Fertility management of the corn-soybean succession cropping system at three Florida locations

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Title:
Fertility management of the corn-soybean succession cropping system at three Florida locations
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ix, 120 leaves : ; 28 cm.
Language:
English
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Read, Michael Dean, 1953-
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Subjects / Keywords:
Corn -- Fertilizers   ( lcsh )
Soybean -- Fertilizers   ( lcsh )
Cropping systems -- Florida   ( lcsh )
Agronomy thesis M.S
Dissertations, Academic -- Agronomy -- UF
Genre:
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (M.S.)--University of Florida.
Bibliography:
Bibliography: leaves 115-119.
Statement of Responsibility:
by Michael Dean Read, Jr.
General Note:
Typescript.
General Note:
Vita.

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Source Institution:
University of Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 000013944
oclc - 05982800
notis - AAB7118
System ID:
AA00003485:00001

Full Text








FERTILITY MANAGEMENT OF THE CORN-SOYBEAN SUCCESSION CROPPING
SYSTEM AT THREE FLORIDA LOCATIONS








By

MICHAEL DEAN READ, JR.


A THESIS PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF MASTER OF SCIENCE



UNIVERSITY OF FLORIDA


1979












ACKNOWLEDGMENTS


I would like to express my deepest appreciation of Dr. Raymond

Gallaher for his planning, guidance, and assistance in conducting this

research and for serving as major professor. Special thanks are also

due Dr. W. T. Scudder and Dr. R. B. Forbes for overseeing the research

operations at Sanford and to Dr. F. M. Rhoads for overseeing the research

at Quincy and for serving on the supervisory committee. I wish to thank

Dr. W. G. Blue for serving on the supervisory committee and for reviewing

the manuscript so thoroughly in such a short period of time.

The scope and magnitude of this study were made possible only by

the cooperation of many competent and dedicated support personnel too

numerous to mention. I would like to especially thank Ms. Jan Ferguson

and Ms. Ruth Schuman for their laboratory assistance and for their keen

sense of humor which helped keep things in perspective during the

seemingly endless hours of grinding, extracting, digesting, and

analyzing plant and soil samples. Mrs. Anna Marie Martin did a tre-

mendous job of typing and editing the manuscript.

Finally, no words can express the gratitude due Ms. Joy Barrett

for her constant inspiration and love and for her understanding nature

during the most difficult days of completing this degree program.













TABLE OF CONTENTS

Page

ACKNOWLEDGMENTS . . .... ... .. ii
LIST OF TABLES. . . .... .. .. iv
ABSTRACT . . . .viii

INTRODUCTION. . . .. . 1

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

Multiple Cropping . . 3
Planting Date. . . .. 5
Water Management . .. 5
Plant Population . .. 6
Row Spacing. . . 6
Cultivars. . . . 6
Tillage. . . ..... .. 6
Herbicide Program. . ... .. 7
Fertility Management . . 7
Crop Nutrition--General . . 7
Soil Analysis . . . 9
Plant Analysis. . . .. 12
Nutrition of Corn . .. 15
Nutrition of Soybeans . . .. 16

MATERIALS AND METHODS . . 20

RESULTS AND DISCUSSION. . . .. 25

Leaf Analysis . . 28
Soil Analysis . . .. 33
Nutrient Removal. . . .. 36

SUMMARY AND CONCLUSIONS . ... .. 38

TABLES . . . .. 40

APPENDIX TABLES . . . 113

REFERENCES CITED. . . ... .. 115

BIOGRAPHICAL SKETCH . .... .. 120












LIST OF TABLES


Page

1 APPROXIMATE UPTAKE OF NUTRIENTS BY A CROP OF CORN .... 40

2 APPROXIMATE UPTAKE OF NUTRIENTS BY A CROP OF SOYBEANS 41

3 NUTRIENT CONCENTRATIONS IN CORN EAR LEAVES REPORTED
IN THE LITERATURE ....... . 42

4 NUTRIENT CONCENTRATIONS IN SOYBEAN LEAVES REPORTED
IN THE LITERATURE ........ . 43

5 FERTILIZER TREATMENTS IMPOSED ON THE CORN PLOTS OF CORN-
SOYBEAN SUCCESSION SYSTEMS AT THREE LOCATIONS IN FLORIDA. 44

6 DEGREES OF FREEDOM AND SOURCES FOR THE SPLIT-PLOT
ARRANGEMENT WITHIN A LOCATION IN FLORIDA FOR ONE
YEAR'S DATA . ... .. ......... .... 45

7 MANAGEMENT VARIABLES USED ON THE CORN-SOYBEAN
SUCCESSION CROPPING SYSTEMS IN FLORIDA. . ... 46

8 PLANTING, SAMPLING, AND HARVEST DATES FOR THE
CORN-SOYBEAN SUCCESSION CROPPING STUDY. . ... 47

9 VARIABLES MEASURED IN THE CORN-SOYBEAN SUCCESSION
CROPPING STUDY. . . .. ... 48

10 CORN GRAIN YIELDS (QTL/HA) AT SANFORD, GAINESVILLE
AND QUINCY. . . .. 49

11 CORN FORAGE YIELDS (TONS/HA) AT SANFORD, GAINESVILLE
AND QUINCY. . . .. 50

12 CORN YIELDS AS INFLUENCED BY THREE RATES OF NITROGEN
AT THREE LOCATIONS IN FLORIDA (TWO YEAR AVERAGE). ... 51

13 ANALYSIS OF VARIANCE F VALUES FOR THE EFFECTS OF YEAR
AND TWO RATES EACH OF N, P, AND K ON CORN YIELD AT
THREE LOCATIONS (TWO YEAR AVERAGE). . 52

14 SOYBEAN YIELDS AT SANFORD DURING 1977, 1978, AND THE
TWO YEAR AVERAGE. . . .. .53










15 SOYBEAN YIELDS AT GAINESVILLE DURING 1977, 1978,
AND THE TWO YEAR AVERAGE. . .

16 SOYBEAN YIELDS AT QUINCY DURING 1977, 1978, AND
THE TWO YEAR AVERAGE. . .

17 COMPARISON OF THE TWO CROPPING SYSTEM YIELDS AT
SANFORD, GAINESVILLE, AND QUINCY (TWO YEAR AVERAGE)

18 REVENUE COMPARISON OF THE TWO CROPPING SYSTEMS AT
SANFORD, GAINESVILLE, AND QUINCY (TWO YEAR AVERAGE)

19 CORN EARLEAF NITROGEN CONCENTRATIONS (%) AT SANFORD


CORN EARLEAF PHOSPHORUS CONCENTRATIONS (%) AT SANFORD .

CORN EARLEAF POTASSIUM CONCENTRATIONS (%) AT SANFORD .

CORN EARLEAF CALCIUM CONCENTRATIONS (%) AT SANFORD .

CORN EARLEAF MAGNESIUM CONCENTRATIONS (%) AT SANFORD. .

CORN EARLEAF NITROGEN CONCENTRATIONS (%) AT GAINESVILLE .

CORN EARLEAF PHOSPHORUS CONCENTRATIONS (%) AT GAINESVILLE

CORN EARLEAF POTASSIUM CONCENTRATIONS (%) AT GAINESVILLE.

CORN EARLEAF CALCIUM CONCENTRATIONS (%) AT GAINESVILLE. .


. 54


. 55


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S. 64

S. 65


CORN EARLEAF MAGNESIUM CONCENTRATIONS (%) AT GAINESVILLE. .

CORN EARLEAF NITROGEN CONCENTRATIONS (%) AT QUINCY. .

CORN EARLEAF PHOSPHORUS CONCENTRATIONS (%) AT QUINCY. .

CORN EARLEAF POTASSIUM CONCENTRATIONS (%) AT QUINCY .

CORN EARLEAF CALCIUM CONCENTRATIONS (%) AT QUINCY .


33 CORN EARLEAF MAGNESIUM CONCENTRATIONS (%) AT QUINCY .

34 NUTRIENT CONCENTRATIONS (%) IN CORN LEAVES AS INFLUENCED
BY THREE RATES OF NITROGEN AT THREE LOCATIONS
(TWO YEAR AVERAGE) . . .

35 ANALYSIS OF VARIANCE F VALUES FOR THE EFFECTS OF TWO
RATES EACH OF N, P, AND K ON CORN EARLEAF NUTRIENT
CONCENTRATIONS (TWO YEAR AVERAGE) . .


Page


66

67

68

69

70

71


. .










SOYBEAN LEAF NITROGEN CONCENTRATIONS (%) AT SANFORD .

SOYBEAN LEAF PHOSPHORUS CONCENTRATIONS (%) AT SANFORD .

SOYBEAN LEAF POTASSIUM CONCENTRATIONS (%) AT SANFORD. .

SOYBEAN LEAF CALCIUM CONCENTRATIONS (%) AT SANFORD .

SOYBEAN LEAF MAGNESIUM CONCENTRATIONS (%) AT SANFORD. .

SOYBEAN LEAF NITROGEN CONCENTRATIONS (%) AT GAINESVILLE

SOYBEAN LEAF PHOSPHORUS CONCENTRATIONS AT GAINESVILLE .

SOYBEAN LEAF POTASSIUM CONCENTRATIONS (%) AT GAINESVILLE.

SOYBEAN LEAF CALCIUM CONCENTRATIONS (%) AT GAINESVILLE. .

SOYBEAN LEAF MAGNESIUM CONCENTRATIONS (%) AT GAINESVILLE.

SOYBEAN LEAF NITROGEN CONCENTRATIONS (%) AT QUINCY .

SOYBEAN LEAF PHOSPHORUS CONCENTRATIONS (%) AT QUINCY. .


48 SOYBEAN LEAF POTASSIUM CONCENTRATIONS (%) AT QUINCY

49 SOYBEAN LEAF CALCIUM CONCENTRATIONS (%) AT QUINCY .

50 SOYBEAN LEAF MAGNESIUM CONCENTRATIONS (%) AT QUINCY

51 ANALYSIS OF VARIANCE F VALUES FOR THE EFFECTS OF TWO
RATES EACH OF N, P, AND K ON SOYBEAN LEAF NUTRIENT
CONCENTRATIONS (TWO YEAR AVERAGE) . .

52 SOIL TEST RESULTS FOR SAMPLES TAKEN AT SANFORD
DURING CORN GROWING SEASON, 1977. . .

53 SOIL TEST RESULTS FOR SAMPLES TAKEN AT SANFORD
DURING THE SOYBEAN GROWING SEASON, 1977 ..

54 SOIL TEST RESULTS FOR SAMPLES TAKEN AT SANFORD
DURING CORN GROWING SEASON, 1978 . .

55 SOIL TEST RESULTS FOR SAMPLES TAKEN AT SANFORD
DURING SOYBEAN GROWING SEASON, 1978 . .

56 SOIL TEST RESULTS FOR SAMPLES TAKEN AT GAINESVILLE
DURING CORN GROWING SEASON, 1977 .

57 SOIL TEST RESULTS FOR SAMPLES TAKEN AT GAINESVILLE
DURING SOYBEAN GROWING SEASON, 1977 .


Page

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Page


58 SOIL TEST RESULTS FOR SAMPLES TAKEN AT GAINESVILLE
DURING CORN GROWING SEASON, 1978. . ... 98

59 SOIL TEST RESULTS FOR SAMPLES TAKEN AT GAINESVILLE
DURING THE SOYBEAN GROWING SEASON, 1978 . .. 99

60 SOIL TEST RESULTS FOR SAMPLES TAKEN AT QUINCY
DURING THE CORN GROWING SEASON, 1977. . ... 100

61 SOIL TEST RESULTS FOR SAMPLES TAKEN AT QUINCY
DURING THE SOYBEAN GROWING SEASON, 1977 . .. 101

62 SOIL TEST RESULTS FOR SAMPLES TAKEN AT QUINCY
DURING CORN GROWING SEASON, 1978. . ... 102

63 SOIL TEST RESULTS FOR SAMPLES TAKEN AT QUINCY
DURING THE SOYBEAN GROWING SEASON, 1978 . 103

64 SOIL TEST VALUES TAKEN DURING THE SOYBEAN GROWING
SEASON 1978 AS INFLUENCED BY THREE RATES OF NITROGEN
APPLIED OVER A TWO YEAR PERIOD. . ... 104

65 ANALYSIS OF VARIANCE F VALUES FOR THE EFFECTS OF
TWO RATES EACH OF N, P, AND K ON SOIL TEST VALUES
OF SAMPLES TAKEN DURING THE SOYBEAN GROWING SEASON, 1978. 105


66 NUTRIENT CONCENTRATIONS IN CORN FORAGE GROWN
DURING 1977 AND 1978 AT SANFORD, FLORIDA. .

67 NUTRIENT CONCENTRATIONS IN CORN FORAGE GROWN
DURING 1977 AND 1978 AT GAINESVILLE, FLORIDA.

68 NUTRIENT CONCENTRATIONS IN CORN FORAGE GROWN
DURING 1977 AND 1978 AT QUINCY, FLORIDA .

69 NUTRIENTS REMOVED IN CORN FORAGE DURING 1977
AND 1978 AT SANFORD, FLORIDA. .

70 NUTRIENTS REMOVED IN CORN FORAGE DURING 1977
AND 1978 AT GAINESVILLE, FLORIDA. .

71 NUTRIENTS REMOVED IN CORN FORAGE DURING 1977
AND 1978 AT QUINCY, FLORIDA . .


. 107


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110


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A-1 CORN PLANT POPULATIONS AT HARVEST FOR EACH LOCATION
AND YEAR IN THE CORN-SOYBEAN SUCCESSION CROPPING
SYSTEM STUDY . . .

A-2 CORN HEIGHT MEASUREMENTS (cm) AT THREE LOCATIONS
IN FLORIDA DURING 1977 AND 1978 . .


S. 113


. 114






Abstract of Thesis Presented to the Graduate Council
of the University of Florida in Partial Fulfillmeit of the Requirements
for the Degree of Master of Science

FERTILITY MANAGEMENT OF THE CORN-SOYBEAN SUCCESSION CROPPING
SYSTEM AT THREE FLORIDA LOCATIONS

By

Michael Dean Read, Jr.

March 1979

Chairman: Raymond N. Gallaher
Major Department: Agronomy

Mild temperatures and a long frost-free growing period give the

Southeastern U.S. a tremendous potential for multiple cropping. One

system of considerable interest is the sequential growing of corn

(Zea maiv L.) and soybeans (Glycine max (L.) Merrill) in the same warm

season. This study investigated the yield potential and fertility

requirements of corn harvested for grain and for forage followed by soy-

beans at three Florida locations. Twelve N-P-K combinations were applied

to the corn with one K-sidedress treatment applied to the soybeans. Soil

and plant samples were taken during each crop growing season and analyzed

for soil pH, double acid extractable P, K, Ca, and Mg and plant N, P, K,

Ca, and Mg.

Corn responded to 168 kg of N/ha but not to 280 kg of N/ha or to

P or K fertilization. Soybeans did not respond to fertilization but yields

were 135 to 540 kg/ha higher following corn grain than following forage.

This lack of response to fertilization was attributed to high native

fertility levels in the soils studied. Two year averages of the three

top yielding fertility treatments were as follows: Quincy 113 qtl/ha

(1 qtl = 100 kg) corn grain followed by 18.3 qtl/ha soybeans and 27.7


viii







metric tons/ha corn forage followed by 16.3 qtl/ha soybeans; Gainesville -

77.6 qtl/ha corn grain followed by 20.9 qtl/ha soybeans and 18 metric

tons/ha corn forage followed by 19.4 qtl/ha soybeans; Sanford 68.3

qtl/ha corn grain followed by 30.1 qtl/ha soybeans and 16.2 metric tons/ha

corn forage followed by 28.8 qtl/ha soybeans.

Corn earleaf N responded to applied N and K at all locations. No

consistent response in earleaf P was noted, however, probably due to a

wide variation in soil test P values among locations. The two corn hy-

brids differed significantly in earleaf concentrations of N, P, K, Ca,

and Mg. Maximum nutrient removal in harvesting the corn forage occurred

at Quincy, Florida, where 123 kg/ha, 21 kg/ha, and 149 kg/ha of N, P,

and K were removed in the harvested corn forage. When soil-test K was

high, considerably greater luxury consumption of K by the corn forage

was noted.

Soybean leaf concentrations were not affected by fertilizer N or P

applications on corn, but leaf K was higher on plots receiving 224 kg of

K/ha than on those receiving only 112 kg of K/ha. The nutrient concen-

tration of K in soybean leaves decreased with the application of N on

corn while the concentrations of Ca and Mg increased. This indicated a

significant interaction if K, Ca, and Mg was present under the three

rates of N studied. In addition, the K concentration in soybean leaves

following corn forage was lower than in soybean leaves following corn

grain at high rates of N when no P or K was applied.





Chairman













INTRODUCTION


The challenge facing today's agronomist is to provide the knowledge

needed to produce more food on a declining amount of arable land. Popula-

tion continues to rise in the lesser developed nations at a rapid rate

while the richer nations are demanding more meat in their diets. Between

400 and 500 kg of corn (Zea mays L.) are required to produce 100 kg of

corn-fattened pork. The U.S. farmer experiences this as a constant and

ready market for all the food grains he can produce, although prices are

not always as high as he would like. Production inputs such as fertilizers,

fuels, and equipment costs become more and more expensive while the prices

received per unit of output rise only slowly. Farmers are forced to try

and make up the difference by increasing the efficiency of farm operations

and improving yields.

