Citation
Development of multiple cropping systems for small farmers of El Salvador

Material Information

Title:
Development of multiple cropping systems for small farmers of El Salvador
Creator:
French, Edwin Charles, 1945-
Place of Publication:
Las Cruces
Publisher:
New Mexico State University
Publication Date:
Language:
English
Physical Description:
xv, 110 leaves : ill. ; 28 cm.

Subjects

Subjects / Keywords:
Cropping systems -- El Salvador ( lcsh )
Crop rotation ( lcsh )
Genre:
bibliography ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaves 94-98).
General Note:
Reproduced from typewritten copy.
General Note:
M.S. thesis--New Mexico State University.
General Note:
Vita.
Funding:
Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
Statement of Responsibility:
by Edwin Charles French, III.

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University of Florida
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University of Florida
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The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. This item may be protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact Digital Services (UFDC@uflib.ufl.edu) with any additional information they can provide.
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Full Text







DEVELOPMENT OF MULTIPLE CROPPING SYSTEMS

FOR SMALL FARMERS OF EL SALVADOR BY

EDWIN CHARLES FRENCH, III







A Thesis submitted to the Graduate School in partial fulfillment of the requirements

for the Degree

Master of Science






Major Subject: Horticulture






New Mexico State University

Las Cruces, New Mexico

June, 1975









"Development of Multiple Cropping Systems for Small Farmers of El Salvador," a thesis prepared by Edwin Charles French, 111 in partial fulfillment of the requirements for the degree, Master of Science, has been approved and accepted by the following:






Deano te G tobho




Chirman of the Examinig Committee





Date




Committee in charge:

Dr. Joe N. Corgan, Chairman

Dr. Donald J. Cotter Dr. Ricardo E. Gomez Dr. Boyce C. Williams










Ui










DISCLAIMER


The research for this thesis was conducted under the auspices of United States Peace Corps through the Ministry of Agriculture and Centro Nacional Tecnologi*a Agropecuaria in El Salvador. The work was accomplished in conjunction with the Agency for International Development/University of Florida, and partially funded by a grant from North Carolina State University. Therefore, New Mexico State University claims no publication rights to the contents of the thesis.






























iii









ACKNOWLEDGEMENTS


The author wishes to express his gratitude to all administrators, instructors, technicians, and field personnel who made the project possible. Special thanks goes to the Ministry of Agriculture of El Salvador, Ing. Armando Alas and Centro Nacional de Tecnologia Agropecuaria, Ing. Antonio Cabezas and Ing. Alex Aguiluz and the National School of Agriculture for their support and the use of their facilities; Mr. Chico Rodriguez and the Peace Corps, Adrian Chac6n, M.S. and Ing. Mario Barahona and the Department of Agriculture Economics/MAG for their combined efforts to make the project successful; Dr. Richard Bradfield for his suggestions and ideas; Dr. Peter E. Hildebrand USAID/University of Florida whose guidance, support, and cooperation was of inestimable value; and to Drs. Joe N. Corgan and Donald J. Cotter whose encouragement, patience, and dedication made this

thesis possible,















iv









VITA

January 2, 1945 Born at New Rochelle, New York 1970 B. S., New Mexico State University, Las Cruces 1970-1971 Teaching Assistant, Horticulture Department,
New Mexico State University, Las Cruces 1972 Research Assistant, Horticulture Department,
New Mexico State University, Las Cruces

1973-1974 U. S. Peace Crops Volunteer to El Salvador

PROFESSIONAL AND HONORARY SOCIETIES

Sociedad Americana de Ciencias Horticolas, Regibn Tropical Pi Alpha Xi

American Society for Horticultural Science PUBLICATIONS

French, Edwin Charles, and Peter E. Hildebrand, "Un
Sistema Salvadoreho de Multicultivos: Su
Potencial y Sus Problemas." Ministerio de Agricultura y Ganaderia, Centro Nacional de
Tecnologia Agropecuaria, Febrero, 1974

French, Edwin Charles, and Peter E. Hildebrand, "Produccibn de Pepinos Utilizando Tallos de
Mai1z." Ministerio de Agricultura y Ganaderia,
Centro Nacional de Tecnologia Agropecuaria,
Febrero, 1974

FIELD OF STUDY

Major Field: Horticulture

Vegetable Production
Professors Joe N. Corgan and Donald J. Cotter









V









ABSTRACT





DEVELOPMENT OF MULTIPLE CROPPING SYSTEMS

FOR SMALL FARMERS OF EL SALVADOR BY

EDWIN CHARLES FRENCH, I1




Master of Science in Horticulture

New Mexico State University Las Cruces, New Mexico, 1975

Doctor Joe N. Corgan, Chairman





Nine different multiple cropping rotations were designed and tested for production feasibility in El Salvador. All rotations were generally successful, except for specific crops in a few rotations, and all made good use of family labor. The basic crops were corn and beans in combination with a number of vegetable crops. The main feature of the rotations was the use of corn stalks, after corn harvest, as stakes for tomatoes, beans, or cucumbers. A bean cultivar test indicated some variability among cuLtivars in their adaptation to a corn-bean multiple cropping rotation.
vi









TABLE OF CONTENTS

Page

LIST OF TABLES . . . . . . . . . ix

LIST OF APPENDIX TABLES . . . . . . xi

LIST OF FIGURES . . . . . . . . xii

LIST OF APPENDIX FIGURES . . . . . . . xv

INTRODUCTION . . . . . . . . . 1

LITERATURE REVIEW . . . . . . . . 4

CROP ROTATION DEVELOPMENT . . . . . . 13

Overview . . . . . . . . . . 13

Experimental Site . . . . . . . . 15

Soil . 16

Trial Design . . . . . . . . . 16

Statistical Analysis . . . . . . . 17

Time of Planting . . . . . . . . 17

Field Preparation . . . . . . . . 18

Transplants . . . . . . . . * 18

Fertilizer . . . . . . . . . 20

Observation Trial-Corn (All Rotations) . . . 22 Observation Trial Rotation 1 . . . . . 24 Observation Trial Rotation 2 . . . . . 28

Observation Trial Rotation 3 . . . . . 31

Observation Trial Rotation 4 . . . . . 34

Observation Trial Rotation 5 . . . . . 39

Observation Trial Rotation 6 . . . . . 39

Field Trial Phase I (Rotations 1 and 2) . . 43 vii









Pag~e

Field Trial Rotation 1. . . . . . 43

Field Trial Rotation 2 . . . . . . 49

Bean Cultivar Trial . . . . . . 52

RESULTS . . . . . . . . . . 58

Observation Trial-Corn (All Rotations) . . 58 Observation Trial Rotation 1 . . . . . 58 Observation Trial Rotation 2 . . . . . 61 Observation Trial Rotation 3 . . . . . 61 Observation Trial Rotation 4 . . . . . 62 Observation Trial Rotation 5 . . . . . 65 Observation Trial Rotation 6 . . . . . 65 Field Trial Rotation I . . . . . . 66

Field Trial Rotation 2 . . . . . . 69

Bean Cultivar Trial Phase I (Corn, Beans) . 71 Bean Cultivar Trial Phase II (Corn, Beans) . 78 DISCUSSION . . . . . . . . . 80

CONCLUSIONS . . . . . . . . . 92

LITERATURE CITED . . . . . . . . 94

APPENDIX A . . . . . . . . . 100

APPENDIX B . . . . . . . . . 103

APPENDIX C . . . . . . . . . 104

APPENDIX D . * . . 106

APPENDIX E . . . . . . . 108





viii









LIST OF TABLES


Table

L. Soil analysis of a composit sample taken in the field trial area and analyzed by the Soils Dept., Centro Nacional de Tecnologia Agropecuaria (CENTA),
Santa Tecla, El Salvador, 1973 . . . 16

2. Annual rainfall distribution based on a 30 year average 1944-1974, and minimum
recorded annual rainfall occuring in 1957 for the San Andres experimental
area (ENA) . . . . . . * . 19

3, Chronological calendar of events for rotation 1. Observation Trial, 1973 . . 25

4. Chronological calendar of events for rotation 2. Observation Trial, 1973 . . 29

5. Chronological calendar of events for rotation 3. Observation Trial, 1973 . . 32

6. Chronological calendar of events for rotation 4. Observation Trial, 1973 . . 35

7. Chronological calendar of events for rotation 5. Observation Trial, 1973 . . 40

8. Chronological calendar of events for rotation 6. Observation Trial, 1973 . . 42

9. Chronological calendar of events for rotation 1. Field Trial, 1973-1974. . . 44

10. Chronological calendar of events for
rotation 2. Field Trial, 1973-1974. . . 45

11. Bean cultivar plots. Planting and harvest dates and planting systems, phase
1, Bean Cultivar Trial, May, 1974. . . 53

12. Bean cultivar plots. Planting and harvest dates, phase II, Bean Cultivar
Trial, August, 1974 . . . . . 54

13. Chronological order of development for
the corn cv. H-3. Observation Trial,
1973 . . . . . 59

1x









Table Page

14. Yields in M.T./ha and numbers of fruit/ha of cucumbers grown on 5 different trellising systems, phase II, rotation 4, Observation Trial, October 8-November
22, 1973 . . . . . . . . 63

15. Crop yields for phase 1, rotation 1, Field Trial, 1974 . . . . . . 67

16. List of crops and their respective yields categorized by phase. Rotation 2,
Field Trial, December 10, 1974 . . . 70

17. Mean number of bean plants emerged 10 days after seeding and their mean yield
of dry beans (M.T./ha) for all cvs., for 2 planting systems. Bean Cultivar Trial,
May, 1974 . . * * . . . 72

18. Mean number of bean plants emerged 10 days after seeding and their mean yield
of dry beans (M.T./ha) for cv. Centa 105
for 2 planting systems. Bean Cultivar
Trial, May, 1974 . . . . . . . 72

19. Percentage of bean plant losses from emergence to harvest for bean cvs. of
phase I, Bean Cultivar Trial, May, 1974 . 74

20. Days to flowering, days to.harvest, and yield (M.T./ha) for 7 cvs. of Bean
Cultivar Trial, May and August plantings,
1974 . o 75

21. The mean bean yields (cv. Centa 105) for the
modified and original planting systems.
Bean Cultivar Trial, May, 1974 . . . 77

22. Range and average of corn yield of ears
harvested/ha and M.T./ha dry grain (12%
humidity) from 12 plots of corn-bean
rotation, phase 1, Bean Cultivar Trial,
May, 1974 . . . . . . . . . 77

23. The mean of all bean cv. yields for the May
and August plantings. Bean Cultivar
Trial, 1974 . . . . . . . . 78



x









LIST OF APPENDIX TABLES

Table Page

23. Cultivars and seed sources of crops used in observation (OT), field trial (FT),
and bean cultivar trial (BCT). 19731975 . . . . . . . . . . 100

24. Pesticides used in 3 multiple cropping trials (ENA) El Salvador, 1973-1975. . . 104

25. Fertilizer applications for observation trial (OT), field trial (FT), and
bean cultivar trial (BCT) 1973-1975. . . 106

