Agro-economic evaluation of four vegetable cropping patterns for north Florida as influenced by crop and fertilizer mana...

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Agro-economic evaluation of four vegetable cropping patterns for north Florida as influenced by crop and fertilizer management levels
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xi, 97 leaves : ill. ; 28 cm.
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Palada, Manuel Celiz, 1944-
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Vegetable gardening -- Florida   ( lcsh )
Cropping systems -- Florida   ( lcsh )
Vegetables -- Fertilizers -- Florida   ( lcsh )
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

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Thesis:
Thesis--University of Florida.
Bibliography:
Includes bibliographical references (leaves 81-95).
Statement of Responsibility:
by Manuel Celiz Palada.
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Typescript.
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Vita.

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Full Text









AGRO-ECONOMIC EVALUATION OF FOUR VEGETABLE CROPPING
PATTERNS FOR NORTH FLORIDA AS INFLUENCED BY
CROP AND FERTILIZER MANAGEMENT LEVELS














By



MANUEL CELIZ PALADA


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE EQUIRElTS'ETS FOR l-
DEGREE OF DOCTOR OF PHILOSOPHY


UNIVERSITY OF FLORIDA


1980



























DEDICATED



TO



THE SMALL-SCALZ VEGETABLE GCF.CWER IN
NORTH FLORIDA AND EEVE'L.PING
COUNTRIES IN THE TROPICS









ACKNOWLEDGMENTS


This research has been completed because of the help of a great

number of people. The supervision and assistance from the members of

the author's graduate committee, Dr. R. D. William, former chairman,

Dr. D. N. Maynard, present chairman, and Dr. W. G. Blue, Prof. L. H.

Halsey, Dr. S. R. Kostewicz, Dr. G. M. Prine, and Dr. G. B. Wall are

gratefully acknowledged. Dr. William served as chairman of the super-

visory committee for the entire course of the research and graduate

training program and helped stimulate an environment conducive to the

author's academic development. The author appreciates the interest

and willingness of Dr. D. N. Maynard who served as chairman of the

supervisory committee after Dr. William left the Vegetable Crops Depart-

ment. The help and guidance of Dr. William and Dr. Maynard in develop-

ing and improving the author's skill in writing are highly appreciated.

The helpful suggestions and assistance of Prof. Halsey in the conduct

of the field experiment are gratefully acknowledged.

Acknowledgments are due also to Mr. L. C. Bryant, and other

technicians of the Horticultural Unit and Soil Science Department

Testing Laboratory who helped and assisted the author in conducting

field work and analyzing soil samples. The author is thankful to Dr.

N. Gammon, and Dr. W. G. Blue for allowing him to use the facilities

of the Tropical Pastures and Soils Laboratory. Special appreciation

is also extended to Dr. S. J. Locascio for allowing the author to use

the facilities of the Vegetable Nutrition Laboratory. The help and










assistance of his fellow graduate students and friends in Vegetable

Crops Department are also appreciated.

The author is grateful to the Rockefeller Foundation for

providing a graduate fellowship and to the persons who recommended

him for this fellowship, namely, Dr. N. C. Brady, Director General,

International Rice Research Institute (IRRI), Los Banos, Philippines,

and Dr. Richard R. Harwood, Director, Organic Gardening and Farming

Research Center, Kutztown, Pennsylvania.

Finally, the author wishes to express his sincere thanks to

his wife, Elie; daughter, Daffodil; and son, Ted Peter, for their

love, constant inspiration, encouragement, and understanding.









TABLE OF CONTENTS


Page

ACKNOWLEDGMENTS iii

LIST OF TABLES vii

LIST OF FIGURES ix

ABSTRACT x

INTRODUCTION 1

CHAPTER I. LITERATURE REVIEW 3

Concepts of Cropping Systems 3
Cropping Systems Research Approaches and
Methodologies 4
Management of Vegetables in Cropping Systems 8
Soil and Fertilizer Management in Vegetable
Cropping Systems 13
Economic Evaluation of Vegetable Cropping
Patterns 20

CHAPTER II. AN EVALUATION OF FOUR VEGETABLE CROPPING PA'TTE.:S
FOR NORTH FLORIDA 25

Introduction 25
Materials and Methods 27
Results and Discussion 32
Crop environment 32
Crop duration 35
Marketable yields 35
Biological stability 39
Production costs and returns to management 40
Returns to production inputs 40

CHAPTER III. CROP AND FERTILIZER MANAGEMENT LEVELS IN FOUR
SEQUENTIAL CROPPING PATTERNS INVOLVING
VEGETABLES 44

Introduction 44
Materials and Methods 47
Experimental site 47
Soil characteristics 47
Classification of vegetable crops 47
Selection of vegetable crops 47
Design of cropping patterns 48









Levels of fertilizers 48
Experimental design 51
Data collection 51
Soil sampling and chemical analyses 52
Statistical analysis of data 52
Results and Discussion 53
Shifts in Soil Properties 53
Total soluble salts 53
Soil reaction 53
Soil organic matter 55
Soil nitrogen 55
Soil potassium 59
Effects of Crop and Fertilizer Management
Levels on Marketable Yields 59
Cropping pattern HM-HM-HM 59
Cropping pattern LM-LM-L 61
Cropping pattern H-M-MMIM 61
Cropping pattern Hi-LM-MM 61
Resource Utilization of Cropping Patterns 63
Labor profile 63
Production costs 63
Income and Returns to Production Inputs 65
Gross and net income 65
Returns to production inputs 68
Rates of return to production inputs 68
Economic Implications 72

SUMMARY AND CONCLUSIONS 74

LITERATURE CITED 81

BIOGRAPHICAL SKETCH 96







LIST OF TABLES


Table Page

1 Cultural practices for vegetable crops grouped in three
management levels and grown in four cropping patterns at
Gainesville, FL, 1977-79. 29

2 Average fertilizer, pesticide, cultural labor, and
harvest costs for high, medium, and low management
vegetable crops in Florida, 1973-1977. 30

3 Crop duration and interval between crops in four vegetable
cropping patterns over two cropping cycles in the period
1977-79, Gainesville, FL. 36

4 Marketable yields of vegetable crops in four cropping
patterns at Gainesville, FL. 37

5 Production costs and returns to management of vegetable
crops in four cropping patterns over two cropping cycles
in the period 1977-79, Gainesville, FL. 41

6 Returns to fertilizer, cash, labor, and management of
vegetable crops in four cropping patterns over two crop-
ping cycles in the period 1977-79, Gainesville, FL. 42

7 Nitrogen and potassium levels for low, medium, and high
management crops, Gainesville, FL, 1977-79. 50

8 Soil pH after harvest of each crop as influenced by crop
and fertilizer management levels over two cropping cycles
in the period 1977-79, Gainesville, FL. 56

9 Soil organic matter content after harvest of each crop
as influenced by crop and fertilizer management levels
over two cropping cycles in the period 1977-79, Gainesville,
FL. 57

10 Marketable yields of component vegetable crops in four
cropping patterns as influenced by crop and fertilizer
management levels over two cropping cycles in the period
1977-79, Gainesville, FL. 62

11. Production costs of four vegetable cropping patterns as
influenced by crop and fertilizer management levels over
two cropping cycles in the period 1977-79, Gainesville,
FL 66

12 Gross and net incomes of four vegetable cropping patterns
as influenced by crop and fertilizer management levels over
two cropping cycles in the period 1977-79, Gainesville, FL. 67










13 Returns to production inputs of four vegetable cropping
patterns as influenced by crop and fertilizer management
levels over two cropping cycles in the period 1977-79,
Gainesville, FL. 69

14 Rates of return to production inputs of four vegetable
cropping patterns as influenced by crop and fertilizer
management levels over two cropping cycles in the period
1977-79, Gainesville, FL. 70


viii


Table


Page









LIST OF FIGURES


Figure Page

1 Four vegetable cropping patterns plotted against rainfall
and temperature at Gainesville, FL, 1977-78. 33

2 Four vegetable cropping patterns plotted against rainfall
and temperature at Gainesville, FL, 1978-79. 34

3 A conceptual model of crop management approach to vegetable
cropping systems research. 46

4 Planting sequences of low, medium, and high management
vegetable crops in four cropping patterns over two crop-
ping cycles in the period 1977-79, Gainesville, FL. 49

5 Total soluble salts after harvest of each crop as influenced
by crop and fertilizer management levels over two cropping
cycles in the period 1977-79, Gainesville, FL. 54

6 Soil nitrogen after harvest of each crop as influenced by
crop and fertilizer management levels over two cropping
cycles in the period 1977-79, Gainesville, FL. 58

7 Soil potassium after harvest of each crop as influenced
by crop and fertilizer management levels over two cropping
cycles in the period 1977-79, Gainesville, FL. 60

8 Labor profile of four vegetable cropping patterns as
influenced by crop management levels over two cropping
cycles in the period 1977-79, Gainesville, FL. 64







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

AGRO-ECONOMIC EVALUATION OF FOUR VEGETABLE CROPPING
PATTERNS FOR NORTH FLORIDA AS INFLUENCED BY
CROP AND FERTILIZER MANAGEMENT LEVELS

By

Manuel Celiz Palada

March, 1980

Chairman: Donald N. Maynard
Major Department: Horticultural Science (Vegetable Crops)

Appropriate crop management technologies for year-round vegetable

cropping systems are essential to increase productivity and improve farm

income among small-scale vegetable farmers. A 2-year study was conducted

to determine and evaluate the influence of crop and fertilizer manage-

ment levels on productivity, income, and nutrient levels in soil from

four vegetable cropping patterns for North Florida and to develop

appropriate crop and fertilizer management practices for sequential

vegetable cropping systems.

Seven vegetable crops were classified into three management

groups (low, LM; medium, MM; and high, HM) and planted in four cropping

patterns (HM-HM-HM, LM-LM-LM, Hr-;..!-LM, and -lM-l-;-.1). Vegetable crops

included bulb onion (Allium cepa L.), collard (Brassica oleracea L.

Viridis Cr;up), English pea (Pisum sativum L.), mustard (Brassica

juncea L. Czern. and Coss.), pole bean (Phaseolus vulgaris L.), southern

pea (Vigna unguiculata L. Walp.), and crookneck squash (Cucurbita pepo L.).

The four cropping pattern main plots were split into three fertilizer

level sub-plots (low, medium, and high N and K) arranged in a randomized

block design.








Cropping duration was longest in cropping pattern HM-HM-HM

(bulb onion-pole bean-collard) and shortest in LM-LM-LM (English pea-

southern pea-southern pea) and HM-LM-MM (bulb onion-southern pea-

mustard). At the end of the cropping sequence, soil pH was lower than

the initial value in all cropping patterns, but the difference between

initial and final pH was greater in cropping patterns HM-HM-HIM, HM-MM-M,

and H-M-LM-MM than in LM-LM-LM. Soil organic matter content decreased,

whereas total soluble salts increased in cropping pattern HM-HM-EM,

where high levels of fertilizer were applied. Cropping pattern LM-LM-LM

resulted in highest soil organic matter content after harvest of the

third crop. Soil N and exchangeable K were significantly higher in

cropping pattern HM-FHM-HM than in the other cropping patterns. Exchange-

able K increased as fertilizer level increased in all cropping patterns.

Increases in marketable yields were not observed with increasing

fertilizer level except for bulb onion, squash, and English pea, where

significant yield responses resulted from application of the medium

fertilizer level. Cropping pattern HMI-M-HM resulted in significantly

higher resource use and gross and net incomes, but rates of return to

production inputs such as fertilizer, labor, cash, and management were

similar among the cropping patterns. Planting low management and a

combination of high, medium, and low management crops in sequential

vegetable cropping patterns required low production inputs and were

efficient and profitable. Such cropping patterns offer greater yield

stability and the possibility of improved farm income.







INTRODUCTION


Vegetable growers in North Florida produced 12 vegetable crops

commercially in 1978 (45). Enterprises range in scale from full-time

businesses to part-time small-scale market garden operations (42, 89,

163). In general, vegetable growers in North Florida plant vegetable

crops during the spring and fall seasons because the climate is more

favorable than in summer and winter (175, 176). The higher temperatures

and rainfall in summer and freezing temperatures in winter limit the

production of most vegetables in North Florida (36, 63, 175, 176).

Vegetable production in North Florida is characterized by few total

hectares (19, 45) and lower yields compared to South Florida (29, 45).

Small-scale farmers generally produce vegetables using low levels

of crop management (29, 45). In a survey of 50 small-scale growers in

North Florida, a majority of the growers used low levels of fertilizers

and pesticides (29). Marketing alternatives were limited and prices

for most vegetables were below the break-even price (30, 50). Thus,

the feasibility of increasing and improving vegetable production in

North Florida is dependent upon both efficient cropping and marketing

systems.

Several studies have been conducted to extend and improve vege-

table production in North Florida (20, 164, 175, 176). For example,

the use of black and white plastic mulches to reduce the effect of

intense rainfall and high soil temperatures improved yields of mus.melon

(Cucumis melo L.), watermelon [Citrullus lanatus (Thum.b.) Mansf.], and

squash (20). Production of vegetables under tobacco (Nicotania taba-

cum L.) shades also increased total yield of cucumber (Cucumis sativus L.)

1







2

(164, 175). By selecting adapted cultivars, many vegetable crops can

be grown sequentially (63). For instance, promising cultivars of cru-

cifers, cucurbits, leguminous, leaf, bulb, and solanaceous crops produced

high marketable yields in Gainesville (61, 62, 64, 65, 66, 67).