Given this situation, it is inevitable that farms will continue to

be more and more intensively managed. In Florida, multiple cropping is

likely to play a key role. By growing two or even three crops during

the year, farmers can increase their total income. If irrigation

facilities are installed, consistently high yields can be expected under

good management and the farmer can thereby reduce the risk of economic

damage by an extremely dry year while at the same time increasing his

annual profit.

Florida's subtropical climate allows production of a wide variety

of agricultural products. Beef cattle, citrus, winter vegetables, and

field crops all play an important role in the state's economy. Field








crop production is centered in the northern and western areas where corn,

soybeans (Glycine max (L.) Merrill), peanuts (Arachis hypogaea L.), and

wheat (Triticum aestivum L.) are the principle crops grown. Much of the

land lies fallow during a large portion of the year. Corn, peanuts, and

watermelons (Citrullus lanatus (Thumbs) Mansf.) are usually grown as

monocrops while wheat and soybeans are often grown sequentially in the

same year. Soybeans may also be grown as the only crop in a year. With

a frost-free growing season of over 240 days, the potential for multiple

cropping in north and north central Florida is apparent. Many systems

are currently being researched and the results are in demand. Management

practices are different for multicropping systems than for conventional

monocropping. Planting dates, tillage, herbicides, cultivars, and fer-

tility requirements all vary to one degree or another, and the farmer

cannot afford to use trial and error techniques in his own fields.

This study was initiated to determine the fertility requirements of

growing corn followed by soybeans in the same warm season at three loca-

tions in Florida. Corn was grown for either grain or forage and followed

by a late-maturing soybean variety. Twelve fertilizer treatments were

applied; yield response, soil tests, and plant analysis were used to

determine the optimum fertilizer application rate. The results of this

study, when combined with research on other management practices, will

help in formulating extension recommendations and increase the knowledge

of sequential multicropping systems in Florida.











REVIEW OF LITERATURE


Multiple Cropping


Andrews and Kassam (3) defined multiple cropping as the intensifi-

cation of cropping in time and space dimensions in which two or more

crops are grown on the same field in a year. They recognized two major

types of multiple cropping--intercropping and sequential cropping.

Intercropping is the growing of two or more crops simultaneously in the

same field. This can take any form from a random mixture of several

crops planted together to the growing of crops in rows where rows (or

groups of rows called strips) of one crop are alternated with rows or

strips of another. Also included in the intercrop category is relay

cropping in which the second crop is planted after the first has reached

its reproductive stage but before it is ready for harvest. Intercropping

is primarily found in the tropics where its advantages may include one

or more of the following: higher total yields per unit of land, increased

farm income, fewer insect problems, reduced risk of complete crop failure,

more efficient use of solar radiation and nutrients, and improved nutri-

tional diet for the farm family (24, 42, 49). The primary disadvantage

of intercropping is the difficulty of mechanization. Unless machinery

is developed which can effectively plant, cultivate, and harvest mixtures

of crops, intercropping in the higher mechanized temperate zone countries

will be limited to the planting of forage and pasture combinations and

will have little role in field crop production.








In contrast to intercropping, sequential cropping is the growing of

two or more crops in sequence on the same field during a year. Double

cropping is the growing of two, triple cropping the growing of three,

etc. Sequential cropping is found in both temperate and tropical areas.

Because only one crop is in the field at any given time, mechanization

is possible. The potential advantages of sequential cropping are similar

to those of intercropping--greater annual production, more efficient use

of solar radiation and nutrients, increased farm income, and reduced risk

of total crop loss. Dalrymple (4) has reviewed the extent and types of

multiple cropping found throughout the world. Additional information is

found in Papendick et al. (43), Sanchez (49), and Bradfield (8). The

success of different combinations is determined by local climatic, edaphic,

and management variables.

The sequential growing of corn and soybeans has not been reported

widely in the literature and nearly all the published work has been done

in Florida. In a nonscientific article, Johnson (28) reports that one

central Florida grower followed 94 qtl/ha corn with 30 qtl/ha soybeans

(1 qtl = 100 kg). Rezende (46) reported yields of 23.7 qtl/ha for soy-

beans planted on 13 July at Gainesville. This is sufficiently late to

allow a crop of corn to be grown and harvested prior to the soybeans.

Guilarte et al. (21) report soybean yields of 32.1 qtl/ha and 14.3 qtl/ha

for soybeans planted on 12 July and 5 August at Gainesville. Perez-Levy

grew soybeans, peanuts, southernpea (Vigna unguiculata (L.) Turner),

pigeonpea (Cajanus cajan (L.) Druce), and black bean (Phaseolus vulgaris

L.) following corn at Gainesville, Florida, as double crops (45).

The management of a multiple cropping system such as this differs

significantly from simply growing corn or soybeans as a full season








monocrop. Some of the factors which must be considered are planting

population, row spacing, cultivars, tillage, herbicides used, and

fertility management.


Planting Date

Monocropped corn is generally planted in March or April in north

Florida. To maximize the useable growing season, multicropped corn must

be planted as early in the year as possible. Aldrich (2) reports that a

freeze during the early stages of growth does not kill corn and, in fact,

may have little effect on later growth and final yield. Soybeans must

be planted as soon as possible after the corn is harvested--usually in

mid to late July. Smith (52), Guilarte (20), and Perez-Levy (45) all

reported a reduction in yield of soybeans as the date of planting was

delayed. The optimum planting date for monocropped soybeans in Florida

is considered to be 15 May-15 June (27, 51). Perez-Levy planted "Jupiter"

variety soybeans at Gainesville, Florida, on 12 July, 5 August, and 9

August and obtained yields of 40 qtl/ha, 24.9 qtl/ha, and 21.4 qtl/ha,

respectively (45).


Water Management

Florida normally experiences a minor dry season in the spring and

autumn which is accentuated on the sandy textured soils with low water

holding capacities (9). Many farmers wait to plant until late spring

when they can be sure of adequate rainfall. In a multicropping system,

this delay in planting is impossible. Farmers must either invest in

irrigation equipment, plant early and hope for a good year, or plan to

multicrop on only those soils which have the best moisture holding

capacities.









Plant Population

If irrigation is not available, lower plant populations may be

needed to compensate for the anticipated lack of moisture during the

growing season. In addition, late-planted soybeans were found to yield

better when planted at higher than usual populations in Florida (46).


Row Spacing

Late planted soybeans do not grow as tall as full season beans and

may fail to provide complete canopy closure when planted at normal row

spacings (1, 20). Narrow rows are recommended for very late planted

soybeans(46).


Cultivars

The corn hybrid chosen should be a short-season variety if grain is

to be harvested before soybeans are planted. If the corn is to be en-

siled, the farmer may either plant a full-season hybrid and harvest in

mid July or plant an earlier maturing variety and harvest still earlier,

thereby allowing him to plant the soybeans earlier and obtain greater

bean yields. Akhanda et al. (1) recommend that double-cropped soybeans

be selected from maturity group VIII or IX. They screened 24 breeding

lines for yield when planted on 24 July and 8 August 1975, at Gainesville,

Florida. Of these, the variety "Cobb" yielded highest. Group IX

varieties did not mature until after 10 November which may be after the

first frost occurs in some areas of north Florida.


Tillage

Minimum tillage is becoming more and more popular, especially in

multicropping systems (17). It can save valuable time in getting the








soybeans established after corn is harvested and also eliminates the

need for plowing under large quantities of fresh corn stover.


Herbicide Program

Certain herbicides commonly used on corn are toxic to soybeans

(atrazine (2 chloro-4 ethylamino-6 isopropylamino-1,3,5 triazine) for

example). The herbicide program for a corn-soybean multicropping system

will differ somewhat from that used in a monocropping situation.


Fertility Management

Gallaher (16), Munsen (39), Oelsligle et al. (41), and others have

pointed out the need for maintaining adequate soil fertility levels to

assure proper crop nutrition throughout the full growing season. Galla-

her stated that "double cropping means extra fertilizer will probably

be needed compared to monocropping because a successful second crop

will increase the amount of nutrients removed during the year." Deter-

mining the fertility requirements of corn followed by soybeans was the

main purpose of this research. In order to evaluate this system, it

was first necessary to know something about the fertility requirements

of the individual crops.


Crop Nutrition--General


The nutrient status of soil is constantly changing. In an undis-

turbed ecosystem, nutrients accumulate in the surface soil and biomass

until a dynamic equilibrium is reached where nutrients leave the system

(through leaching, oxidation, herbivary, erosion, and other means) at

the same rate they are supplied (through rain, animal feces, mineraliza-

tion of organic matter, mineralization of soil, leaf fall, etc.).








Cropping of the soil upsets this balance. The soil is frequently bare

and subject to rapid oxidation of organic matter. Leaching, erosion,

and crop harvest all remove nutrients from the system. As the soil's

fertility declines, yields of successive crops are reduced. Unless the

balance is restored through the addition of soil amendments, yields

will plateau at a low level. At this point, the soil is once again in

balance with the small quantities of nutrients removed in each harvest

being equal to the nutrients supplied through rain, mineralization, and

other processes. Multiple cropping involves intensive cropping and

demands large amounts of nutrients. This invariably means the addition

of fertilizers. In determining the quantities of fertilizers needed,

it is necessary to know something about the requirements of the individ-

ual crops being grown. Several studies have shown that higher yields

require more nutrients (Table 1). Tisdale and Nelson (55) stated that

268 kg of N/ha, 49 kg of P/ha, and 224 kg of K/ha are taken up by a

corn crop yielding 113 qtl/ha of grain. Of this, 78 kg of N, 15 kg of

P, and 179 kg of K are returned in the stover. This means that roughly

30, 30, and 80% of the N, P, and K, respectively, are returned to the

soil and are potentially available for uptake by the following crop.

The nutrients required to produce various yields of soybeans are

summarized in Table 2. Hanway and Webber (22) reported that 271 kg of N,

23 kg of P, and 94 kg of K are taken up by a 29 qtl/ha crop of soybeans.

Of this, 90 kg of N, 6 kg of P, and 43 kg of K are returned to the soil

if only the beans are removed. The percentage of N, P, and K returned

to the soil are approximately 33, 24, and 45%, respectively.

An estimate of the absolute minimum quantity of nutrients needed

for growing corn and soybeans can be calculated using the data in Tables








1 and 2. Over the course of a year, 178 kg of N/ha, 66 kg of P/ha, and

275 kg of K/ha will be removed from the system and must be replaced if

corn is harvested for forage. The quantities are substantially less if

only the grain is removed; only 100 kg of N/ha, 51 kg of P/ha, and 96

kg of K/ha are removed with the harvest each year. These quantities

represent only the amounts of nutrients which are removed in a year and

not the amounts of fertilizer which would be needed. The latter must

take into account inefficiency of nutrient uptake, fixation of minerals

by the soil, oxidation of organic N, leaching, and initial soil-test

levels. Thus, the actual fertilizer recommendations will probably be

greater (but may be less) than the amounts of nutrients removed.

In establishing the fertilizer recommendations for crops, two

techniques are commonly employed--soil analysis and plant analysis.

Soil analysis is used to predict the quantity of various nutrients which

must be added to the soil for maximum yields. Plant analysis is used

to ascertain the nutritional status of a crop while it is growing.

Together, they provide a more complete picture of crop nutrition than

when used alone. Reviews of both soil and plant analysis procedures

are found in Walsh and Beaton (60), Sanchez (49), and Tisdale and

Nelson (55).


Soil Analysis


The soil analysis procedure can be divided into four distinct parts:

1. Sampling
2. Analysis
3. Correlation with field and greenhouse tests
4. Interpretation and recommendations

The following discussion will be limited to soil testing for N, P, K,

Ca, and Mg.








The first step in soil analysis is sampling. Sanchez (49) stated

that taking a representative soil sample is the largest source of error

in the soil fertility evaluation program. Ten to twenty subsamples are

recommended and should include the complete rooting zone. Time of year

has also been shown to affect the soil test results (54). After sampling,

the soil is air dried, ground to a uniform particle size, and treated

with one of several extractants. The most commonly used extractants are

the double acid, Bray, and Olsen extractants (13). These extractants

differ primarily in their abilities to extract meaningful quantities of

P from the soil which correlate well with plant uptake.

The double-acid extractant (sometimes called North Carolina or

Mehlich) consists of 0.05 H HC1 + 0.025 N H2SO and has a pH of 1.2.

The acid causes rapid dissolution of Ca-phosphate (Ca-P) minerals so it

is not recommended for use in alkaline soils or where substantial

quantities of Ca-P minerals are suspected. Aluminum-phosphate minerals

(Al-P) are dissolved more slowly and Fe-phosphates (Fe-P) hardly at all

(54). Soils high in Fe oxides and clay give low P values because they

neutralize the acid. The quantity of K extracted is similar to that

found when 1.0 N NH4OAc at pH 7 (considered the standard extractant for

K, Ca, and Mg) is used. Calcium and Mg minerals may be dissolved by the

acid, thus giving higher values than those found with ammonium acetate

(11).

There are two Bray extractants. Bray #1 consists of 0.03 N NH F

and 0.025 N HC1 while Bray #2 consists of 0.03 N NH F and 0.1 N HC1.

They work well on soils with low to medium cation exchange capacities

(CEC) which are moderately weathered or well weathered (49). Soils with

free CaCO3 or soils with high CEC and high percent base saturation will








neutralize the acid and lessen the effectiveness of the extractant. Doll

and Lucas (13) stated that the extractant is effective in determining

available K, Ca, and Mg. The extraction of P occurs when F ions complex

Al and P is released. Because the pH is somewhat higher in Bray #2 than

in the double-acid extractant, it dissolves basic Ca-P minerals such as

hydroxyapatite more completely.

The Olsen bicarbonate extractant consists of 0.5 M NaHCO, buffered

to pH 8.5. Sanchez (49) stated that it is applicable over a wider range

of soil types than the other extractants for determination of P. It

is the only extractant which releases much Fe-P. Within certain types

of soils, however, P extracted by NaHCO3 has not been as closely related

to plant response as the P extracted by NH F-HC1 (54). Because of the

high pH, it is effective on alkaline soils and soils with medium to high

CEC values. It is also well suited to soils with high degrees of base

saturation or moderate amounts of Ca-P and free CaCO3 (49, 54). The

carbonate ions precipitate out Ca- forming CaCO3 and bringing Ca-P

compounds into solution. Iron and Al phosphates are dissolved by the

high pH. The NaHCO3 is also an effective extractant for K, Ca, Mg, Zn,

Mn, Fe, Cu, and NH4-N (13).

Ammonium acetate is frequently mentioned as an excellent extractant

for soil K, Ca, and Mg (13, 25), but it is rarely used for extraction of

P. Bingham (6) surveyed all the U.S. land grant universities in 1961

and reported on the extractants used in soil-testing programs. Florida

was the only state which used ammonium acetate buffered to a pH of 4.8

with acetic acid for extraction of P. Presumably, the mild acidity

dissolves some Ca, Al, and Fe phosphates and the acetate ions complex








with Al and Fe to prevent readsorption of P. Florida has since changed

to the double-acid extractant.

Once the soil is extracted, the solution is analyzed quantitatively

and the results are correlated with field trials. It should be empha-

sized that the concentration of nutrients in the soil extractant is only

a relative number and has no real meaning until correlated with greenhouse

and field trials. Often, greenhouse tests show a strong correlation

between soil-test values and yield or mineral uptake by plants while

field trials show much greater variability. This is because yield is a

function of many variables beyond the single nutrient under consideration

(10). For this reason, soil-test results generally report the soil to

be "high," "medium," or "low" in a particular element and recommendations

are made by determining the amount of fertilizer which will bring the

soil test nutrient levels to values associated with adequate yields.

This quantity will depend on the crop and the soil type.


Plant Analysis


One objective of plant analysis is to determine if the nutrient

concentration in a growing plant is adequate for maximum yield. Macy

(35) first proposed this concept in 1936 and stated that "luxury con-

sumption" of nutrients occurs above the critical percentages and little

or no yield response can be correlated with the higher concentrations.

Below the critical concentration, a zone of "poverty adjustment" was

proposed where yield is reduced in proportion to a decrease in nutrient

concentration. Tyner (56) recognized that the actual relationship

between yield and nutrient concentration is curvilinear rather than

linear. He assumed, however, that a linear relationship exists over








much of the range and used linear regression analysis to correlate yield

with percent N, P, and K. He computed mathematical formulae for estimating

yield as a function of nutrient concentrations but conceded that climatic

variability could render the model useless, even when working with

similar soils and crop varieties.

The concept of critical nutrient level has been modified since its

conception to fit the realities of experimental data. Tyner (57) pro-

posed critical levels in the sixth corn leaf at silking of 2.9% N, 0.295%

P, and 1.30% K. Bennet et al. (5) found that the critical level of N

in corn leaves varied from 2.6 to 3.1% in eight experiments. Dumenil

(14) proposed that the critical N and P levels in corn do not occur at

a single point or even over a narrow range of values. Instead, they

include a wide range of values which reflect nutrient interactions and

levels of other factors which interact with nutrient uptake.