26. Analysis of variance (ANOVA) on emergence of beans planted in center and
on side of ridge. Bean Cultivar Trial
May, 1974 . . . . . . . . . 108

27. ANOVA on yield of beans planted in center and on side of ridge. Bean Cultivar
Trial, May, 1974 . . . . . . . 108

28. ANOVA on emergence of beans planted in center and on side of ridge for cv.
Centa 105. Bean Cultivar Trial, May,
1974 . . . . . . . . . . 109

29. ANOVA on yield of beans planted in center and on side of ridge for cv. Centa 105.
Bean Cultivar Trial, May, 1974 . . . 109

30. ANOVA on mean yield of beans planted in May and August. Bean Cultivar Trial,
1974 . . . . . . . . 110

31. ANOVA on mean yield of cv. Centa 105 for modified and original planting systems.
Bean Cultivar Trial, May, 1974 . . . 110










xi









LIST OF FIGURES


Figure Page

1. Cross section of fertilizer bands incorporated in phases I and II, Observation
Trial and Field Trial, 1973-1974 . . . 21

2. Cross section of fertilizer bands and
hilling of corn. Observation Trial, Field Trial, and Bean CuLtivar Trial,
1973-1975 . . . . . . . . 22

3. Diagram of triangular planting pattern
used for seeding corn. Observation
Trial, 1973 . . . . . 22

4. Cross section of plots seeded with corn,
showing the 4 closely spaced double
corn rows and their spacing. Observation Trial, 1973 . . . . . . . 23

5. Doubled corn stalk with the ear hanging
so that the corn husk sheds the rain.
Observation Trial, Field Trial, and
Bean Cultivar Trial, 1973-1975. . . . 23

6. Cross section of plots illustrating (a)
mature corn ready for transition to
phase II and (b) phase II vegetable beds
formed and planted. Observation Trial,
1973 . . . . . . . . . . 26

7. Top view of corn rows with tomatoes transplanted in phase II. Observation Trial,
1973 . . . . . . . . . . 26

8. Corn stalks tied to form tripods and the
horizontal support twine tied to the legs of the tripods and the end posts. Rotations 1, 2, 4, 5, and 6, Observation Trial,
1973 . . . . 27

9. Cross section of plots for rotations 1, 2,
and 5, phase 11. (a) Phase III transplants and muskmelon planted beneath tomato vines. (b) Tomato and tripod
debris placed in the furrows. Observation Trial, 1973 . . . . . . . 28


xii









Figure Page

10. Tomatoes interplanted with pole beans.
Rotation 2, Observation Trial, 1973 . . 30

LL. Top view of double corn rows with pole beans seeded in rotation 3. Observation Trial, 1973 . . . . . . 33

12. Cross section of plot illustrating phase 11, Rotation 3, Observation
Trial, 1973 . . . . . . . 33

13. Five trellising methods for cucumbers in rotation 4, Observation Trial, 1973. . 36

14. Two systems of seeding cowpeas with broccoli. Rotation 4, Observation
Trial, 1973 . . . . . . . 37

15. Bed formation and seeding of phase IV.
(a) Overlap period of cowpeas with
carrots and beets and (b) carrots and
beets after removal of cowpeas. Rotation 4, Observation Trial, 1973 . . . 38

16. Phase I, rotation 5, iLlustrating the planting arrangement and row spacings
of corn, squash, and radish. Observation Trial, 1973 . . . . . 41

17. Bush beans seeded beneath tomato vines in phase III, rotation 6, Observation Trial,
1973 . . . . . . . . . 41

18. Row and plant spacings for rotations 1 and 2. (a) Single row of beans planted in
rotation 2 and (b) double row of beans
planted in rotation 1, Field Trial, 1973. 47

19. Beds formed and corn stalks de-leaved.
Dotted line represents the row configuration in phase I. Solid line represents
phase II vegetable beds. Field Trial,
1974 . . . . . . . . . .47

20. Phase III, rotation I illustration of (a)
3 rows of cowpeas seeded beneath tomatoes,
and later (b) tomato vines and tripods
placed in the furrow. Field Trial, 1974. 48

xiii









Figure Page

21. Diagram of phase IV, rotation 1, Field Trial, 1974 . . . . * * 49

22. Two rows of cabbage transplanted on the
sides of the cucumber beds. Rotation
2, Field Trial, 1974 . . . . . 50

23. Diagram of corn seeding between cabbage rows. Rotation 2, Field Trial, 1974 . . 50

24. Transition of vegetable beds from phase III to phase IV. (a) Dotted line represents old cabbage beds. Solid Line represents newly formed bean and sweet potato
beds. (b) Planting position of pole beans and sweet potatoes over banded nematocide.
Rotation 2, Field Trial, 1974 . . . 51

25. Row and plant spacing for original and modified bean planting systems. (a) Original system, (b) modified system and method of planting for south half
of plots, and (c) modified system and method of planting for north half of
plots. Bean Cultivar Trial, 1974 . . 55

26. Transition to phase I illustrating (a) phase II beans seeded beneath corn and
(b) phase I corn doubled and phase I
corn seeded. Bean Cultivar Trial, 1974. . 56



















xiv









LIST OF APPENDIX FIGURES

Figure Page

27. Field plan for area of investigation (ENA)
including plot numbers for observation trial, field trial, and bean cultivar
trial, 1973-1975 .103











































xv









Introduction

A world food shortage places countries which are

not self-sufficient in food production in a very precarious position (16, 19, 30). Dependence of one nation on another to make up its domestic food production deficit is risky. The risk can present itself if the donor nation fails to meet its production goals (19) or if world competition makes it impossible for the needy nation to afford needed food products. The balance between the welfare of natibns and disaster is made much more delicate today by growing populations, agriculture's dependence on petroleum

(21), and unsure climatic conditions. Thus, the need for individual national self-sufficiency in the production of basic foods becomes obvious.

Because of its geographical susceptibility to drought as was experienced in 1972-73, El Salvador is a potential famine area (45). Coupled with a population growth rate of 3.8%., and a population density which ranks third highest in the world (45), the circumstances for disaster brought about by a food shortage are real and frightening.

In a recent study by the Sociedad de Ingenieros

Agronomos de El Salvador, an estimated 22,500 sq km of land, dedicated exclusively to the production of food, will be required to adequately supply a Salvadorean population now approaching 4 million (2). Combining a







2

high population (approximately 312 persons per sq km) (10) and limited cultivated land, insufficient land is available to meet this need under traditional agricultural systems.

A logical solution for meeting the increasing food demand is to increase food production on the existing cultivated land (49). Difficulties range from problems associated with land tenure (34) to modern day problems related to a petroleum shortage (21). Methods for increasing food production should include modern technology and new ideas, as well as a concern for tradition, formulated in such a way as to be acceptable to the farmer

(19). One method, which has the flexibility to comply with the varied needs of the Salvadorean farmer, would be multiple cropping or as it has been coined, "multicultivos."

The Salvadorean Ministry of Agriculture (MAG) in 1971 established a 5 year plan (17) directed towards increasing the production of basic grains. In addition, plans were made to increase vegetable production through the coordinated efforts of the University of Florida (by contract with the Agency for International Development), Peace

Corps, and Centro Nacional de Tecnologia Agropecuaria (a branch of extension and research of MAG). Contributing within Peace Corps as a volunteer, the author worked as a multiple cropping specialist. The multiple cropping program developed was a result of a re-analysis of the






3

countries needs and priorities, focusing on the production of basic grains and horticultural crops (26).

The purpose of this thesis is to report the development of a multiple cropping system which increased productivity and was flexible enough to meet the necessities of the small farmer.









Literature Review

Multiple cropping is of much interest in many less

developed areas, but, despite a long history and increasing importance, no comprehensive report on multiple cropping is published. Available studies usually focus on a technical aspect in the program of one country. The subject is vast and involved and little solid research exists in the area (15).

Multicropping, intercropping, interplanting, multicropsequences, intensive cropping, double cropping, triple cropping, rotation planting, mixed farming, shifting cultivation, duoculture, polyculture, and relay interplanting are some of the many names given to various types of multiple cropping (4, 15, 23, 27, 28, 47). However, the term multiple cropping generally refers to growing more than one crop on the same piece of land in one year (14, 23, 27, 28).

According to Dalrymple (15), forms of multiple cropping were in existence before the time of Christ. It was usually found in densely populated "garden areas" of the world such as Babylon, Egypt, China, India, and Japan. Its existence was closely associated with the availability of water for irrigation, and was usually limited to the production of two crops per year. The earliest known reference to multiple cropping is found in a work known as Taittiriya Samhita written between 3000 and 1000 B.C.

4







5

in India. It distinctly mentions that two crops were harvested from the same field in the course of one year

(15).

Multiple cropping has long existed in China (37). In the northern provinces, the systems were designed around winter wheat as the basic crop while in the south, multiple cropping of rice was more prevalent. The development of an early maturing rice known as Champa around 1012 A.D. made possible the harvesting of two rice crops in one season. By the Ming period (1368-1644 A.D.), cold resistant cultivars of rice, which could be planted in mid-summer, encouraged further practice of multiple cropping. Fukien Province became very well known for its double cropping of rice, but the actual area thus cultivated in not known. Officials of Hunan, in the north, encouraged the planting of second crops other than rice during the seventeenth and eighteenth centuries (37).

Multiple cropping was also carried out in Egypt and India during the 1800's but was limited to the Nile and Ganges river valleys and in general was not extensive

(15).

The most extensive programs of multiple cropping

today are being conducted by the International Rice Research Institute (IRRI) to improve the welfare of the southeast Asian rice farmers (22). Within this program, Bradfield has conducted extensive research on multiple







6

cropping. He developed some very sophisticated systems, involving the cultivation of five crops per year (15). These systems have been implemented in the Phillipines, Java, the lower Mekong Basin, and other tropical areas (4, 6, 23, 28). It consists primarily of preparing the soil in an alternation of low beds for rice and high beds

for the other crops. The low beds are 60 cm wide and the length varies according to topography. Four to 5 rows of rice can be planted on them. The higher beds are 40 cm wide.and 30-40 cm higher than the low beds which they separate. One row of corn or 2 rows of soybean, sorghum, or other crops can be planted on these high beds. An advantage of this system is that the second crop can be planted before the harvest of the first paddy crop. The low beds later serve as irrigation furrows for these crops. A disadvantage is the large amount of water required to fill these low beds sufficiently to irrigate the crops on the higher beds. This system also requires some specialized mechanization which is for the most part unavailable to the majority of small farmers. However, all the data show that with irrigation, this system is economically feasible (4).

Bradfield (6) has worked with rice in sequence with sorghum, corn, soybean, mung bean, and sweet potato to give good distribution of planting and harvesting dates throughout the year. The frequent harvests, Bradfield







7

states, give the farmer something to market regularly and can simplify his credit problems (6). IRRI (28) trials of these patterns have shown that with improved varieties having approximately the same growth duration as farmer's varieties, multiple cropping makes better use of a farmer's land resources.