These studies report only the management system of an individual

crop from planting to harvesting without considering interactions

between crops within cropping and farm management systems. Most of these

studies are specialized, narrow in scope, and often oriented to a speci-

fic discipline. In contrast, cropping systems research involves the

study of cropping patterns and their interaction with farm resources,

other farm enterprises, and available technology on a year-round crop-

ping basis (5, 68, 138).

Since different vegetable crops respond to different levels of

management, research methods such as the cropping systems approach

which integrates crop production with farmer's management capabilities

are needed to develop appropriate technologies. The objectives of this

study were to (a) evaluate productivity, resource use, and profitability

of several vegetable crops planted in four cropping patterns for North

Florida, (b) determine and evaluate the influence of crop and fertilizer

management levels on productivity, income, and nutrient levels in soil

from four vegetable cropping patterns, and (c) develop appropriate crop

and fertilizer management practices for sequential cropping patterns.

The principles and methodology developed from this research study can

be used in both developing and developed countries where small-scale

farmers have limited resources and low energy technologies.






CHAPTER I

LITERATURE REVIEW

Concepts of Cropping Systems

A cropping system is defined as a collection of distinct functional

units or of elements that are interrelated and interacting (31, 94, 118,

119, 138). These components are crops, soils, marketing activities,

production inputs, farmer's management skills, and other environmental

factors. The farmer sometimes manipulates some of these factors in order

to achieve his goals.

Common terms used in cropping systems include:

A crop system comprises components required for the production

of a particular crop and the interrelationships with the environment.

These components include the necessary physical, biological, and techno-

logical factors as well as labor (31).

Monoculture involves the growing of only one crop on the same

plot of land in one year (5, 31, 138, 157).

Multicropping is the growing of more than one crop on the same

land in one year (5, 68, 138).

Sequential cropping is the growing of two or more crops in

sequence on the same field per year (5, 138, 157).

Intercropping is the growing of more than one crop on the same

field at the same time (5, 47, 69, 138, 157).

Relay intercropping is the planting of a second crop before the

first crop is harvested (5, 47, 69, 138).

A -rTppling pattern is a yearly sequence and arran-ement of crops

or fallow on a given land area (5, 31). The interaction of cropping

patterns with physical and socio-economic factors results in cropping

systems for a given area (68).







4

Cropping Systems Research Approaches and Methodologies

Agricultural research generally has been designed to investigate

component technologies based on objectives of increasing yields, product-

ion efficiencies, and profitabilities (37, 121). This research often

benefits large, commercial farmers. Small-scale farmers, however, are

seldom benefited because their objectives are influenced not only by

risk, but also by religion, culture and tradition (80, 118). Improved

technologies for small-scale farmers often fail and are sometimes un-

acceptable because these technologies are not appropriate to their

farming systems. For example, in the central highlands of Guatemala,

Hildebrand (80) reported that farmers do not fertilize their corn

(Zea mays L.) although they recognize that fertilizers increase yields.

These farmers would rather apply the fertilizer to their vegetables

where return to cash or to fertilizer is greater than for corn. In

northern Nigeria, where mixed cropping is practiced, Baker and Norman

(8) reported that farmers are reluctant to adopt recommendations for

single crops because these improved technologies were not relevant to

the local environment or their multiple cropping system. Upland rice

(Oryza sativa L.) farmers in the Philippines prefer a tall cultivar

over the short and high yielding cultivars because weed competition

is less serious (85).

A lack of appropriate methods for conducting multiple cropping

research has hampered the development of more effective technologies

for small-scale farmers (177). Development of relevant, farmer-oriented

methodologies that utilize a multidisciplinary, farm-oriented, farmer

participation, and resource utilization approach have recently been






5

utilized by an increasing number of researchers (8, 23, 69, 77, 81, 97).

An interdisciplinary research team is a prerequisite in develop-

ing cropping system programs (48, 77, 79, 118, 119). Based on assess-

ment of factors that limit production and farm income, the researchable

parts of problems are identified. Research workers from different

disciplines and farmers agree on researchable problems followed by a

combined and joint research effort. In this approach, everyone in the

team works and makes decisions together on a regular basis. These

farming research teams are often composed of an agronomist, economist,

and anthropologist or sociologist (31, 69, 77, 80). The entire team

often conducts a survey to understand and interpret the small farmers'

agro-socio-economic conditions. Each member of the team interviews

the farmer to reduce interviewer bias and increase cross-disciplinary

exchange. The group meets each night to discuss the day's interview.

The farmer participation approach in testing appropriate tech-

nologies in on-farm research is essential in cropping systems studies

(8, 54, 69, 80, 145). On-farm trials can reduce perceived risk by

allowing farmers to observe the technology under the rigors of their

production environment. Farmers can express their opinions and criti-

cisms during the early stage of research process so that technology

is culturally, economically, and biologically viable. The communica-

tion between the farmer-participant and researcher permits small-scale

farmers to become part of the research process and insures that the

technology is appropriate (69, 118, 119).

Most studies using the farmer participation approach are asso-

ciated with small farm development projects whose objectives are to






6

develop, adopt, and transfer improved technologies to small farms in

developing countries (37, 57, 79, 83, 178). For example, the Caqueza

project near Bogota, Colombia, provided farmers with incentive for adapt-

ing a "complete package" of agricultural practices under a risk-reducing

credit scheme (178). Dramatic increases in both yield [200%o for corn

and 50% for potato (Solanum tuberosum L.)] resulted from incorporation

of improved production technologies consisting of new cultivars, opti-

mum population density, additional fertilizer and insect control (178).

A methodology for the design and transfer of agronomic techno-

logy to increase bean production was studied on small farms in a coffee

(Coffea sp. L.)-growing area of Colombia (82). The objective was to

develop a low-cost, low-risk technology. Unlike most agronomic studies

that emphasize yield maximization, the goal of this study was to increase

economic returns with minimum risk. The three components of the study

were to observe traditional bean production systems, design a techno-

logical package, and evaluate the economics of this package at the

farm level. Farmer participation was an integral part of the methodo-

logy. The low-cost technology consisting of combined use of improved

cultivars at optimum population densities and low levels of agrochemi-

cals resulted in a 30% increase in bean production and a 54% net

income (82).

In Asia, projects designed to introduce and validate technolo-

gical innovations for small farms were developed (83, 162). For example,

researchers in India tested rice technological packages in 1966 to

screen cultivars in farmers' field (57). At the same time, economic

data were obtained on the farmers' traditional production system which

allowed researchers to design complementary inputs within the scope of






7

the small farmers' land, labor, and capital resources. In the Philip-

pines, a 50% adoption rate for high-yielding rice cultivars was observed

within a 6-year period (73). Rice "microkits" were tried in other

Asian countries to maximize the dispersal of technology to small farmers

(44). These "microkits" contained five cultivars of rice to be planted

in the farmer's field alongside the local variety. Two levels of ferti-

lizer and two levels of insecticide also were included. Seed yield of

the best variety was sufficient to plant one fourth hectare the follow-

ing season. Through this approach, farmers multiplied the seeds of the

best cultivars, thereby eliminating the necessity of purchasing govern-

ment supplied seed (44).

A similar project was initiated in Nigeria by the International

Institute of Tropical Agriculture with both rice and corn (158). The

package included four improved cultivars and one local cultivar, two

fertilizer levels, and a record book. One farmer in each village was

selected by local extension agents and village leaders to test and

manage the experiment. Results indicated that small farmer adoption

rates were enhanced by these on-farm demonstrations of productivity and

profitability (158).

In El Salvador, the basic multiple cropping system developed for

complex relay and intercropping of corn, pole bean, cabbage (Brassica

oleracea L. Capitata Group), cucumber, bush bean, and radish (Raphanus
2
sativus L,) produced a net income of $772/900 m (78).

The resource utilization approach is another method which is

applicable for the study of cropping systems (16, 68). In this approach,

the farmer seeks to integrate farm resources into farm enterprises by

using available technologies and management skills. An example is






8

intercropping practices in Southeast Asia and in Africa. Short-season

crops such as corn or sorghum (Sorghum bicolor L.) are frequently inter-

cropped with upland rice and cassava (Manihot esculenta L.) or pigeon

pea (Cajanus cajan Millsp.) creating a 9 to 10-month cropping season

with several harvests and a single major tillage operation. This system

enables efficient utilization of land, solar radiation, water, and labor

resources (8).

Most farmers use a combination of enterprises with different

resource requirements. Some enterprises may be of lower productivity

but higher in stability. Others may be labor or cash-intensive and

highly productive, but unstable from the biological, management or

economic standpoint. The net effect is to balance the farmer's resources

in meeting his needs for productivity and stability (68).


Management of Vegetables in Cropping Systems

Vegetables are often grown as component crops in a wide array

of cropping patterns (167). Thus, management of vegetable crops is

dependent on the type of cropping patterns. Asian farmers plant field

and vegetable crops following rice or other staple crops (47, 68, 70,

138). The vegetable crops planted depend on the availability of

resources such as irrigation, labor, cash inputs, and market. High

management vegetable crops such as cabbage, pole bean, cauliflower

(Brassica oleracea L. Botrytis Group), and tomato (Lycopersicon escu-

lentum Mill.) are grown after rice where there is sufficient irrigation

and market incentive (24). Farmers use stakes, high levels of ferti-

lizers and pesticides on crops like tomato and pole lima bean (Phaseolus

lunatus L.) where crop market value is high. Conversely, low






9

manaSgement crops such as mungbean (Vigna radiata L. Wilczek) and cowpea

(Vigna unguiculata L. Walp.) are often planted after rice by farmers in

rain-fed areas where market is limited and a major portion of the produce

is consumed by the farm family (26, 114, 177). Although these crops

require low management levels, studies indicate that they respond to

improved levels of cultural management. For example, Herrera et al.

(76) reported that adequate control of insect pests from vegetative to

flowering stages significantly increased yield of mungbeans.

In Taiwan, vegetable crops are planted sequentially after irri-

gated rice field crops (47, 105). The rice-rice-vegetables cropping

pattern is most common where variety of medium to high management

vegetables can be grown during the period between the production of

two rice crops. There is sufficient time for growing short-season

vegetable crops such as bunching onion (Allium fistulosum L.), cabbage,

mustard, lettuce (Lactuca sativa L.), radish, and bean. In-certain

parts of Malaysia where there are efficient irrigation and drainage

systems, high management vegetable crops such as hot peppers (Casicim

frutescens L.), tomato, yard lcng bean [Vigna sinensis (Stickm) Savi

ex Hassk. Sesquipedalis Group], and cucumber are planted after rice (165).

Some double cropping vegetables with field crops are also possible

under irrigation during the warm season in North Florida (55, 133).

For example, southern pea, pigeon pea, wax and black beans (Phaseolus

sn_. L.) were successfully grown as second crops after early or mid-

season corn (55). Under double cropping, these crops required high

plant populations and narrow row widths compared to lower populations

and wider spacings when grown as single crops. With a snort-maturi:g.

small .rain crop like barley (Hordeum vulgare L.), it was possible to






10

grow three crops in sequence with vegetables such as sweet corn, English

pea, southern pea, and snap bean (51, 52). These crops are planted

using zero tillage and no fertilizer except for the sweet corn. The

vegetable legumes utilize the residual fertilizer from the preceding

crop to make more efficient use of soil nutrients. Double cropping of

vegetables was feasible in South Florida (21, 43, 129). Butternut

squash produced high yields without additional fertilizer when planted

after tomato grown under full-bed plastic mulch (21). In this study,

complete or partial incorporation of fertilizer in beds under mulch

resulted in higher yields of tomato and second crop butternut squash

than banding all the fertilizer on top of the bed. Everett (43) reported

that yields of tomato or cucumber planted as second crop on plastic

mulched beds previously planted to fall tomato did not significantly

increase at fertilizer rates higher than 70 kg/ha N and 100 kg/ha K

regardless of placement methods. Thus, multiple cropping on mulched beds

can reduce energy use and production costs by permitting efficient use

of both physical and applied resources (21).

Small-scale farmers in the tropics have developed a variety of

intercropping systems involving vegetable crops (6, 24, 79, 92, 169).

For example, short-maturing crops such as mungbean, cowpea, and soybean

(Gldcine max L.) can be intercropped with tall, short-maturing crops

such as corn (84). Paner (1Z7) reported that vegetable crops can also

be intercropped with tall, lr.g--aturing crops such as r'.ngieanr in

sugarcane (Caccharua officinarum L.). Also, tall permanent or perennial

crops such as coconut (Cocus nucifera L.), rubber (Hevea brasilienses

L.), banana (Musa soDierntum L. Schaft) can be intercropped with ginger






11

(Zingeber officinale Roscoe), dasheen (Colocasia esculenta L.), arrow--

root (Maranta arundinacea L.), mungbean, and other crops producing eco-

nomic yield for small-scale farmers.

In Taiwan, small-scale farmers also plant short-duration vegetable

crops under grape (Vitis spp.) vines during the dormant period or between

young fruit trees such as mango (Mangifera indica L.) (169). This

practice provided incentives for additional income. Intensive vegetable

growers in Taiwan also interplant mustard spinach (Brassica campestris

L. Perviridis Group) and bunching onion. Following the harvest of

mustard spinach, cauliflower is transplanted between alternate rows of

onion (169). In south-central Taiwan, farmers interplant cauliflower

and pole lima bean or other crops in rotation with paddy rice (24, 169).

Management of intercropping systems is sometimes more complex

than sequential cropping and may depend on several factors such as

season, crop, farm resources, market, and farmer skills. For example,

in Taiwan, farmers intercropped lima bean and cauliflower using three

methods (24). Farmers with abundant labor and small landholdings planted

high populations of cauliflower (21,000-30,000 plants/ha) with low seed-

ing rates for lima bean (25-30 kg/ha) to obtain high farm income.

