control, and plant population management could result in a need for higher N rates, in order to obtain higher yields. Economic considerations would also play an important part in the decision making process. Results from these studies showed that the percent N removed in relation to N applied was higher at the 0 and 100 kg N/ha rate. It was observed that high N rates caused a drop in pH and extractable nutrients in the soil, and an increase in N, Ca, Mg, Zn and Mn in the leaves and whole plant samples. Phosphorus and K fertilization of the crops on old vegetable land tended to decrease grain and dry matter yields, suggesting salinity problems and possibly nutrient toxicity. The effect of the previous 1 156

PAGE 153

137 fertilization of vegetable crops contributed to this problem. Potassium showed ion antagonism in several cases. Fertilizer K decreased Mg concentration and content in plant samples, similar results occured with N, P, and Ca. Magnesium and Mn showed good correlations with other elements. Magnesium in the leaves was negatively correlated with K, Ca, Mg, and Zn concentrations in the soil. Use of the traditional 1.0m potato bed resulted in an apparent waste of space and yield reduction for the sorghum crop. All modifications imposed in the 1.0 m beds and in the new 1.5 and 2.0 beds resulted in improved yields. Highest grain yield (19% average Increase) was obtained from the 2.0 m beds. The highest yield (A0% Increase over the control) was from the 2.0m bed four rows treatment. Total sorghum plant dry matter was also higher in 1.5 and 2.0 m beds. Nitrogen removal in relation to N applied in the bedding studies was very high, 233% for the 1.5 m bed broadcast treatment in 1977 and 101% for the 1.5 m bed five rows treatment in 1978, reflecting the N uptake of the sorghum crop in this sandy soil. The cultivar experiments demonstrated the potential of sorghum as a forage crop for the area. The cultivar Dekalb FS-24 removed almost 100% of the N applied and recycled 74, 29, and 203 kg/ha of N, P, K, respectively Several concluding remarks giving step by step management for growing sorghum and corn follow.

PAGE 154

138 Grain Sorghum 1. Grain sorghum should be planted in double rows on the traditional 1.0 m beds. Beds should be knocked down sufficiently for rows to be about 25 cm apart on each bed. Another alternative is to plant 3 rows 50 cm apart on 2.0 m beds. 2. A rate of 100 kg N/ha should be applied to grain sorghum, one half at planting and one half sldedress. 3. Phosphorus or K fertilizer should not be applied on old vegetable land unless soil tests suggests otherwise, 4. The most appropriate sorghum varieties were Dekalb BR-54 or Grower Ml-135 for grain and Dekalb FS-25A or FS-24 for forage. 5. Weeds in sorghum should be controlled by use of timely cultivation and/or herbicides. Atrazine and Propachlor gave good control when applied at planting. Other herbicides like paraquat applied post directed 4-6 weeks after planting could also be very effective. 6. Grain sorghum should be planted as early as possible after potatoes to avoid damage by sorghum "midge." 7. If rainfall is not sufficient, irrigation should be considered as an essential management practice to make a crop of grain sorghum. 8. The third leaf from the top of the sorghum plant can be used to monitor nutrient-element concentration for proper fertilization requirements. Fifteen to 20 leaves over the affected area should be taken at mid bloom of the sorghum. 9. Whole plant samples should be taken just prior to grain harvest to determine dry matter production, plant-nutrient uptake, and recycled plant-nu trients

PAGE 155

139 Corn 1. A recommended hybrid should planted on the traditional 1.0 m beds in single rows. The Florida Cooperative Extension Service recommendations should be followed. 2. One-hundred kg N/ha should be applied to corn grain, one half at planting and one half sidedress. 3. Phosphorus or K fertilizer should not be used on old vegetable land unless soil test suggests otherwise. 4. Timely cultivation and/or use of herbicides should be considered as an essential part of the management program. Post directed application of Evick + 2,4 D provided good control under the conditions of this study. 5. Irrigation should also be used during the life cycle of corn if rainfall is inadequate, 6. The ear leaf of the corn plant can be used to monitor nutrient-element concentration for proper fertilization requirements. Fifteen to 20 leaves over the affected area should be taken at silk time. Assistance should be obtained through the county agent. 7. Whole plant samples should be taken just prior to grain harvest to determine dry matter production, plant-nutrient uptake, and recycled plant-nutrients