More land is multiple cropped in Mainland China

than in the rest of the developing world combined (15). The main forms of multiple cropping in northern China are winter wheat followed by coarse grains such as millet or corn. Further south, systems of winter wheat followed by industrial crops such as oilseeds, toabcco, or cotton and rice followed by a winter crop of barley, pulses, or rapeseed are found (37). Other more unusual cropping combinations found in China include cotton followed by winter wheat, corn followed by rice, corn followed by soybeans, rice followed by tobacco, and jute followed by rice (15).

India has the second largest multipLe cropped area

in the world (15). Extensive research and implementation of multiple cropping in India has been provided by the Ford Foundation (29). A surprisingly large portion of the multiple cropped areas in India depend on natural rainfall rather than irrigation (24). Many systems are. used depending on Location and terrain. Some of the more common sequences used are hybrid corn followed by







8

wheat, rice followed by wheat, and rice followed by rice. Other profitable rotations are rice, rice, and wheat; rice, corn, and wheat; corn, potato, and tobacco; and corn, potato, and pumpkin (1). Some new 4 crop sequences now being tested in India include moong (a legume), corn, wheat, and potato (24). Although yield

data is unavailable, it appears that results are good based on India's projected doubling of their multiple cropped area by 1980 (15).

Multiple cropping is being practiced today in many other Eastern countries but usually on a smaller scale and less intensively than those discussed.

Although some forms of multiple cropping have long

been practiced in the Americas, little if any information regarding this has been recorded.

Double cropping rotations of winter wheat or barley followed by grain sorghums have apparently been practiced in the southern United States for 40 to 50 years (15)., Other systems found in the United States include soybeans combined with sorghum, wheat combined with soybeans, and buckwheat combined with early harvested small grains. Specialized multiple cropping systems are found in Florida, Alabama, and California and usually involve vegetables (15).

A common rotation found in several Latin American countries is planting beans in the same field with corn






9

after the corn has reached the drying stage (2).

A limited amount of corn is double cropped with a second corn crop in Guatemala (15). Other combinations now being introduced in Guatemala include vegetables with grains, grains with grains, and grains with pasture crops (13, 14).

Montague (33) reported Brazilian farmers to use

some double cropping involving wheat followed by soybeans, or dry and wet season peanuts, or dry and wet season beans.

Recently, Latin American agricultural experts declared a need and presented proposals for increasing the area multiple cropped in all Central America (43). More than half the population of Central America is in the rural sector, and the majority of the farmers have small land holdings. Intensive land use is necessary if the farm family is to attain satisfactory food supply and sufficient employment and income to provide a modest standard of living. In response, the Tropical Agricultural Research and Training Center in Costa Rica is conducting research directed toward developing polycultural systems which consider the type of crop, growth cycle duration, degree of affinity and competition between mixed, overlapping, and crops grown in sequence. Experimental crops include beans, rice, corn, sweet potato, and cassava, the basic foods of Central American rural people (44).







10

Ruthenberg (38) states that traditional agricultural research in the tropics has been directed towards individual crops and monoculture, resulting in substantial improvement in productivity of certain crops such as corn, wheat, rice, coffee, cacao, sugar cane, bananas, and others. However, because monoculture usually requires fairly large land areas and usually involves some form of mechanization, this research has benefitted those farmers with the greatest financial capacity and .has had little or no impact on the majority of Latin America's rural population (38, 42).

In the process of developing cropping systems, IRRI has examined the small farmer's current practices. The Javanese farmer was found to use labor intensive methods to grow several field crops in various combinations, both with rainfall and irrigation, in a low cash-input situation. The widespread use of these practices by the small farmer throughout the tropics has encouraged study as to their efficiency in meeting his needs (27).
There is a positive correlation between the expansion of population and multiple cropping growth (15). The highest population densities are found in east and south Asia--multiple cropping is most prevalent in these regions. The lowest densities are found in Africa, Latin America, and the near East, and with the exception of Egypt, multiple cropping in considerably less common







11

in these areas.

Boserup (5) states that population increases

encourage the adoption of more intensive systems of

agriculture.

Ben-Nun (4) has found that multiple cropping is not

only feasible with irrigation and of great economic impact in the Mekong Basin, but may also prove to be the chief factor in the future development of the region in light of the predicted population growth of 30 million people

in the next 20 years.

Thus, it seems likely, based on very limited data, that multiple cropping may best fit in land-limiting, labor-surplus situations. It may also be far more productive under situations where management and capital availability are less than optimum for monoculture (27).

Dalrymple (15) concludes that multiple cropping,

from a social point of view, appears to hold promise of: improving employment, reducing rural income disparities, and expanding the quantity and quality of output. Careful mixtures of legumes, grain crops, and root crops have exciting potential, not only for high levels of nutrient production, but also for total productivity

(28). On the other hand, multiple cropping may increase the demands on scarce human administrative and scientific skills, and may increase foreign exchange costs for certain inputs. Still, on balance, multiple cropping appears






12

to be a most promising use of resources (15).

Forms of multiple cropping have been used for

centuries in various countries of the world. The development of early maturing and cold resistant cultivars and irrigation systems greatly expanded its possibilities. Multiple cropping appears to be associated with areas of high population density, limited cultivated land, limited resources, high unemployment, and low mechanization. Multiple cropping offers a means of greater employment

(15), greater yield per unit of land area (27), more efficient utilization of resources (28), and possible income increase (23).









Crop Rotation Development


Overview

Traditionally farmers of El Salvador plant corn at the beginning of the rainy season. Beans follow corn and reach maturity at the beginning of the dry season (9). The farmer is dependent on these crops for his subsistance, and his needs must be considered in the design of any multiple cropping program. Those few farmers having access to irrigation or low humid land often grow vegetables after corn and beans are harvested.

The following procedures outline the development of a multiple cropping system that offers farmers without irrigation or humid land a method to produce their basic foods (corn, beans) plus high income vegetable crops during the rainy season. Those farmers with irrigation can use the system to grow several vegetable crops and basic grain crops within a years time.

Vegetables such as tomato and cucumber must be staked if grown during the rainy season, but staking material is scarce and expensive. The primary objective of the preliminary observation trial was to examine the possibility of growing corn in such a manner that the stalks could subsequently be used as stakes. A secondary objective was to formulate techniques for an efficient crop rotation. Subsequent trials focused on the further 13







14

development and testing of cropping systems on the production of basic grains and vegetable crops.

The first experiments were designated 'observation

trial' and consisted of the following crop rotations:

Rotation 1: Rotation 2:

Phase I Corn Phase I Corn
(fresh) (fresh)
Phase II Tomato Phase II Tomato
Phase III Broccoli Pole Bean
Muskmelon (fresh)
Phase III Cauliflower Muskmelon

Rotation 3: Rotation 4:

Phase I Corn Phase I Corn
(dry) (fresh)
Phase II Pole Bean Phase I Cucumber
(dry) Phase III Broccoli
Phase III Tomato Cowpea
Phase IV Carrot
Beet

Rotation 5: Rotation 6:

Phase I Corn Phase I Corn
(dry) (dry)
Radish Radish
Squash Phase II Tomato
Phase II Tomato Phase III Bush Bean
Pole Bean (dry)
(dry)
Phase III Cabbage
Muskmelon

Following the observation trial, 2 larger plots,

designated as a 'field trial' were initiated. The rotations in both plots of the field trial began with corn

and beans, the 2 most basic grains of the country. Other

crops were selected on the basis of their market demand







15

plus experience gained in the observation trial. Okra

was selected because of its demand by a freezer processing plant in the area. The field trial was composed of

the following rotations:

Rotation 1: Rotation 2:

Phase I Corn Phase I Corn
(dry) (fresh)
Radish Radish
Bush Bean Bush Bean
(dry) (dry)
Phase II Tomato Phase II Cucumber
Phase III Cowpea Phase III Cabbage
(dry) Corn
Phase IV Okra (dry)
Phase IV Pole Bean (dry)
Sweet Potato

A third experiment, the 'bean cultivar trial' was

designed to evaluate the cultivar rotation interactions

which might occur in a corn-bean multiple cropping program. The following rotation was used for all cultivars:

Phase I Corn
(dry)
Bush Bean
(dry)
Phase II Corn
(dry)
Bush Bean
(dry)

Cultivars and sources of all crops planted are listed

in Appendix A.

Experimental Site

The trials were conducted at the National School of

Agriculture (ENA), located 25 km northwest of San Salvador






16

at a latitude of 130481 north of the equator. Soil

A soil analysis indicated high potassium, medium to high phosphorus, low nitrogen, intermediate calcium, intermediate magnesium, and pH 5.5 to 6.5 (Table 1). The soil in the test area was a sandy loam. Table 1. Soil analysis of a composit sample taken in the
field trial area and analyzed by the Soils Dept.,
Centro Nacional de Tecnologia Agropecuaria (CENTA),
Santa Tecla, El Salvador, 1973.



pH P K m.e. Ca/ m.e. Mg/
(ppm) (ppm) 100 g 100 8 .


6.4 27 +200 8.57 1.72 Sandy Loam



Trial Design

In each of the 3 trials, land was divided into plots. A plot is a given area of land upon which a rotation of crops was grown (Appendix B). A rotation is divided into phases. A phase is defined as the time span which each crop or association of crops occupied a plot.

The observation trial was composed of 6 plots, each 49 m long by 4.8 m wide. Each plot had a different rotation (page 14). The plot 4 rotation covered a time span of 4 phases while the remaining plots covered only 3. The field trial was composed of 2 plots each 30 s-qan, The






:17

plots had different rotations, each covering 4 phases. The bean cultivar trial was composed of 14 plots, each 14 m by 6 m wide. Each plot had the same rotation, which covered 2 phases. All plots are illustrated in Appendix B.

Statistical Analysis

In the bean cultivar trial, varietal effect was

considered constant among plots and each plot was considered a replication of the treatment, Data was analyzed by analysis of variance (41). Correlation was conducted to determine a possible relationship between the data set.

Levels of probability for significance were .05

and .01 indicated by and ** respectively in the tables and significant and highly significant in the text. The abbreviation N.S. indicates a non-significant difference between treatments at the .05 level of probability.

Time of Planting

The observation trial was conducted over a time

period of 237 days between June 8, 1973 and January 31, 1974. This trial was initiated 20 days after the beginning of the rainy season. The field trial covered 360 days beginning on December 6,.1973 and terminating on December 2, 1974. This trial began approximately 2 months after the initiation of the dry season. The bean cultivar trial covered 220 days commencing on May 30, 1974







18

and ending on January 5, 1975. The trial began 1 week after the initiation of the rainy season.

Although the 30 year average (Table 2) for the San Andres Station (representative of the experimental area) indicates measurable rainfall for each month of the year

(32), the period during which these trials were conducted experienced a dry season with no precipitation from November through the later part-of May. The rainfall pattern of 1957 was typical of the seasonal distribution of rain during the trials.