Farmers who planted late in the season used low populations of cauli-

flower (15,000-16,000 plants/ha) with high seeding rates for lima bean

(60-90 kg/ha) because they predict that the price of cauliflower will

drop during the peak harvest period of vegetables while the price of

lima bean will rise in response to reduced supply. Farmers who planted

early in the season used 20,000-29,000 seedlings/ha for cauliflower and

50-70 kg/ha of lima bean seed because they predict that the price





12

of early planted cauliflower will be very high.

Relay intercropping which is another method of crop intensifi-

cation, can save time in the cropping sequence, permit the first crop

to protect the second crop during the early stages of growth by acting

as a "nurse crop" and distribute labor peaks throughout the cropping

year (92, 117). In relay interplanting, the primary limiting factor

seems to be competition for light, whereas moisture and nutrients are

less critical (84). For example, experiments at IRRI demonstrated that

mungbean and radish were least tolerant to shading because these crops

can stand only two to three days of dense shade, whereas sweet potato

(Ipomoea batatas L.) can stand four to five weeks of dense shade with

little yield reduction when relay intercropped with rice (84).

Several vegetable crops relay interplanted into annual field

crops or vegetable crops benefited small-scale farmers (7, 84). For

instance, relay interplanting tomato, cabbage, bush snap bean, and

sweet potato as early as 20 days before harvest of sweet corn did not

reduce yield (7). Relay intercropping vegetables into rice increased

total production, yet maintained critical planting dates for the main

rice crop within the cropping pattern. For instance, small-scale

farmers in central Taiwan relay interplant short duration vegetable

crops during a 60 to 100-day period between two rice crops (96).

Vegetable crops that require 10 to 30 additional days to mature can be

planted and harvested before the critical rice planting dates. Summer

melon (Cucumis melo L.), pickling melon (Cucumis melo L. Var. Conomon),

or watermelon [Citrullus lanatus (Thumb.) Mansf.] are planted on small

mounds of soil two weeks before rice harvest during the summer season.






13

During winter, a single crop such as sweet potato or edible-podded pea

(Pisum sativum L. Macrocarpon Group) and many green leafy vegetables

can be relay interplanted before rice harvest to increase total

production within the 100-day period (169).

In North Florida, relay interplanting of sweet potato and pigeon

pea in corn did not reduce corn grain yield (3). Higher yields of sweet

potato and pigeon pea were obtained with early maturing corn at low

populations than at high populations.

Relay intercropping vegetable crops has some limitations because

of managementt constraints. For instance, the Taiwan method of planting

sweet potato into puddled rice imposed difficulty in seedbed preparation

particularly in fine textured soils (47). This method is also expensive

since construction of ridges takes 400 to 500 hours/ha. Management of

these ridges is extremely difficult in terms of weed control (47).


Soil and Fertilizer Management in Vegetable Cropping Systems

Soil and fertilizer management studies in vegetable multiple

cropping systems are limited. As fertilizer costs increase every year

because of high energy cost for their production, many researchers are

finding methods to reduce fertilizer use or to increase efficiency

(122, 123, 143). Oesligle et al. (122) stated that high analysis ferti-

lizers, if available at any price, frequently constitute a direct input

cost that is beyond the means of the marginal farmer. High fertilizer

prices in developing countries imply that this input be used efficiently.

Thus, consideration of the economics of manaFemen-:t practices simul-

taneously with their biological potential is important when developing








fertilizer practices for multiple cropping patterns (122). This is

especially true for vegetable crops because of their high crop value,

intensive cultivation, and responsiveness to fertilization (104). Soil

and fertilizer management studies in multiple cropping usually deal with

yield responses to residual fertilizers (21, 33, 134, 136) or to applied

fertilizers in continuous cropping (75, 91, 152, 153). Associated with

these studies are effects of previous crops on yields of succeeding

crops (6, 13, 87, 88, 102, 112, 137, 144, 143). These studies provide

some bases for fertilizer recommendations in sequential cropping sys-

tems.

In sequential cropping patterns, the basic precept is that the

farmer manages only one crop at a time. From the soil management point

of view, improved practices for single crop stands are not entirely

applicable to sequential cropping systems because of the influence of

previous crops on soil physical properties, water, and nutrient availa-

bility to succeeding crops (143). Soil and fertilizer management

practices should be geared to the crop sequence or rotation rather

than to individual crops.

Sanchez (143) stated that the residual effects of N fertilization

are influenced by many variables such as the: rate of application, reco-

very of added fertilizer by previous crop, leaching, immobilization,

denitrification, and rainfall pattern. Thus, residual effects should

be considered in fertilizing succeeding crops. For example, in India,

soybean yields increased from 1.3 to 1.9 tons/ha when N appllicati' n

to the preceding rice crop was increased from 0 to 130 kg/ha (136).

The residual N fertilizer, however, decreased nodulation in soybean.






15

Jones (91) reported that when corn followed cotton (Gossypium hirsutum L.),

the response to N was maximum at 84 kg/ha, whereas corn following sorgh&'m,

peanut (Arachis hypogaea L.), and cowpea required 168 kg/ha to achieve

maximum yield. Experiments in Sudan Gezira (22) have shown that soc-rghum

and wheat (Triticum aestivum L.) were responsive to fertilizer N and

were affected by residual N, whereas hyacinth bean (Dolichos lablab L.)

did not respond to residual N but yield consistently increased by increas-

ing residual P.

Residual N from previous crops had a greater influence on tomato

yield than fertilizer applied specifically to the tomato crop (123).

For example, Osterli and Meyer (123) found that tomato yields responded

favorably to 336 kg/na N applied to the previous sugar beet (Beta

vulgaris L.). When additional N was applied directly to tomato there

was no significant increase in fruit size and quality.

Hayami (72) stated that optimum elemental concentrations for

most vegetable crops are about 5 to 1C times trose required for rice.

Under lowland puddled soil conditions in tropical Asia, Hayami (72) found

that fruiting vegetables such as tomato and cucumbers accumulated

nitrate N prfreferentially from the initial growth stage. Since this

form of N would be found only before the soil is puddled, growers can

benefit if they plant tomato and cucumber before rice. However, with

proper soil, fertilizer, and water management, growers may also benefit

by growing these vegetables after rice. Leafy and heading cabbages

absorb ammonium N and required an increasing amount throughout the

growing period. These crops are suited for production in post rice

soils (72).







16

In Florida, high management vegetable crops such as tomato and

pepper (Carsicum annuum L.) are double cropped with either low or high

management vegetables and field crops (21, 33, 43, 52, 55, 95). The

objective is to utilize applied fertilizer more efficiently and increase

productivity by eliminating added costs. Kretschmer et al. (95) suggested

that field corn is a good crop to follow fall tomato and other heavily

fertilized vegetable crops on sandy soils in Florida. When corn was

planted following these crops, additional applications of P, K, and

micronutrients, were not necessary. Yields of carrot (Daucus carota L.),

green onion, lettuce, and radish were significantly higher in plots

where no additional fertilizers were applied than in plots applied with

fertilizers after a fall tomato (33). The low yield of vegetables in

the fertilized plots was the result of high total soluble salts that

inhibited germination and reduced seedling survival.

As cropping intensity increases, high levels of added chemical

fertilizers may cause rapid shifts in soil properties such as pH (12,

52, 85, 98, 135, 140), total soluble salts (34, 53, 73, 103, 161),

organic matter (1, 2, 10, 71, 98, 111, 114, 147, 151, 166), N (38, 39,

135, 142, 146), P (139, 141), and K (14, 135, 137). Consequently,

shifts in soil properties may create a soil environment that can

restrict crop growth and limit cropping potential of soils. For

example, shifts in pH may result in excesses and deficiencies of both

micro and macronutrients (85).

An example of the effect of intensive sequential cropping on

soil properties was studied by Nair et al. (114). Rice, wheat, and

mungbean or potato were grown sequentially per year. In spite of high






17

amounts of nutrient removal, there were no appreciable changes on soil

organic carbon, total N and available P and K (114). On double cropping

of paddy rice in Taiwan for 48 years, average rice yields were similar

among fertility treatments with the same amount of N added (100). The

effects on chemical properties were also similar with those observed

by Nair et al. (114), and suggested an equilibrium level without major

differences among treatments.

Continuous cropping does not always result in stable or increased

yields. Yield levels of succeeding crops depend on resultant soil

fertility which is influenced by changes in soil chemistry (143).

Double or triple cropping sequences involving sweet potato, taro

(Colocasia esculenta L. Schott), sorghum, and cowpea conducted in New

Guinea on volcanic alluvial soils showed progressive yield decreases

with time (15). These decreases were related to decreases in soil

fertility parameters. Crops were not fertilized but when cropping was

alternated with legwTes or green manure, the fertility decline was

delayed. Intensive cropping of this nature required fertilization to

sustain long-term sequential cropping (116). In a 2-year continuously

cropped rotation of early and late crops including corn, cotton, bean,

sweet potato, peanut, finger millet (Eleusine corocana L.), and sorghum,

yields of all crops declined steadily during the first two cycles (153),

but application of N, P, K, and farm yard manure increased yields.

After a few years of continuous cropping, K deficiency limited yields,

especially of sweet potato.






18

Several reports indicated that soil organic matter changes with

continuous and with intensive cropping systems (40, 98, 111, 114, 166).

The changes can be an increase or decrease depending on the crop species,

tillage level, and fertilizer level. For example, rotation of spinach

(Spinacea oleracea L.) and cabbage with green manures such as alfalfa

(Medicago sativa L.), timothy (Trifolium pratense L.), red clover

(Lolium multiflorum L.), and sweet clover (Melilotus indica L.) resulted

in higher carbon and N in the soil than rotations with continuous

vegetables (40). Continuous cropping of corn for three consecutive

years followed by four seasons of cultivation with cropping sequences

of corn-corn-cowpea, pigeon pea-corn, soybean-soybean, corn-soybean,

and cowpea-cowpea resulted in greater decline in organic matter than

the no-tillage plots (98). The rate of decline was much higher under

cowpea and soybean where smaller amounts of crop residues were produced

than with corn. Standifer and Ismail (151) also found that organic

matter was lower in conventional tillage plots than in minimum tillage

plots after four years of multiple cropping crimson clover (Trifolium

incarnatum L.), sweet corn, and cowpea. Stevenson (154) reported that

rotations including legumes maintained higher organic matter contents

than continuous cropping with non-leguminous crops.

A combination of moderate manuring and medium rates of complete

fertilizer application is most effective in producing hih yields of

vegetables without depleting soil fertility (111). In a continuous

corn-green manure crop rotation, Thompson and Robertson (160) found

that organic matter in the high fertilized corn plots was more than in

the unfertilized plots. In India, Havanagi and Mann (71) reported that





19

soil organic carbon was increased by application of farm yard manure and

by rotation including both green manure and legume crops.

The preceding crop species can have beneficial or detrimental

effects on yields of succeeding crops. For example, onion and lettuce

planted after sweet corn with a winter crop of vetch (Vicia sativa L.)

developed a severe root rot gradually reducing the yield and often

killing the vegetables (87, 88). They postulated that during the de-

composition of corn residue under cool temperatures of spring, a toxin

was formed which injured plant roots (88). Mack et al. (102) observed

that average crop yield indices following cabbage, onion, summer pumpkin

(Cucurbita pepo L.), and carrot were significantly greater than those

crops following sweet corn, potato, and tomato. The low yields follow-

ing sweet corn, potato, and tomato might have been the result of low

soil fertility after grozing these crops. Some vegetables planted

after rice respond favorably to N application but not to residual N.

For instance, yields of sweet potato and tomato planted after rice

significantly increased when N was applied directly to the vegetable

crops (6). Jones (91) also reported that corn yields were higher when

preceded by peanut than by cowpea. The differences were larger without

N application and decreased at the optimum application of 84 kg/ha.

Detrimental effects have also been observed with grain legumes. Expe-

riments proved that mungbeans have a depressing effect on yield, parti-

cularly at low levels of N (83). Apparently, mur.ab=ans secrete certain

toxins which depress growth.






20

Economic Evaluation of Vegetable Cropping Patterns

Cropping patterns are sometimes assessed in terms of various

economic parameters (105, 113, 120, 131, 132). Methods and analytical

tools have been developed to enable farm management researchers to

evaluate yield responses of new crop cultivars, various levels of

mechanization, input-output relationships and net income (105). These

methods, however, were often developed and used for single crop enter-

prises. Menegay (105) reported that current analytical tools for

measuring, evaluating, studying, or comparing multiple cropping patterns

are limited in scope and flexibility.

Two general economic criteria involving land use and production

are commonly used in evaluating performance of cropping patterns.

Several indices such as multiple cropping index (MCI), diversity index

(DI), harvest diversity index (HDI), simultaneous cropping index (SCI),

cultivated land utilization index (CLUI), and crop intensity index

(CII) have been used to measure this criterion (105, 106, 107, 157).

Crop intensity index (CII) is more precise because it provides an assess-

ment of farmer's actual land use from an area-time perspective and

defines the composition of land use (107). The use of indices to com-

pare economic performance of cropping patterns is more appropriate in

studies conducted under actual farm conditions where farm sizes are

variable and cropping patterns within a farm vary from parcel to parcel.

Level of returns to resources and other production inputs is

the most commonly used criterion in evaluating economic performance

of cropping patterns because it relates inputs and products in terms






21

of a common denominator which is usually money (48, 49, 105, 120, 132).