More recently, Voss, Hanway, and Dumenil (58) measured corn grain

yield and leaf N, P, and K concentrations on 575 plots at 23 sites in

western Iowa. Multiple regression equations for yield as a function of

linear, quadratic, and interaction terms for leaf N, P, and K resulted
2
in an R of only 0.24. By adding several environmental factors such as

past cropping, plant population, soil moisture, soil yielding potential

and interaction terms, they were able to improve the model considerably.

They concluded that the observed grain yields could not be satisfactorily

predicted by a regression model that contained only leaf N, P, and K

concentration terms because yield was too much a function of soil,

management, and climatic factors.

Peck et al. (44) demonstrated the influence of micronutrients and

their interactions with macronutrients on yield. They reported an R2








of 0.45 from fitting yield to nine linear and quadratic leaf N, P, and

K concentration forms. Upon adding seven minor nutrients and inter-
2
actions, an R2 of 0.81 was obtained. The resulting model contained 37

terms, however, and interpretation of such relationships becomes a

difficult task.

Gallaher (15) found differences in nutrient uptake and concentra-

tion of P, K, Ca, and Mg among different corn genotypes. In one in-

stance, he found that the variety with highest P, K, Ca, and Mg con-

centrations in leaf tissue yielded the lowest of all inbreds studied.

He also found significant differences in leaf concentrations among the

same genotypes from year to year.

The only conclusion which can be drawn from such data is that there

is no single "critical percentage" of a mineral element which is valid

for different varieties grown on different soils under different environ-

mental conditions. The best that can be expected is a wide range of

values which will account for the influence of these factors. Such a

range would be of little value in determining the nutritional status of

crops which are only slightly deficient in a certain nutrient. It

would, of course, be useful in detecting severe nutritional deficiencies.

This is not to say that plant analysis isn't a useful tool in evaluating

the nutritional status of crops, but simply that many factors must be

considered. Generally, good correlations between nutrient concentration,

yield, and nutrient supply are obtained at a specific location in a

given year but the year to year and location to location influences on

the relationship are often quite significant and difficult to determine.

Munsen and Nelson (40) stated that plant analysis will probably become

more important in the future. They predicted that the days of looking








only at N, P, and K concentrations are over and that factors such as

micronutrients, irrigation, and date of planting will be considered.

Through field tests and sampling of farmers fields, critical or optimal

range values could be determined for specific hybrids or varieties grown

in a particular area under specified management conditions. In con-

clusion, it is apparent that field trials and proper interpretation of

results are as crucial in the success of a plant-analysis program as

they are in soil analysis.


Nutrition of Corn


Corn does best on fertile, well drained, loamy soils with pH

between 5.5 and 8.0 (37). Nutrient requirements are a function of

moisture availability and plant population. Rhoads (47) obtained yields

of 150 qtl/ha in Quincy, Florida, under ideal irrigation with the

application of 336 kg of N/ha, 100 kg of P/ha, and 280 kg of K/ha.

He concluded that corn yields in excess of 125 qtl/ha could consistently

be produced in north Florida if all production practices were managed

properly. Due to the sandy texture of most Florida mineral soils, it

is best to apply the N in one or two sidedress applications.

Sampling of corn plants for the determination of nutrient concen-

trations has been the subject of many studies. Since the concentrations

of nutrients vary with plant age, plant part being sampled and position

on plant (30, 31, 59), these factors must be clearly specified when

values are given. Jones et al. (31) recommended three sampling pro-

cedures for corn: (1) sample the complete above-ground portion of

seedlings less than 30 cm.; (2) sample the first fully developed leaf








below the whorl just prior to tasseling; or (3) sample the entire leaf

at the ear node (or immediately above or below it) between tasseling and

the beginning of silking. Some nutrient concentrations found in the

literature are summarized in Table 3. Several authors have suggested

looking at the ratios of the concentrations of elements to each other

(40). Some of the ratios looked at are N/K, N/P, Ca/P, Ca/K, and (Ca +

Mg)/K. Dumenil (14) reported that the N/P balance in corn leaves at

silking appears to be critical near the maximum yield. Vosset et al.

(58) reported a nearly constant 10:1 ratio for %N:%P over a wide range

from 3.5% N and 0.35% P to less than 2.5% N and 0.25% P in Iowa experi-

ments. This ratio held true regardless of environmental effects, soil

test, or fertilization.

Gallaher et al. (18) examined cation sums and ratios in corn and

found the K/Ca, K/Mg and K/(Ca + Mg) ratios in corn leaves were dependent

on age, fertilizer K applied, and yearly variations. Tissue Ca and Mg

concentrations were found to decrease as a result of K application while

tissue K concentration increased. Although it is obvious that nutrient

interactions exist in plants, the effectiveness of using element ratios

as a diagnostic tool needs to be evaluated more completely (40).


Nutrition of Soybeans


Soybeans grow best on soils of high fertility with a pH of 5.5 to

6.5 (48). Soybean response to direct fertilization has been generally

small and inconsistent except on soils of low nutrient availability

(22, 33). Well inoculated soybeans do not usually respond to N fertili-

zation (32, 36) and response to P and K is variable. Florida Cooperative








Extension Service recommendations are for 40, 20, or 10 kg of P/ha on

soils testing low, medium, or high in P and for 75, 37, or 19 kg of K/ha

on soils low, medium, or high in K (61). Kamprath (33) reported that on

three Alabama soils testing low in available K, soybean yields increased

from 350 to 1350 kg/ha with the addition of K but no increase was ob-

tained on soils with a medium or high soil test K. Maples (36) reported

increases ranging from 270 to 880 kg/ha on soils with low soil test K

in Arkansas. A response to P was obtained only when the soil test value

was very low (less than 22 kg P/ha). On these soils, an application

rate of 15 kg of P/ha was adequate for maximum yield. Jones, Lutz, and

Smith (29) found that the application of either P or K increased nodula-

tion and pod formation with a greater increase from K than P application.

Maximum response was observed when both P and K were applied together.

This experiment was conducted in Virginia. DeMooy et al. (12) compared

the response of corn with that of soybeans when fertilized with P and K

and the response of each to residual P and K in the soil. They found

that corn was significantly more responsive to direct and residual

fertilizer P and to direct application of K. Soybeans showed little

difference between the effect of direct and residual fertilizer on yield.

In addition, the following observations were reported: 1. only a small

response from applied P and K fertilizers on land of low fertility was

noted; 2, there was no response to anything greater than a maintenance

rate of P fertilization; and 3. soybeans did not respond appreciatively

to a second cycle of P and K fertilization applied during the following

year although the soil remained low in P and low to medium in K. From

this study conducted in Illinois, they concluded that soybeans have only








limited nutritional requirements. A more consistent response to fertili-

zation has been noted in the southern part of the U.S.A. (50). In Georgia,

Boswell and Anderson found that high rates of P and K (49 kg/ha and 93

kg/ha, respectively) resulted in significantly greater yields and larger

seed size during each year of a 3-year study than low rates (24 kg/ha

and 45 kg/ha) (22).

When sampling soybeans for nutrient concentrations, the stage of

growth and plant part sampled are very important (53). Hanway and

Weber report that N, P, and K concentrations will be influenced by the

plant part chosen, position on the plant, stage of development and level

of fertilization (23). Several studies have reported on the seasonal

accumulation of nutrients in soybeans and the changes in leaf concen-

trations which occur over a growing season (22, 50). Melsted et al. (38)

reported that significant plant composition differences have seldom been

observed between different commercial varieties of soybeans and that any

differences which are present can be minimized by analyzing the youngest

mature leaves on the plant. Small and Ohlrogge (50) recommended samples

be taken during the early bloom or early seed development stage and that

the uppermost fully mature trifoliate leaves be taken. Jones et al. (30)

recommended sampling at the seedling stage (less than 30 cm high), or

else prior to or during the initiation of flowering. They did not

recommend sampling after the pods begin to set. Some values for soybean

leaf samples found in the literature are presented in Table 4.

Several studies have demonstrated a significant effect on leaf

nutrient concentrations as a result of fertilization (7, 23, 34).

Nutrient interactions have also been reported. Hanway and Weber (23)

found that application of N fertilizer to soybeans generally decreased







the P concentration and that N-deficient plants (nonnodulated) were high

in P. Lutz and Jones (34) reported that liming tended to decrease the P

and K concentrations in soybean leaves and that the concentration of K

decreased as the rate of P fertilization increased. Boswell and Anderson

(7) found that when N was applied without P or K, the K concentration

in the tissue was reduced. By putting fertilizer N, P, and K, soil P,

K, and pH, and year into a regression model for predicting yield, they

obtained a relationship which was able to account for 65% of the varia-

tion in yield.













MATERIALS AND METHODS


The study was conducted at Sanford, Gainesville, and Quincy, Florida,

during the years 1977 and 1978. Experiments at Sanford were located at

the University of Florida Agricultural Research and Education Center

(AREC) in Sanford on Immokolee fine sand (member of the sandy, silicious

hyperthermic family of the arenic Haplaquods) which had previously been

in vegetable production. Experiments at Gainesville were located at the

University of Florida's Green Acres Agronomy Farm on Arrendondo loamy

sand (member of the loamy, silicious hyperthermic family of the grossarenic

Paleudults) which had previously been under bahiagrass (Paspalum notatum

Flugge) sod. Experiments at Quincy were located at the University of

Florida AREC in Quincy on Ruston loamy sand (member of the fine loamy,

silicious thermic family of the typic Paleudults) which had previously

been used for growing shade tobacco (Nicotiana tobacum L.).

Two systems were studied--corn for grain ("Funks G4507") followed

by soybeans ("Cobb") and corn for forage ("Dekalb XL395") followed by

soybeans ("Cobb"). These two systems were the whole plots in a split-

plot experimental design. The split plots consisted of twelve N-P-K

fertilizer treatments (Table 5). Nitrogen fertilizer was applied at

planting and in two sidedress operations. The P fertilizer was applied

at planting and the K fertilizer was applied in two applications as

indicated. All fertilizer treatments were applied to the corn crop

with the exception of treatment 12 which received a sidedress application

of 112 kg of K/ha on the soybeans at early bloom. No other fertilizer







was applied to the soybeans. This experiment was replicated four times

at each of the three locations over a 2-year period. A breakdown of the

degrees of freedom is given in Table 6.

The land was moldboard plowed and double disc harrowed before each

crop was planted. Varieties, rowspacings, plant populations, herbicides,

pesticides, and irrigation facilities used are presented in Table 7.

Corn was planted as soon as the danger of frost had passed at each loca-

tion. Planting date at Sanford was in late February, and at Gainesville

and Quincy approximately 7 to 10 and 15 to 20 days later, respectively.

Corn was harvested approximately 100 days after planting and the soybeans

were planted as soon as the land could be prepared following corn har-

vest. Soybeans were harvested in November. Dates of planting, harvesting,

and sampling are given in Table 8.

One set of soil samples was taken during each crop-growing season

at each location. Nine cores were taken from the plow layer (0 to 18 cm)

of each plot, air dried, and ground to pass through a 2 mm stainless

steel sieve. Five grams of soil were weighed and extracted with 20 ml

of double-acid extractant (.05 N HC1 + 0.025 N H2SO4) for 5 minutes in

an Eberback mechanical reciprocating shaker (160 oscillations/minute).

The extracts were filtered through Whatman No. 6 filter paper and then

stored in 25-ml vials under refrigeration until analyzed for P, K, Ca,

and Mg. Phosphorus was determined colorimetrically using a Technicon

Auto Analyzer. Potassium was determined by flame emission photometry

and Ca and Mg were determined by atomic absorption spectrophotometry.

Soil pH was determined for each sample using a Corning glass electrode

potentiometer. A 1:2 soil to water ratio was used. This soil-water








mixture (50 ml) was stirred, left standing for one half hour, and

stirred again prior to reading.

Corn leaf samples were taken during the early silk stage with the

complete earleaf being taken from the lowest ear on 12 to 15 plants per

plot. Soybean leaf samples were taken at early pod swell. The upper-

most fully mature trifoliate leaves (without petioles) were selected

from 20 to 30 plants on each plot. Forage samples were taken at harvest

from each of the plots where corn was grown for forage. Five complete

plants (less roots) were selected and analyzed for nutrient concentra-

tions.

Plant samples were dried in forced-air forage dryers at 65 C for at

least 48 hours. Leaf samples were ground either in a Wiley Mill (1 mm

screen) or a Cristy Norris Mill which pulverized the sample. The samples

were mixed thoroughly after grinding and dried again at 70 C for 24 hours

before being stored in airtight sample bags. Forage samples had to be

chopped twice in a mulching machine and subsampled before they could be

ground in the smaller mills.

Nitrogen analysis was performed according to approved procedures

(19). A 100-mg sample of the ground plant tissue was placed into a

75-mm pyrex digestion tube along with 3.4 g of prepared catalyst (90%

anhydrous K2SO4 + 10% anhydrous CuSO4), two or more Alundum boiling

chips, and 10 ml of concentrated H2S04. The contents were mixed and a

total of 2 ml of 30% H202 was carefully added in 0.5 ml, 0.5 ml, and

1 ml increments. The samples were allowed to stand for about 15 minutes

until reaction of H202 ceased. Samples were digested at 3850C in an

aluminum block as described by Gallaher et al. (19). The digested








solution was then diluted to 75 ml with distilled water and analyzed

with a Technicon Auto Analyzer.

Phosphorus, K, Ca, and Mg were analyzed by routine methods. One

gram of plant sample was placed into a 50 ml pyrex beaker and ashed at

4800C for 4 hours. A small amount of distilled water and 2 ml of HC1

were added to the ash and this mixture was gently heated on a hotplate

until dry. Following this, another 2 ml of HC1 were added with 10 ml of

distilled water. This mixture was covered with a watchglass and digested

for one-half hour before being diluted to 100 ml and stored in a

plastic vial. Phosphorus was determined colorimetrically using a

Technicon Auto Analyzer. Potassium was determined by flame emission

photometry and Ca and Mg were determined by atomic absorption spectro-

photometry.

Statistical analysis of the data consisted of performing an analysis

of variance for the effect of system and treatment on each factor measured

(Table 9 ). In addition to the analysis of variance for differences

between treatments, the data was broken into two subgroups. The first

consisted of treatments 1, 2, and 3 where three rates of N were applied

(0, 168, and 280 kg/ha) without any P or K. The effects of these three

rates of N on yield and leaf nutrient concentrations was examined. The

second subgroup was composed of treatments 4 to 11 which lent itself to

analysis as a 2x2x2 factorial experiment with all combinations of the

two higher rates of N (168 and 280 kg/ha), the two rates of P (56 and

112 kg/ha), and the two rates of K (112 and 224 kg/ha). The following

regression model was used to evaluate the effects of year, N, P, K, and

all interactions on yield: Yield = p + B + c + year + N + P + K + year








x N + year x P + year x K + NxP + PxK + NxK + NxPxK + year x NxP + year

x NxK + year x PxK + year x NxPxK. In this instance, p is the overall

mean, B is the block effect, and e is an error term. Coefficients for

the terms in the model were not determined, but the R2 value was.

Throughout the tables in this text, treatment means with the same

letter are not significantly different at p = .05 according to Duncan's

New Multiple Range Test. System means marked with an asterisk are

different at p = .05 when analyzed as the whole plots in a split plot

experimental design. Where only one set of letters is given beside the

two year average treatment mean, no system by treatment (system x treat-

ment) interaction exists and the treatment differences are similar in

the two systems. Where one set of letters is given for each system in

the two year average analysis, a significant system x treatment inter-

action was found and the two systems were, therefore, studied

individually for treatment effects.














RESULTS AND DISCUSSION


Yields varied considerably between years and among locations (Tables

10 and ll)--a fact which can be explained by the quantity of water avail-

able during the corn growing season. Yields were low at Sanford during

1977 because of inadequate irrigation and a dry spring. The only treat-

ment effect noticeable was a significantly lower grain yield on the check

plots where no fertilizer was applied. Yields at Quincy were very high

in 1977 because of excellent irrigation but were reduced in 1978 due to

an unidentified disease which developed midway through the growing sea-

son. There was some effect of treatment on corn yields at Quincy during

1977 and this was accentuated during 1978. Even without fertilizer,

however, corn grain yields were 100 qtl/ha during 1977 which was only

25% lower than the highest-yielding treatment. This high yield reflected

the high native fertility levels of the land used in this study. It was

previously well fertilized and used for shade tobacco production. Forage

yields followed the same pattern as grain yields. In spite of the dif-

ferences between treatments during both 1977 and 1978 at Sanford and

Quincy, the analyses of variance for the two averages showed virtually

no effect of treatment on yield. This was probably a result of a high

coefficient of variability caused by the differences between years and

does not accurately reflect the true situation. Corn grain and forage

yields at Gainesville yielded significantly less over the 2-year period

on the check plots where no fertilizer was applied.