Field Preparation

In all the trials the fields were disk-plowed,

disked, then re-disked with a drag. In the observation trial and field trial, Aldrin (see Appendix C for rates of all pesticides) was applied over the trial area and incorporated by the final disking. The bean cultivar trial was treated in the identical manner except Phoxim was applied as a pre-plant soil insecticide. In all trials, except the observation trial, the original rows were formed with a team of oxen and a wooden plow. Transplants

Preparation and care of seed beds for transplants

used in the observation and field trial followed the same procedure. Raised brick beds (10 x 1 x .3 m) were filled with a mix of a third part each of decomposed manure, sand, and soil. One kg.triple-super-phosphate was






19


Table 2. Annual rainfall distribution based on a 30
year average 1944-1974, and minimum recorded annual rainfall occuring in 1957 for the San Andres experimental area (ENA).


Rainfall in Millimeters
Month Average Minimum (1957)


January 5 0

February 2 0

March 8 0

April 62 8

May 198 71

June 259 156

July 312 179

August 263 164

September 299 166

October 145 54

November 37 0

December 7 0

Totals 1597 798







20

distributed evenly over the soil surface and incorporated. The beds were wetted, titled, and covered with burlap bags followed by a polyethylene plastic cover over the entire bed container. A soil sterilant was applied beneath the plastic cover. Three to 4 days after fumigation, the beds were uncovered and allowed to aerate 1 day. The following day the soil was tilled and leveled. Rows 10 cm apart were planted to the appropriate crop. The burlap bags were replaced over the seed beds. When emergence had begun, the bags were removed. One week after emergence, the plants were thinned leaving 2-3 cm between plants. Ten and 17 days after seeding, a starter fertilizer solution was applied (see Appendix D for rates and formulas of all fertilizers). The seed beds were watered twice daily. Insecticides, nematocides, and fungicides applied in the seed beds and field followed recommended practices (39). Each transplant was dipped in a fungicide solution and then placed in holes 4 cm in diameter by 10 cm deep that were filled with a starter fertilizer solution followed by soil. Fertilizer

The fertilizer programs used during the trials were based on previous investigation with monocultured crops

(36). Generally the first fertilizer application to any crop was placed in bands or evenly spaced holes 12 cm







21

deep and 10-15 cm to one or both sides of the plant row. To avoid root damage and/or root inoculation of disease causing bacteria, the second fertilization was applied in bands on the ground surface 15-20 cm to one or both sides of the plant row and covered with soil pulled from the furrows (Fig. 1).

Second
Fertilization
of Phase 11
Phase 11
Crop










Second Fertilization Residual First Fertilization
of Phase I Phosphorus of Phase 11
of Phase I


Fig. 1. Cross section of fertilizer bands incorporated
in phases I and 11, Observation Trial and Field Trial,
1973-1974.



Hilling soil over the fertilizer and around the base of the corn stalks helped to prevent lodging and began to form the vegetable beds beneath the corn upon which the succeeding crops were planted (Fig. 2).






22












First Fertilizer Hilled Second Fertilizer
Band Corn Band



Fig. 2. Cross section of fertilizer bands and hilling
of corn. Observation Trial, Field Trial, and Bean
Cultivar Trial, 1973-1975.



Fertilizer placement near the corn and the vegetable beds made it possible for succeeding crops to utilize residual fertilizer of preceding phase. Observation Trial-Corn (All Rotations)

Since corn was the initial crop in all rotations, and procedures for corn were similar in all rotations, procedures for corn are presented separately. The corn was planted in the triangular pattern illustrated in Fig. 3.



4t--25 cm --P ,-------1
25 cm 25 cm / 21.7 cm




Fig. 3. Diagram of triangular planting pattern used
for seeding corn. Observation Trial, 1973.






23

This planting configuration is referred to as a double corn row.(Fig. 4).



Double
25 cm 120 cm Corn Row







Fig. 4. Cross section of plots seeded with corn, showing the 4 closely spaced double corn rows and their
spacing. Observation Trial, 1973.


The day of corn seeding is designated as day 0.

This planting system remained constant for all 6 rotations. Each of the rotations were seeded with 4 double corn rows.

The corn in rotations 1, 2, and 4 was harvested as

fresh corn while that of rotations 3, 5, and 6 was doubled and left to dry in the field (Fig. 5).








1.5 m
Drying Phase II1.
C orn Earl Crop





Fig. 5. Doubled corn stalk with the ear hanging so that
the corn husk sheds the rain. Observation Trial, Field
Trial, and Bean Cultivar Trial, 1973-1975.






24

Observation Trial Rotation 1

Refer to Table 3 for a chronological calendar of events for rotation 1. In the observation trial, bed preparation for transition from phase I to phase II was done in the same manner for all rotations independent of the crop. The preparation was carried out in the following steps and illustrated in Fig. 6:

1. The corn stalks were stripped of their leaves.

2. ALdrin was applied to the plots.

3. The double corn rows were hilled forming the
vegetable beds.

4. Nematocide was incorporated on the tops of the
beds (excluding rotation 3).

5. The beds were planted.

The tomatoes were transplanted in the center of the vegetable beds between the corn stalks (Fig.7). After transplanting, the remainder of the corn leaves and top

section were removed leaving the bare stalks 1.5 m in height.

The tomato trellising system was initiated by tying together 3 corn stalks approximately 1.3 m up from the base of the stalks forming a tripod structure. Then, 4 pairs of horizontal twine supports were tied to the legs of the tripods. The lower supports began 30 cm from ground level and the remaining 3 pairs were evenly spaced to a height of 1.2 m. The horizontal twine supports were secured to posts located at the ends of






25

Table 3. Chronological calendar of events for rotation
1. Observation Trial, 1973.



Month Day Procedure



0 Corn seeding
June
---12 Corn thinning and first fertilization


--35 Second corn fertilization r. July
.s4
0
a--60 Seed bed planting of phase I tomato
Aug. j-73 Phase II bed preparation
j__-78 August fresh corn harvest
t-81 Tomato transplant and fertilization
T_ 85 De-leaving and topping of corn stalks
1!-95 Formation of tomato tretlising system
Sept.


0
Oct.
132 Second tomato fertilization
0
E4-150 First tomato harvest, seed bed planting of phase II broccoli Nov.

177 Phase III bed preparation
-180 Transplant and fertilization of broccoli, seeding of muskmelon o Dec. 185 Final tomato harvest, windrowing of
plant debris


an.,

0

0 --250 Plot terminated
Q Feb.






26




















a. b.


Fig. 6. Cross section of plots illustrating (a) mature
corn ready for transition to phase II and (b) phase
I vegetable beds formed and planted. Observation
Trial, 1973.










Tomato Corn Stalk
\ .

0 0 0 0 6 0

50 cm



Fig. 7. Top view of corn rows with tomatoes transplanted
in phase II. Observation TriaL, 1973.






27

the beds (Fig. 8).






Tripod


Tying Post








Horizontal
Twine





Fig. 8. Corn stalks tied to form tripods and the horizontal support twine tied to the legs of the tripods
and the end posts. Rotations 1, 2, 4, 5, and .6,
Observation Trial, 1973.


Transition from phase 11 to phase III was done in

the same manner for plots 1, 2, and 5 independent of the crop as follows:

1. Removal of lower tomato leaves.

2. Re-shaping of the sides of the tomato beds.

3. Transplant and seeding of phase III crops.

4. Windrowing of tomato vines and tripods in
furrows after the last tomato harvest.

The phase III broccoli of rotation 1 was transplanted






28

on the sides of the tomato beds 40 cm between plants. The muskmelon were seeded between the broccoli transplants (Fig. 9).







(? Cauliflower,
Broccoli,
or Cabbage Muskmelon




Muskme lon Plant Debris a. b. of Phase 11


Fig. 9. Cross section of plots for rotations 1, 2, and
5, phase III. (a) Phase III transplants and muskmelon planted beneath tomato vines. (b) Tomato and
tripod debris placed in the furrows. Observation
Trial, 1973.


The plant debris of the tomatoes and tripods served as a bed of mulch upon which the muskmelons grew. Observation Trial Rotation 2

A chronological calendar of events for rotation 2

is presented in Table 4. The transition 'from phase I to phase II tomatoes followed that of rotation 1. Immediately following the tomato transplant, pole beans were seeded between the tomato plants (Fig. 10).

The tomato trellising was done identically to rotation I (Fig. 8).







29

Table 4. Chronological calendar of events for rotation 2.
Observation Trial, 1973.



Month Day Procedure



0 Corn seeding
June 12 Corn thinning and fertilization


--35 Second corn fertilization
1.4
o July

-60 Seed bed planting of phase II tomato
73 Phase I bed preparation
Aug. ---78 Fresh corn harvest
-- 81 Tomato transplant, bean seeding, first bean fertilization 85 De-Leaving and topping of corn stalks 0 95 Formation of tomato trellising system
co Sept.

0
0,-132 Second tomato fertilization
Oct. 136 First bean harvest
0
---150 First tomato harvest, last bean harvest, seed bed planting of phase II caulifloo
wer
Nov.
--177 Phase III bed preparation
7-180 Transplant and fertilization of cauliflower, seeding of muskmelon o 185 Last tomato harvest, windrowing of
Dec. plant debris



p Jan.
0
o :
"4
--250 Plot terminated
Feb.







30





Corn Stalk Tomato Pole Bean


0~0 0 0


50 cm 50 cm




Fig. 10. Tomatoes interplanted with pole beans. Rotation 2, Observation Trial, 1973.







31

The pole beans were harvested as fresh beans. After the last harvest, the main stems were cut at ground level and left to dry.

The transition from phase I to phase III was the

same as in rotation 1 except that cauliflower was transplanted in place of broccoli.

After the final tomato harvest, the tripods and

vines were cut at the base and placed in the furrow along with the dried bean plants to serve as mulch for the muskmelons (Fig. 9).

Observation Trial Rotation 3

A chronological calendar of events for rotation 3 is summarized in Table 5. The transition from phase I to phase II was the same as that of rotation 1, substituting pole beans for tomatoes. The pole beans were planted (Fig. 11) immediately after the doubling of corn.

Tomato transplant procedure was the same as that

used in rotation 1 except that tomatoes were transplanted on the sides of the beds (Fig. 12) instead of the center as in rotation 1.

The dried pole beans and corn were then harvested.

Following harvest, the corn stalks were placed across the furrows in the manner illustrated for cucumbers in rotation

4. The corn stalks which bridged the furrows between the tomato plants formed a support bed for the tomato vines.






32

Table 5. Chronological calendar of events for rotation 3.
Observation Trial, 1973.




Month Day Procedure



0 Corn seeding
June --12 Corn thinning, first fertilization



--35 Second corn fetilization
July:



Aug.

----85 Phase 11 bed preparation
o ---90 Corn doubling, pole bean seeding
a !-'95 Pole bean fertilization
Sept.



0 Oct.

148 Seeding of phase III tomatoes in seed bed
0
oov
Nov L168 Phase III nematocide application
: 170 Phase Ill tomato transplant
7"175 First tomato fertilization, bed of stalks
formed, corn and bean harvest
Dec.
Ot

0
Jan.
-235 Rotation terminated

Feb.






33





Corn Stalk Pole Bean
0. 0 9 0 0 0 6


0 25 cm




Fig. 11. Top view of double corn rows with pole beans
seeded in rotation 3. Observation Trial, 1973.