Levels or return are usually measured and expressed in terms of returns

to physical resources such as land ($/ha), irrigation water or rainfall

($/inch) or returns to purchased and applied production inputs such as

fertilizer ($/kg) or labor ($/hr). Price (132) stated that rates of

return to resources should be regarded as secondary criteria after net

returns criteria are met. Measuring rates of return to resources is

useful if a farmer is interested in profit maximization. A farmer will

achieve this goal through maximizing return to his limiting resource

(120). For example, a farmer with large amounts of available labor

compared to cash will adopt cropping patterns that produce high rates

of return to cash (132). Conversely, an appropriate cropping pattern

in an area characterized by a marked shortage of labor at certain times

of the year will maximize returns per unit of labor (120).

The rate of return to both physical and applied resources is

affected by farmer's crop management interacting with physical, biolo-

gical, and socio-economic factors. Hence, motivation and production

decisions of farmers are influenced by these factors (24). For example,

small-scale farmers in Taiwan intercrop tomato for processing with mango

to utilize more fully their land and family labor resources. Production

practices for tomato intercropped with mango are similar to those in

the monocrop and intercrop with sugarcane, but adverse physical and

environmental factors reduced yields. Net returns and farm income were

much lower when tomato was intercropped with mango than when tomato was

a monocrop or intercropped with sugarcane (24). Since there was no

close relationship between fertilizers applied and yield in tomato







22

intercropped with mango, lower levels of fertilizer application reduce

input costs without significant yield loss (24).

Some Taiwan farmers plant sweet potato stem cuttings near rice

stubble with no tillage and minimum input requirement. Others use

complete tillage before planting or intercropping with corn and edible

sugarcane. The tillage method requires higher inputs, whereas the inter-

crop method involves the least inputs. Survey data showed that yields

were increased with increased net returns, but the correlation value

between yield and net return was low with tillage method suggesting

that added costs did not result in higher yields (24). There was no

significant relationship between capital inputs notably fertilizer and

yield. Farmers may be applying excessive capital inputs to sweet

potato but returns to fertilizer and material costs were lower than

returns from tomato. The highest net return and farm return were not

associated with high yield but with low cost (24). Although the inter-

crop method produced intermediate yields, production costs were lowest,

and therefore, farm returns, net return, and revenue-cost ratio were

highest (24).

Charreau (28) reported that improved cropping patterns consisting

of high tillage and fertilizer levels were more profitable in the central

zone of West Africa where rainfall was higher than in the northern zone.

This was a situation where potential of improved technology to increase

productivity and profitability was limited by climatic factors.

The goal of most cropping systems research has been to improve

productivity and income among small farms (8, 31, 69, 70, 118, 177).

Since adoption of cropping patterns not only depends on economic






23

returns but also on farmer's motives, studies should emphasize LTLprove-

ment of farmer's traditional cropping systems before recommending alter-

native cropping patterns. Cropping systems of small-scale farmers are

usually characterized by diversity, stability, and low productivity

(70). To improve income, productivity should be increased without

sacrificing diversity and stability.

Improving crop management practices attempts to increase productiv-

ity. Researchers develop improved production technologies for each

stage of crop production from tillage to harvesting by varying levels

of production inputs or introducing a new technique. These studies

generally focus on one crop with yield maximization as the main objective,

but exclude economic considerations (16, 24). For some crops, a signi-

ficant increase in agronomic yield may not be economically acceptable

to farmers (24). Although economic evaluation of different crop manage-

ment practices is common, similar studies for year-round cropping

patterns are limited. Most studies compare costs and returns from

various types of cropping patterns using standard cultural practices

which are in some situations higher than the farmer's management level

(25, 85). For example, in Chiang Mai, Thailand, Calkins (25) reported

that the cropping pattern peanut-tomato-rice had higher economic potential

than tomato-mungbean-rice because a heat-tolerant tomato cultivar was

planted in the first pattern resulting in yields with high market price.

In the Philippines, the cropping pattern rice-watermelon was the most

profitable, whereas the cropping patterns rice-mungbean and rice-sweet

potato resulted in equal net returns as the rice-rice or rice-sorghum

(127). Economic evaluation of the cropping pattern rice-sweet potato

using three power sources was studied by Banta (9). Costs and returns






24

were different among the three power sources but returns to labor were

higher using handtractor compared to either animal power or hand labor

(9). He suggested that the use of a machine in intensive cropping

patterns can provide better labor efficiency but may not be economically

profitable.

In a study of economic performance of rice-based cropping pat-

terns, labor requirement was slightly higher in a rice-rice pattern

than in rice-upland crops patterns (86). Cash requirements were higher

with rice-upland crops because of high costs of upland crop seeds and

insecticides (86). The upland crops included vegetables such as mung-

bean, cowpea, and muskmelon. The rice-mungbean pattern produced the

highest net return because mungbean received a high market price (86).

Increasing intensity of cropping patterns increased gross and

net returns to labor in four cropping patterns evaluated in Hissar

District, india (35, 138). Singh et al. (149) reported that the more

intensive pattern involving corn-potato-tomato and mungbean was more

profitable than cotton-wheat or pearl millet (Pennisetum glaucum L.)-

wheat-mungbean. Darlymple (35) also reported that net returns per

hectare and net returns per hour of labor increased with increasing

cropping index. A more complex intensive cropping pattern involving

sequential and relay intercropping of pole bean, corn, cabbage, cucumber,

bean, and radish resulted in high net returns in El Salvador (78).

Although some studies involving economic evaluation of cropping

patterns were conducted in experiment stations using small plots,

results have shown high level of accuracy because of high degree of

control. Therefore, these studies should compliment or support those

evaluated under actual farm conditions.






CHAPTER II

AN EVALUATION OF FOUR VEGETABLE CROPPING
PATTERNS FOR NORTH FLORIDA


Introduction

Vegetable production in North Florida among small-scale growers

is characterized by relatively few total hectares (45), a short cropping

period (63), limited and inefficient marketing systems (29, 50, 129),

and a low level of crop management (42). Climate and soil conditions

favor the growing of vegetables during spring and fall seasons, whereas

higher temperatures and intense rainfall during summer and freezing

temperatures (36) in winter limit production of vegetables.

In general, average yields of vegetable crops grown by small-

scale farmers in North Florida are lower than in South Florida (29, 45).

For example, average yields of eight out of ten vegetables were higher

in South Florida than in North Florida (45). Climate, cropping systems,

labor, and market constraints limit production levels and profit margins

from vegetable production in North Florida (29, 30, 50). In addition,

low income (42) and limited education levels (115, 170, 172) among

small-scale growers contribute to marginal vegetable production enter-

prises.

Crop management levels utilized by many vegetable growers also

contribute to lower yields in North Florida. Crop management level is

defined as capital, labor, and other production inputs including pro-

duction skills that the farmer allocates to produce various crops.

Examples are levels of irrigation, weed control, insect and disease

management, tillage, mulching, staking, crop establishment, and






26

fertilizing. Insect, disease, and fertilizer management levels were low

among small-scale growers in North Florida (29).

Double cropping, or the planting of two crops in one year, is

practiced comTmonly in Florida (129). In 1973-74, 147,200 hectares of

vegetables were harvested, but only 80,000 to 100,000 hectares were

planted to vegetables (129). For example, four or five crops of radishes

are generally harvested from the same field in the Everglades and Zell-

wood (Shuler, per. comm.). Some growers alternate part of their radish

hectarage with other crops such as sweet corn, celery (Apium graveolens

L.), carrot, and leafy crops.

Double cropping tomato on full-bed plastic mulch with other crops

is practiced by many growers. Some tomato growers in Quincy plant pick-

ling cucumbers or winter squash after tomato. In South Florida, Bryan

and Dalton (21) obtained high yields of butternut squash planted after

fall-grown tomato on full-bed plastic mulch. Csizinszky (34) reported

that several vegetable crops can be grown after tomato without additional

fertilizer. As the land area planted to more than one vegetable crop

per year increases, year-round cropping systems studies are required to

provide information on appropriate crop management practices for effi-

cient production systems and improved returns to production inputs.

Several studies have been conducted to extend the production

season and improve vegetable production in North Florida (20, 164, 175,

176). The use of black and white plastic mulches to reduce the effect

of heavy rainfall and high soil temperature during summer increased

yield and improved quality of several vegetable crops (20). The use of

black plastic mulch was more profitable for cantaloupe, whereas clear









mulch was most effective for watermelon. Squash produced highest yield

when grown with white on black mulch (20). Growing vegetables under

tobacco shades increased total yields of cucumber, but reduced tomato and

pole bean yields (164, 175).

Sequential planting of selected vegetable cultivars also extended

the production season to late spring and summer in Gainesville (61, 63,

64, 65, 66, 67). Halsey and Kostewicz (63) reported high marketable

yields for some vegetable crops grown during extended seasons. Vegetable

crops-included in their cultivar and date of planting experiments were

snap bean, southern pea, lima bean, cabbage, collard, squash, and onion.

In sequential plantings involving seven vegetable crops arranged in four

cropping patterns, Palada et al. (126) reported no significant yield

increase with increasing levels of fertilizer, but returns to manage-

ment on a dollar/ha basis were higher in high management crops than in

low management crops.

Research aimed at developing appropriate crop management technc-

logies for sequential cropping patterns is needed to improve vegetable

cropping systems throughout Florida. The purpose of this study was to

evaluate resource use, productivity, and profitability of several

vegetable crops planted in four year-round cropping patterns for North

Florida.


Materials and Methods

This 2-year study was conducted at the Horticultural Unit of the

University of Florida at Gainesville (29 45' N latitude, 820 20' W

longitude) beginning in October 1977, and terminating in October 1979.






28

The soil was classified as Kanapaha fine sand (loamy, siliceous, hyper-

thermic, Grossarenic Paleauquult) with 1% organic matter and a CEC of

2.52 meq/100 g (27). The climate is warm (average max 310C; min 11C)

and humid (average 229 mm rainfall/month) from April to September, where-

as October to March is cool (average max 240C; min 0.550C) and dry

(average 76 mm rainfall/month).1

Soybean was planted as a cover crop prior to initiating the experi-

ment. Soybean was mowed to a stubble and the land disc plowed before

fumigating with 66 liters/ha SMDC (sodium N-methyl-dithiocarbamate).

The fumigant was injected into the soil with a gravity-flow distributor

using two coulter applicators. Basal fertilizer was broadcast and roto-

tilled into the soil at varying rates depending on crop requirement

(Table 1). Raised beds were formed using a disc-hiller and bed press.

Subsequent land preparation between crops consisted of mowing, disc

plowing, rototilling, fertilizing, and bedding. Seven vegetable crops

including 'Texas Grano 502' bulb onion, 'Blue Lake' pole bean, 'Morris

Heading' collard, 'Early Golden Summer Crookneck' squash, 'Wando' Eng-

lish pea, 'Zipper Cream' southern pea, and 'Florida Curled Leaf' mustard

were classified into low (LM), medium (MM), and high (HM) management

groups. These management groups were based on average costs of ferti-

lizers, pesticides, cultural labor, and 5-year average harvesting costs

for producing each vegetable crpp in Florida (Table 2).

Four basic cropping patterns were developed using combinations

of seven vegetable crops (Figs. 1 and 2), Two cropping patterns were


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31

three high management crops planted in sequence (bulb onion-pole bean-

collard), and three low management crops planted in sequence (English

pea-southern pea-southern pea). The other two cropping patterns were

a combination of low, medium, and high management crops planted in

sequence as follows: HM-MM-LM (bulb onion-squash-southern pea), and

HM-LM-MM (bulb onion-southern pea-mustard). These patterns were designed

to estimate the effect of crop management sequences on resource use,

total productivity, and profitability.

The four cropping patterns were arranged in a randomized block

design with four replications. Each plot measured 21 m 1_:; by 4 m

wide. Rows were oriented in an east-west direction. Bulb onion,

southern pea, English pea, squash, and mustard were field-seeded on

raised beds using an Earthway seeder. Pole bean was hand-seeded into

holes22 cm deep. Collards were grown in peat pots and transplanted

after 30 days. Planting practices and seeding rates were based on

recommended practices (109, 110, 171).

Crops were planted in a single row per bed, except for bulb

onion which was seeded in double rows. Each plot consisted of three

beds 40 cm wide and 15 cm high spaced 1.10 m apart. A 5-m section

of the center bed was harvested for yields.

Fertilizer rates for each crop (Table 1) were based on fertilizer

and vegetable production studies conducted in Florida (21, 56, 58, 59,

60, 74, 93, 159, 168). Basal fertilizer for each crop was applied and

incorporated into the soil prior to planting. Depending on the crop,

supplemental fertilizer was sidedressed or topdressed one or three

times during each crop cycle. Insects and diseases were controlled






32

using the recommended practices for Florida. Weeds were controlled

by cultivation and handweeding, except for first crop of bulb onion

where DCPA (dimethyl tetrachloroterephthalate) at 6.7 kg a.i./ha and

chlorpropham isopropyll m-chlorocarbanilate) at 1.0 kg a.i./ha were

sprayed preemergence. Information about cultural practices for each

crop is summarized in Table 1.

Crop and cropping pattern duration including the interval

between crops were recorded. Crop duration was counted from seeding to

last harvest. Bulb onions were graded according to standard sizes of

large (diameter greater than 7 cm), medium (5 to 7 cm), and small

(less than 5 cm). Production costs and returns to management were

based on 2-year average prices of production inputs and market prices

at the time of harvest. These production costs and market prices

(46, 108, 150) were compared with 5-year averages (19) to determine

long-term profitability.