PAGE 156

LITERATURE CITED Adams, J. E. 1970. Effect of mulches and bed configuration. II. Soil temperature and growth and yield responses of grain sorghum and corn. Agron. J. 62:785-790. Akhanda, A. M. J. T. Mauco, V. E. Green, and G. M. Prine. 1978. Relay intercropping peanut, soybean, sweetpotato and pigeonpea in corn. Soil and Crop Sci. Soc of Florida Proc. 37:95-98. Allen, R. R. and J. T. Musick. 1972. Wheat and grain sorghum irrigation in a wide bed-furrow system. Amer. Soc. Agr. Eng. Trans. ASAE 15:61-63. Bishop, J. C, H. Timm, D. W. Grimes, and J. VJ. Perdue. 1976. Apparatus for measuring change in the potato soil bed profile and relationship of change to soil density and air permeability. Am. Potato J. 53:311-317. Blevins, R. L. A. W. Thomas, and P. L. Cornelius. 1977. Influence of no-tillage fertilization on certain soil properties after 5 years of continuous corn. Agron. J. 69:383-386. Bradfleld, R. 1970. Increasing food production in the tropics by multiple cropping. p. 229-242. In D. G. Aldrich, Jr. (ed.) Research for the world food crisis. Pub. 92. Am. Assoc. Adv. of Sci., Washington, D. C. 1972. Maximizing food production through multiple cropping systems centered on rice. p. 143-163. In Rice, science and man. IRRI. Los Banos, Philippines. Cope, J. T. Jr. 1970. Response of cotton, corn and bermudagrass to rates of N, P, and K. Circular 181. Agricultural Experiment Station, Auburn University, Auburn, Alabama. Dingus, D. D. and R. F. Keefer. 1968. Effect of interrelations among the elements zinc, copper, manganese, and magnesium on the growth and composition of corn. Proc. W. Va. Acad. Sci. 40:12-18. Dunavin, L. S. 1975. Sorghum alone vs. corn and sorghum in doubleharvest program for silage. Soil and Crop Sci. Soc. of Florida Proc. 34:143-146. 140

PAGE 157

141 11. Engelstad, 0. P. and W. L. Parks. 1976. Buildup of P and K in soils and effective use of these reserves. In T.V.A. Fertilizer Conference, Cincinnati, Ohio. 12. Florida Statistical Abstract. 1978. Bureau of Economic and Business Research. College of Business Administration. University of Florida, Gainesville. 13. Gallnher, R. N. 1975. Fertilization of double cropping and notill systems: a review and a projection. Georgia Agric. Res. 17(l):lA-20, 27. 14. 1975. Triple cropping in the Georgia Piedmont. Georgia Agric. Res. 17(2):19-25. 15. and L. R. Nelson. 1977. Soil fertility management of double cropping systems. Research Report 248. Georgia Station, Experiment, Georgia. 16. C. 0. Weldon, and F. C. Boswell. 1976. A semiautomated procedure for total nitrogen in plant and soil samples. Soil Sci, Soc. Am. Proc. 40:887-889. 17. and J. G. Futral. 1975. An aluminum block digestor for plant and soil analysis. Soil Sci. Soc. Am. Proc. 39:803-806. 18. Geraldson, C, M. 1977. Nutrient intensity and balance, p. 75-84. In Soil testing: correlating and interpreting the analytical results. ASA Special Publication No, 29, Madison, Wisconsin. 19. Green, V. E., 1973. Yield and digestibility of bird resistant and non-bird resistant grain sorghum. Soil and Crop Sci. Soc. of Florida. 33:13-16. 20. Guilarte, T. C, R. E. Perez-Levey and G. M, Prine. 1975. Some double cropping possibilities under irrigation during the warm season in North and West Florida, Soil and Crop Sci. Soc. of Florida Proc. 34:138-143. 21. Guzman, V. L. H. W. Burdine, W. T. Forsee, E, D. Harris, J. R. Orsenigo, R, K. Showalter, C. Wehlburg, J. A. Winchester, and E. A. Wolf. 1967. Sweet com production on the organic and sandy soils of South Florida. Bull. Fla Agr. Exp, Sta, 714: 12-13, 22. Hensel, D. R. 1964, Irrigation of potatoes at Hastings, Soil and Crop Sci. Soc, of Florida Proc, 24:105-110. 23. 1975. Subsurface drains for irrigation and drainage of potatoes, Program-Field Day Activities, ARC-Hastings Florida, p. 9.