) C.C.







Tomatoes Pole Beans




Fig. 12. Cross section of plot illustrating phase III,
Rotation 3, Observation Trial, 1973.






34

Observation Trial Rotation 4

A chronological calendar of events for rotation 4 is summarized in Table 6. The transition from phase I to phase II followed that of rotation 1, substituting cucumbers for tomatoes (Fig. 7).

Five trellising systems were used for the cucumbers (Fig. 13). The corn stalks from beds 1 and 2 were bent at ground level bridging the furrow and forming a bed of stalks. Corn leaves were evenly distributed over one half of this bed. One half of the corn stalks of bed

3 and all of bed 4 were formed into tripods. The tripods on the west half of beds 3 and 4 had one end of a piece of twine tied at the apex of the tripod and the other end secured to the base of one leg. The corn stalks on the east half of bed 3 were left standing, as added support for the branches (approximately 1.5 m in height) which were embedded upright every 50 cm between each group of cucumber plants. -The east half of bed 4 was trellised in the manner described for tomatoes in Fig. 8.

Cucumber fruit 15 cm and longer were harvested twice weekly.

The plant spacing and transplant procedure for phase III was the same as that of the broccoli transplant of rotation 1 (Fig. 9). Since the corn stalks in unstaked beds were mulched in the furrow, transplants in these plots were exposed to full sun.






35

Table 6. Chronological calendar of events for rotation 4.
Observation Trial, 1973.



Month Day Procedure



--- 0 Corn seeding
June
4-12 Corn thinning, first fertilization


July ---35 Second corn fertilization
$4
0

Aug.
73 Phase 11 bed preparation
-78 Fresh corn harvest
:2' 81 Phase II cucumber seeding
T N85 Cucumber thinning and first fertilizaSept. tion, upper corn leaves and tassels
$4 removed
95 Trellising of cucumber
L11 Second cucumber fertilization
119 First cucumber harvest
Oct. L22 First seed bed planting of phase III
0 broccoli
129 Second seed bed planting of phase III broccoli
Nov. 146 Broccoli transplant (beds 1 and 2)
148 Last harvest of untreLlised cucumber, seeding of cowpea U 158 Fertilization of cowpea
U Dc159 Broccoli transplant (beds 3 and 4)
$ Dec164 Last harvest of treLlised cucumber and
removal, seeding and fertilization of cowpea
180 Second fertilization of broccoli (aLl
Jan, beds)
I 215 First broccoli harvest
o
-i,,-246 Last broccoli harvest
Feb. '-247 Bed preparation and seeding of phase IV
carrots and beets _7'-261 Dry cowpea harvest
'264 Data collection terminated







36



West Half of Plot 4












Bed3 NBed


Bed of Corn Vertical Twine
Stalks with Leaves



East Half of Plot 4










Bed Bed Bed Bed
JNo. L1 No. 2 /No. 3 No. 4

Bed of Corn Branches Horizontal
Stalks Without Leaves Twine






Fig. 13. Five trellising methods for cucumbers in
rotation 4, Observation Trial, 1973.







37

Immediately after the last cucumber harvest of beds 1 and 2, the corn stalks and cucumber vines were cut at ground level and compacted in the furrow between the beds. A single row of cowpeas was then seeded in the center of the furrow 15 cm apart.

After the last cucumber harvest of beds 3 and 4,

cowpeas were seeded 15 cm apart in rows on the sides of the vegetable beds. Immediately following the seeding of the cowpeas on beds 3 and 4, the tripods and cucumber vines were cut at ground level and compacted in the furrow (Fig. 14).





Broccoli
Cowpea Cowe


/ e dBed Bd3 Bd


Plant Debris



Fig. 14. Two systems of seeding cowpeas with broccoli.
Rotation 4, Observation Trial, 1973.


The cowpeas of beds I and 2 were harvested as fresh

green beans over a 2 week period. Cowpeas which developed after this period were left to dry. The 2 rows of cowpeas between beds 3 and 4 were harvested as dry beans.

Data taking for all rotations was terminated after






38

phase III, but to examine the possibility of continuing a crop sequence, phase IV was initiated in rotation 4.

After the last broccoli harvest, phase IV began with the removal of the broccoli plants. The soil on the old broccoli beds was loosened and spread to form a new lower and wider bed (Fig. 15). Beds 1 and 2 were seeded with carrots and beds 3 and 4 with beets (Fig. 15).











ed BBed
No. 1 No.2 No.3 No. 4




a.
Cowpeas
Carrots Beets








b.





Fig. 15. Bed formation and seeding of phase IV. (a)
Overlap period of cowpeas with carrots and beets and
(b) carrots and beets after removal of cowpeas.
Rotation 4, Observation Trial, 1973.






39

Observation Trial Rotation 5

A chronological calendar of events for rotation 5 is summarized in Table 7. Rotation 5 was seeded with radish and squash in addition to corn in phase I in the manner illustrated in Fig. 16. The squash were seeded in the middle of each double corn row at a spacing of

1 m.

The squash were removed before transition from

phase I to phase II began. From this point, rotation 5 followed that of rotation 1 with the exception that cabbage was transplanted in place of broccoli in phase III.

Observation Trial Rotation 6

A chronological calendar of events for rotation 6 is summarized in Table 8. In phase I, rotation 6 was seeded identically to rotation 5 wxcept for the squash (Fig. 16).

The transition from phase I to phase II tomatoes was the same as that of rotation 1.

The transition from phase 11 to phase III was the

same as that of rotation 1, with the exception that bush beans were planted on the sides of each bed (Fig. 17).

Following the Last tomato harvest, the tripods and vines were cut at ground level and placed in the furrows between the beds.






40


Table 7. Chronological calendar of events for rotation 5.
Observation Trial, 1973.



Month Day Procedure




---0 Corn seeding
June ---3 Radish seeding
7 Squash seeding
.24 L2 Corn and radish thinning, first corn
fertilization July 4-33 First radish harvest
--38 Last radish harvest, second corn fertilization

01 Aug. ---65 Seed bed planting of phase 1I tomato
4-73 Removal of squash, phase II bed preparation
-f---85 Tomato transplant, bean seeding, first fertilization o St 90 Corn de-leaving and doubling, phase II
termination


Oct.
Oc. 1--130 Dry corn harvest

t-145 Seed bed planting of phase 111 cabbage
'~Nov.
-4
o --172 Phase II1 bed preparation
Th-175 Transplant and fertilization of cabbage,
seeding of muskmelon Dec.



SJan.
0 3-4
Fe.4-245 Rotation terminated
.Feb.






41





1.2 m 20 cm 20 cm 21.7 cm




Radish Corn Squash




Fig. 16. Phase 1, rotation 5, illustrating the planting
arrangement and row spacings of corn, squash, and
radish. Observation Trial, 1973.





















Phase II Phase III
Tomatoes Bush Beans




Fig. 17. Bush beans seeded beneath tomato vines in
phase 1II, rotation 6, Observation Trial, 1973.






42

Table 8. Chronological calendar of events for rotation 6.
Observation Trial, 1973.



Month Day Procedure




June -0 Corn seeding
3 Radish seeding
7,-12 Corn and radish thinning, first corn fertilization

July -33 First radish harvest
--38 Last radish harvest, second corn fertilization

-60 Seed bed planting of phase 11 tomato
Aug.

_L--80 Phase I1 bed preparation
j.- 85 Tomato transplant
87 First tomato fertilization
Sept. 90 Corn de-leaving and doubling
0 99 Trellising of tomatoes
*

Oct. ---130 Second tomato fertilization, dry corn
4 : harvest ca
0
-1--154 First tomato harvest
Nov.


_L184 Bed preparation and seeding of phase III bush beans
Dec. 189 Last tomato harvest, windrowing of
plant debris, bean fertilization


Jan.



Feb. ---254 Bush bean harvest, rotation terminated






43

Field Trial Phase I (Rotations 1 and 2)

The field trial (Tables 9, 10) differed from the

observation trial in that phase I was planted on raised beds instead of level land. The planting system used for corn and radish was the same for both rotations. The beans were seeded differently for each rotation (Fig. 18). The beans were seeded 15 cm apart. The radish spacing was 5 cm. The corn was seeded in the triangular pattern (Fig. 3). The spacing between the rows of each double row was increased from 21.7 to 25 cm. The 2 rotations were treated the same through the transition to phase II except that the corn from rotation

1 was doubled and harvested as dry corn and that of rotation 2 was harvested as fresh corn. Field Trial Rotation 1


In the field trial, bed preparation for transition

from phase I to phase I was the same for both rotations. The preparation was as foLlows (Fig. 19):

1. Double corn rows were hilled forming vegetable
beds.

2. Corn stalks were stripped of lower leaves.

3. Nematocide was incorporated on tops of beds.

4. Beds were planted.

From this point to the transition to phase III, refer to observation trial, rotation 1, phase II (page 23).

The transition from phase II to phase III was the






44

Table 9. Chronological calendar of events for rotation 1.
Field Trial, 1973-1974.



Month Day Procedure

-1 Seeding of radish
!=z77J::O Seeding of corn
Dec. : I Seeding of bean
Dc 5 Fertilization of corn
10 Thinning of corn and radish
12 Fertilization of bean
(0 731 Radish harvest
Jan* 32 Hilling of corn
35 Seeding of phase 11 tomato in seed bed
47 Second seeding of phase II tomato in
Z seed bed
74 Bean harvest
Feb* 78 Phase II bed preparation, first fertilization of tomato 83 Tomato transplant
7 .88 Upper corn leaves removed, corn doubled
Mar. :_-97 Trellising of tomato

0
O
Apr.

-_-.143 Second tomato fertilization
o -50 Harvest of dry corn

May ---164 First tomato harvest



June
---201 Seeding of cowpea
206 Final tomato harvest, windrowing of vines and tripods 211 Fertilization of cowpea
July



0 Aug.



Sept. 287 Cowpea harvest, bed preparation of phase

293 Seeding of Okra







45

Table 10. Chronological calendar of events for rotation 2,
Field Trial, 1973-1974.



Month Day Procedure


I Radish seeding
0 Corn seeding
Dec. Bush bean seeding
7-*10 Radish thinning, corn and bean fertili.A zation
14 Corn thinning
1--35 Radish harvest
Jan. T'37 HilLing of corn
CO

,,-70 Bush bean harvest
Q Feb. -z7 3 Bed preparation for phase 11 cucumber,
o cucumber fertiLization
82 Cucumber seeding
8 5 Fresh corn harvest, de-Leaving and reMar. moval of tassel
\96 Trellising of cucumber


127 First cucumber harvest
Apr.
-140 Seeding of phase 111 cabbage in seed bed


May
Ma169 Phase III cabbage transplant
v-174 Last cucumber harvest
Z-,.181 Seeding of phase III corn

June -:-191 Fertilization of cabbage and corn



July

-239 Cabbage harvest "-240 HilLing of corn
Aug.






46

Table 10. Continued.