Results and Discassion

Crop environment. The first cropping year (1977-78) was character-

ized by higher rainfall (1,495 mm) compared to the second year (726 mm)

(Figs. 1 and 2). Most rainfall occurred during July and August in

1977-78. The rainfall pattern for 1978-79 followed the 13-year weekly

average, except that the dry period was extended (Fig. 2).

The winter of 1977-78 was colder than 1978-79 (Figs. 1 and 2).

The lowest weekly minimum temperature was -1.40C in 1977-78 and 0.020C

in 1978-79. Low temperatures in winter retarded the growth of bulb

onion and English pea resulting in an extended growing period. The















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35

highest weekly maximum temperatures were 38 C in June 1978, and 360C in

July 1979 (Figs. 1 and 2). The growing period of the second crops in

all cropping patterns coincided with high rainfall and temperature.


Crop duration. Using average data for 2 years, the longest

cropping duration was 322 days in cropping pattern HM-H-HM while the

shortest duration of 300 days was observed in cropping patterns LM-LM-LM

and HM-LM-MM (Table 3). The interval between crops was longest (68 days)

with cropping pattern LM-LM-LM and shortest (44 days) with HM-HM--H M.

In general, crops grown during winter had prolonged growing periods.

This prolonged growing period delayed the planting of second crops in

cropping patterns HM-HM-HM, HM-MM-IM, and HM-LM-MM.


Marketable yields. In general, marketable yields of vegetables

were affected by planting dates (Table 4). Cropping patterns involving

bulb onion resulted in late planting and reduced yields of second crops.

For example, yields of pole bean and squash following bulb onion were

low because these crops were planted in June when harvesting coincided

with high rainfall and temperature. A difference of two to four weeks

in planting dates reduced marketable yields of these crops compared

to normal spring planting.

Cropping patterns involving large crop residues also delayed

planting of succeeding crops. Bulb onion produced lower yield when

planted after southern pea where large crop residue remained in the

soil than onion planted after collard and mustard. Janes (88) observed

that onion planted after sweet corn and vetch had reduced growth and

died, whereas onion following spinach and beet produced satisfactory

growth.














Table 3.


Crop duration and interval between crops in four vegetable
cropping patterns over two cropping cycles in the period
1977-79, Gainesville, FL.


Cropping Crop Crop Interval
patternz duration between crops


Bulb onion
Pole bean
Collard


English pea
Southern pea
Southern pea


Bulb onion
Squash
Southern pea


Bulb onion
Southern pea
Mustard


--------- days

199
74
49


-------------

19
20
5


Total 322 44

152 24
78 11
70 33
Total 300 52

192 24
43 11
72 17
Total 307 52

192 24
70 18
38 14
Total 300 56


ZHM=high management; MM=medium management; LM=low management.


HM-HM-HM





LM-IM-LM





HM-MM-LM





HM-IM-MM

















Table 4. Marketable yields of vegetable crops in four cropping
patterns at Gainesville, FL.


T-test
Cropping Cropping year betwte
Crop between
pattern 1977-78 1978-79 yearsy

-Marketable yield, MT/ha-
HM-HM-HM Bulb onion 33.5 14.9 *
Pole bean 1.7 1.5 NS
Collard 15.3 6.1 **


LM-LM-LM English pea 3.8 6.5 NS
Southern pea 3.9 4.1 NS
Southern pea 2.4 1.6 NS


HM-MM-LM Bulb onion 14.1 5.5 **
Squash no data 2.1
Southern pea 5.8 1.2 **


HM-LM-MM Bulb onion 14.1 9.8 NS
Southern pea 1.6 2.2 NS
Mustard 7.4 3.2


ZCrop failure due to herbicide damage.


Y** = Significant at 1% level; NS = Not significant.





38

Marketable yields of bulb onion were significantly greater during

the first year of the cropping cycle than in the second year (Table 4).

Within a cropping year, onion planted early in the season produced higher

yields than late-planted onion. A difference of 4 weeks in planting

bulb onion during 1977-78 resulted in a 20-metric ton yield difference.

Larger onion plants were produced in early plantings which tolerated

low temperatures in January and February. Guzman and Hayslip (56) and

Corgan and Izquierdo (32) observed that yield of bulb onions decreased

as planting was delayed during the period from September to December.

Halsey (61) reported that bulb size decreased after October planting

dates in Gainesville.

Marketable yields of pole bean were lower compared to normal

planting in North Florida (Table 4). Bryan (20) obtained yields of

4.5 metric tons/ha from an early spring planting. In Dade county, average

yields ranged from 5.6 to 7.8 metric tons/ha (19). High rainfall and

temperature at flowering and pod set resulted in low yields. Pole bean,

therefore, represents a risk when planted during late spring.

A total of 15.3 metric tons/ha of marketable collards was picked

from four successive harvests of mature leaves (Table 4),which were simi-

lar with yields reported by Halsey and Kostewicz (67). Yields during

the second year were significantly lower (6.1 metric tons/ha) because

planting coincided with higher temperature and rainfall during late

summer.

Marketable yields of English pea were lower in 1977-78 than in

1978-79 because prolonged low temperatures severely retarded early

growth which predisposed some plants to killing frost in January and

February. Halsey and Kostewicz (64) reported low production throughout






39

the fall months, whereas yield of about 6,7 metric tons/ha were harvested

when planted from January to March in Gainesville.

Yields of southern pea were not significantly different between

years except in cropping pattern HM-MM-LM (Table 4). High residual

nutrients in the soil from previous squash (126) and earlier planting

dates resulted in higher yields in 1977-78 than in 1978-79. In general,

the third crop of southern pea produced low yields. Several reports (60,

63 4, 64, 101) indicated that yields from fall plantings were lower compared

to spring plantings of southern peas. Lorz (101) reported that crops

planted in late spring produced excessive vines at the expense of yield.

Planting squash in early summer in cropping pattern HM-MM-LI

resulted in yields equivalent to 2.1 metric tons/ha (Table 4). Halsey

and Kostewicz (66) harvested comparable yields when squash was planted

in early summer because of foliar disease incidence associated with

high humidity and temperature.


Biological stability. Biological stability is defined as the
2
degree to which the outcome of any event is predictable. One method

of increasing the degree of biological stability in cropping patterns

is to plant crops at the proper time. In cropping patterns HM-Hi-HML

and f.-MM-LM, the inclusion of pole bean and squash resulted in unstable

yields due to impr:.per time of planting. Cropping pattern LM-LI.-L'

provided some stability, but yields of southern pea decreased with

successive plantings. A high degree of biological stability was




2R. R. Harwcod. 1974. Stability in cropping systems (mimeo).
International Rice Research Institute, Los Banos, Philippines.






40

observed in cropping pattern HM-LM-MM although southern pea produced

low yields.


Production costs and returns to management. Cropping pattern

HM-HM-HM required the highest production costs of $8,580/ha, whereas

cropping pattern IM-LM-LM required only $3,970/ha (Table 5). Cropping

patterns HM-MM-LM and HM-LM-MM required similar production costs as the

IM-LM-LM. In general, cash inputs for materials were higher than

labor costs in the four cropping patterns. The low yields of most

vegetable crops reduced harvest labor costs. Since total labor costs

included harvest labor cost, total labor costs were lower than material

costs. Gross income was highest with HM-HM-HM and lowest with HM-MM-LM

(Table 5).

Crop management groupings significantly influenced relative

returns to management. Total returns to management were highest with

cropping pattern HM-HM-HM (Table 5). No significant differences in

returns to management were calculated among cropping patterns LM-LM-LM,

HM-MM-LM and HM-LM-MM. Growing low management crops was as profitable

as growing a combination of low, medium, and high management crops.


Returns to production inputs. To assess profitability of crop-

ping patterns, returns to production inputs such as fertilizer, cash,

labor, and management were calculated in terms of dollar/dollar invest-

ment. In terms of dollar return per dollar invested in production

inputs, cropping pattern HM-HM-HM was similar to both LMd-LM-LM or

HM-LM-MM (Table 6). Palada et al. (126) also reported that increasing

production inputs such as fertilizer above recommended levels did not






















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43

increase returns to management or to various production inputs in four

cropping patterns.

Thus, growers with limited cash receive similar returns per dol-

lar spent on production inputs as those growers with more available cash

resource. Although both groups of growers assume risk during unfavorable

cropping years, growers who grow high management crops will incur a much

greater risk of loss than growers with limited cash. With limited cash,

small-scale growers benefit from growing a sequence of low management

crops because of low and efficient resource use and stable yields.

Growers with available cash can grow low and high management crops and

earn a greater gross income if they operate efficiently.







CHAPTER III

CROP AND FERTILIZER MANAGEMENT LEVELS IN FOUR SEQUECTIAL
CROPPING PATTERNS INVOLVING VEGETABLES

Introduction

Many horticulturists working with small-scale vegetable growers

in the tropics are concerned with improving crop production and profi-

tability of year-round cropping systems (49, 107, 151). These cropping

systems often involve the study of crops grown in numerous multiple

cropping combinations ranging from single crops grown sequentially to

crops grown together in various combinations (69). Productivity and

profitability often depend on the management level utilized by farmers

which depends on the type of vegetable crop, its market value (24, 105),

and the capital, labor, and other production inputs that a farmer allo-

cates to produce the crops (125). Generally, high value vegetable

crops such as tomato are grown using high management levels, whereas

low value crops such as mungbean are grown under low management levels

(70).

Crop management in vegetable production is often limited to

single crops grown in monoculture (31). However, small-scale farmers

are often engaged in diversified production involving several crop and

livestock enterprises (31, 68, 69, 70, 80, 118, 138). Therefore, a

research approach that integrates the entire crop production enterprise

with the farming system and the farmer's management skills is required

to develop appropriate technologies for year-round vegetable cropping

systems.

A conceptual model of the crop management approach in developing

appropriate technologies for vegetable cropping systems is presented in

44








Fig. 3. Any vegetable cropping pattern involving a single, double or

triple crop, or complex intercrop will interact with the biological,

physical, and socio-economic factors and the type of available techno-

logy. The degree of interaction measured in terms of biological and

economic productivity depends on the farmer's skill in integrating and

manipulating these factors. The crop management approach seeks to

integrate a cropping pattern with the available resources, production

technologies, and skills which ultimately result in better nutrition,

improved farm income, and a balanced ecology (68, 94).

In developing countries, fertilizers constitute a major cost in

vegetable production for marginal farmers. Cost of high analysis ferti-

lizer is often beyond their means (122). As chemical fertilizers become

more expensive, researchers are developing methods to reduce rates of

application through improved crop and soil management systems (71, 72,

75, 143). Increasing fertilizer use efficiency also can be achieved

through efficient year-round cropping patterns (21, 33, 43, 52, 124).

For example, squash, cucumber, carrot, lettuce, and onion required no

additional fertilizer when planted after tomato on full-bed plastic

mulch (21, 34, 43). Similarly, English pea and southern pea were not

fertilized when planted after barley in a triple cropping pattern (51,

52).

This study was conducted to determine and evaluate the influence

of crop and fertilizer management levels and their interactions on

productivity, income, and soil nutrient stability in four vegetable

cropping patterns, and to develop appropriate crop and fertilizer

management practices for sequential cropping systems for North Florida.


























































,co

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aIJ
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47

Materials and Methods

Experimental site. This 2-year study was conducted at the Horti-

cultural Unit of the University of Florida at Gainesville (290 45' N

latitude, 820 20' W longitude) beginning in October 1977, and termi-

nating in October 1979. The climate is warm (average max 31 C; min 110C)

and humid (average 229 mm rainfall/month) from April to September,

whereas October to March is cool (average max 24 C; min 0.550C) and dry

(average 76 mm rainfall/month).


Soil characteristics. The soil was classified as Kanapaha fine

sand (loamy, siliceous, hyperthermic, Grossarenic Paleauquult) with 1%

organic matter and a CEC of 2.52 meq/100 g (27). Initial soil chemical

analysis resulted in a pH of 6.5, 0.04% N, 385 and 46 ppm of double-acid

extractable P and K, respectively.


Classification of vegetable crops. Since vegetable crops require

different levels of management, they were classified into three manage-

ment groups: low (LM), medium (MM), and high (HM). These management

groups were based on average costs of fertilizers, pesticides, cultural

labor, and 5-year average harvesting costs for producing each vegetable

crop in Florida (19). For example, HM crops such as pole bean and bulb

onion required a production cost of $2,550/ha, whereas LM crops such as

southern pea and English pea required only $790/ha. Labor and harvest-

ing costs constitute the largest portion of the total production costs.


Selection of vegetable crops. Seven vegetable crops were selected

based on total production costs and marketing potentials in North Florida.






48

High management crops included 'Texas Grano 502' bulb onion, 'Blue Lake'

pole bean, and 'Morris Heading' collard. 'Early Golden Summer Crookneck'

squash, and 'Florida Curled Leaf' mustard were selected as MM crops,

whereas 'Wando' English pea and 'Zipper Cream' southern pea were classi-

fied as LM crops.


Design of cropping patterns. Based on crop management grouping,

four basic cropping patterns were developed using combinations of three

crops (Fig. 4). Cropping pattern HM-HM-HM (bulb onion-pole bean-collard)

was designed to estimate the effect of HM crop sequence and fertilizer

interactions on total productivity, profitability, and nutrient levels

in soil. Within this pattern subsequent effects of HM crops on succeed-

ing crops were observed. Similarly, cropping pattern LM-LM-LM (English

pea-southern pea-southern pea) was designed to estimate the effects of

1M crop sequence on the same parameters. Cropping patterns H-f~I--LM

(bulb onion-squash-southern pea) and HM-LM-MM (bulb onion-southern pea-

mustard) were designed to determine and estimate the effects of combi-

nation of LM, MM, and HM crops on the same parameters.