PAGE 158

142 24. Hensel, D. R. 1977. Subsurface tile drainage and irrigation system for potatoes. Program 24th Field Day Activities, ARC -Hastings, Florida, p. 6. 25. Hipp, B. W. and C. J. Gerard. 1971. Influence of previous crop and nitrogen mineralization on crop response to applied nitrogen. Agron. J. 63:583-586. 26. Ishizuka, Y. 1974. Multiple cropping systems in Taiwan. Fodd and Fertilizer Technology Center. Taiwan, Republic of China. 27. Johnson, J. T., D. W. Jones, D. W. Dickson, W. L. Currey, J. R. Strayer, and T. C. Skinner. 1974. Field corn production guide. Florida Cooperative Extension Service, IFAS, Circular 144-E, University of Florida, Gainesville. 28. Jones, D. W. G. M. Prine, and J. R. Strayer. 1970. Sorghum production guide. Coop. Ext. Serv. Circular 346A. IFAS, University of Florida, Gainesville. 29. Jones, J. B. Jr. 1967. Interpretation of plant analysis for several agronomic crops, p. 49-58. In soil testing and plant analysis. Part 2. SSSA Special Publication Series //2, Soil Sci. Soc. Am. Madison, Wisconsin. 30. and H. V. Eck. 1973. Plant analysis as an aid in fertilizing corn and grain sorglium. In L. M. Walsh and J. 0. Benton (eds.) Soil testing and plant analysis. Soil Sci. Soc. Am., Madison, Wisconsin. 31. Kamprath, E. J. 1967. Residual effect of large applications of phosphorus on high phosphorus fixing soils. Agron. J. 59:2527. 32. Kretschmer, Jr., A. E. and N. C. Hayslip. 1959. Plant field corn following tomatoes. Florida Grower and Rancher 57(2): 15, 44. 33. N. C. Hayslip, and W. T. Forsee. 1963. Spring field com and sorghum production after fall vegetables. Circular S-145. Agric. Exp. Sta. University of Florida, Gainesville. 34. Larssen, E. R. 1966. Effect of nitrogen fertilization on yield and chemical composition of corn and certain grass species. Diss. Abstr. 26:62828. 35. Lim, K. L. and T. C. Shen. 1978. Lime and P. applications and their residual effects on corn yields. Agron. J. 70:927-932.

PAGE 159

143 36. Locknan, R. B. 1972. Mineral composition of grain sorghum plant samples. Part III: suggested nutrient sufficiency limits at various stages of growth. Comm. Soil Sci. Plant Anal. 3:295304. 37. Lutrick, M. C. 1971. Comparative production of com and sorghum for grain. Soil and Crop Sci. Soc. of Fla. Proc. 31:45-48. 38. McCollum, R. E. 1978. Analysis of potato growth under differing P regimes. I. Tuber yields and allocation of dry matter and P. Agron. J. 70:51-57. 39. Moore, J. E. and D. A. Dunham. 1971. Procedure for the two-stage in vitro organic matter digestion of forages. Nutrition Laboratory, Dept. of Animal Science. University of Florida, Gainesville. 40. Murdock, L. W. and K. L. Wells. 1978. Yields, nutrient removal, and nutrient concentrations of double-cropped corn and small grain silage. Agron. J. 70:573-576. 41. Musick, J. T. and D. A. Dusek. 1972. Irrigation of grain sorghum and winter wheat in alternating double-bed strips. J. Soil Water Conserv. 27:17-20. 42. National Oceanic and Atmospheric Administration. 1978. Climatological Data. Annual summary, Florida 82(13) :2-4. 43. Nelson, L. R. R. N. Gallaher, R. R. Bruce, and M. R. Holmes. 1977. Production of corn and sorghum in double-cropping systems. Agron. J. 69:41-45. 44. Nolte, B. H. 1978. Better drainage with ridges or beds. Ohio Report on Res. and Develop. 63:78-79. 45. Papendick, R. I., P. A. Sanchez, and G. B. Triplett. 1976. Multiple cropping. ASA special publication No. 27. Madison, Wisconsin. 46. Parish, R. L. and D. E. Mermond. 1974. Evaluating wide-bed narrowrow culture in soybeans, grain sorghum, and corn. Arkansas Agr. Exp. Sta. Arkansas Farm Res. 23:6. 47. Powell, R. D. 1968. The yield, growth and chemical composition of corn as influenced by hybrids and high rates of N, P, and K fertilizers. Diss. Abst. 29B(4):1238. 48. Rhoads, F. M. 1978. Water and nutrient management for maximum corn yields in North Florida. AREC, Quincy Res. Rep. 78-1, University of Florida, Gainesville.