To investigate further the effects of treatment on yield, treatments

1, 2, and 3 were analyzed as a subgroup to examine the effect of adding

0, 168, or 280 kg of N/ha without P or K. Both corn grain and corn for-

age responded to 168 but notto 280kgpf N/ha at all three locations (Table

12). Treatments 4 through 11 were also analyzed as a subgroup to deter-

mine the effect of two rates of N (168 vs. 280 kg/ha), two rates of P

(56 vs. 112 kg/ha), and two rates of K (112 vs. 224 kg/ha) on yield. This

analysis will be referred to as the 2x2x2 factorial analysis throughout

the rest of this paper. Results are presented in Table 13 and indicated

that there was no significant effect of N, P, K, or interactions on yield

at Gainesville or Sanford. At Quincy, however, the effects of N, K, NxP,

and NxK were all significant. This means that yields were significantly

affected by N and K. In this instance, an examination of the means shows

that yields were higher where the higher rate of N was applied but lower

where the high rate of K was applied. These results indicated that a

nutrient interaction occurred because on the plots where no P or K was

applied, corn yield did not respond to 268 kg of N/ha but where P and K

were applied, a yield response to the high rate was noted. A significant

interaction term such as NxP or NxK indicated that the yield change due

to N at the low rate of P or K was not the same as that which occurred

at the high rate of P or K.

Soybean yields for 1977, 1978 and the 2-year average are presented

in Tables 14 through 16. Yield was not influenced by treatment at

Gainesville or Quincy. At Sanford, soybeans following corn grain were

not affected by treatment but soybeans following corn forage were. The

statistical analysis which was performed indicated simply that there

was an overall difference between treatments. There was no one treatment








which consistently outyielded the others, but treatments 1, 2, and 3

appeared to be among the lowest yielding plots in all cases. This was,

however, not a statistically significant difference. As this study

progresses and the soil continues to be cropped on treatment plots 1, 2,

and 3 where no P or K is added, this reduction in yield should become

more pronounced.

A significant difference between systems was noted at Quincy and

Sanford over the 2-year period. Soybean yields were consistently lower

following corn forage than following corn grain. It could have been

that the nutrients removed in the corn forage were of sufficient quantity

to alter the soil's capacity for supplying adequate nutrients to the

soybean crop. It is interesting to note that treatment 12 which in-

cluded a sidedressing of K on the soybeans at early bloom, yielded no

better than the other treatments. This would suggest that all fertilizer

necessary for optimum yields could be applied to the corn crop and the

residual fertility would be sufficient for the soybeans.

Average system yields for the 2-year period are presented in Table

17. Corn yields were primarily a function of the irrigation facilities

available, but soybean yields were affected by the length of the growing

season as well. Soybeans at Sanford were planted earlier in the summer

than those at Gainesville and Quincy and yielded consistently higher.

If a farmer wanted to increase his soybean yields at Quincy, he could

plant a short-season corn hybrid and harvest it for forage. This would

allow him to plant soybeans earlier in the summer and thereby increase

the soybean yield potential. A system such as this (early harvested

corn forage followed by soybeans) would be applicable all along the

southern coastal region of the southeast U.S.









A revenue comparison of the two systems studied is given in Table

18. The actual income will vary according to yield and price variables,

but using the values indicated in the table, corn for forage followed by

soybeans would return a higher gross income per acre than corn grain

followed by soybeans. In the corn grain-soybean system, the soybean

crop was more valuable at Sanford, while the corn crop was more valuable

at Gainesville and Quincy. In a multiple cropping system such as this,

most of the production expenses can be attributed to the first crop.

The second crop provides a considerable amount of additional revenue for

only a small additional investment. When growing soybeans after corn,

the extra expenses would consist of soybean seed, herbicides, pesticides,

and the cost of planting. No additional fertilizer would be necessary.

The early planting of corn in this system assured a virtually pest-

free growing season. No insecticides were used on the corn at Gaines-

ville in 1978 and there were no insect problems. Under good management,

the short-season hybrids planted early should yield as well as full-

season monocropped corn in Florida. Soybean yields will be somewhat

lower at Gainesville and Quincy than would be expected from full-season

beans, but yields at Sanford should not differ much. Soybean yields of

30, 25, and 20 qtl/ha could consistently be produced following corn grain

at Sanford, Gainesville, and Quincy, Florida, under the conditions of

this study.


Leaf Analysis


Earleaf concentrations of all elements except P were influenced

by treatment (Tables 19 through 33). The P concentrations were not








influenced by treatment at Sanford and were only slightly influenced at

Quincy. The two hybrids differed significantly from each other in con-

centrations of all elements at Sanford and Gainesville. Only Ca con-

centrations in the two hybrids were significantly different at Quincy.

To examine just how fertilization affected nutrient concentrations, the

treatments were broken into two subgroups again. Nutrient concentrations

as influenced by the three rates of N (without P or K) are given in Table

34. The first increment of N increased the N concentration in the corn

leaves in every instance but the second increment resulted in a further

increase only in the full-season hybrid at Quincy. Phosphorus concen-

trations in the corn leaves were not consistently affected by N fertili-

zation. There was a tendency for the P concentration to increase with

added N, but no meaningful conclusions could be drawn from the data.

Potassium concentrations were not affected by N fertilization at Sanford

or Gainesville, but increased with the first increment of N at Quincy.

Apparently, the application of N allowed more K to be taken up by the

plant. Potassium uptake was considerably increased because in addition

to the higher concentration of K, there was an increase in dry-matter

production, so the uptake and content of K in the crop (concentration x

dry matter) was far greater on those plots which were fertilized with

N. There was a tendency for N fertilization to cause a decrease in K

concentration at Sanford and Gainesville, especially in System II where

forage was harvested. This effect was much more pronounced in 1978 than

in 1977 after 1 year of cropping and nutrient removal (see Tables 21 and

26). At Gainesville and Sanford, the N fertilizer caused an increase in

dry matter production, but the soil's ability to supply K was limited so

a dilution effect occurred and the concentration of K in the leaves was









lower. This was different from the situation at Quincy where soil K

reserves were high and luxury consumption occurred.

Earleaf Ca and Mg concentrations increased when 168 kg/ha N was

applied in almost every case. This increase was larger at Sanford and

Gainesville than at Quincy, indicating that perhaps Ca and Mg were being

absorbed in place of K. This hypothesis was further supported by the

fact that there was a tendency for the Ca and Mg concentrations to be

higher at Sanford and Gainesville (where the K earleaf concentrations

were low) than at Quincy (where the K concentrations were high).

Earleaf N was significantly higher when the high rate of N was

applied to both hybrids at Sanford and Gainesville and to the short-

season hybrid at Quincy (Table 35). This is in contrast to the results

found when N but no P or K were applied. In the latter case, there was

no response to the second increment of N. Once again, this suggested

that a nutrient interaction was present where the lack of one nutrient

(K) inhibited uptake of another (N).

Corn-leaf P responded positively to the high rate of fertilizer P

in System I at Sanford and in System II at Gainesville. Earleaf P also

increased when the high rate of N was applied at Gainesville. These

conclusions are of dubious value, however, because P concentration in

the leaf tissue did not differ by much more than a few hundredths of

one percent among treatments.

Earleaf K concentrations responded to the higher rate of K at

Sanford and Gainesville but not at Quincy. Once again, this is a re-

flection of the higher soil K reserves at Quincy. At Sanford, earleaf

K was depressed by the higher rate of P in System I and the same was









found at Gainesville in System II. Earleaf Ca was negatively correlated

with K application rate at Gainesville. The higher K rate caused an

increase in leaf K concentration and a decrease in Ca concentration.

This demonstrated that a certain amount of competition between K and

Ca was occurring. Interactions between Mg and K were also evident.

Corn earleaf Mg was consistently higher where only the low rate of K

was applied than where the high rate was applied at all locations.

In summary, the major trends in corn earleaf analysis were for N

fertilization to increase earleaf N concentration and to decrease ear-

leaf K concentration unless fertilizer K was applied or the soil had a

high soil K level (as was the case at Quincy). An interaction was noted

between K, Ca and Mg in which Ca and Mg concentrations were high when

earleaf K was low. The addition of fertilizer K resulted in a decrease

in earleaf Mg in almost every case and a decrease in earleaf Ca in both

hybrids at Gainesville.

Soybean leaf N and P were not affected by treatment or system ex-

cept in one case--soybean leaf N was significantly lower following corn

forage than following corn grain at Quincy (Tables 36 through 50). Re-

moval of the large quantity of forage grown at Quincy from the field in

some way affected soybean development or nodulation enough to alter the

leaf N concentration. This low N concentration may have been responsible

for the reduced soybean yields which occurred in this system.

Soybean leaf K was lower in the corn forage-soybean system than in

the grain-soybean system at all three locations. This indicated that

removing the corn forage and associated K reduced the supply of K avail-

able for soybean uptake. Soybean leaf Ca and Mg were higher following









corn forage than following corn grain at Quincy. This would seem to

suggest a cation interaction between Ca, Mg, and K in soybeans, just

as in corn.

Treatment effects on soybean leaf K, Ca, and Mg were found to be

significant so an analysis of variance was performed on treatments 4

through 11 to ascertain the individual effects of N, P, and K on leaf

nutrient concentrations. The F values for this analysis are presented

in Table 51. Although several significant F values are shown, a close

examination of the treatment means shows no consistent effects of

fertilizer N, P, or K on leaf concentrations of N or P. Soybean leaf K

was significantly higher where the high rate of K was applied at Sanford

and Gainesville but not at Quincy. This is exactly analogous to the

effect of treatment on corn earleaf K concentration. Also similar is

the way Ca and Mg concentrations in the leaf are inversely related to

applied fertilizer K. Treatments receiving the high rate of K fertilizer

were lower in soybean leaf Ca and Mg than those receiving the low rate.

Two additional points are also worth mentioning. First, the effect of K

fertilizer rate on Ca and Mg concentrations was more pronounced in

System II where corn forage and the associated nutrients were harvested

than in System I where only the grain was removed. Second, soybean leaf

Ca was much more influenced by K fertilization than leaf Mg while just

the opposite was true in the corn. Corn earleaf Mg was more affected

by the K fertilizer rate than was earleaf Ca. This would suggest either

a different soil Ca:Mg ratio during the two growing seasons or perhaps

a difference in the ability of the two crops to substitute one cation

for another (in this case Ca or Mg for K).









Several other effects of fertilizer nutrients on soybean leaf K

were noted, but they were inconsistent and unexplainable. The high rate

of fertilizer N appeared to depress soybean leaf K concentrations at

Gainesville. The high rate of P increased leaf K concentrations in

System I at Gainesville but had just the opposite effect in System II.

Results such as these are difficult to interpret and give little

useable information.


Soil Analysis


Soil test results for all three locations over the 2-year period

are given in Tables 52 through 63. The first set of samples was taken

just prior to planting of corn in early spring, 1977. These samples

show that the initial P and K soil levels in the soil were extremely

high at Sanford and Quincy and were uniform across the 12 treatments.

There were some initial treatment differences in soil Mg on System II

plots at Sanford and a significant difference between the two systems

in Ca soil levels at Quincy. The initial P and K levels at Gainesville

were considerably lower but still would be classified as high. There

is some indication that the initial soil-test K may have been different

among the treatments in System II at Gainesville. The soil had been

limed at all three locations so the pH was around 6.0 at Sanford and

Quincy and 5.8 at Gainesville.

The 2 years of cropping had a significant effect on soil test levels

at Sanford and Gainesville but little effect at Quincy. Because plots

at the different locations responded differently over the 2-year period,

they will be discussed individually.









Soil tests taken during the 1978 soybean growing season (September)

at Sanford are given in Table 55. They showed that the soil changed over

the two year period as a result of the fertilizer treatments applied.

Soil K and Ca were significantly lower in System II where the forage

was harvested. Treatment affected soil P and soil K in both systems.

To investigate further these treatment effects, the treatments were

broken into two groups. The effects of three rates of N without P or

K (treatments 1 to 3) are shown in Table 64. No consistent trends can

be seen,in this data. If treatments 1 through 3 are compared with

treatments 4 through 12, however, it is evident that the three treatments

which received no P or K fertilizer are lower in these elements than the

other nine treatments. Treatments 4 through 11 were also analyzed as

a 2x2x2 factorial experiment to check for the influence of N, P, and K

applications on soil test. The computed F values are given in Table 65.

Two significant effects were noted in this analysis. The first was a

reduction in pH on those plots receiving the high rate of N. This is

not surprising because NH NO3 was the form of N fertilizer used and it

reacts to lower soil pH. The second effect was a higher soil K level on

those plots which received the higher K fertilizer rate. This was only

significant in System II where corn forage was harvested.

Certain trends in the soil-test results for Gainesville can be seen

although they are not all statistically significant (Tables 56 through

59). Soil K at Gainesville was generally lower in System II than in

System I, just as it was at Sanford. This was statistically significant

only in the second set of soil samples taken in 1977, but the tendency

was consistent throughout. The natural heterogeneity of soil samples









results in a large amount of variability and this can mask some treatment

or system influences which may be present. In the second year, there was

a tendency for soil K to be lower in treatments 1 through 3 where no K

was applied. Data in Table 64 give the soil test results for the last

set of samples taken and compare treatments 1, 2, and 3 for effect of

fertilizer N. In System II, soil P and K seem to decrease as the amount

of N applied increases. The cumulative effect of N, P, and K on soil-

test values for samples taken in September 1978 are shown in Table 65.

The higher rate of N caused a slight decrease in pH while the high rate

of K increased soil pH in System I. Fertilizer P and K both had a

positive effect on raising soil P levels. The higher rate of fertilizer

K also resulted in a higher soil test K level. Soil Ca and Mg did not

appear to have been affected by fertilizer treatment to any great extent.

The soil at Quincy was extremely fertile at the beginning of this

study and even after 2 years of cropping there was little detectable

change in fertility. There was a slight tendency for treatments 1 through

3 (which received no P or K) to be lower in K than the other treatments,

especially during the soybean growing season. Even so, the soil-test K

at Quincy was 4 to 5 times greater than at Gainesville'where no response

to K fertilizer was evident. Soil-test results were not significantly

affected by fertility treatment as of late summer, 1978 (Tables 64 and

65). A significant difference between the two systems was evident,

however. Soil-test P and K were higher in the corn grain-soybean system

than in the corn forage-soybean system. Soil Ca and Mg levels were higher

during 1978 because dolomite was applied prior to planting the corn in

1978. No micronutrient levels have been studied to date, but the









intensive cropping which is being practiced in this multicropping

system will draw down the micronutrient reserves in the soil quickly

and they could be a limiting factor in achieving consistently high

yields.


Nutrient Removal


Nutrient removal was calculated for the corn forage system to get

an idea of how quickly the soil is being mined of nutrients. This was

computed by multiplying dry matter production times the concentration

of nutrients in the forage. Forage nutrient concentrations are given

in Tables 66 to 68 for the three locations and the 2 years. It is

interesting to compare these nutrient concentrations with the corn

earleaf concentrations taken midway through the growing season. The

concentrations of N, K, and Ca in corn forage were roughly half what

they were in the earleaf while P and Mg were about one-third lower.

Forage N and P concentrations were similar among the locations but the

K concentrations were higher at Quincy while the Ca and Mg concentra-

tions were lower. This indicated that luxury consumption of K occurred

at Quincy where the soil test K was high. The K concentration in San-

ford forage was lower than that found at Quincy but higher than at

Gainesville which correlated well with the intermediate level of soil K

found there. The concentrations of N and K were relatively low at

Gainesville in the 1978 forage crop. This was probably due to leaching

of these nutrients by summer rains because the forage harvest was some-

what delayed past the optimum period.

The amount of N harvested ranged from 22 to 168 kg/ha depending on

location, year, and treatment (Tables 69 through 71). The data are








widely variable for two reasons. First, it was difficult to obtain a

completely homogeneous mix of all portions of the corn plant. Further-

more, the quantity of plant material analyzed was only 0.1 g for N and

1.0 g for P, K, Ca, and Mg. Secondly, when multiplying two measured

variables (yield and concentration of nutrients) the variability among

the individual measurements is compounded. Because of the high vari-

ability, it is difficult to note any consistent treatment effects. The

check plots which received no fertilizer were almost always lower in all

nutrients. In addition, treatments 2 and 3 which received N but no P

or K tended to be low in K and slightly above average in Ca and Mg at

Gainesville and Sanford. Finally, the quantity of K removed per ton of

forage was well correlated with the soil-test level of K. Much more K

was removed in a ton of forage at Quincy than at Gainesville, while the

amount of Ca and Mg removed was higher at Gainesville. This indicates

that considerable luxury consumption of K occurred at Quincy where the

soil-test K was high. A dilation effect of N and K in the plant tissues

was also noted at Gainesville and Sanford. When forage yields were low,

the concentrations of N and K were high. When yields were high, the

concentrations of these nutrients were low.














SUMMARY AND CONCLUSIONS


Corn grown in any area of Florida can be followed by a crop of

soybeans. In central Florida, no reduction in yield from that expected

of monocropped corn or soybeans will necessarily occur. In the northern

part of the state, soybean yields may be somewhat lower than comparable

monocropped soybeans due to the shorter growing season. Under good

management, 125 qtl/ha corn grain can be grown followed by 30, 25, and

20 qtl/ha soybeans in central, north-central and north Florida,

respectively. This study showed that corn responded to 168 kg of N/ha

but no additional response was noted when 280 kg of N/ha was applied.