Levels of fertilizers. The crops were fertilized with low,

medium, and high levels of N and K depending on crop management grouping

(Table 7). These rates were based on several fertilizer and vegetable

production studies conducted in Florida (20, 56, 59, 159). For each

level, the combined N and K fertilizer treatments were considered as

single treatments. Rate of P application was fixed depending on crop

requirement. Basal fertilizer for each crop was applied and incorpo-

rated into the soil prior to planting. Depending on crop, the remaining





























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Table 7. Nitrogen and potassium levels for low, medium, and
high management crops, Gainesville, FL, 1977-79.


Fertilizer Crop management level
levelz
levelLow Medium High

Low 0 ix 2x

Mediumy Ix 2x 4x

High 2x 3x 6x


ZNitrogen and potassium
kg/ha, respectively.


increments (x) were 30 kg/ha and 40


YMedium fertilizer level was regarded as recommended level
for each crop.







51

amounts of fertilizer were side or topdressed once for ILM and MM crops,

but twice for HM crops during each crop cycle.


Experimental design. A randomized block design with a split-

plot arrangement and four replications was used. The four cropping

patterns were main plots within each block and the three fertilizer

levels were subplots. Each subplot measured 4 x 7 m and consisted of

three beds, 40 cm wide and 15 cm high, spaced 1.10 m apart. Land

preparation, planting practices, and pest and disease control were

based on recommended practices and methods reported by Palada et al.

(125).


Data collection. Yields were harvested from a 5-m section of

the center bed. Bulb onion was hand-pulled, oven-dried at 800C for

48 hours, and graded to sizes of large (diameter greater than 7 cm),

medium (5 to 7 cm), and small (less than 5 cm). Mature green marketable

pods of pole bean, southern pea, and English pea were picked two to

four times during each crop season. Marketable squash were harvested

three times during the crop season. Tender leaves from the base of

collard plants were stripped four times during each season, whereas

mustard plants were cut slightly above the ground 38 days after seeding.

Production costs and returns to management were based on 2-year

average prices of production inputs and market prices (150) at the time

of harvest. Return to management was calculated by subtracting total

production costs from gross returns. Rates of return to labor, cash,

and fertilizer were calculated by deducting either labor, material,

or fertilizer costs from gross returns and dividing the difference by






52

either labor, material, or fertilizer costs. For example, rates of

return to labor were calculated as follows:

Return to labor ($/$) = Gross return Material cost
Labor cost

Similarly, return to material cash was calculated:

Return to cash ($/$) = Gross return Labor cost
Material cost

Production costs and market prices (46, 108, 150) were compared with

5-year averages (19) to determine long-term profitability.


Soil sampling and chemical analyses. Soils were sampled from

the top center of each bed to a depth of 15 cm. Samples.were oven-dried

at 700C for 48 hours, screened to pass a 25-mesh sieve, and analyzed

for organic matter (OM),content, total soluble salts (TSS), pH, nitrate-

nitrogen (N03-N), ammonium-nitrogen (NH4-N), and K. Equal volumes of

soil and water were prepared as suspensions for determination of pH

and total soluble salts. Soil pH was measured using a combination pH

electrode. Total soluble salts were determined from soil solution

conductivity readings using a solubridge. Organic matter was analyzed

by the method of Walkley and Black as outlined by Allison (4). Nitrate

and ammonium were determined by steam distillation (18). Potassium was

analyzed at the Soil Testing Laboratory of Soil Science Department

using a double-acid extractant (130).


Statistical analysis of data. Analyses of variance on marketable

yields and soil test results were run by computer using programs from

the Statistical Analysis System (11). Treatment means of marketable

yields and costs and returns from each crop were compared using Duncan's






53

multiple range test, whereas treatment means from interactions between

crop and fertilizer management levels were compared using least signi-

ficant difference. Except for marketable yields, all data were analyzed

and treatment means compared using the statistical model for split-plot

design.


Results and Discussion

Shifts in Soil Properties

Total soluble salts. Cropping pattern HM-HM-HM resulted in

higher TSS among the four cropping patterns (Fig. 5). In cropping pat-

tern HM-HM-HM, application of medium to high levels of fertilizer

resulted in significant increase in TSS (Fig. 5), whereas no significant

differences in TSS were found after harvest of the first crops in the

other cropping patterns.

High soluble salts after pole bean and collard can be attributed

to fertilizer level and crop duration. Pole bean and collard are short

maturing crops compared to bulb onion. The low TSS after bulb onion

might have been the result of long and extended crop duration which en-

hanced more leaching and absorption of fertilizer salts. Sequential

planting of HM crops increased soluble salt accumulation, whereas

sequential planting of LM, MM, and HM crops in combination stabilized

soluble salt levels. Previous studies (34, 73, 103, 161) showed that

large fertilizer applications to HM crops such as tomato, cabbage,

and celery resulted in high residual soluble salts at harvest.


Soil reaction. Soil reaction (pH) was lowest after harvest of

second and third crops (Table 8). Differences in soil pH after harvest















8000

SLOW NK
H MEDIUM NK
6000 HIGH NK




4000 3

ab

- 2000 -
(3 (3



S. ONION P BEAN COLLARD
CROPPING PATTERN HM-HM-HM

6000

o ^LOW NK
SI MEDIUM NK
4000 HIGH NK




2000

baa a ao


B.ONION SQUASH S. PEA
CROPPING PATTERN HM-MM-LM


E.PEA
CROPPING


S.PEA
PATTERN


S. PEA
LM-LM-LM


B. ONION S. PEA MUSTARD
CROPPING PATTERN HM-LM-MM


Fig. 5. Total soluble salts after harvest of each crop as in-
fluenced by crop and fertilizer management levels over
two cropping cycles in the period 1977-79, Gainesville,
FL. Letters on the bars indicate mean separation among
fertilizer levels within each crop by least significant
difference, 5% level.


LOW NK
| MEDIUM NK
l HIGH NK












^ 1:, ,:
_,~ii~l^






55

of first and third crops were greater in cropping patterns HM-HM-HM,

HM-MM-LM, and HM-LM-MM than in LM-LM-LM. Cropping pattern LM-LM-LM

resulted in pH above 6.0 after the third crop, whereas cropping patterns

involving combinations with HM crops resulted in pH below 6.0 (Table 8).

In all cropping patterns, soil pH tended to equilibrate to its initial

level after each year of cropping. The low soil pH in HM-HM-HM can be

attributed to replacement of Hf on the exchange complex and by hydrolysis

of exchangeable A13+ and hydroxy Al resulting from high management ferti-

lizer application rates.


Soil organic matter. Soil OM content decreased with successive

cropping in all cropping patterns except for cropping pattern LM-LM-LM

(Table 9). Average reductions in soil OM content were greater with

cropping pattern HM-HM-HM than other cropping patterns. In contrast,

cropping pattern LM-LM-LM resulted in increased soil OM content from

0.86 to 0.94% after harvest of third crops. After harvest of third crops,

cropping pattern HM-HM-HM resulted in significantly lower OM content

among the four cropping patterns (Table 9). For each cropping pattern,

the effect of high fertilizer levels generally resulted in greater OM

contents after harvest of second and third crops (Table 9). These

data are consistent with other studies (1, 12, 40, 41, 111, 135, 166),

and suggest that OM stability can be achieved by including vegetable

legnes in sequential cropping patterns.


Soil nitrogen. Except for collard, fertilizer levels had no

significant influence on soil N measured as IH4-N and NO3-N (Fig. 6).

In cropping pattern HM-Hi-:-l, high soil N after collard was caused by

high levels of fertilizer. In addition, residual fertilizer from













Table 8.


Soil pH after harvest of each crop as influenced by crop and
fertilizer management levels over two cropping cycles in the
period 1977-79, Gainesville, FL.


Cropping Fertilizer C r o p
pattern level First Second Third

-------------- pH ----------------


LM-LM-LM





HM-MM-LM


HM -LM -MM


Low
Medium
High
Mean


Low
Medium
High
Mean


Low
Medium
High
Mean


Low
Medium
High
Mean


Bi .Onion
6.4 az
6.4 a
6.5 a
6.4 B

E. Pea
6.7 a
6.8 a
6.8 a
6.8 A

B. Onion
6.4 a
6.5 a
6.5 a
6.5 B

B. Onion
6.5 a
6.6 a
6.6 a
6.6 B


P. Bean
6.4 a
6.4 a
6.3 a
6.4 A

S. Pea
6.4 a
6.4 a
6.5 a
6.5 A

Squash
6.3 a
6.3 a
6.3 a
6.3 A

S. Pea
6.3 a
6.4 a
6.4 a
6.4 A


Collard
5.7 a
5.6 'a
5.7 a
5.6 B

S. Pea
6.5 a
6.5 a
6.4 a
6.5 A

S. Pea
5.9 b
5.9 b
6.0 a
5.9 B

Mustard
6.0 a
5.9 ab

5.9 B


ZMean separation in columns within crops by least significant
difference at 5% level. Fertilizer means (lower case letters),
cropping pattern means (upper case letters).














Table 9.


Soil organic matter content after harvest of each crop as
influenced by crop and fertilizer management levels over
two cropping cycles in the period 1977-79, Gainesville, FL.


Cropping Fertilizer C r o p
pattern level
Fpatternirst Second Third

------------------- % -----------------


LM-LM-LM






HM-MM-LM






HM -LM -MM


Low
Medium
High
Mean



Low
Medium
High
Mean



Low
Medium
High
Mean



Low
Medium
High
Mean


B. Onion
:0.88 a
0.88 a
0.95 a
0.90 A

E. Pea
0.84 a
0.88 a
0.85 a
0.86 A

B. Onion
0.92 a
0.91 a
0.96 a
0.93 A

B. Onion
0.90 a
0.93 a
0.95 a
0.93 A


P. Bean
0.76 b
0.75 b
0.82 a
0.78 A

S. Pea
0.82 b
0.88 a
0.91 a
0.87 A

Squash
0.77 c
0.85 b
0.93 a
0.85 A

S. Pea
0.88 b
0.80 c
0.97 a
0.88 A


Collard
0.60 a
0.45 c
0.58 b
0.54 c

S. Pea
0.99 a
0.88 b
0.96 a
0.94 A

S. Pea
0.86 a
0.79 b
0.86 a
0.84 B

Mustard
0.84 b
0.78 c
0.90 a
0.84 B


ZMean separation in columns within crops by least significant
difference, 5% level. Fertilizer means (lower case letters),
cropping pattern means (upper case letters).




































9. ONION P BEAN COLLARD
CROPPING PATTERN HM-HM-HM


8. ONION SQUASH
CROPPING PATTERN


S. PEA
HMI-MM-LM


LOW NK
MEDIUM NK
HIGH NK














E. PEA S. PEA S. PEA
CROPPING PATTERN LM-LM-LM




Q LOW NK
] MEDIUM NK
HIGH NK






1 a



B.ONION S. PEA MUSTARD
CROPPING PATTERN HM-LM- MM


Fig. 6. Soil nitrogen after harvest of each crop as influenced
by crop and fertilizer management levels over two crop-
ping cycles in the period 1977-79, Gainesville, FL.
Letters on the bars indicate mean separation among
fertilizer levels within each crop by least signifi-
cant difference, 5% level.


40


20-


LCW NK
_ MEDIUM NK
- HIGH NK







a C C aC
C-C
5r~T~i -^







59

previous bulb onion and pole bean significantly contributed to higher

soil N. These results agree with Rao and Sharma (135) who reported

that soil N decreased at low fertilizer levels after each crop in six

cropping patterns, whereas soil N increased at high fertilizer levels.


Soil potassium. A consistent increase in double-acid extractable

soil K was observed with successive cropping in HM-HM-HM but not with

the other three cropping patterns (Fig. 7). For each cropping pattern,

high fertilizer levels increased soil K except the third crop in the

HM cropping pattern (Fig. 7). However, residual soil K remained almost

constant with successive crops in all cropping patterns except the HM

cropping pattern (Fig. 7).

In general, residual K was higher than applied K for the LM

cropping pattern, whereas HM and MM vegetable crops required supplemen-

tal applications of about 40 to 80 kg/ha K. Results from this study

do not agree with Biswas et al. (14), and Rao and Sharma (135) who

reported that soil K remained low after two cycles and after harvest

of different crops at various fertilizer levels.


Effects of Crop and Fertilizer Management Levels on Marketable Yields

Cropping pattern HM-HM-HM. Marketable yield of bulb onion was

generally high because of early planting date (Table 10). Onion ferti-

lized with the medium level of fertilizer (120 kg/ha N, and 160 kg/ha K)

yielded significantly higher than onion fertilized with low level

(Table 10). Application of a high fertilizer level resulted in no sig-

nificant yield increase (Table 10). Marketable yield of pole bean was

generally low because of late spring planting which subjected the crop




























I00


300




200


100


B. ONION BEAN COLLARD
CROPPING PATTERN HM -HM-HM


3, ONION SQUASH S. PEA
CROPPING PATTERN HM-MM-LM


SLOW NK
MEDIUM NK
- HIGH NK


- a


E. PEA S. PEA S. PEA
CROPPING PATTERN LM- LM- LM


SLOW NK

MEDIUM NK
- HIGH NK


a
-bb





S. ONION
CROPPING


a


, D
**.. N '.


S. PEA
PATTERN


MUST7ARO
HM -LM- MM


Soil potassium after harvest of each crop as influenced
by crop and fertilizer management levels over two crop-
ping cycles in the period 1977-79, Gainesville, FL.
Letters on the bars indicate mean separation among
fertilizer levels within each crop by least significant
difference, 5% level.