PAGE 160

144 49. Rogers, J. S., D. R. Hensel, and K. L. Campbell. 1975. Subsurface drainage and irrigation for potatoes. Soil and Crop Sci. Soc. of Fla. Proc. 34:16-17. 50. Rudgers, L. A., J. L. Demeterio, J. M. Paulsen, R. Ellis. 1970. Interaction among atrazine, temperature, and P-induced Zn deficiency in corn. Proc. Soil Sci. Soc. Am. 34:240-244. 51. Sabbe, W. K. and H. L. Breland. 1974. Procedures used by state soil testing laboratories in the southern region of the United States. Bulletin 190, Southern Cooperative Series. 52. Sanchez, P. A. 1976. Properties and management of soils in the tropics. Wiley-Interscience, New York. 53. Sharma, K. C, B. A. Krantz, A. L. Brown, and J. Quick. 1968. Interaction of Zn and P. in top and root of corn and tomato. Agron. J. 60:453-456. 54. Soltanpour, P. N. A. 1966. Interrelation of N, Zn, and Fe on the growth of three corn hybrids. Diss. Abstr. 27B(2):348. 55. Stout, G. J. 1975. Florida's fight to save irrigation water. Am. Veg. Grower 23:10-12. 56. Stukenholtz, D. D., R. J. Olsen, A. Gogan, R. A. Olson. 1966. On the mechanism of P-Zn interaction in corn nutrition. Soil Sci. Soc. Am. Proc. 30:759-763. 57. Summer, M. E. 1979. Interpretation of foliar analysis for diagnostic purposes. Agron. J. 71:343-348. 58. Terman, G. L. 1957. Variability in phosphorus rate and source experiments in relation to crop and yield levels. Agron. J. 49:271-276. 59. S. E. Allen, and B. N. Bradfold. 1975. Nutrient dilution-antagonism effects in com and snap beans in relation to rate and source of applied potassium. Soil Sci. Soc. Am. Proc. 39:680-685. 60. and 0. P. Engelstad. 1966. Fertilizer N: its role in determining crop yield levels. Agron. J. 58:536-539. 61. Terman, G. L. and J. C. Noggle. 1973. Nutrient concentration changes in corn as affected by dry matter accumulation with age and response to applied nutrients. Agron. J. 65:941-945. 62. Tisdale, S. L. and W. L. Nelson. 1975. Soil fertility and fertilizers, Macmillan Co., New York.

PAGE 161

145 63. Walsh, L. M. 1971. Instrumental methods for analysis of soils and plant tissue. Soil Science Society of America Inc., Madison, Wisconsin 64. Whitty, E. B. and D. W. Jones. 1974. Florida field and forage crop variety report. Agronomy research report. Ag. 75-3. IFAS, University of Florida, Gainesville. 65. D. W, Jones, A. Kidder, and C. A. Chamhliss. 1976. Field and forage crop variety recommendations. Florida Cooperative Extension Service Agronomy Facts No. 63. IFAS, University of Florida, Gainesville.

PAGE 162

BIOGRAPHICAL SKETCH Nicolas Mateo Valverde, son of Nicolas Mateo Perez and Flor Marfa Valverde Castro, was born on June 10, 1945, In San Jose, Costa Rica. 1970, he received the Ingeniero Agronomo degree from the University of Costa Rica. From 1971 to 1973 he worked for the Costa Rican Ministry of Agriculture in Extension Service for small farmers. In 1972 he attended a Vegetable Crop Production course in Wageningen, Holland, for 4 months. He joined the staff of CATIE in Turrialba, Costa Rica, in 1973. There he worked in cropping systems research for small farmers and also obtained his M.S. degree. In 1976 he came to the University of Florida to pursue a Ph.D. in agronomy. He is married to Lorna Vega Rojas and they have two children, Elena and Javier. 146

PAGE 163

I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adeqxiate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Gallaher, Chairman Associate Professor of Agronomy I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Dale R. Hense] Professor of Soil Science I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Victor E. Green Professor of Agronomy I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy, Elmo B. Whitty 7 Professor of Agronomy

PAGE 164

I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Herman L. Breland Professor of Soil Science This dissertation was submitted to the Graduate Faculty of the College of Agriculture and to the Graduate Council, and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. August, 1979 Dean, Graduate School