Month Day Procedure





Aug. :L-255 Bed preparation for phase IV
-260 Planting of sweet potato
S7-265 Seeding of pole beans 1271 Doubling of corn
0 Sept.



Oct.

-335 Harvest of pole beans and dry corn o Nov.






47



1.4 m

25 cm 25 cm 47 cm 20 cm



a. Radish Corn Beans
1.4 m

20 cm 20 cm




b~mRadish .Beans b.



Fig. 18. Row and plant spacings for rotations 1 and 2.
(a) Single row of beans planted in rotation 2 and
(b) double row of beans planted in rotation 1. Field
Trial, 1973.

















Phase II
Phase I Bean Row Vegetable Bed

Fig. 19. Beds formed and corn stalks de-leaved. Dotted
line represents the row configuration in phase 1. Solid
line represents phase II vegetable beds. Field Trial,
1974.






48

same as that of the observation trial, rotation 1 except that 3 rows of cowpeas were seeded on the sides and middle of the tomato beds (Fig. 20).












a. Tomato Cowpeas







b. Tomato and Tripod Debris



Fig. 20. Phase III, rotation 1 illustration of (a) three
rows of cowpeas seeded beneath tomatoes, and later (b) tomato vines and tripods placed in the furrow. Field
Trial, 1974.


After the cowpea harvest, the plant debris was windrowed between the beds and the okra seeded over bands of a nematocide (Fig. 21).






49




Okra




60 cm 80 cm Banded Plant Debris
Nematocide





Fig. 21. Diagram of phase IV, rotation 1, Field Trial,
1974.


Field Trial Rotation 2

Phase II cucumbers were seeded in the same manner

described in the observation trial (Fig. 7). The cucumbers were staked using 3 different systems. One third

of the field was staked with branches and one third with vertical twine (Fig. 13). The remaining third was the horizontal twine system (Fig. 8) except that only half the number of strings were used.

The phase III cabbage was transplanted in 2 rows 50 cm apart on the cucumber beds with 40 cm between

plants (Fig. 22).

After the final cucumber harvest, the tripods and

vines were windrowed between the cabbage beds. Corn was then planted on each side of the windrows. The planting system was the same as illustrated in Fig. 3, except the rows were seeded 35 cm apart (Fig. 23).







50














Cabbage 50 cm Cucumber
Plant



Fig. 22. Two rows of cabbage transplanted on the sides
of the cucumber beds. Rotation 2, Field Trial, 1974.





140 cm
r A50 cm 35 cm





Plant Cabbage Corn
Debris






Fig. 23. Diagram of corn seeding between cabbage rows.
Rotation 2, Field Trial, 1974.







51

After the cabbage harvest, soil was hilled around

the base of the phase 111 corn forming the beds for the

phase IV pole beans and sweet potatoes (Fig. 24).







yN









a. Plant Debris of Phase II







Corn
Leaf
Debris



b. Pole Bean
Sweet Banded
Potatoes Nematocide


Fig. 24. Transition of vegetable beds from phase III to
phase IV. (a) Dotted line represents old cabbage beds.
Solid line represents newly formed bean and sweet potato
beds. (b) Planting position of pole beans and sweet
potatoes over banded nematocide. Rotation 2, Field
Trial, 1974.






52

Immediately after the bed formation, sweet potato

cuttings were planted. Then the pole beans were seeded. The corn was then doubled and later harvested as dry corn along with the dried pole beans, leaving only the sweet potatoes.

Bean Cultivar Trial

In both phase I and phase II, 7 bean cultivars

(Tables 11, 12) were interplanted with corn. All plots had 1 m borders left at each end leaving 12 m in which yield data was collected.

Two systems for planting beans and corn were used. The original system is described in phase I of the field trial. A modification of that system is shown in Fig. 25. The north half of all plots under the modified system

were planted with beans on the tops of the ridges and the south half had beans planted on the inside of the 2 ridges between the double corn rows (Fig. 25).

The corn was seeded in the triangular pattern (Fig. 3). There was an increase from 21.7 cm to 30 cm between corn rows and 1.4 m to 1.5 m from center to center of the double corn rows (Fig. 25).

The transition to phase II began with the removal of all lower corn leaves which were windrowed between the pairs of rows. The phase II beans were then seeded in rows adjacent to the corn stalks (Fig. 26). The phase







53

Table 11. Bean cultivar plots. Planting and harvest
dates and planting systems, phase I, Bean Cultivar
Trial, May, 1974.



Cultivar Plot Planting Harvest Planting
No. Date Date System

127-R' 2 5-30-74 8-3-74 Modified
8-8-74

'Centa 105' 3 5-31-74 8-19-74 Original

'Sensuntepeque' 7 5-30-74 8-29-74 Modified 'Centa 105' 8 5-31-74 8-19-74 Modified

'Centa 105' 10 5-31-74 8-22-74 Original

IS-184' 12 5-30-74 8-8-74 Modified

'Centa 105' 14 5-31-74 8-23-74 Original

'Centa 105' 15 5-31-74 8-22-74 Modified

'Porrillo 70' 17 5-30-74 8-12-74 Modified 'Centa 105' 20 5-31-74 8-22-74 Original

'San Fernando' 21 5-30-74 7-31-74 Modified
8-3-74

'Arbolitol 22 5-30-74 8-12-74 Modified

'Centa 105' 23 5-31-74 8-16-74 Modified
'Centa 105' 25 5-31-74 8-22-74 Modified







54

Table 12. Bean cultivar plots. Planting and harvest
dates, phase II, Bean Cultivar Trial, August, 1974.



Cultivar Plot Planting Harvest
No. Date Date


'27-R' 2 8-26-74 11-4-74
'27-R' 3 8-26-74 10-30-74

'Sensuntepeque' 7 8-26-74 10-28-74

'Sensuntepeque' 8 8-26-74 10-29-74

'Centa 105' 10 8-26-74 11-18-74
'S-184' 12 8-27-74 11-6-74

*Centa 105' 14 8-27-74 11-7-74

'S-184' 15 8-27-74 11-7-74

'Porrillo 70' 17 9-3-74 11-11-74

'Porrillo 70' 20 8-27-74 11-18-74
'San Fernando' 21 8-29-74 11-7-74

'Arbolito' 22 8-27-74 11-14-74

'Arbolito' 23 8-27-74 11-18-74
'San Fernando' 25 8-29-74 11-8-74






55










1.5 m 50 cm 30 cm




as Corn Beans

1.5 m 50 cm 30 cm 30 cm




b. Beans Corn


1.5 m 35 cm 50 cm 30 cm




co Beans Corn






Fig. 25. Row and plant spacing for original and modified
bean planting systems. (a) Original system, (b)
modified system and method of planting for south half of plots, and (c) modified system and method of planting for north half of plots. Bean Cultivar Trial, 1974.






56






















a. Beans Plant Debris

1.5 m

L.5 m 45 cm 30 cm







Beans
ben Plant Debris Corn Doubled
b, of Phase I Corn Corn








Fig. 26. Transition to phase 11 illustrating (a) phase
II beans seeded beneath corn and (b) phase I corn doubled and phase II corn seeded. Bean Cultivar
Trial, 1974.







57

11 corn was planted immediately after the corn stalks were topped and doubled (Fig. 26).









Results


Observation Trial-Corn (All Rotations)

The corn from phase I was harvested as fresh corn in rotations 1, 2, and 4. The data on weight and/or size of ears was not recorded although they appeared average as compared to monocultured corn. The corn from plots 3, 5, and 6 was harvested as dry corn. The average yield for the 3 plots was 3.6 M.T./ha. This yield was slightly inferior to the average yield (3.9 M.T./ha) of monocultured corn grown under experimental conditions by the Plant Science Department of CENTA.

The corn stalks tended to etiolate, but lodging due to weak or corn borer (Ostrinia nubiLalis HUbner) (7, 8, 20) damaged stalks occured in less than 1% of the stand.

The observations and physiological data in Table 13 apply to all plots. This table is included because of its relationship to the timing of events that occured in this and following trials. Observation Trial Rotation 1

Phase I Phase II Phase III

Corn Tomato Broccoli
Muskmelon

The crop sequence of rotation 1 was generally successful. The phase II tomatoes and phase 1II broccoli had high yields, but muskmelon did not yield any 58







59

Table 13. Chronological order of development for the
corn cv. H-3. Observation TriaL, 1973.



Physiological Occurance Number of Days From Seeding


Emergence 5

"Knee High Stage" 30

Tasseling 58

Anthesis 65

Harvest of Fresh Corn 78

Doubling of Stalks for Drying 90

Harvest of Dry Corn 120







60

marketable fruit. The tripods served very well as a support for the tomatoes during the entire growing season.

The tomatoes yielded 51.4 M.T./ha which was much

better than average farm yields (30 M.T./ha). The yield of broccoli per plant was excellent, but due to a low planting population, the total yield per unit of area was lower than that of a planting with normal row spacing. The broccoli yield was not recorded. The muskmelon were discarded -because of a 100% infection of 'Soft Rot' bacteria (Bacterium carotovora L.R. Jones) (18).

During the transition from corn to tomatoes, the

canopy of corn leaves provided shade for the tomato transplants, which facilitated establishment.

The incidence of Bacterial Spot (Xanthomonas

vesicatoria Gardner and Kendrick) (18), Early Blight (Alternaria solani E. and M.) (12), and Late Blight (Phytophthora infestans Mont. DeBary) (12) appeared to be less in the corn staked tomatoes than in unstaked tomatoes.

The tomato vines provided shade which was beneficial for the transplants in the transition to phase III. Muskmelon germination was poor. This appeared to be

due to inadequate lateral water movement across the wide beds.







61

Observation Trial Rotation 2

Phase I Phase II Phase III

Corn Tomato CauLiflower
Pole Bean Muskmelon

The crop sequence of rotation 2 was not generally successful. The tomato-pole bean combination and the cauliflower-muskmelon combination produced poorly.

The association in rotation 2 of tomatoes and pole beans resulted in substantial drop in tomato yield (18.6 M.T./ha) below the average farm production. The pole beans were a vigorous cv. and quickly surpassed the tomatoes in height. Due to this shading of the tomato plants, the yields were low as compared with rotation 1. The green bean yield (3.8 M.T./ha) and plant development was good. The beans were seeded at a lower density than monocultured pole beans, therefore the total yield for

the plot area was lower than average. This was also true for the cauliflower, which yielded well on a per plant basis but low per unit of area. The cauliflower yield was not recorded. The muskmelon yielded no marketable fruit due to a 100% infection of 'Soft Rot' bacteria (Bacterium carotovora L.R. Jones) (18). Observation Trial Rotation 3

Phase I Phase II Phase III

Corn Pole Bean Tomato

In general, rotation 3 worked well. The pole beans after corn followed the traditional system, and the







62

tomato vines were supported by the bed of corn stalks.