SI I j I


200


SLOW NK
l MEDIUM NK
a
- \HIGH NK .


ct7ii
b
, *- *S ,i


,i
.,


S LOW NK
MEDIUM NK

- HIGH NK




a a

b3
h2S :' a !


Fig. 7.


a

~
i
:







61

to high rainfall and temperature (Table 10). Fertilizer levels did not

influence pole bean yield. Leafy vegetable collard responded equally

to all levels of fertilizer (Table 10).


Cropping pattern LM-LM-LM. Only English pea produced a low yield

at the low fertilizer level (Table 10). Successive plantings of vegetable

legumes resulted in low yield of the third crop southern pea (Table 10).

This result was consistent with previous studies (83, 84). Fertilizer

levels did not influence yields of southern pea which support the data

reported from previous investigations (17, 59, 128, 155, 156, 174).


Cropping pattern HM-M-M M. Low yield of bulb onion was due to

late fall planting (Table 10). Combined effects of previous southern

pea residue and low residual nutrients in soil contributed also to low

yields. Late planting predisposed onion seedlings to freezing tempe-

ratures, whereas pea residue reduced germination and seedling survival.

Squash productivity was low when planted in June because of high tempe-

rature and humidity (Table 10). The high management fertilizer level

did not result in significant yield increase (Table 10). Southern pea

produced satisfactory yields after squash; however, low yield was

obtained without fertilizer application (Table 10).


Cropping pattern HM-LM-MM. No significant differences in yield

of bulb onion were observed as a result of fertilizer levels (Table 10).

These yields, however, were generally lower than yields obtained from

cropping pattern HM-HM-HM. Low yield was the result of late planting

in November. A low yield of second crop southern pea was caused by late













Table 10.


Marketable yields of component vegetable crops in four
cropping patterns as influenced by crop and fertilizer
management levels over two cropping cycles in the period
1977-79, Gainesville, FL.


Cropping Fertilizer C r o p
pattern level First Second Third

------------------ MT/ha ---------------
B. Onion P. Bean Collard
Low 18.5 bz 0.8 a 10.0 a
HM-HM-HM Medium 24.2 a 1.5 a 10.7 a
High 22.3 ab 0.9 a 10.0 a

E. Pea S. Pea S. Pea
Low 4.6 b 3.4 a 2.0 a
LM-LM-IM Medium ;5'2 .a 4.0 a 2.0 a
High 5.3 a 3.8 a 1.9 a

B. Onion Squash S. Pea
Low 10.0 a 0.6 b 2.7 b
HM- DI -LM Medium 9.8 a 2.1 a 3.5 a
High 8.5 a 3.1 a 3.5 a

B. Onion S. Pea Mustard
Low 11.7 a 2.0 a 4.6 a
HM-LM-MM Medium 11.9 a 1.9 a 5.3 a
High 12.6 a 1.8 a 4.3 a



ZMean separation in columns within each crop by Duncan's multiple
range test, 5% level.






63

planting in June which subjected the crop to high rainfall and

temperature. Mustard responded equally to fertilizer levels (Table 10).


Resource Utilization of Cropping Patterns

Labor profile. Cropping pattern HM-HM-HM was characterized by

three labor peaks (Fig. 8). Planting and harvesting constituted 30

and 50%, respectively, of the total labor requirements. The high labor

required for planting and harvesting was due to many hours required

for transplanting collard, handseeding pole bean, and multiple harvests

of both crops.

Cropping patterns LM-LM-LM, HM-MM-LM, and HM-LM-MM were character-

ized by only one labor peak for harvesting (Fig. 8). However, labor

required for harvesting in cropping pattern LMM-LM-M was equal to

HM-HM-HM because of multiple harvests of three successive vegetable

legume crops.

Vegetable growers who have limited year-round labor resources

should grow a combination of LM, MM, and HM crops where labor demands

are low and evenly distributed throughout the year. Growers who have

abundant labor and cash can probably benefit by growing HM vegetable

crops in their year-round cropping patterns. Growers who have abundant

labor but are limited in cash resource may have an advantage by growing

a sequence of LM vegetable crops.


Production costs. For each cropping pattern, fertilizer levels

had no influence on production costs (Table 11). Therefore, cropping

patterns were compared based on mean production cost across fertilizer

levels. Cropping pattern -HM-HM-HM required the highest total mean





















III ,






111 :









I I
ill


C C

(Dt4,'Ju;-UD3; d0Fl7


IIII I lillllIIIIIII IIIII <



IIII

IiI


li _


I llIl l II j I






I



Illli f













Is
i --


U3 *HCH



Cd I 0



-H *HS-1
P4 1 Cd
11 -) -I


-0 0 aj
u4-) -4


-r- 0 T-



*H H *


- 0 0 4

> a) bZ bf
h a)
o HCH
*rI 1
SC
0 r'- 1


C) '-'
(D a
r- H .
-Ia n
CH i 0!=
a 6 *r-

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ft f (
0 o- c
a-?hi i-




*H~3.
&, ~-~


~IIIII1II j-


r'
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III_
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1111111lll l


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N
iDLi/JY-Ci3~' ~i3er-







65

production cost of $7,630/ha which was significantly different from

the other three cropping patterns (Table 11). Except for material cost,

cropping patterns L-IL- -Ll, HM-MM-LM, and HM-LM-MM were similar in

cultural and harvest labor costs (Table 11). In terms of harvest labor

cost, the four cropping patterns were similar although cropping

patterns HMI-H'IM-HM and LM-LM-LM required more harvest labor.

In general, production cost data indicated that planting HM

vegetable crops in year-round cropping patterns required high cash

and labor inputs, but planting a combination of LM, MM, and HM reduced

total production costs by about 50o.


Income and Returns to Production Inputs


Gross and net income. Gross and net incomes were significantly

higher in cropping pattern HM-HM-HM than the other three cropping

patterns (12). Cropping patterns LM-LM-LM, HM-YM-LM, and HT-LTH-Hi

resulted in statistically similar gross income, although cropping

pattern HM-MM-LM produced the lowest gross income (Table 12). The low

gross income from pattern HM-MM-LM was caused by low marketable yields

of bulb onion and squash.

Regardless of fertilizer levels, the best pattern seemed to be

NM-HM-HM if growers consider total net income as the criterion for

profitability, However, this pattern required the highest total costs

and labor inputs (Table 12). Cropping pattern HM-IM-MM netted $3000/ha

income, but total production costs were lower than 1I!-.I-0-HI, and yields

were stable than the other cropping patterns.













Table 11.


Production costs of four vegetable cropping patterns as
influenced by crop and fertilizer management levels over
two cropping cycles in the period 1977-79, Gainesville, FL.


Cropping Fertilizer Production inputs Total
pattern level Cultural Harvest cost
Material labor labor
-------- Costs, $/ha ------------------
Low 2,990 a 1,430 a 1,440 a 5,860 a
Medium 5,420 a 1,430 a 1,720 a 8,570 a
HM-HM-HM 5,00 a 1,430 a 1640 a 8,470 a
Mean 4,600 A 1,430 A 1,600 A 7,630 A


Low 1,840 a 400 a 1,520 a 3,760 a
Medium 2,010 a 400 a 1,560 a 3,970 a
LM-LM-LM High 2070 a 400 a 1,700 a 4,170 a
Mean 1,970 C 400 B 1,590 A 3,950 B


Low 1,890 a 750 a 800 a 3,440 a
Medium 2,370 a 520 a 930 a 3,820 a
HM-MM-LM High 2,210 a 800 a 970 a 3,930 a
Mean 2,160 B 90 B 900 A 3,730 B


Low 2,420 a 560 a 1,060 a 4,040 a
Medium 2,660 a 560 a 1,230 a 4,450 a
HM-LM-MM High 3040 a 560 a 990 a 4,590 a
Mean 2,710 B 560 B 1,090 A 4,360 B



Mean separation in columns within each cropping pattern by least
significant difference, 5% level. Fertilizer means (lower case letters),
cropping pattern means (upper case letters).













Table 12.


Gross and net incomes of four vegetable cropping patterns as
influenced by crop and fertilizer management levels over two
cropping cycles in the period 1977-79, Gainesville, FL.


Cropping Fertilizer Total Income
pattern level cost G
Gross Net
---------- $/ha --------------------
Low 5,860 az 10,990 b 5,130 a
t-edium 8,570 a 13,440 a 4,870 a
HM-H'H-'.I
High 8,470 a 11,920 a 3,450 a
Mean 7,630 A 12,120 A 4,490 A


Low 3,760 a 5,830 a 2,070 a
Medium 3,970 a 5,890 a 1,920 a
High 4,170 a 6,500 a 2,300 a
Mean 3,950 B 6,070 B 2,120 BC


Low 3,440 a 3,920 a 480 a
Medium 3,810 a 5,110 a 1,300 a
M-MM-LM
High 3,930 a 4,410 a 480 a
Mean 3,730 B 4,480 B 750 C


Low 4,040 a 6,940 a 2,900 a
Medium 4,450 a 7,030 a 2,580 a
HM-LM-VM
High 4,590 a 7,990 a 3,400 a
Mean 4,360 B 71320 B 2,960 B



ZMean separation in columns within each cropping pattern by least
significant difference, 5% level. Fertilizer means (lower case
letters), cropping pattern means (upper case letters).







68

Returns to production inputs. Except for cash, returns to ferti-

lizer, labor and management on a dollar/ha basis were not significantly

influenced by fertilizer levels (Table 13). Comparing returns to ferti-

lizer, cash, and labor on the basis of total mean, indicated that

cropping pattern HM-EM-HM produced a higher return to production inputs

(Table 13). Cropping pattern HM-MM-LM resulted in lowest returns to

fertilizer, cash, labor, and management (Table 13).


Rates of return to production inputs. Rate of return to pro-

duction inputs expressed in terms of dollar/dollar is a measure of

return per unit investment of production inputs. This provides a

measure of resource use efficiency for each cropping pattern and is

useful in comparing economic performance of cropping patterns. Rates

of return to fertilizer were influenced by fertilizer levels in cropping

pattern HM-HM-HM and LLM-M-LM but not in HM-EM-LM and HM-LM-MM (Table 14).

Rates of return to fertilizer decreased with increasing fertilizer levels

for each cropping pattern. Among cropping pattern means, rates of return

to fertilizer were significantly higher with LM-LM-LM than the other

three patterns. This suggested that growers with limited fertilizer

input can make more efficient use of this limiting resource by growing

a sequence of IM crops, whereas growers who adopt cropping patterns

HM-HM-HM and H4-LM-MM can profit by reducing fertilizer application.

Although cropping pattern HM-HM-HM produced high return to

cash on a dollar/ha basis (Table 13), rates of return to cash on a

dollar/dollar basis did not differ with pattern LM-LM-LM (Table 14).

For every dollar spent on cash input, pattern HI-HM-HM resulted in $2.50,













Table 13.


Returns to production inputs of four vegetable cropping
patterns as influenced by crop and fertilizer management
levels over two cropping cycles in the period 1977-79,
Gainesville, FL.


Cropping Fertilizer Production inputs
pattern level Fertilizer Cash Labor Management
--------------- Returns, $/ha ---------------
Low 5,650 a 8,120 b 8,010 a 5,130 a
Medium 5,440 a 10,290 a 8,020 a 4,870 a
M-HM-M High 4,880 a 4240 b 6,900 a 3,450 a
Mean 5,320 A 7,550 A 7,640 A 4,490 A


Low 2,120 a 3,860 a 3,890 a 2,070 a
Medium 2,170 a 4,010 a 3,980 a 1,920 a
LM -LM High 2,630 a 4,400 a 4,430 a 2,330 a
Mean 2,310 BC 4,090 BC 4,100 B 2,120 BC


Low 1,160 a 2,370 a 2,040 a 480 a
Medium 1,170 a 3,110 a 2,240 a 1,300 a
-MM-LM High 1,040 a 2,720 a 2,270 a 480 a
Mean 1,120 C 2,730 C 2,180 C 750 C


Low 2,480 a 4,430 b 4,520 a 2,900 a
Medium 3,290 a 5,240 ab 4,360 a 2,580 a
High 3,470 a 5,970 a 4,960 a 3,400 a
Mean 3,080 B 5,210 B 4,610 B 2,960 B



ZMean separation in columns within each cropping pattern by least
significant difference, 5fo level. Fertilizer means (lower case
letters), cropping pattern means (upper case letters).













Table 14.


Rates of return to production inputs of four vegetable
cropping patterns as influenced by crop and fertilizer
management levels over two cropping cycles in the period
1977-79, Gainesville, FL.


Cropping Fertilizer Production inputs
pattern level
patternlevelFertilizer Cash Labor Management

------------ Returns, $/$ -------
Low 11.80 az 2.90 a 2.90 a 1.00 a
Medium 9.70 a 3.10 a 2.50 b 0.60 b
HM-HM-HM
High 5.20 b 1.60 a 2.10 c 0.40 c
Mean 8.90 B 2.50 A 2.50 A 0.70 A


Low 20.80 a 2.10 a 2.00 b 0.60 a
L-LM-LM Medium 14.40 b 2.00 a 2.00 b 0.50 a
High 8.70 c 2.10 a 2.50 a 0.50 a
Mean 14.60 A 2.10 AB 2.20 A 0.50 A


Low 2.50 a 1.30 a 1.90 a 0.10 a
Medium 2.70 a 1.20 a 1.40 a 0.30 a
HM -MM-LM
High 1.90 a 1.10 a 1.80 a 0.10 a
Mean 2.40 C 1.20 C 1.70 A 0.20 B


Low 7.90 a 1.90 a 2.30 bc 0.70 a
Medium 7.70 a 1.90 a 2.50 b 0.60 a
HM-LM-MM
High 6.50 a 1.90 a 3.20 a 0.70 a
Mean 7.30 B 1.90 B 2.60 A 0.70 A



ZMean separation in columns within each cropping pattern by least


significant difference, 5%
letters), cropping pattern


level. Fertilizer means (lower case
means (upper case letters).