There was no yield response to P or K on these soils which tested high

in both nutrients. All the fertilizer needed for adequate nutrition

of both crops was applied to the corn and there was no benefit derived

from a sidedressing of K on the soybeans at early bloom. Water was

found to be the single most important factor limiting yield of the

system, making irrigation facilities a necessity for optimum yields

because of the dry spring and autumn conditions in Florida. Soybeans

were found to yield slightly higher when planted after corn grain than

after corn forage.

Corn earleaf N and K concentrations were positively correlated

with applied N and K. Soybean leaf K concentrations were also in-

fluenced by K fertilization of the previous corn crop. The K concen-

tration in soybean leaves was somewhat lower in the corn forage-soybean

system than in the corn grain-soybean system. This shows the effect




39



of the proceeding crop of corn on the soybeans. Finally, even after

2 years of cropping there was no significant reduction in the soil P

or K level where only the low rates of P and K were applied. This

indicates that in any case, no more than 56 kg of P and 112 kg of K/ha

are justified.

















































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TABLE 6
DEGREES OF FREEDOM AND SOURCES FOR THE SPLIT-PLOT
ARRANGEMENT WITHIN A LOCATION IN FLORIDA
FOR ONE YEAR'S DATA


SOURCE df


Total overall (TO) 4R x 2WP x 12 FT 1 = 95


Total whole plots (TWP) 4R x 2WP 1 = 7
Replications (R) 4R 1 = 3
WP 2WP -1 = 1
Error (a) dfR + dfWP = dfTWP = 3


Total Split-Plot (TSP) TO-TWP = 88
Split Plot (SP) 12SP 1 = 11
WP x SP (2WP 1) (12SP 1) = 11
Error (b) dfSP + dfWP x SP TSP = 66


Replications = 4, whole plots are corn forage versus corn grain
systems = 2, fertility treatments = 12.





















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TABLE 8
PLANTING, SAMPLING, AND HARVEST DATES FOR THE
CORN-SOYBEAN SUCCESSION CROPPING STUDY


Year Operation Sanford Gainesville Quincy


1977 Soil samples 25-2 3-3 22-2
Plant corn 25-2 4-3 11-3
Corn ear leaf samples 19-5 25-5 31-5
Harvest corn 27-6 30-6 18-7
Sbil samples 27-6 2-7 36-7
Plant soybeans 18-7 11-7 31-7
Soybean leaf samples 20-9 14-9 22-9
Harvest soybeans 21-11 15-11 18-11


1978 Plant corn 1-3 11-3 15-3
Soil samples 22-5 23-5 1-3
Corn ear leaf samples 22-5 23-5 12-6
Harvest corn 5-7 17-7 24-7
Plant soybeans 19-7 22-7 26-7
Soil samples 20-9 25-9 28-8
Soybean leaf samples 20-9 25-9 30-9
Harvest soybeans 27-11 7-11 28-11











TABLE 9
VARIABLES MEASURED IN THE CORN-SOYBEAN
SUCCESSION CROPPING STUDY


+1. Soil test for pH, P, K, Ca, and Mg (once during the corn and
once during the soybean growing season).

2. Corn ear leaf analysis for N, P, K, Ca and Mg.

3. Corn forage analysis for N, P, K, Ca, and Mg.

4. Corn grain yield (reported at 15.5% H20).

5. Corn 'forage yield (reported as fresh forage wt.).

6. Soybean leaf analysis for N, P, K, Ca, and Mg.

7. Soybean yield (reported at 12% HO).

*8. Corn plant height at harvest.

*9. Corn plant population at harvest.

+Double-acid extractant
*This data reported in Appendices 1 and 2.




49


TABLE 10
CORN GRAIN YIELDS (QTL/HA) AT SANFORD, GAINESVILLE AND QUINCY

Treatment Sanford Gainesville Quincy


1977
18.9 b 9.9
43.1 a 67.1
38.6 a 69.1
45.8 a 62.6
40.2 a 69.8
42.3 a 76.4
42.0 a 65.2
33.9 a 66.1
39.1 a 48.4
47.6 a 59.6
44.7 a 70.1
48.7 a 53.5
40.4 59.8


1978
36.9 b 20.3
86.7 a 72.9
67.3 a 80.1
78.1 a 73.5
87.2 a 78.7
88.0 a 83.0
81.8 a 84.1
71.7 a 77.0
94.0 a 72.7
92.4 a 87.4
85.7 a 87.1
87.7 a 83.8
79.8 75.0


1
2
3
4
5
6
7
8
9
10
11
12
Mean


Two Year Average
27.9 a 15.1 b
64.9 a 70.0 a
53.0 a 74.6 a
62.1 a 68.1 a
63.7 a 74.2 a
65.1 a 79.7 a
61.9 a 74.7 a
52.8 a 71.6 a
66.6 a 60.5 a
70.1 a 73.5 a
65.2 a 78.6 a
68.2 a 68.7 a
60.1 67.4


70.7 a
113.3 a
114.2 a
105.5 a
103.0 a
99.8 a
112.4 a
91.2 a
97.4 a
105.6 a
105.0 a
108.3 a
102.2


b 100.0 c
a 126.7 ab
a 128.3 ab
a 124.8 ab
a 125.1 ab
a 125.4 ab
a 134.7 a
a 115.5 ab
a 121.0 ab
a 124.2 ab
a 124.7 ab
a 131.9 ab
123.4


b 41.5 d
a 100.0 a
a 100.2 a
a 86.3 abc
a 80.9 abc
a 74.0 bc
a 90.2 ab
a 66.8 c
a 73.7 bc
a 87.1 abc
a 85.4 abc
a 84.6 abc
80.9


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean







TABLE 11
CORN FORAGE YIELDS (TONS/HA) AT SANFORD, GAINESVILLE AND QUINCY

Treatment Sanford Gainesville Quincy


1977
6.0 a 4.2
9.7 a 15.7
10.1 a 12.6
9.1 a 14.9
9.1 a 14.6
7.8 a 15.1
8.9 a 14.3
7.9 a 13.3
9.0 a 11.8
9.7 a 14.1
9.8 a 16.6
9.4 a 11.5
8.9 13.3
1978


8.5 b 8.0
19.2 a 17.0
17.4 a 15.8
22.4 a 19.4
21.1 a 20.3
20.4 a 19.0
22.7 a 19.4
20.9 a 19.7
19.4 a 21.1
23.2 a 19.7
21.4 a 22.0
23.5 a 20.7
20.0 18.5


b
a
a
a
a
a
a
a
a
a
a
a


23.2 e
30.0 bed
31.2 b
25.4 cde
28.5 bcd
26.7 bcde
30.2 bc
39.0 a
28.3 bed
28.9 bed
26.4 cde
28.7 bcd
28.9


e
cd
d
b
ab
bc
b
ab
ab
ab
a
ab_


12.9 b
21.3 a
21.4 a
21.3 a
19.3 a
21.3 a
21.0 a
21.7 a
20.0 a
24.2 a
20.0 a
22.1 a
20.5


Two Year Average

7.2 a 6.1
14.4 a 16.4
13.7 a 14.2
15.7 a 17.2
15.1 a 17.5
14.1 a 17.0
15.8 a 16.8
14.4 a 16.5
14.2 a 17.1
16.5 a 16.9
15.6 a 19.3
16.4 a 16.1
14.4 15.9


c 18.0 c
ab 25.6 ab
b 26.3 ab
ab 23.4 be
ab 23.9 abc
ab 24.0 abc
ab 25.6 ab
ab 30.4 a
ab 24.1 abc
ab 26.5 ab
a 23.2 c
ab 25.4 ab
24.7


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean








TABLE 12
CORN YIELDS AS INFLUENCED BY THREE RATES OF NITROGEN
AT THREE LOCATIONS IN FLORIDA (TWO YEAR AVERAGE)

N rate Location
(kg/ha) Sanford Gainesville Quincy

Corn grain yield (qtl/ha)
0 27.9 b 15.1 b 70.7 b
168 64.9 a 70.0 a 113.3 a
280 53.0 a 74.6 a 114.2 a

Corn forage (metric tons/ha)
0 7.2 b 6.1 b 18.0 b
168 14.4 a 16.4 a 25.6 a
280 13.7 a 14.2 a 26.3 a







TABLE 13
ANALYSIS OF VARIANCE F VALUES FOR THE EFFECTS OF YEAR AND TWO RATES EACH
OF N, P, AND K ON CORN YIELD AT THREE LOCATIONS (TWO YEAR AVERAGE)

Source df Sanford Gainesville Quincy

Corn grain
N 1 0.0 0.4 2.6
P 1 1.2 2.6 3.7
K 1 0.2 0.1 1.4
NxP 1 0.9 0.7 1.9
PxX 1 2.3 0.8 0.4
NxK 1 0.5 0.7 0.1
Year 1 401** 12.7** 167**
Corn forage
N 1 0.0 0.1 5.1*
P 1 0.8 1.1 0.5
K 1 0.0 1.3 5.3*
NxP 1 2.4 2.9 4.9*
PxK 1 0.3 0.6 1.5
NxK 1 0.6 1.1 12.8*
Year 1 254** 58.6** 88.2**

*indicates F test is significant at .05 < p < .01.
**indicates F test is significant at .01 < p.







TABLE 14
SOYBEAN YIELDS AT SANFORD DURING 1977, 1978, AND THE TWO YEAR AVERAGE

System I System II
Treatment (Following grain) (Following forage) Mean


1977 (qtl/ha)
27.4 a 26.1 c
29.9 a 28.1 be
30.8 a 27.3 be
31.3 a 32.6 a
33.3 a 30.6 ab
31.8 a 27.7 bc
32.9 a 31.4 ab
31.3 a 29.0 abc
32.0 a 33.3 a
30.4 a 31.6 ab
31.6 a 30.1 abc
32.6 a 31.1 ab
*31.3 *29.9


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1978 (qtl/ha)
1 22.0 a 19.a cd
2 27.1 a 21.3 abcd
3 24.9 a 17.7 d
4 28.8 a 22.7 abed
5 26.3 a 26.9 ab
6 28.0 a 24.1 abed
7 22.3 a 27.8 a
8 27.4 a 25.3 abc
9 30.4 a 22.8 abed
10 30.3 a 24.6 abc
11 26.5 a 20.8 bed
12 26.7 a 23.3 abcd
Mean 26.7 23.0
Two Year Average (qtl/ha)


24.7 22.7 23.7 c
28.5 24.7 26.6 abc
27.9 22.5 25.2 be
30.1 27.7 28.8 ab
29.8 28.8 29.3 ab
29.9 25.9 27.9 ab
27.6 29.6 28.6 ab
29.4 27.2 28.3 ab
31.2 28.1 29.6 a
30.4 28.1 29.2 ab
29.1 25.5 27.3 ab
29.1 27.2 28.4 ab
29.0 26.5 27.7


*Indicates systems are significantly different at p=.05


26.7
29.0
29.0
31.9
31.9
29.7
32.2
30.2
32.6
31.0
30.9
31.9
30.6


20.6
24.2
21.3
25.7
26.6
26.1
26.1
26.4
26.6
27.5
23.6
25.0
24.8


1
2
3
4
5
6
7
8
9
10
11
12
Mean




54


TABLE 15
SOYBEAN YIELDS AT GAINESVILLE DURING 1977, 1978,
AND THE TWO YEAR AVERAGE

System I System II
Treatment (Following grain) (Following forage) Mean

1977 (qtl/ha)
1 25.6 a 23.5 a 24.5
2 26.3 a 21.2 a 23.7
3 26.2 a 24.7 a 25.4
4 27.2 a 25.4 a 26.3
5 26.8 a 24.2 a 25.5
6 25.7 a 23.8 a 24.7
7 23.9 a 25.0 a 24.4
8 25.2 a 22.6 a 23.9
9 25.2 a 25.5 a 25.3
10 27.6 a 26.0 a 26.8
11 26.0 a 27.4 a 26.7
12 25.2 a 24.3 a 24.8
Mean 25.9 24.5 25.2
1978 (qtl/ha)
1 13.8 a 12.4 a 13.1
2 15.8 a 11.6 a 13.7
3 13.0 a 9.1 a 11.0
4 13.2 a 13.1 a 13.1
5 13.1 a 12.9 a 13.0
6 15.1 a 12.9 a 14.0
7 13.4 a 12.4 a 12.9
8 13.5 a 12.0 a 12.7
9 13.0 a 11.7 a 12.3
10 14.7 a 11.4 a 13.1
11 15.3 a 13.1 a 14.2
12 14.8 a 11.9 a 13.4
Mean 14.1 12.0 13.1
Two Year Average (qtl/ha)
1 19.7 17.9 18.8 a
2 21.0 16.4 18.7 a
3 19.6 16.9 18.2 a
4 20.1 19.3 19.7 a
5 20.0 18.6 19.3 a
6 20.4 18.3 19.4 a
7 18.6 18.7 18.7 a
8 19.3 17.3 18.3 a
9 19.1 18.6 18.8 a
10 21.1 18.7 19.9 a
11 20.7 20.3 20.5 a
12 20.0 18.1 19.1 a
Mean 20.0 18.3 19.








SOYBEAN YIELDS AT


TABLE 16
QUINCY DURING 1977, 1978, AND THE TWO YEAR AVERAGE


System I System II
Treatment (Following grain) (Following forage Mean

1977 (qtl/ha)


14.1 a 11.3 a
16.5 a 10.0 a
16.2 a 15.1 a
17.6 a 10.9 a
14.0 a 9.1 a
13.8 a 9.5 a
15.7 a 10.6 a
12.9 a 13.2 a
14.8 a 12.3 a
13.6 a 11.8 a
13.8 a 8.3 a
15.6 a 11.7 a
*14.9 *11.1


12.7
13.2
15.7
14.2
11.6
11.6
13.1
13.0
13.5
12.7
11.0
13.7
13.0


1978 (qtl/ha)
1 20.5 a 18.3 a 19.4
2 19.9 a 16.8 a 18.3
3 21.0 a 20.1 a 20.6
4 18.5 a 20.4 a 19.4
5 17.5 a 16.1 a 16.8
6 19.9 a 16.6 a 18.3
7 17.6 a 15.1 a 16.4
8 17.7 a 17.6 a 17.7
9 20.4 a 16.7 a 18.6
10 20.1 a 19.8 a 20.0
11 22.4 a 20.8 a 21.6
12 20.7 a 17.9 a 19.3
Mean 19.7 18.0 18.9
Two Year Average (qtl/ha)
1 17.3 14.8 16.0 a
2 18.2 13.4 15.8 a
3 18.6 17.6 18.1 a
4 18.0 15.6 16.8 a
5 15.8 12.6 14.2 a
6 16.9 13.0 15.0 a
7 16.6 12.8 14.7 a
8 15.3 15.4 15.4 a
9 17.6 14.5 16.1 a
10 16.8 15.8 16.3 a
11 18.1 14.6 16.3 a
12 18.1 14.8 16.5 a
Mean 17.3 14.6 15.9

*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean








TABLE 17
COMPARISON OF THE TWO CROPPING SYSTEM YIELDS AT
SANFORD, GAINESVILLE, AND QUINCY (TWO YEAR AVERAGE)

System Crop Sanford Gainesville Quincy

I Corn grain
(qtl/ha) 60.1 67.4 102.2
Soybeans after
grain (qtl/ha) 29.0 a* 20.0 a 17.3 a
II Corn forage
(tons/ha) 14.4 15.9 24.7
Soybeans after
forage (qtl/ha) 26.5 b 18.3 a 14.6 b

+Average of twelve treatments.
*Within locations, means with the same letter are not significantly
different at p = .05.



TABLE 18
REVENUE COMPARISON OF THE TWO CROPPING SYSTEMS AT
SANFORD, GAINESVILLE, AND QUINCY (TWO YEAR AVERAGE)

System* Crop Sanford Gainesville Quincy

I Corn grain $ 511 $ 572 $ 869
Soybeans 696 480 415
Total $1207 $1052 $1284
II Corn forage $ 916 $1034 $1606
Soybeans 636 439 350
Total $1552 $1473 $1956


forage.


*Average of twelve treatments.
Assumes $8.50/qtl corn grain, $24.00/qtl soybeans, and $65/ton
Figures given are gross return/ha.