Although the yield of the pole beans was not recorded, their growth and development appeared good. The bean plant population was Lower than that of traditional systems by approximately one half. Therefore, a lower yield of dry beans was expected. The pole beans, which were mature and drying during the transition to phase Ill, gave very little shade to the phase III tomato transplants. There was a 20% re-transplant of the tomatoes. Due to a severe mosaic-type viral infection, the plants were removed 60 days after transplant. No fruit was harvested. Observation Trial Rotation 4

Phase I Phase II Phase III Phase IV

Corn Cucumber Broccoli Carrot
Cowpea Beet

Rotation 4 worked well. The cucumbers and phase III crops performed well. Phase IV was shown to be

feasible with some modifications to the system. Two staking systems using tripods and-another with branches worked well as supports for cucumbers and increased their yield over unstaked vines.

The phase II stand of cucumber seedlings incurred a 20% loss due to Damping Off (Pythium debaryanum Hesse and Rhizoctonia solani Kuhn) (12, 50) during the first

4 days after emergence which occured during a high rainfall period. An even stand was established by re-seeding.







63

Several methods of training cucumber vines were

compared in this rotation (Fig. L3). The staked cucumbers had a significant increase in yield and produced

16 days longer than the cucumbers grown on the beds of corn stalks, with and without leaves (Fig. 13). Yields were outstanding. The cucumbers grown on the beds of corn stalks produced over 40% more per ha than traditional field grown cucumbers which at maximum yield 25 M.T./ha (25). The staked cucumbers produced almost 250% more than traditional methods (Table 14). The

staked cucumbers also provided shade to the phase III broccoli transplants.


Table 14. Yields in M.T./ha and numbers of fruit/ha of
cucumbers grown on 5 different trellising systems,
phase 11, rotation 4, Observation Trial, October 8November 22, 1973.



Trellising Yields
System M.T./ha No. Fruit/ha


Vertical Twine 86.86 404,714

Branches 86.57 399,000

Horizontal Twine 71.70 345,571

Stalks Without Leaves 34.57 149,143

Stalks With Leaves 32.70 150,000







64

The cucumber fruit on the staked vines were

straighter and had less yellowing than the fruit on the plants growing on the beds of corn stalks.

The 3 fungal diseases most commonly found in unstaked cucumbers, Cottony Leak (Pythium debaryanum Hesse) (12, 46, 47), Downy-Mildew (Pseudoperonospora cubensis B. and C. Clint) (12, 46, 47, 50), and Angular Leaf Spot (Pseudomonas lachrymans Sm. and Bryan) (12,46, 47) occured less frequently and were much easier to control in the staked cucumbers.

Although yields for the phase III crops were not

recorded, the growth and development of both crops were very good. Neither crop was planted at a normal monoculture population, therefore the yield per crop was expected to be Low per unit area. Slugs in the plant debris inflicted extensive damage to the cowpeas during the seedling stage. The cowpeas, which were in the maturing and drying stage at the beginning of phase IV, could not be irrigated. This combined with the wide vegetable beds is a possible explanation for the sparse stand of carrots and beets, which lacked sufficient moisture during germination.

The trial was stopped and no yield data was recorded for phase IV.







65

Observation Trial Rotation 5

Phase I Phase II Phase III

Corn Tomato Cabbage
Squash Pole Bean Muskmelon
Radish

The association of corn, radish, and squash in rotation 5 was unsatisfactory. The tomato stand was poor, cabbage produced an average yield, and muskmelon

produced nothing.

The radish and squash were severely shaded. The

radish top growth seemed adequate, but only one half the plants produced marketable roots. The squash produced only staminate flowers, therefore no fruit were harvested.

Although the yields of the cabbage were not recorded, the growth and development was average, but because of a low planting population, the yield per unit was expected to be below average. As in rotations I and 2, all the

muskmelon were discarded. Observation Trial Rotation 6

Phase I Phase 11 Phase III

Corn Tomato Bush Bean
Radish

The association of corn and radish in rotation 6 was unsatisfactory. The phase 11 tomatoes staked with corn tripods and the phase III bush beans both performed very well. With the exception of radish, the rotation did exceptionally well.







66

The growth and development of radish in rotation 6 was similar to rotation 5. A 25% loss of tomato plants due to Southern Bacterial Wilt (Pseudomonas solanacearum Smith) (18) was incurred. Presumably, this resulted from infection through roots wounded during cultivation. Tomato yield was adjusted on the basis of numbers of producing plants in rotation 6. The majority of corn stalk tripods supported the tomato plants during the entire growing period. A small section of 1 row lodged. This,section was reinforced by placing bamboo stakes where necessary. The bush beans were harvested as dry beans. The bush bean yield (2.04 M.T./ha) was considered good compared to monoculture. Field Trial Rotation I

Phase I Phase II Phase III Phase IV

Corn Tomato Cowpea Okra
Bush Bean
Radish

The crop sequence for.rotation 1 worked well. The corn, radish, and beans performed well (Table 15) and the transition from phase I to phase II was good. The tomatoes had fair yields, and the tripod supports functioned well throughout the entire growing period.

The transition from phase II to phase III went

smoothly. Phase III did not overlap with phase IV although the old phase 11 tomato beds served as beds for the okra. The inaccuracy of hand seeding resulted in an






67



Table 15. Crop yields for phase I, rotation 1, Field
Trial, 1974.



Phase Crop Yield/ha

I Radish 228,570 (No. of roots)

I Bush Beans 0.5 M.T. (dry)

I Corn 3.5 M.T. (dry)







68

average increase of 30 cm between plants and a decrease in population of 8,889 plants/ha from the projected

53,328 plants/ha.

Thirty days after seeding, the corn, beans, and

radish had formed a completely closed canopy which appeared to supress weed growth. This marked the point of maximum competition between the 3 crops. With the harvest of the radish, additional light was available for the beans. The date of radish harvest corresponded to the first bean flowering. The beans had set fruit before the corn completely shaded them.

The yield of dry corn in rotation 1 was about the

same as that of the dry corn harvested in the observation trial.

The incidence of Damping Off (Pythium debaryanum

Hesse and Rhizoctonia solani KUhn) (12, 50) of the phase 11 tomato transplants was much less of a problem under dry season conditions. Approximately 10% of the tomato plants in rotation 1 were lost to Bacterial Wilt (Pseudomonas solanacearum Smith) (18). As the tomato plants began flowering, symptoms of Curly Top Vizus (40) appeared. Tomato yield was estimated at half of that produced in rotation 6 of the observation trial.

The plant debris placed between each set of 3

cowpea rows during phase II (Fig. 20) resulted in proliferation of slugs which caused damage to the young cowpeas.







69

Yield data for phases 111 and IV are not available. The okra of phase IV was severely damaged by Root Knot Nematodes (Meloidogyne sp. Berkely) (11, 39).


Field Trial Rotation 2

Phase I Phase II Phase III Phase IV

Corn Cucumber Cabbage Pole Bean
Bush Bean Corn Sweet Potato
Radish

The crop sequence for rotation 2 was satisfactory.

The transition to phase II proceeded smoothly and

the cucumber yield was good. Cabbage yield in phase 111 was low although the associated corn performed well. The transition of sweet potatoes and pole beans into phase IV worked well. The pole bean production was average (Table 16) as compared to commercial monocuLture.

Cucumber yield was 16% lower than that recorded for the observation trial (TabLe 14). A single fertilizer application, an extensive infection of Angular Leaf Spot (Pseudomonas achrymans Sm. and Bryan) (12, 46, 47), an infestation of Root Knot Nematodes (Meloidogyne sp. Berkely) (11, 39), and difference in time of year could

explain the decrease.

There was a 10-15% loss of phase II cabbage within the first 4 days after transplant due to Damping Off (Pythium debaryanum Hesse and Rhizoctonia solani Kuhn) (12, 50). Cabbage was severely shaded by corn and not







70



Table 16. List of crops and their respective yields
categorized by phase. Rotation 2, Field Trial,
December 10, 1974.



Phase Crop Yield/ha


I Radish 228,570 (No. of roots)

I Bush Bean 0.49 M.T. (dry)

I Corn 36,399 (fresh ears)

Ii Cucumber 74.347 M.T. (fresh weight)

ill Cabbage 480 (No. of heads)

III Corn

IV Pole Bean 4.09 M.T. (dry)

IV Sweet Potato







71

much marketable yield was obtained. The remainder of the plants were loose, undeveloped heads. The infestation of Root Knot Nematodes (Meloidogyne sp. Berkely) (11, 39) was severe. The phase III corn began to shade the cabbage approximately 30 days after seeding.

Yield data for the corn is not available, although its growth and development appeared good.

Four of the 20 beds which were seeded with the phase IV pole beans were destroyed by slugs. The pole bean yield is based on the remaining 16 beds. An estimated 80% stand of sweet potatoes was achieved. Yield data were not obtained.

Records of labor input (man hours) were maintained throughout the field trial. The labor requirement necessary to carry out the operations of each rotation appeared to be high, although no comparison was made of these crops grown under monoculture.

Bean Cultivar Trial Phase I (Corn, Beans)

Beans planted on the sides of the ridges showed a highly significant increase in numbers of plants that emerged but a non-significant increase in bean yield (Table 17).

Unlike the other bean cvs., Centa 105 was replicated

4 times. Analysis of this cv. showed a non-significant increase in emergence success and yield between the 2 planting systems (Table 18). However, the averages of







72

Table 17. Mean number of bean plants emerged 10 days
after seeding and their mean yield of dry beans (M.T./ha) for all cvs., for 2 planting systems.
Bean Cultivar Trial, May, 1974.



Mean No. of Mean Yield
Plants Emerged (M.T./ha)


Planted on Center 77,885 .292
of Ridge

Planted on Side 106,124 .375
of Ridge

Significance ** N.S.

**Treatment means were significantly different at the
.01 level of probability.
N.S.--Treatment means were not significantly different
at the .05 level of probability.


Table 18. Mean number of bean plants emerged 10 days
after seeding and their mean yield of dry beans
(M.T./ha) for cv. Centa 105, for 2 planting systems.
Bean Cultivar Trial, May, 1974.


Mean No. of Mean Yield
Treatment Plants Emerged (M.T./ha)


Planted on Center 74,221 .255
of Ridge

Planted on Side 97,715 .333
of Ridge

Significance N.S. N.S.

N.S.--Treatment means were not significantly different
at the .05 level of probability.








73

the cv. Centa 105 followed that of the other cultivars. Non-significance is probably due to the low f value.

The primary diseases which were encountered in the May planting were Damping Off (Pythium debaryanum Hesse and Rhizoctonia solani Kihn) (12, 50), Mustia (Pelticularia filamentosa Pat) (35, 48), and Angular Leaf Spot (Isariopsis griseola Saccardo) (35, 51).

The cultivars exhibited various degrees of tolerance to the fungal diseases. An indication of their disease susceptibility can be seen in the percentage of plants lost (Table 19) during the time period of 1 week after emergence until the date of harvest. The cv. Centa 105 had the lowest percentage loss while the cv. S-184 had the highest percentage loss. However, the percentage of plant survival (inverse of % figures in Table 19) was non-significantly correlated with dry bean yield (r=0.122--N.S.).

Cultivar Porrillo 70 produced 0.29 M.T./ha (dry beans) more than the next highest producer, cv. 27-R and yielded twice that of cvs. Centa 105 and 27-R which had a lower percentage of plant loss (Tables 19, 20).