71

whereas rate for LM-LM-IM was $2.10 (Table 14). Rates of return to

cash were similar for cropping patterns LM-LM-LM and HM-LM-MM, whereas

HM-MM-LM provided the lowest rate of return to cash input. Growers

with limited cash often adopt cropping patterns with high cash returns.

Except for cropping pattern HM-MM-LM, rates of return to labor

were influenced by fertilizer levels within cropping pattern but not

among cropping patterns (Table 14). In cropping pattern HM-HM-HM,

increasing fertilizer levels significantly decreased rates of return

to labor, whereas the reverse was true in cropping pattern LM-LM-LM

and HM-LM-MM. Thus, it pays to increase fertilizer levels when labor

is limited for cropping patterns involving LM and a combination of IM,

MM, and HM vegetable crops.

Except for cropping pattern HM-HM-HM, fertilizer levels did not

affect rates of return to management (Table 14). In cropping pattern

HM-HM-HM, increasing fertilizer levels decreased rates of return to

management. Thus, growers who face constraints to management can make

more efficient use of their management skills by reducing rates of

fertilizer if they grow a sequence of HM vegetable crops. Among cropping

patterns, HM-HM-HM, LM-LM-IM, and HM-LM-MM, average rates of return to

management were similar (Table 14). This implies that low-labor and

low-cash requiring cropping patterns are as efficient and profitable as

cropping patterns requiring high labor and high cash inputs. Therefore,

growers with limited resources can grow a sequence of LM or a combination

of LM, MM, and HM vegetable crops and obtain profitable economic returns

without necessarily increasing production inputs such as fertilizer.









Economic Implications

Economic evaluation of four cropping patterns based on costs

and returns analysis indicated that resource use, income, and returns

to production inputs were influenced by management level associated

with crop grouping and levels of component technology within each group.

Although levels of component technology such as fertilizer management

did not cause significant differences in marketable yields, resource

use in terms of production costs and rates of return to production

inputs for cropping patterns were affected by fertilizer levels. This

implies that insignificant difference in agronomic yields may sometimes

be misinterpreted in economic terms, especially when the grower bases

production decisions on economic criteria.

Cropping patterns involving HM vegetable crops are highly pro-

ductive and profitable but may not be more efficient in terms of resource

use and rates of return to production inputs than cropping patterns

involving LM and a combination of HM, MM, and LM vegetable crops. This

was shown by high total marketable yield and gross and net incomes, but

non-significant rates of return to fertilizer, cash, labor, and manage-

ment in cropping pattern HM-HM-HM. With increasing costs of production

inputs, vegetable growers with limited cash for purchasing these inputs

will have an advantage by planting either a sequence of LM or a combi-

nation of LM, MM, and HM crops for year-round cropping patterns.

Growers who have available production resources can benefit more by

reducing levels of production inputs such as fertilizer if they grow a

sequence of HM vegetable crops.







73

This study showed that crop and fertilizer management levels can

influence productivity, profitability, and income in year-round crop-

ping systems involving vegetables. Thus, economic returns are a

function of farmer's integration and manipulation of component techno-

logy levels and their interaction with biological, physical, and socio-

economic factors. In understanding and improving management of vegetables

in year-round cropping systems, horticulturists can study other aspects

of component technologies such as insect pest, disease, weed, and water

management through joint effort with entomologists, plant pathologists,

weed scientists, and economists. Through joint research efforts, techno-

logies can be developed and become more relevant and appropriate for

small-scale vegetable farmers.







SUMMARY AND CONCLUSIONS


A 2-year study on four vegetable cropping patterns was conducted

at the Horticultural Unit of the University of Florida, Gainesville, in

1977 to 1979. The objectives of this study were to evaluate productiv-

ity, resource use, and profitability of several vegetable crops planted

in four year-round cropping patterns for North Florida, to determine

and evaluate the influence of crop and fertilizer management levels on

productivity, income, and nutrient levels in soil from four vegetable

cropping patterns, and to develop appropriate crop and fertilizer manage-

ment practices for sequential vegetable cropping systems.

To achieve the first objective, seven vegetable crops including

bulb onion, pole bean, collard, crookneck squash, English pea, mustard,

and southern pea were classified into low (LM), medium (MM), and high

(HM) management groups. These management groups were based on average

costs of fertilizers, pesticides, cultural labor, and a 5-year average

harvesting costs for producing each vegetable crop.

Four basic cropping patterns were developed using combinations

of seven vegetable crops. Two cropping patterns were three HM crops

planted in sequence (bulb onion-pole bean-collard), and three LM crops

planted in sequence (English pea-southern pea-southern pea). The other

two cropping patterns were a combination of LM, MM, and HM crops planted

in sequence as follows: HM-MM-IM (bulb onion-squash-southern pea) and

HM-LM-MM (bulb onion-southern pea-mustard). The four cropping patterns

were arranged in a randomized block design with four replications. To

achieve the second and third objectives, three levels of fertilizer N

74






75

and K (low, medium, and high) were superimposed on each of the four

cropping pattern main plots.

The longest cropping duration was 322 days in cropping pattern

HM-HI-HM, while the shortest duration of 300 days was observed in crop-

ping patterns IM-IM-LM and HM-LM-MM. Crops grown during winter had

prolonged growing periods which delayed the planting of second crops

in cropping patterns involving bulb onion.

In general, marketable yields of vegetables were affected by

planting dates. Cropping patterns involving bulb onion resulted in

late planting and reduced yields of second crops. Cropping patterns

involving large crop residues also delayed planting of succeeding crops.

Bulb onion produced lower yield when planted after southern pea where

large crop residue remained in the soil than onion planted after collard

and mustard.

High rainfall and temperature at flowering and pod set resulted

in low yields of pole bean in both years. Marketable yield averaged

only 1.7 metric tons/ha in 1977-78 and 1.5 metric tons/ha in 1978-79.

These yields were lower than those obtained from normal spring planting

in Florida.

Marketable yields of English pea were lower in 1977-78 than in

1978-79 because prolonged low temperature severely retarded early

growth which predisposed some plants to killing frost in January and

February.

Yields of southern pea were not significantly different between

years except in cropping pattern HM-MM-lM. High residual nutrient

level in soil from previous squash and early planting dates contributed





76

to increased yields in 1977-78 than in 1978-79. In general, the third

crop of southern pea produced low yields.

Cropping pattern LM-LM-IM provided some biological stability but

yields of southern pea decreased with successive plantings. A high

degree of biological stability was observed in cropping pattern HM-LM-MM.

In cropping patterns HM-HM-HM and HM-MM-LM, inclusion of pole bean and

squash resulted in unstable yields due to improper time of planting.

Crop and fertilizer management levels significantly influenced

total soluble salts (TSS). Cropping pattern HM-HM-HM resulted in higher

TSS among the four cropping patterns. Differences were apparent after

harvest of second and third crops. Fertilizer levels significantly

affected TSS only in cropping pattern HM-HM-HM, where high levels of

fertilizer were applied. High TSS was due to high rates of fertilizer

and crop duration in pattern HM-HM-HM. The shorter the crop duration,

the higher the TSS content.

In general, soil pH decreased after harvest of second and third

crops. Differences in soil pH after first and third crops were higher

in all cropping patterns except IM-LM-IM. Cropping pattern LM-LN-LTM

maintained soil pH above 6.0, whereas cropping patterns involving HM

and a combination of HM, MM, and LM crops resulted in pH below 6.0

after the third crop. Fertilizer levels significantly affected soil

pH only after the harvest of third crops, but there was no tendency for

pH to decrease or increase with increasing fertilizer levels.

Soil organic matter (OM) content decreased with successive crop-

ping in all cropping patterns except for IM-LM-IM. Differences among

cropping patterns were significant after harvest of third crops. Soil

OM decreased from 0.90 to 0.54% between the first and third crops in






77

HM-HM-HM, whereas soil OM increased from 0.86 to 0.94% in IM-LM-IM.

High OM content in pattern LM-LM-LM was probably due to large amount of

crop residues from southern peas. Effect of fertilizer levels on soil

OM was apparent after harvest of second and third crops in all cropping

patterns. After harvest of second crops, soil OM content was signifi-

cantly higher at high than at low fertilizer level, but this trend was

not consistent at harvest of third crops.

Significant differences in soil nitrogen (N) were observed among

cropping patterns after harvest of second and third crops. Cropping pat-

terns HM-HM-HM and HM-LL-MM resulted in significantly higher soil N

than LM-LM-LM and HM-MM-LM after harvest of second crops. After harvest

of third crops, highest soil N (95 ppm) was measured in HM-HM-HM. Low

soil N was observed in cropping patterns HM-MM-LM, HM-LM-MM, and

LM-LM-LM even after harvest of third crops. Differences in soil N were

only observed after collard in HM-HM-HM. Application of low, medium,

or high fertilizer level resultedd in similar soil N after each crop

in cropping patterns LM-LM-LM, and HM-LM-MM.

A consistent increase in soil K was observed with successive

cropping in HM-HM-HM, but not with the other cropping patterns. Soil K

increased from 84 ppm after bulb onion to 176 ppm after collard. In

general, soil K was lowest with LM-LM-LM where low levels of fertilizer

were applied, but after harvest of second and third crops, soil K was

not different between cropping patterns LM-LM-LM and HM-MM-LM. Soil K

was influenced by fertilizer levels, in that, increasing fertilizer level

increased soil K for each crop in all cropping patterns. Application

of medium to high levels of fertilizer usually resulted in higher soil

K than low fertilizer level. The residual soil K levels from all





78

fertilizer treatments were higher than applied K indicating that K ferti-

lizer is less limiting compared to N fertilizer in sequential cropping.

The overall effects of fertilizer levels on marketable yields of

vegetable crops in four cropping patterns indicated that more responses

were observed on first crops than on second and third crops. Differences

in yield responses due to fertilizer levels were not consistent with

differences in soil test values for N and K. Improved yields of crops

in four cropping patterns were achieved at medium fertilizer level

although most yields obtained from this level were not significantly

higher than yields at low fertilizer level. Application of high ferti-

lizer rate beyond the medium level resulted in no additional yield

increase for most crops.

Labor requirement and total production costs were significantly

higher in cropping pattern HM-HM-HM than LM-LM-LM, HM-MM-LM, and BM-

LM-MM at all fertilizer levels. For each cropping pattern, increasing

level of fertilizer did not significantly increase total production

costs.

In general, cropping pattern HM-HM-HM produced high gross and

net income and returns to production inputs. Except for cash, returns

to fertilizer, labor, and management were not influenced by-fertilizer

levels for each cropping pattern. Although cropping pattern HM-HM-HM

produced high gross and net incomes, and returns to production inputs

on a dollar/dollar basis, rates of returns to fertilizer, cash, labor,

and management did not differ with patterns IM-LM-LM and HM-LMI-MM.

Rates of return to fertilizer decreased with increasing fertilizer

level for each cropping pattern.






79

Rates of return to cash were not influenced by fertilizer levels

within each cropping pattern, but among cropping patterns, rates of

return to cash were significantly different. Cropping pattern HM-HM-HM

had similar rates of return to cash as the LM-LM-LM.

Rates of return to labor were influenced by fertilizer levels

within each cropping pattern, but not among cropping patterns. In crop-

ping pattern HM-HM-HM, increasing fertilizer level significantly decreased

rates of return to labor. In cropping patterns LM-LM-LM and HM-LM-MM,

high fertilizer level resulted in higher rate of return to labor than

medium and low levels.

Rates of return to management were not affected by fertilizer

levels except for cropping pattern HM-HM-HM, where increasing fertilizer

levels decreased rates of return to management.

Based on the results obtained from this study, the following

conclusions can be drawn:

1. Classifying vegetables according to low, medium, and high

management groups and growing them in sequential cropping patterns

influenced productivity and relative economic returns.

2. In this study, the sequence of HM vegetable crops increased

total soluble salts, soil N and K, but decreased soil pH and OM content.

This suggested that additional fertilizer applications might not have

been required for succeeding crops in cropping patterns involving HM

crops.

3. Increasing fertilizer application above the recommended levels

did not increase marketable yields of vegetable crops in this study.

Vegetable crops that belong to any of the management groups did not

respond to high levels of applied fertilizer when grown in sequential







cropping patterns.

4. In this study, applications of the same rate of fertilizers

to each crop in sequential cropping patterns with HM vegetable crops

were not profitable. Residual fertilizer from previous crops should

be considered in formulating fertilizer rates for succeeding crops.

5. Successive plantings of related LM crops such as English

pea and southern pea in a year-round cropping pattern resulted in low

yields of successive crops.

6. Cropping patterns involving HM vegetable crops were highly

productive and profitable, but were not more efficient than cropping

patterns involving LM and a combination of HM, MM, and LM vegetable

crops in terms of resource use and rates of return to production inputs.

7. The low-labor and low-cash requiring cropping patterns were

as efficient and profitable as cropping patterns requiring high labor

and cash inputs. Therefore, vegetable growers with limited resources

can grow a sequence of LM or a combination of HM, MM, and LM crops and

improve their income without additional production costs.







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