TABLE 19
CORN EARLEAF NITROGEN CONCENTRATIONS


(%) AT SANFORD


Treatment System I System II Mean

1977


1.31 d
2.05 c
2.17 abc
2.10 bc
2.31 abc
2.16 abc
2.21 abc
2.25 abc
2.37 a
2.33 ab
2.30 abc
2.15 abc
2.15
1978


1.24 c
2.29 ab
2.16 ab
2.12 b
1.99 b
2.20 ab
2.15 b
2.27 ab
2.29 ab
2.27 ab
2.33 a
2.25 ab
2.13


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


Two Year Averages
1 1.56 1.27 1.41 c
2 2.35 2.41 2.38 ab
3 2.44 2.39 2.41 ab
4 2.37 2.18 2.28 b
5 2.46 2.23 2.35 ab
6 2.45 2.37 2.41 ab
7 2.49 2.32 2.40 ab
8 2.53 2.47 2.50 ab
9 2.57 2.53 2.55 a
10 2.60 2.52 2.56 a
11 2.56 2.57 2.56 a
12 2.44 2.42 2.43 ab
Mean 2.41 2.31 2.36


1.29 e 1.55
2.53 bc 2.59
2.63 abc 2.67
2.25 d 2.45
2.48 c 2.55
2.54 be 2.64
2.49 c 2.63
2.68 abc 2.74
2.78 a 2.77
2.76 ab 2.82
2.81 a 2.82
2.59 abc 2.66
2.49 2.58


1.28
2.17
2.16
2.11
2.15
2.18
2.18
2.26
2.33
2.30
2.31
2.20
2.14


1.80 b
2.65 a
2.71 a
2.65 a
2.61 a
2.74 a
2.76 a
2.81 a
2.76 a
2.87 a
2.83 a
2.73 a
2.66








TABLE 20

CORN EARLEAF PHOSPHORUS CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


0.34 a
0.26 a
0.27 bc
0.29 be
0.29 be
0.30 ab


0.24 a
0.29 a
0.27 a
0.29 a
0.28 a
0.30 a


0.29 be 0.30 a
0.30 ab 0.28 a
0.29 be 0.30 a
0.29 be 0.30 a
0.29 be 0.30 a
0.30 ab 0.29 a
0.29 0.29


1978
0.36 a
0.36 a
0.37 a
0.34 a
0.34 a
0.38 a
0.36 a
0.36 a
0.35 a
0.40 a
0.39 a
0.36 a
0.36


0.32
0.36
0.35
0.35
0.35
0.35
0.36
0.37
0.37
0.39
0.41
0.34
0.36


0.29
0.28
0.27
0.29
0.28
0.30
0.29
0.29
0.29
0.30
0.29
0.29
0.29


c
be
be
be
be
be
be
ab
ab
ab
a
be


0.34
0.36
0.36
0.35
0.35
0.36
0.36
0.36
0.36
0.39
0.40
0.35
0.36


Two Year Average
1 0.35 0.28 0.32 a
2 0.31 0.33 0.32 a
3 0.32 0.31 0.32 a
4 0.32 0.32 0.32 a
5 0.31 0.31 0.31 a
6 0.34 0.33 0.33 a
7 0.32 0.33 0.32 a
8 0.33 0.33 0.33 a
9 0.32 0.33 0.33 a
10 0.34 0.34 0.34 a
11 0.34 0.35 0.35 a
12 0.33 0.31 0.32 a
Mean 0.33 0.32 0.33


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean








TABLE 21
CORN EARLEAF POTASSIUM CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


1.95 abc 1.91
1.73 bc 1.91
1.93 ab 1.78
2.00 ab 2.01
2.11 a 2.16
1.75 be 1.87
1.78 bc 1.85
1.91 ab 1.72
1.86 b 1.95
1.67 c 1.81
1.80 bc 1.75
1.81 bc 1.85
1.86 1.88


a
a
a
a
a
a
a
a
a
a
a
a


1.93
1.82
1.86
2.00
2.13
1.81
1.81
1.81
1.90
1.74
1.77
1.83
1.87


1978
1.52 be 1.72 c
1.42 c 1.25 d
1.37 c 1.23 d
2.13 a 1.78 bc
2.36 a 2.21 a
2.00 ab 2.04 abc
2.33 a 2.18 ab
2.16 a 1.77 bc
2.26 a 2.28 a
2.01 ab 2.05 abc
2.26 a 2.13 abc
2.21 a 2.11 abc
2.01 1.90


1.62
1.33
1.30
1.95
2.28
2.02
2.26
1.96
2.27
2.03
2.20
2.16
1.96


1.71 cd
1.58 d
1.58 d
1.98 abc
2.21 a
1.92 bc
2.03 ab
1.89 bc
2.09 ab
1.88 bc
1.98 abc
1.99 abc
1.91


Two Year Average
1 1.73 1.81
2 1.58 1.58
3 1.65 1.51
4 2.06 1.90
5 2.23 2.18
6 1.87 1.96
7 2.06 2.01
8 2.03 1.75
9 2.06 2.11
10 1.84 1.93
11 2.03 1.94
12 2.01 1.98
Mean 1.93 1.89


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean








TABLE 22

CORN EARLEAF CALCIUM CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


0.48
0.80
0.85
0.74
0.77
0.76
0.77
0.74
0.79
0.75
0.84
0.79
*0.76


c
ab
a
b
ab
ab
ab
ab
ab
ab
ab
ab


0.34
0.57
0.53
0.55
0.50
0.55
0.54
0.57
0.53
0.49
0.55
0.57
*0.52


1978
0.49 d 0.31
0.71 ab 0.56
0.81 a 0.61
0.62 bcd 0.49
0.56 cd 0.46
0.60 bed 0.55
0.57 ed 0.45
0.71 ab 0.51
0.60 bed 0.49
0.71 ab 0.53
0.64 be 0.49
0.66 bc 0.52
0.64 0.50
Two Year Average
0.49 0.33
0.75 0.56
0.83 0.57
0.68 0.52
0.66 0.48
0.68 0.55
0.67 0.50
0.73 0.54
0.70 0.51
0.73 0.51
0.74 0.52
0.72 0.54
*0.70 *0.51


c
ab
a
b
b
ab
b
ab
b
ab
b
ab_


0.41
0.68
0.69
0.64
0.64
0.66
0.66
0.66
0.66
0.62
0.69
0.68
0.64


0.40
0.63
0.71
0.55
0.51
0.57
0.51
0.61
0.54
0.62
0.56
0.59
0.57


0.41 d
0.66 ab
0.70 a
0.60 be
0.57 c
0.61 bc
0.58 be
0.63 abc
0.60 be
0.62 be
0.63 abc
0.63 abc
0.60


*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean


11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean




61



TABLE 23
CORN EARLEAF MAGNESIUM CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


0.39 ab
0.41 a
0.37 abc
0.32 ed
0.35 bed
0.31 d
0.31 d
0.32 cd
0.32 cd
0.29 d
0.29 d
0.30 d
*0.34
1978


0.42
0.62
0.58
0.31
0.24
0.32
0.22
0.31
0.24
0.30
0.20
0.35
0.35


bc
a
ab
cd
ed
cd
cd
cd
ed
ed
d
cd


Two Year Average
0.41


0.52
0.48
0.32
0.30
0.32
0.27
0.32
0.29
0.30
0.25
0.33
0.34


0.25 b
0.32 a
0.35 a
0.27 ab
0.25 b
0.29 ab
0.25 b
0.28 ab
0.28 ab
0.25 b
0.25 b
0.26 ab
*0.28


0.27 bed
0.55 a
0.61 a
0.32 be
0.24 bcd
0.33 bc
0.23 cd
0.36 b
0.19 d
0.27 bed
0.22 cd
0.27 bcd
0.33


0.27
0.44
0.48
0.30
0.25
0.32


0.32
0.36
0.36
0.30
0.30
0.30
0.28
0.30
0.30
0.27
0.27
0.28
0.31


0.35
0.58
0.59
0.32
0.24
0.32
0.22
0.34
0.21
0.28
0.21
0.31
0.34


0.33 b
0.47 a
0.47 a
0.31 bed
0.27 bed
0.31 bcd
0.25 cd
0.32 be
0.26 bed
0.28 bed
0.24d
0.30 bcd
0.32


0.24
0.33
0.24
0.26
0.24
0.27
0.30


*Indicates systems are significantly different at p=.05


11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


6
7
8
9
10
11
12
Mean







TABLE 24
CORN EARLEAF NITROGEN CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


1.55 b 1.27 c
2.66 a 2.54 b
2.79 a 2.73 ab
2.47 a 2.50 b
2.76 a 2.63 ab
2.73 a 2.63 ab
2.65 a 2.85 ab
2.89 a 3.00 a
2.80 a 2.67 ab
2.80 a 2.69 ab
2.80 a 2.81 ab
2.74 a 2.76 ab
*2.64 *2.59
1978


1.41
2.60
2.76
2.49
2.69
2.68
2.75
2.95
2.73
2.75
2.80
2.75
2.62


1.48 d
2.49 ab
2.69 a
2.12 c
2.42 abc
2.48 ab
2.16 c
2.40 abc
2.63 a
2.54 a


11 2.68
12 2.73
Mean *2.40


a
a


0.98 e 1.23
2.07 cd 2.28
2.31 ab 2.50
1.98 d 2.05
1.91 d 2.16
1.91 d 2.20
2.12 bcd 2.14
2.29 abc 2.34
2.27 abc 2.45
2.32 ab 2.43
2.43 a 2.55
2.29 abc 2.51
*2.08 2.24


Two Year Average
1 1.51 1.13 1.32 c
2 2.57 2.30 2.44 ab
3 2.74 2.52 2.63 a
4 2.30 2.24 2.27 b
5 2.59 2.27 2.43 ab
6 2.60 2.27 2.44 ab
7 2.40 2.49 2.45 ab
8 2.65 2.64 2.64 a
9 2.71 2.47 2.59 a
10 2.67 2.51 2.59 a
11 2.74 2.62 2.68 a
12 2.73 2.53 2.63 a
Mean *2.52 *2.34 2.43

*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean




63



TABLE 25
CORN EARLEAF PHOSPHORUS CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


0.27 c
0.30 ab
0.32 ab
0.31 ab
0.32 ab
0.29 be
0.30 ab
0.33 a
0.31 ab
0.33 a
0.31 ab
0.31 ab
0.31


1978
0.36 c
0.38 abc
0.38 abc
0.37 be
0.34 c
0.36 c
0.35 c
0.39 abc
0.36 c
0.41 a
0.39 abc
0.41 abc
0.38


0.23 c
0.28 b
0.28 b
0.28 b
0.29 ab
0.29 ab
0.30 ab
0.30 ab
0.30 ab
0.30 ab
0.31 a
0.31 a
0.29


0.29
0.31
0.36
0.28
0.28
0.31
0.33
0.34
0.36
0.35
0.37
0.35
0.33


c
be
a
c
c
be
ab
ab
a
ab
a
ab


0.25
0.29
0.30
0.29
0.30
0.29
0.30
0.32
0.31
0.32
0.31
0.31
0.30


0.33
0.35
0.37
0.32
0.31
0.34
0.34
0.36
0.36
0.38
0.38
0.38
0.35


Two Year Average
1 0.31 0.26 0.29 e
2 0.34 0.30 0.32 abed
3 0.35 0.32 0.33 abed
4 0.34 0.28 0.31 cde
5 0.33 0.28 0.31 de
6 0.33 0.30 0.31 bcde
7 0.33 0.32 0.32 abed
8 0.36 0.32 0.34 abe
9 0.34 0.33 0.33 abed
10 0.37 0.33 0.35 a
11 0.35 0.34 0.35 ab
12 0.36 0.33 0.35 a
Mean 0.34 0.31 0.33

*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean


10
11
12
Mean




64



TABLE 26
CORN EARLEAF POTASSIUM CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


7
8
9
10
11
12
Mean


2.02 d
2.07 d
2.07 d
2.37 be
2.57 ab
2.42 abc
2.60 ab
2.35 a
2.55 c
2.45 abc
2.35 c
2.15 d
*2.33


1.75 ef
1.50 g
1.70 fg
2.05 bed
2.30 a
1.95 cde
2.37 a
2.17 abc
2.27 ab
1.92 def
1.92 def
1.77 ef
*1.98


1.88
1.78
1.88
2.21
2.43
2.18
2.48
2.26
2.41
2.18
2.13
1.96
2.15


1978


1.85 b
1.85 b
1.60 b
2.25 a


1.47
1.20
1.17
1.77


5 2.42 a 2.00
6 2.25 a 1.75
7 2.35 a 2.02
8 2.22 a 1.75
9 2.52 a 2.00
10 2.32 a 1.57
11 2.40 a 2.00
12 2.42 a 1.65
Mean *2.21 *1.70

Two Year Average


1 1.93
2 1.96
3 1.83
4 2.31
5 2.50
6 2.33
7 2.47
8 2.28
9 2.53
10 2.38
11 2.37
12 2.28
Mean *2.27


c
d
d
b
a
b
a
b
a
be
a
bc


1.66
1.52
1.38
2.01
2.21
2.00
2.18
1.98
2.26
1.95
2.20
2.03
1.95


1.61
1.35
1.43
1.91
2.15
1.85
2.20
1.96
2.13
1.75
1.96
1.71
*1.84


1.77d
1.65d
1.63d
2.11 be
2.32a
2.09 be
2.33a
2.12 be
2.33a
2.06 be
2.16b
2.00 c
2.05


*Indicates systems are significantly different at p=.05




65


TABLE 27
CORN EARLEAF CALCIUM CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


1
2
3
4
5
6
7
8
9
10
11
12
Mean


0.44
0.65
0.64
0.67
0.65
0.72
0.65
0.67
0.61
0.64
0.65
0.56
0.63


d
abc
abc
ab
abc
a
abe
ab
bc
abc
abc
c


0.31
0.60
0.60
0.55
0.55
0.59
0.52
0.56
0.52
0.58
0.59
0.67
0.55


0.23
0.53
0.66
0.39
0.42
0.47
0.44


1978


0.34 f
0.62 ab
0.67 a
0.46 e
0.52 cde
0.56 bcd
0.48 de


8 0.58 abcd 0.52
9 0.53 bcde 0.47
10 0.60 abc 0.51
11 0.56 bcde 0.50
12 0.53 bcde 0.48
Mean *0.54 *0.48
Two Year Average


0.39
0.64
0.66
0.57
0.58
0.64
0.57
0.62
0.57
0.62
0.61
0.54
*0.58


10
11
12
Mean


c
ab
ab
ab
ab
ab
b
ab
b
ab
ab
a


0.37
0.63
0.62
0.61
0.60
0.66
0.58
0.62
0.57
0.61
0.62
0.61
0.59


0.28
0.58
0.66
0.48
0.47
0.52
0.46
0.55
0.50
0.55
0.53
0.51
0.51


e
b
a
bcd
d
bcd
cd
b
bcd
bc
bc
bcd


0.27 0.33 d
0.57 0.60 ab
0.63 0.64 a
0.52 0.54 bc
0.48 0.53 c
0.53 0.59 abc
0.48 0.52 c
0.54 0.58 abc
0.49 0.53 c
0.55 0.58 be
0.54 0.57 bc
0.57 0.56 bc
*0.51 0.55


*Indicates systems are significantly different at p=.05








TABLE 28
CORN EARLEAF MAGNESIUM CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


0.21 cd 0.17
0.32 a 0.40
0.32 a 0.39
0.27 b 0.25
0.24 bed 0.23
0.25 bc 0.31
0.23 bed 0.22
0.25 bed 0.27
0.22 bed 0.26
0.24 bed 0.28
0.21 d 0.26
0.25 bcd 0.28
*0.25 *0.28
1978


0.26 d
0.42 b
0.48 a
0.27 ed
0.23 de
0.23 de
0.23 de
0.32 c
0.25 de
0.26 d
0.17 f
0.20 ef
*0.28
Two Year Average
0.24 bed
0.37 a
0.41 a
0.27 be
0.24 bed
0.25 be
0.24 bed
0.29 b
0.24 bed
0.25 be


d
a
a
be
bc
c
b
c
bc
be
be
be
bc
bc


0.19
0.36
0.36
0.26
0.23
0.28
0.23
0.26
0.24
0.26
0.23
0.26
0.27


0.22 e
0.52 b
0.62 a
0.29 cde
0.22 e
0.30 cde
0.27 cde
0.34 ed
0.28 cde
0.35 c
0.24 de
0.31 cde
*0.33


0.20 d
0.46 a
0.51 a
0.28 be
0.22 ed
0.31 b
0.25 bed
0.31 b
0.28 be
0.32 b


0.24
0.47
0.55
0.28
0.22
0.26
0.25
0.33
0.26
0.31
0.21
0.25
0.31


0.21
0.41
0.45
0.27
0.23
0.27
0.24
0.29
0.25
0.28
0.22
0.26
0.29


0.19 d 0.26 bed
0.23 d 0.30 b
*0.27 *0.31


*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


11
12
Mean









TABLE 29
CORN EARLEAF NITROGEN CONCENTRATIONS (%) AT QUINCY

Treatment System I System II Mean


1977


1 2.45 b
2 3.24 a
3 3.03 a
4 3.23 a
5 3.30 a
6 3.24 a
7 3.34 a
8 3.29 a
9 3.40 a
10 3.43 a
11 3.27 a
12 3.27 a
Mean *3.21


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1.69
2.87
2.92
2.90
2.88
2.76
2.83
2.94
3.03
2.90
2.94
2.85
*2.80


1978
d
abc
abc
abc
abc
c
bc
ab
a
abc
ab
be


Two Year Average
1 2.07
2 3.06
3 2.98
4 3.06
5 3.09
6 3.00
7 3.09
8 3.11
9 3.22
10 3.17
11 3.10
12 3.06
Mean *3.00