In those plots in which corn was seeded 5 days after the seeding of the beans (which excluded cv. S-184 and cv. Porrillo 70), cv. 27-R flowered 5 days after cv. Sensuntepeque and still out-yielded it by .08 M.T./ha







74

Table 19. Percentage of bean plant losses from emergence
to harvest for bean cvs. of phase I, Bean Cultivar
Trial, May, 1974.



Cultivar Percentage of Plants Losta


127-RI 34%

'Centa 105' (modified) 21%

'Centa 1050 (original) 38.2%

'San Fernando' 25.4%

'Sensuntepeque' 27.5%

IS-184' 53%

'Arbolito' 30%

'Porrillo 70' 29%

aNumber of plants lost is based on data collected from the beans seeded on the sides of the ridges.









Table 20. Days to flowering, days to harvest, and yield (M.T. /ha) for 7 cvs.
of Bean Cultivar Trial, May and August planting, 1974.



Cultivar No. Days to Flowering No. Days to Harvest Yield (M.T./ha)
May August May August May Augus t


127-R' 33 30 65 65 .47 .55

'Centa 105,a 49 41 83 80 .33 .55

'San Fernando' 30 28 70 70 .30 .68

'Sensuntepeque' 28 28 60 63 .39 .61

'S-184' 32 30 70 71 .35 .91

'Arbolito' 30 30 74 79 .15 .95

'Porrillo 70' 35 35 74 69 .76 1.05


aModified planting system






76

(dry beans). Cultivar Centa 105 flowered 21 days after cv. Sensuntepeque and yielded .12 M.T./ha (dry beans) less (Table 20). Cultivar Sensuntepeque not only flowered first, but also was the first to be harvested with cv. 27-R following 5 days later (Table 20).

Cultivar Centa 105 was planted under 2 systems, the original system and the modified system (Fig. 25). The mean bean yields were significantly different between the 2 systems with the modified system yielding higher (Table 21.)

The corn cv. H-3 normally produces one usable ear of corn per plant, therefore the number of ears produced in

1 plot is a fairly reliable index of plant population. Based on the number of ears harvested per plot, none of the plots reached the projected plant population of 53,328 plants/ha. The highest number of ears harvested for any I plot was 39,032 (Table 22). This represents a decrease of 14,296 corn ears from the theoretical number possible. The plot which had the lowest number of corn ears harvested, had a decrease of 24,294 ears/ha. An increase in yield-had a highly significant correlation to increase in population (number of ears harvested) in the plots (r=0.692**). The average production of the 12 plots was 3.38 M.T./ha of dry grain (12% humidity). This is a decrease of 6.5% from the corn yield of the observation trial.







77

Table 21. The mean bean yields (cv. Centa 105) for the
modified and original planting systems. Bean Cultivar
Trial, May, 1974.



Treatment Mean Bean Yield (M.T./ha)


Modified System .33

Original System .22

Significance

*Treatment means were significant at the .05 level of
probability.











Table 22. Range and average of corn yield of ears harvested/ha and M.T./ha dry grain (12% humidity) from
12 plots of corn-bean rotation, phase I, Bean Cultivar
Trial, May, 1974.



Ears/ha M.T./ha Dry Grain
(12% Humidity)


Range 29,034-39,032 2.97-3.83

Average 34,766 3.38







78

Bean Cultivar Trial Phase II (Corn, Beans)

The diseases inherent to the May planting were for the most part, absent in the August planting.

Cultivar Porrillo 70 again was the highest producer of the 7 cvs. with an average 1.05 M.T./ha dry beans. Cultivar Arbolito, which had much better germination in the August planting, ranked close to cv. Porrillo 70 with a mean yield of .95 M.T./ha dry beans. Cultivar 27-R and cv. Centa 105 both increased their production over the May planting but were the lowest producers of the 7 cvs. The mean of all bean cv. yields was highly significant between the May and August plantings (Table 23).


Table 23. The mean of all bean cv. yields for the May
and August plantings. Bean Cultivar Trial, 1974.



Planting Date Mean Bean Yield (M.T./ha)


May .423

August .703

Significance **


**Treatment means were highly significant at the .01
level of probability.


The time period from seeding until flowering was

reduced for the majority of the bean cvs. in the August planting although cvs. Sensuntepeque, Arbolito, and







79

Porrillo 70 remained the same as in the May planting (Table 20). Also, the number of days from flowering to harvest increased in the August planting over the May planting.

Cultivar Sensuntepeque remained the earliest producer. Cultivar Porrillo 70 which was the highest yielder in phase II, matured 5 days earlier than in the phase I planting (Table 20).

The corn yield data for phase II was not available.

This rotation of beans-corn followed by beans-corn was very successful and demonstrated a program which could greatly increase bean and corn yield per unit of land area.

For pertinent statistical information of bean cultivar trial data, refer to analysis of variance (ANOVA) tables in Appendix E.









Discussion


Because of the nature of these trials, the results are based primarily on observations rather than data which could be analyzed statistically. A precise traditional research approach was not used because it would have placed limitations on the scope and development of

the multiple cropping system in the short period of time available. While detailed investigation of specific points needs to be continued, many of the basic concepts and ideas necessary have been developed. The objective of this discussion is to review the concepts and ideas and their implications for future work in multiple cropping in El Salvador.

The investigation began with the objective to determine the potential of planting corn in closely spaced double rows and using the mature stalks, tied in the form of tripods, to stake cucumbers and tomatoes. Corn stalks have traditionally been used in several countries to stake pole beans (2) but a single corn stalk does not have the strength or durability to support a mature tomato or cucumber vine. These trials showed that the mature stalks in their original planted position could be tied together to form a durable tripod structure with the capability to withstand the weight of a mature vine loaded with fruit for a 3-4 month growing period.

80







81

Wood or other material that could be used to stake vegetable crops is scarce in El Salvador. The cost and effort that is required to obtain staking material is not practical for most farmers. The hot and humid conditions which exist in El Salvador during the rainy season make it necessary to stake tomatoes and cucumbers. Plantsoil contact or low air movement around leaves, stems, and fruits result in a high incidence of fungal and bacterial diseases. Therefore, the necessity to stake is an important limiting factor to the production of tomatoes and cucumbers on a large scale during the rainy season. During this period, tomatoes and cucumbers are in short supply and normally bring a high price in the market.

The results of the observation trial indicate that

the longer period of production (Table 14) of staked cucumbers was probably due to a lower disease incidence. Better aeration and better fungicide spray coverage of the staked treatment are probable reasons for less disease and greater production of cucumbers per unit of time than the bed grown treatment. There was a high incidence of yellowing on the bottom side in bed grown cucumbers that was not found in the staked treatment.

Tomatoes, when staked, have less disease problems (39,50). This was observed to be the case in the corn staked tomatoes. Also, there was a low incidence of Southern Bacterial Wilt (Pseudomonas solanacearum Smith)







82

(18) in all tomato plots. This disease is an extremely limiting factor to tomato production in El Salvador. Inoculation of the tomato roots can occur from nematode or other physical damage (18). It is probable that the root system of the corn plants form a protective net around the roots of the tomatoes preventing physical damage and reducing soil erosion of the tomato beds.

The principal grain in El Salvador is corn and

beans are .the most available source of protein. For a large portion of the population which is dependent on their annual harvest of corn and beans, the potential of this system could enable a farmer to produce a high value staked vegetable crop in addition to his corn and beans.

The effect on yield of growing corn in double rows is of major concern. Because of the national dependence on corn, use of this system on a wide scale should be carefully studied. Priority should be given to determining any positive or negative effects of this planting system on total corn yield per unit of area.

Based on the data, no valid conclusions can be

drawn on the interaction of corn spacing and plant population on corn yield. It can only be said that the yields in general are favorably comparable to normal monocultured corn in El Salvador. More information is needed to establish optimum plant population and double corn row spacing.







83

This should involve evaluation of not only corn yields, but also the effect of corn spacing on the interplanted crops and in turn the total output of the combination. An investigation should also carefully examine other crops which could be combined with corn. Work done at the International Rice Research Institute (IRRI) shows that the productivity of mung beans decreases in a linear fashion as the corn population increases although this crop association produced a total yield 20-30% above monoculture. This difference in performance between monoculture and intercropping can be explained by differences in light interception over the entire growing season (28).

Normal monocuLture planting patterns begin with large gaps between the crop rows. One principle of multiple cropping sequences, for example the corn, radish, bean combination, is to fill these unplanted areas with a fast maturing crop that can utilize the unused portion of sunlight. Differences in yield between bean cultivars might be a genetic yield potential difference, varietal difference for earliness to flower and mature, tolerance to competition or a composite of all these factors.

In most monoculture systems, an increase in population results in an increase in yield. In crop interplanting systems, an increase in the upper tier crop such as corn, might result in an increase in corn yield (page 76) while a population increase of the lower tier crop does not infer an increase in its yield. The difference in mean







84

bean yields obtained from 2 methods of seeding on a ridge (Fig. 25) was not significant despite the significant difference between the survival plant population of each system (Table 17). However, the difference between the mean bean yields of the modified and original systems was significant. This indicates that distance between bean rows has a greater influence on bean yield than does plant spacing within a row. This hypothesis is reinforced by the almost identical yields (Tables 15, 16) obtained from the 2 bean planting systems used in the field trial (Fig. 18). These results indicate that the incidence of available light per unit of leaf surface area is increased as the distance between the bean rows was increased, resulting in a higher yield.

The significant difference in bean yield between

planting dates is a strong indicator that time of planting is an important factor controlling yield. Overcast skies, which would affect light level, and increased disease incidence appeared to be 2 probable reasons for lower yields of the May planting.

Another example of lowered yield probably due to

competition was found in the pole -bean-tomato combination in the observation trial. In this case, the tomato yield was sacrificed by the interplanting of pole beans, a late maturing, extremely competitive crop. Interplanting of these 2 upper tier crops inhibited either one from developing and producing as if grown separately. A fast







85

maturing bush bean would have had ample time to grow and produce before the tomatoes became competitive and with much less of a detrimental effect on tomato production.

The cabbage-corn combination in the field trial illustrates that cabbage, the lower tier crop, is not shade tolerant and if interplanted with corn requires a substantial non-competitive period to develop a plant frame necessary to produce a marketable head. The same occured with radish and squash in the observation trial.

The 3 day head start that the corn had over the radish resulted in less non-competitive time and apparently was the cause for a low per cent production of marketable roots. The radish planted in the field trial, which had a time advantage, yielded a high percentage of marketable

roots. More study is needed to establish optimum crop overlap periods for crop combinations.

The second important objective of these trials was to develop a workable combination of techniques which made a continuous cropping system possible for the small Salvadorean farmer. A system was developed that does have potential, although there are many unanswered questions. An integral part of this system is the initial planting pattern of the corn and the subsequent stationary beds which are formed under it. The trellised crops follow the corn and upon their termination, other crops can be grown on and between the beds. The concept of a stationary bed is perhaps the most important point to a Salvadorean