2.11 e
2.76 d
3.10 a
2.86 bed
2.83 ed
2.92 bed
2.89 bcd
3.00 abc
3.03 ab
3.00 abc
2.98 abc
2.88 bcd
*2.87


2.28
3.00
3.07
3.05
3.06
3.08
3.11
3.14
3.22
3.22
3.12
3.07
3.04


1.59 c
2.49 b
2.80 a
2.75 a
2.59 ab
2.66 ab
2.70 ab
2.77 a
2.70 ab
2.62 ab
2.65 ab
2.80 a
*2.60


1.85
2.62
2.95
2.81
2.71
2.79
2.79
2.88
2.86
2.81
2.81
2.84
*2.73


1.64
2.68
2.86
2.82
2.73
2.71
2.76
2.85
2.87
2.76
2.79
2.83
2.70


1.96 b
2.84 a
2.96 a
2.93 a
2.90 a
2.90 a
2.94 a
3.00 a
3.04 a
2.99 a
2.96 a
2.95 a
2.87


*Indicates systems are significantly different at p = .05




68



TABLE 30

CORN EARLEAF PHOSPHORUS CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


5
6
7
8
9
10
11
12
Mean


0.38 a
0.38 a
0.37 a
0.36 a
0.36 a
0.37 a
0.38 a
0.37 a
0.37 a
0.40 a
0.39 a
0.38 a
*0.38


1978

1 0.34 a
2 0.36 a
3 0.35 a
4 0.35 a
5 0.36 a
6 0.37 a
7 0.35 a
8 0.36 a
9 0.36 a
10 0.37 a
11 0.37 a
12 0.35 a
Mean 0.36


0.30 e
0.33 d
0.36 bc
0.35 cd
0.35 cd
0.34 d
0.37 be
0.35 cd
0.37 be
0.38 b
0.42 a
0.37 bc
*0.36


0.29
0.34
0.35
0.36
0.36
0.36
0.37
0.34
0.36
0.34
0.33
0.35
0.35


0.34
0.36
0.37
0.35
0.35
0.36
0.37
0.36
0.37
0.39
0.40
0.37
0.37


0.32
0.35
0.35
0.36
0.36
0.37
0.36
0.35
0.36
0.36
0.35
0.35
0.35


Two Year Average
0.36 a
0.37 a
0.36 a
0.35 a
0.36 a


0.37
0.37
0.36
0.37
0.38
0.38
0.36
*0.37


a
a
a
a
a
a
a


0.29 c 0.33
0.34 b 0.35
0.36 ab 0.36
0.35 ab 0.35
0.36 ab 0.36
0.35 ab 0.36
0.37 ab 0.37
0.34 b 0.35
0.36 ab 0.36
0.36 ab 0.37
0.37 a 0.37
0.36 ab 0.36
*0.35 0.36


*Indicates systems are significantly different at p=.05


6
7
8
9
10
11
12
Mean




69


TABLE 31
CORN EARLEAF POTASSIUM CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean


1977
2.67 a
2.78 a
2.77 a
2.88 a
2.79 a
2.96 a
3.08 a
2.95 a
2.91 a
2.89 a
2.79 a
2.95 a
*2.87


1978
2.43 d
2.82 bc
2.90 abc
3.01 abc
3.11 ab
3.05 abc
2.75 c
3.06 abc
3.06 abc
3.06 abc
3.18 a
3.02 abc
*2.96


1.98 d 2.32
2.40 abc 2.59
2.24 c 2.51
2.38 abc 2.63
2.59 ab 2.69
2.54 ab 2.75
2.64 a 2.86
2.52 ab 2.73
2.34 bc 2.62
2.54 ab 2.71
2.46 abc 2.62
2.47 abc 2.71
*2.43 2.65


1.95
2.32
2.50
2.63
2.68
2.75
2.61
2.68
2.57
2.65
2.85
2.62
*2.57


e
d
cb
abc
abc
ab
bc
abc
bc
abc
a
bc_


2.19
2.57
2.70
2.82
2.90
2.90
2.68
2.87
2.81
2.85
3.01
2.82
2.76


Two Year Average
1 2.55 1.97 2.26 d
2 2.80 2.36 2.58 c
3 2.83 2.37 2.60 bc
4 2.94 2.51 2.72 ab
5 2.95 2.64 2.79 a
6 3.00 2.64 2.82 a
7 2.91 2.62 2.77 a
8 3.00 2.60 2.80 a
9 2.98 2.45 2.72 abc
10 2.97 2.59 2.78 a
11 2.99 2.65 2.82 a
12 2.98 2.55 2.76 a
Mean *2.91 *2.50 2.71


*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean




70


TABLE 32


CORN EARLEAF CALCIUM CONCENTRATIONS


(%) AT QUINCY


Treatment


System I

1977


1 0.53 a
2 0.59 a
3 0.56 a
4 0.54 a
5 0.51 a
6 0.58 a
7 0.57 a
8 0.57 a
9 0.57 a
10 0.59 a
11 0.58 a
12 0.56 a
Mean *0.56


1978
0.43 d
0.55 be
0.55 c
0.57 be
0.56 bc
0.59 abc
0.57 be
0.58 abc
0.60 ab
0.62 a
0.63 a
0.57 bc
*0.57


11
12
Mean


System II


0.31 b
0.38 a


0.41
0.40
0.42
0.42
0.38
0.39
0.40
0.41
0.43
0.39
*0.40


a
a
a
a
a
a
a
a
a
a


Mean


0.42
0.48
0.49
0.47
0.46
0.50
0.48
0.48
0.48
0.50
0.50
0.47
0.48


0.35 c
0.52 ab
0.52 ab
0.47 b
0.47 b
0.52 ab
0.47 b
0.47 b
0.50 ab
0.54 a
0.49 ab
0.51 ab
*0.49


0.39
0.53
0.53
0.52
0.52
0.55
0.52
0.52
0.55
0.58
0.56
0.54
0.53


Two Year Average
1 0.48 0.33 0.41 c
2 0.57 0.45 0.51 ab
3 0.55 0.47 0.51 ab
4 0.55 0.44 0.49 b
5 0.54 0.45 0.49 b
6 0.58 0.47 0.53 ab
7 0.57 0.43 0.50 ab
8 0.58 0.43 0.50 ab
9 0.58 0.45 0.52 ab
10 0.61 0.47 0.54 a
11 0.60 0.46 0.53 ab
12 0.56 0.45 0.50 ab
Mean *0.56 *0.44 0.50

*Indicates systems are significantly different at p=.05










CORN EARLEAF


TABLE 33
MAGNESIUM CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


0.18 abcd
0.20 ab
0.20 a
0.17 bcde
0.15 e
0.17 bcde
0.15 de
0.19 abc
0.17 bcde
0.16 cde
0.15 e
0.17 bcde
*0.18


0.14
0.16
0.20
0.15
0.14
0.15
0.12
0.17
0.17
0.16
0.13
0.15
*0.16


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


def
bc
a
bcdef
cdef
bcde
f
b
bc
bcd
ef
bcdef



bcd
a
a
bc
bcd
b
cd
b
bcd
b
d
bc


0.16
0.18
0.20
0.16
0.14
0.16
0.14
0.18
0.17
0.16
0.14
0.16
0.17


0.14
0.20
0.20
0.16
0.14
0.16
0.13
0.15
0.14
0.15
0.13
0.14
0.16


Two Year Average
1 0.17 bc
2 0.20 a
3 0.19 a
4 0.17 b
5 0.15 c
6 0.17 bc
7 0.15 bc
8 0.17 b
9 0.17 bc
10 0.15 bc
11 0.15 bc
12 0.16 bc
Mean *0.17


0.14 de 0.15
0.19 b 0.19
0.22 a 0.20
0.15 cd 0.16
0.14 de 0.14
0.16 cd 0.16
0.13 e 0.14
0.17 c 0.16
0.16 cd 0.16
0.16 cd 0.15
0.13 e 0.13
0.15 cd 0.15
*0.16 0.16


*Indicates systems are significantly different at p=.05


1978
0.14 de 0.14
0.19 a 0.22
0.17 b 0.23
0.16 bc 0.15
0.14 de 0.13
0.16 bcd 0.16
0.14 e 0.13
0.15 cde 0.16
0.15 cde 0.14
0.14 e 0.15
0.14 e 0.12
0.14 de 0.14
0.16 0.16



































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TABLE 36
SOYBEAN LEAF NITROGEN CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


5.22
5.15
5.03
5.13
5.23
4.95
4.99
4.97
5.11
4.91
4.66
4.74
5.01


5.00
4.93
5.26
5.13
5.16
5.12
5.18
5.13
5.20
5.17
5.20
4.99
5.13


a 4.92
a 5.09
a 4.90
a 5.21
a 5.27
a 4.90
a 5.23
a 5.06
a 5.04
a 5.28
a 5.01
a 5.00
5.08


a
a
a
a
a
a
a
a
a
a
a
a


5.07
5.12
4.96
5.17
5.25
4.92
5.11
5.01
5.07
5.09
4.83
4.87
5.04


1978
a 5.16 a
a 5.00 a
a 5.09 a
a 5.26 a
a 5.28 a
a 5.20 a
a 5.10 a
a 4.98 a
a 5.16 a
a 5.11 a
a 5.00 a
a 5.08 a
5.12


5.08
4.96
5.17
5.19
5.22
5.16
5.14
5.05
5.18
5.14
5.10
5.04
5.12


Two Year Average
5.11 5.04 5.07 abc
5.04 5.05 5.04 be
5.14 4.99 5.07 abc
5.13 5.23 5.18 ab
5.19 5.27 5.23 a
5.03 5.05 5.04 be
5.09 5.17 5.13 abc
5.05 5.02 5.03 bc
5.15 5.10 5.13 abc
5.04 5.19 5.11 abc
4.93 5.01 4.97 c
4.87 5.04 4.95 c
5.07 5.10 5.08


6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


11
12
Mean










SOYBEAN LEAF


TABLE 37

PHOSPHORUS CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


0.33
0.35
0.35
0.34
0.34
0.36
0.36
0.35
0.36
0.37
0.36
0.35
0.35


0.33 a
0.34 a
0.33 a
0.36 a
0.34 a
0.35 a
0.35 a
0.35 a
0.35 a
0.36 a
0.36 a
0.35 a
0.35


1978
0.38 a 0.39
0.35 a 0.36
0.35 a 0.37
0.37 a 0.38
0.37 a 0.40
0.42 a 0.42
0.41 a 0.39
0.39 a 0.39
0.39 a 0.41
0.41 a 0.42
0.41 a 0.41
0.37 a 0.37
0.39 0.39


1
2
3
4
5
6
7
8
9
10
11
12
Mean


a
a
a
a
a
a
a
a
a
a
a
a


Two Year Average

1 0.36 0.36 0.36 cd
2 0.35 0.35 0.35 d
3 0.35 0.35 0.35 d
4 0.35 0.37 0.36 cd
5 0.36 0.37 0.36 bcd
6 0.39 0.39 0.39 a
7 0.39 0.37 0.38 abc
8 0.37 0.37 0.37 abcd
9 0.38 0.38 0.38 abc
10 0.39 0.39 0.39 a
11 0.38 0.38 0.38 ab
12 0.36 0.36 0.36 cd
Mean 0.37 0.37 0.37


0.33
0.34
0.34
0.35
0.34
0.36
0.35
0.35
0.36
0.36
0.36
0.35
0.35


0.38
0.36
0.36
0.37
0.38
0.42
0.40
0.39
0.40
0.42
0.41
0.37
0.39


11
12
Mean










SOYBEAN LEAF


TABLE 38
POTASSIUM CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


1.26 d
1.28 cd
1.33 bcd
1.49 abed
1.62 a
1.47 abed
1.60 ab
1.48 abed
1.63 a
1.47 abed
1.53 abc
1.59 ab
*1.48


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1.44 ab
1.18 cd
1.11 d
1.45 ab
1.51 ab
1.39 abc
1.49 ab
1.23 bc
1.42 ab
1.40 ab
1.53 ab
1.63 a
*1.40


1978
d
d
d
bc
abc
c
a
bc
ab
C
ab
bc


1.35
1.23
1.22
1.47
1.56
1.43
1.54
1.35
1.52
1.44
1.53
1.61
1.44


1.26 d 1.26
1.02 e 1.08
0.94 e 1.08
1.36 cd 1.50
1.71 a 1.73
1.32 d 1.43
1.66 ab 1.82
1.28 d 1.48
1.73 a 1.80
1.41 bed 1.48
1.57 abc 1.69
1.65 ab 1.68
1.41 1.51


Two Year Average
1.26 1.35 1.30 d
1.21 1.10 1.15 e
1.27 1.03 1.15 e
1.56 1.41 1.49 be
1.68 1.61 1.65 a
1.50 1.36 1.43 cd
1.79 1.57 1.68 a
1.58 1.25 1.42 cd
1.75 1.57 1.66 a
1.51 1.41 1.46 c
1.67 1.55 1.61 ab
1.65 1.64 1.64 a
* 1.54 1.41 1.47


*Indicates systems are significantly different at p=.05


1.26
1.13
1.21
1.65
1.75
1.54
1.98
1.68
1.86
1.55
1.82
1.72
1.60


1
2
3
4
5
6
7
8
9
10
11
12
Mean










SOYBEAN LEAF


TABLE 39
CALCIUM CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1.60 ab
1.70 a
1.53 abc
1.43 bed
1.40 bed
1.44 bed
1.34 cd
1.25 d
1.35 ed
1.45 bed
1.37 bed
1.37 bcd
1.44


1.46
1.62
1.68
1.50
1.32
1.42
1.41
1.50
1.40
1.48
1.40
1.32
1.46


1978
1 1.49 a 1.35
2 1.46 a 1.47
3 1.32 ab 1.56
4 1.11 c 1.25
5 1.12 c 1.13
6 1.20 bc 1.36
7 1.09 c 1.20
8 1.23 be 1.41
9 1.07 c 1.19
10 1.20 be 1.30
11 1.07 c 1.07
12 1.16 bc 1.17
Mean 1.22 1.29


1.53
1.66
1.60
1.46
1.36
1.43
1.38
1.37
1.37
1.47
1.38
1.34
1.45


bcde
ab
a
cdefg
fg
bed
defg
abc
defg
bcdef
g
ef


1.42
1.46
1.44
1.18
1.12
1.28
1.15
1.32
1.13
1.25
1.07
1.16
1.25


Two Year Average
1 1.55
2 1.58
3 1.42
4 1.27
5 1.26
6 1.32
7 1.22
8 1.24
9 1.21
10 1.33
11 1.22
12 1.27
Mean 1.33


1.41 1.48 ab
1.54 1.56 a
1.62 1.52 a
1.38 1.32 c
1.23 1.24 c
1.39 1.35 be
1.31 1.26 c
1.46 1.35 be
1.29 1.25 c
1.39 1.36 be
1.23 1.23 c
1.24 1.25 c
1.38 1.35








TABLE 40
SOYBEAN LEAF MAGNESIUM CONCENTRATIONS (%) AT SANFORD


Treatment System I System II Mean

1977


1 0.34
2 0.36
3 0.38
4 0.30
5 0.28
6 0.30
7 0.28
8 0.28
9 0.27
10 0.31
11 0.28
12 0.31
Mean 0.31


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


abc 0.33
ab 0.37
a 0.41
bc 0.32
c 0.26
be 0.31
c 0.27
c 0.34
c 0.31
abe 0.29
c 0.29
bc 0.29
0.32


1978
0.52 a
0.44 a
0.45 a
0.28 b
0.26 b
0.33 b
0.28 b
0.33 b
0.25 b
0.32 b
0.27 b
0.30 b
0.34


abc
ab
a
abc
c
abe

bc
c
abc
be
be
be
bc


0.33
0.37
0.40
0.31
0.27
0.31
0.28
0.31
0.29
0.30
0.28
0.30
0.32


0.48 b 0.50
0.53 ab 0.49
0.59 a 0.52
0.35 c 0.32
0.26 c 0.26
0.37 c 0.35
0.29 c 0.28
0.36 c 0.34
0.31 c 0.28
0.35 c 0.33
0.30 c 0.28
0.32 c 0.31
0.38 0.36


Two Year Average
0.43 0.40 0.42 a
0.40 0.45 0.43 a
0.41 0.50 0.46 a
0.29 0.33 0.31 be
0.27 0.26 0.27 c
0.32 0.34 0.33 b
0.28 0.28 0.28 be
0.30 0.35 0.33 b
0.26 0.31 0.29 be
0.32 0.32 0.32 be
0.27 0.29 0.28 be
0.30 0.30 0.30 bc
0.33 0.35 0.34








TABLE 41

SOYBEAN LEAF NITROGEN CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


5.03 a
4.82 a
4.79 a
4.73 a
4.65 a
4.86 a
5.03 a
4.77 a
4.78 a
4.93 a
4.92 a
4.92 a
4.85


4.51
4.74
4.75
4.86
4.45
4.67
4.59
4.68
4.87
4.79
4.43
4.67
4.66


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1978
a
a
a
a
a
a
a
a
a
a
a
a


4.92
4.82
4.62
4.81
4.80
4.83
4.96
4.78
4.75
4.83
4.88
4.87
4.82


4.82
4.81
4.45
4.88
4.95
4.81
4.88
4.78
4.73
4.73
4.85
4.81
4.79



4.87
4.75
4.82
5.07
5.04
4.55
4.99
4.90
4.86
4.79
4.83
4.79
4.85


4.81 a
4.78 a
4.70 a
4.88 a
4.77 a
4.72 a
4.87 a
4.78 a
4.81 a
4.81 a
4.76 a
4.80 a
4.79


Two Year Average
4.77 4.85
4.78 4.78
4.77 4.64
4.79 4.97
4.55 5.00
4.76 4.68
4.81 4.93
4.72 4.84
4.83 4.80
4.86 4.76
4.68 4.84
4.79 4.80
4.76 4.82


4.69
4.74
4.78
4.96
4.74
4.61
4.79
4.79
4.87
4.79
4.63
4.73
4.76


8
9
10
11
12
Mean



1
2
3
4
5
6
7
8
9
10
11
12
Mean








TABLE 42
SOYBEAN LEAF PHOSPHORUS CONCENTRATIONS AT GAINESVILLE


Treatment System I System II Mean

1977
1 0.35 a 0.35 a 0.35
2 0.36 a 0.37 a 0.36
3 0.36 a 0.35 a 0.36
4 0.37 a 0.36 a 0.37
5 0.38 a 0.35 a 0.36
6 0.35 a 0.35 a 0.35
7 0.37 a 0.36 a 0.36
8 0.35 a 0.35 a 0.35
9 0.34 a 0.35 a 0.34
10 0.35 a 0.34 a 0.35
11 0.36 a 0.37 a 0.36
12 0.36 a 0.35 a 0.36
Mean 0.36 0.35 0.36
1978
1 0.37 a 0.36 a 0.37
2 0.37 a 0.37 a 0.37
3 0.38 a 0.38 a 0.38
4 0.39 a 0.39 a 0.39
5 0.37 a 0.41 a 0.39
6 0.38 a 0.37 a 0.38
7 0.37 a 0.40 a 0.39
8 0.38 a 0.39 a 0.39
9 0.39 a 0.38 a 0.39
10 0.38 a 0.40 a 0.39
11 0.36 a 0.41 a 0.39
12 0.36 a 0.39 a 0.38
Mean 0.38 0.39 0.38
Two Year Average
1 0.36 0.36 0.36 a
2 0.36 0.37 0.37 a
3 0.37 0.37 0.37 a
4 0.38 0.38 0.38 a
5 0.37 0.38 0.38 a
6 0.37 0.36 0.37 a
7 0.37 0.38 0.38 a
8 0.37 0.37 0.37 a
9 0.36 0.37 0.36 a
10 0.36 0.37 0.37 a
11 0.36 0.39 0.37 a
12 0.36 0.37 0.37 a
Mean 0.37 0.37 0.37








TABLE 43
SOYBEAN LEAF POTASSIUM CONCENTRATIONS


(%) AT GAINESVILLE


Treatment System I System II Mean

1977


1.56 ab
1.46 abc
1.29 d
1.49 abc
1.52 abc
1.57 ab
1.61 a
1.35 cd
1.44 abed
1.44 abed
1.42 bcd
1.28 d
1.45

1978


1.47
1.29
1.28
1.64
1.59
1.61
1.78
1.38
1.63
1.41
1.66
1.45
1.52


cde
fg
g
ab
bed
bed
a
efg
abc
efg
ab
def


1.34
1.13
1.04
1.36
1.62
1.40
1.48
1.34
1.27
1.19
1.22
1.20
1.30


be
de
e
be
a
be
ab
be
cd
cde
cde
cde


1.45
1.30
1.17
1.42
1.57
1.48
1.55
1.35
1.35
1.31
1.32
1.24
1.82


1.28 d
1.05 e
1.01 e
1.37 cd
1.65 a
1.33 cd
1.55 ab
1.37 cd
1.56 ab
1.22 d
1.46 bc
1.36 ed
1.35


1.37
1.17
1.14
1.51
1.62
1.47
1.66
1.37
1.59
1.31
1.56
1.40
1.44


Two Year Average
1.52 1.31 1.41 bed
1.38 1.09 1.23 fg
1.28 1.03 1.15 g
1.56 1.36 1.46 b
1.55 1.64 1.59 a
1.59 1.36 1.47 b
1.69 1.51 1.60 a
1.36 1.36 1.36 cde
1.54 1.41 1.47 b
1.43 1.20 1.31 ef
1.54 1.34 1.44 be
1.36 1.28 1.32 def
1.49 1.33 1.41


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean









TABLE 44

SOYBEAN LEAF CALCIUM CONCENTRATIONS


(%) AT GAINESVILLE


Treatment System I System II Mean

1977


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1.22 a
1.35 a
1.41 a
1.36 a
1.37 a
1.47 a
1.27 a
1.33 a
1.37 a
1.31 a
1.26 a
1.46 a
0.63


1 1.41
2 1.73
3 1.73
4 1.36
5 1.33
6 1.46
7 1.29
8 1.59
9 1.37
10 1.64
11 1.45
12 1.66
Mean 1.51


1.27
1.56
1.67
1.39
1.32
1.44
1.32
1.41
1.48
1.57
1.61
1.51
1.46


1978
bed 1.64
a 1.88
a 1.94
ed 1.52
ed 1.28
bed 1.66
d 1.47
abc 1.72
cd 1.48
ab 1.75
bed 1.52
ab 1.64
1.63


Two Year Average
1 1.31 1.45 1.38 de
2 1.54 1.72 1.63 ab
3 1.57 1.81 1.69 a
4 1.36 1.46 1.41 de
5 1.35 1.30 1.32 e
6 1.47 1.55 1.51 bcd
7 1.28 1.40 1.34 e
8 1.46 1.56 1.51 bed
9 1.37 1.48 1.42 de
10 1.48 1.66 1.57 abc
11 1.35 1.56 1.46 cde
12 1.56 1.57 1.57 abc
Mean 1.43 1.55 1.49


d
ab
a
bed
ed
bed
ed
bed
abed
ab
ab
abc


1.25
1.45
1.54
1.37
1.34
1.46
1.30
1.37
1.42
1.44
1.44
1.49
1.05


1.52
1.80
1.84
1.44
1.31
1.56
1.38
1.66
1.43
1.70
1.48
1.65
1.57


ed
a
a
d
e
ed
d
be
d
abc
d
ed







TABLE 45
SOYBEAN LEAF MAGNESIUM CONCENTRATIONS (%) AT GAINESVILLE


Treatment System I System II Mean

1977


0.28 a
0.29 a
0.33 a
0.29 a
0.25 a
0.26 a
0.25 a
0.27 a
0.29 a
0.24 a
0.23 a
0.27 a
0.27


1978
0.36 b
0.45 a
0.48 a
0.35 be
0.34 be
0.31 bc
0.28 c
0.36 b
0.34 bc
0.36 be
0.30 be
0.37 b
*0.36
Two Year Average
0.39
0.46
0.50
0.34
0.29
0.32
0.31
0.34


0.27 bc
0.35 ab
0.43 a
0.27 bc
0.25 c
0.27 bc
0.25 c
0.29 bc
0.30 be
0.29 bc
0.31 be
0.30 bc
0.30


0.27
0.32
0.38
0.28
0.25
0.27
0.25
0.28
0.29
0.27
0.27
0.28
0.28


0.50 ab
0.56 a
0.58 a
0.41 cd
0.32 d
0.37 ed
0.36 ed
0.40 cd
0.36 cd
0.43 be
0.35 cd
0.37 cd
*0.42


0.32
0.37
0.40
0.32
0.29
0.28
0.27
0.32


0.43
0.51
0.53
0.38
0.33
0.34
0.32
0.38
0.35
0.40
0.33
0.37
0.39


0.36 b
0.42 a
0.46 a
0.33 be
0.29 be
0.31 be
0.29 c
0.33 be
0.32 be
0.33 be
0.30 be
0.33 bc
0.34


9 0.33 0.31
10 0.36 0.30
11 0.33 0.27
12 0.33 0.32
Mean 0.32 0.36


*Indicates systems are significantly different at p = .05


1
2
3
4
5
6
7
8
9
10
11
12
Mean


10
11
12
Mean








TABLE 46

SOYBEAN LEAF NITROGEN CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


1
2
3
4
5
6
7
8
9
10
11
12
Mean



1
2
3
4
5
6
7
8
9
10
11
12
Mean


4.09
4.35
4.38
3.91
4.07
4.01
4.42
3.62
4.47
4.65
4.62
4.52
*4.25


a
a
a
a
a
a
a
a
a
a
a
a


3.73
3.67
3.77
3.56
3.70
3.92
3.97
3.91
4.00
4.22
3.74
3.81
*3.82


a
a
a
a
a
a
a
a
a
a
a
a


3.86
4.01
4.08
3.73
3.88
3.97
4.19
3.76
4.24
4.43
4.10
4.16
4.04


1978


5.02 a
4.95 a
4.97 a
4.81 a
4.85 a
4.95 a
4.86 a
4.86 a
4.76 a
4.91 a
4.91 a
4.92 a
*4.90


4.96 a
4.75 abc
4.61 be
4.88 ab
4.72 abc
4.76 abc
4.77 abc
4.62 bc
4.53 c
4.66 bc
4.71 abc
4.85 ab
*4.73


4.99
4.85
4.79
4.84
4.78
4.85
4.82
4.74
4.64
4.78
4.81
4.88
4.82


Two Year Average
1 4.55 4.30 4.43 a
2 4.65 4.21 4.43 a
3 4.67 4.19 4.43 a
4 4.36 4.22 4.29 a
5 4.46 4.21 4.33 a
6 4.48 4.34 4.41 a
7 4.64 4.37 4.50 a
8 4.23 4.26 4.25 a
9 4.61 4.26 4.44 a
10 4.78 4.44 4.61 a
11 4.69 4.22 4.45 a
12 4.72 4.33 4.52 a
Mean *4.57 *4.28 4.42

*Indicates systems are significantly different at p=.05








TABLE 47
SOYBEAN LEAF PHOSPHORUS CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


0.63 a
0.49 a


0.46
0.48
0.56
0.62
0.60
0.44
0.46
0.44
0.57
0.57
0.53


a
a
a
a
a
a
a
a
a
a


0.66 a 0.65
0.56 abc 0.53
0.44 c 0.45
0.58 abc 0.53
0.49 bc 0.52
0.61 ab 0.61
0.50 bc 0.55
0.43 c 0.43
0.49 bc 0.47
0.44 c 0.44
0.51 abc 0.54
0.42 c 0.49
0.51 0.52


1978
0.35 a 0.36 a
0.35 a 0.34 a
0.35 a 0.33 a
0.34 a 0.35 a
0.35 a 0.34 a
0.36 a 0.34 a
0.35 a 0.35 a
0.34 a 0.35 a
0.33 a 0.35 a
0.35 a 0.34 a
0.36 a 0.33 a
0.36 a 0.35 a
0.35 0.35


0.35
0.35
0.34
0.35
0.34
0.35
0.35
0.35
0.34
0.35
0.35
0.36
0.35


Two Year Average
1 0.49 0.51 0.50 a
2 0.42 0.45 0.44 ab
3 0.40 0.39 0.40 ab
4 0.41 0.47 0.44 ab
5 0.46 0.41 0.43 ab
6 0.49 0.48 0.48 ab
7 0.47 0.42 0.45 ab
8 0.39 0.39 0.39 b
9 0.40 0.42 0.41 ab
10 0.39 0.39 0.39 b
11 0.46 0.42 0.44 ab
12 0.46 0.39 0.43 ab
Mean 0.44 0.43 0.43


1
2
3
4
5
6
7
8
9
10
11
12
Mean


10
11
12
Mean




87



TABLE 48

SOYBEAN LEAF POTASSIUM CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


1.61 be
1.66 abc
1.69 ab
1.58 bed
1.44 d
1.59 be
1.77 a
1.69 ab
1.65 abc
1.54 ed
1.54 cd
1.57 bcd
*1.62


1.65
1.61
1.56
1.62
1.63
1.64
1.63
1.67
1.54
1.57
1.51
1.63
*1.61


1.49
1.39
1.39
1.43
1.60
1.62
1.51
1.44
1.40
1.40
1.34
1.40
*1.46


1.52
1.51
1.43
1.53
1.51
1.51
1.62
1.53
1.46
1.42
1.47
1.50
*1.51


1978
a
a
a
a
a
a
a
a
a
a
a
a


ab
b
b
ab
a
a
ab
ab
b
b
b
b


1.55
1.53
1.54
1.50
1.52
1.60
1.64
1.57
1.52
1.47
1.44
1.48
1.54


1.63
1.56
1.50
1.57
1.57
1.58
1.63
1.60
1.50
1.49
1.49
1.56
1.56


a
ab
b
ab
ab
ab
a
ab
b
b
b
ab


Two Year Average
1.63 1.55 1.59 ab
1.63 1.45 1.54 bc
1.63 1.41 1.52 be
1.60 1.48 1.54 be
1.54 1.56 1.55 be
1.62 1.56 1.59 ab
1.70 1.57 1.63 a
1.68 1.49 1.58 ab
1.59 1.43 1.51 be
1.55 1.41 1.48 c
1.52 1.40 1.46 c
1.60 1.45 1.52 bc
*1.61 *1.48 1.55


*Indicates systems are significantly different at p=.05


8
9
10
11
12
Mean



2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean








TABLE 49

SOYBEAN LEAF CALCIUM CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


1 1.63 a
2 1.59 a
3 1.38 a
4 1.60 a
5 1.67 a
6 1.76 a
7 1.48 a
8 1.50 a
9 1.57 a
10 1.41 a
11 1.58 a
12 1.52 a
Mean *1.56


1.60 a
1.84 a
1.90 a
1.73 a
1.53 a
1.88 a
1.58 a
1.77 a
1.78 a
1.64 a
1.96 a
1.72 a
*1.75


1.62
1.71
1.64
1.66
1.60
1.82
1.53
1.63
1.68
1.52
1.77
1.62
1.65


1978


1.53
1.71
1.76
1.74
1.70
1.60
1.72
1.81
1.88
1.87
1.92
1.78
1.76


1.45 d
1.61 cd
1.84 bc
1.75 be
1.87 ab
1.75 bc
1.78 bc
1.93 ab
1.77 be
2.07 a
1.90 ab
1.73 bc
1.79


1.49
1.66
1.80
1.75
1.78
1.67
1.75
1.87
1.82
1.97
1.91
1.76
1.77


Two Year Average


1.58
1.65
1.57
1.67
1.68
1.68
1.60
1.65
1.72
1.64
1.75
1.65
1.66


1.52 1.55 c
1.73 1.69 abc
1.87 1.72 abc
1.74 1.71 abc
1.70 1.69 abc
1.81 1.74 ab
1.68 1.64 bc
1.85 1.75 ab
1.78 1.75 ab
1.86 1.75 ab
1.93 1.84 abc
1.72 1.69 abc
1.77 1.71


*Indicates systems are significantly different at p=.05


1
2
3
4
5
6
7
8
9
10
11
12
Mean


1
2
3
4
5
6
7
8
9
10
11
12
Mean




89


TABLE 50
SOYBEAN LEAF MAGNESIUM CONCENTRATIONS (%) AT QUINCY


Treatment System I System II Mean

1977


0.33 a
0.29 a
0.26 a
0.30 a
0.32 a
0.30 a
0.26 a
0.27 a
0.28 a
0.24 a
0.28 a
0.27 a
0.29


0.33 a
0.34 a
0.36 a
0.32 a
0.27 a
0.33 a
0.27 a
0.31 a
0.31 a
0.29 a
0.33 a
0.30 a
0.32


1
2
3
4
5
6
7
8
9
10
11
12
Mean



2
3
4
5
6
7
8
9
10
11
12
Mean


1 0.28
2 0.28
3 0.26
4 0.26
5 0.28
6 0.26
7 0.24
8 0.27
9 0.27
10 0.24
11 0.27
12 0.26
Mean *0.27


c
abc
ab
abc
bc
c
bc
a
abc
ab
abc
c


0.33
0.32
0.31
0.31
0.30
0.32
0.26
0.29
0.30
0.26
0.30
0.28
0.30


0.23
0.26
0.26
0.24
0.24
0.22
0.24
0.28
0.26
0.27
0.26
0.24
0.25


0.28 a
0.29 a
0.29 a
0.28 a
0.27 a
0.27 a
0.25 a
0.29 a
0.28 a
0.27 a
0.29 a
0.27 a
0.28


0.28
0.30
0.32
0.29
0.26
0.28
0.26
0.30
0.29
0.29
0.30
0.27
*0.29


*Indicates systems are significantly different at p=.05


1978
0.23 a 0.23
0.26 a 0.25
0.25 a 0.28
0.23 a 0.26
0.24 a 0.25
0.21 a 0.23
0.22 a 0.25
0.26 a 0.30
0.25 a 0.27
0.25 a 0.29
0.26 a 0.26
0.25 a 0.23
*0.25 *0.26
Two Year Average













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