irps 33 determining superior cropping patterns for small farms in a dryland rice environment: test...

8/4/2019 IRPS 33 Determining Superior Cropping Patterns for Small Farms in a Dryland Rice Environment: Test of a Methodol

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lRPS No. 33. July 1979

DETERMINING SUPERIOR CROPPING PATTERNS FOR SMALL FARMSIN A DRYLAND RICE ENVIRONMENT: TEST OF A METHODOLOGyl

ABSTRACTA methodology for cropping systems research, proposedin 1975, involved the farmer as an active part~c~pantin the research, with test patterns grown on his landunder joint farmer-researcher management. Experiencewith the use of this methodology in developing a dry-land rice-based cropping systems test site in thePhilippines is discussed.The potential for increased crop productivity in thenajor dryland rice-producing region of easternBatangas province, where the predominant cropping

pattern involves dryland rice followed by field corn,was studied by testing the impact of these croppingpattern alternatives: following rice with field cropsother than the local orange flint corn, an intercroppattern, and a three-crop-per-year pattern. Coopera-ting faFmers applied the alternative patterns onI,OOO-m2 plots adjacent to their rice-corn plots.Some patterns showed yield instability and poor pestresistance. None had any adverse effecE on theyield of the next rice crop when compared with thetraditional pattern.

to .. .emus P. Garrity. Kiessplback Crops Laboratory. Agronomy Department, Uu ivcrsiry o f Nebraska. Lincoln. l:SA;Klcharxi R. Harwood, Roda lc Press. Inc., Organic' Park. Emmau s, Penns y lvan ia , USA; Hub crt G. Zandstra andEdwin C. Price , Cropping Sys rems Program. lRIU. P.O. Box 933. Manila. Philippines. Submitted to the IRRIResearch Paper Series Committee. Janllary 1979.


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IRPS No. 33. July 1979 3

DETERMINING SUPERIOR CROPPING PATTERNS FOR SMALL FARMSIN A DRYLAND RICE ENVIRONMENT: TEST OF A METHODOLOGY

Small-scale farmers generally have diversified farmenterprises -- with different resource requirements-- that may involve various cropping patterns, animalproduction activities, and tree crops grown in thefence rows and homestead areas.Strategies for increasing farm productivity thatfocus on introducing technical changes within asingle-crop enterprise are often rejected by farmersbecause of unforeseen negative effects on productiv-ity or resource utilization in other enterprises, orboth. Cropping systems research approaches theproblem of fitting relevant technology into the smallfarm operation by determining the effects of poten-tial technical changes on the entire system. If thebest cropping patterns for small-scale farmers ineach major production environment are to be deter-mined, crop determinant variables, the present crop-ping systems, and the productivity of alternativesmust be defined.A methodology for cropping systems research wasproposed in 1975 by the Cropping Systems Working'";roupCIRRI 1975)., The process consists of seven.r ag e s :

1. selection of target areas;2. description of the target areas;3. design of cropping patterns;4. testing of cropping patterns;5. applied research and preproduction testing;6. production programs;7. evaluation of change.

The last three stages must consider extension of theresearch results into a nation's programs for agri-cultural production.The proposed methodology involves the farmer as anactive participant in the research team: the testpatterns are grown on a portion of each cooperatingfarm under joint farmer-researcher management. The[armer's participation in pattern testing facilitatesearly detection of some of the constraints' toadop-tion at the farm level, which frequently go uhnoticed(Zandstra 1976). The'IRRI Cropping Systems Programfocuses on the rice-growing environments of South andSoutheast Asia: dryland, rainfed wetland and,to alesser extent, irrigated wetland. The methodologywas first applied to research for crop intensifica-tion on drylan~ rice-based systems. Experience withthe use of the first four stages of the methodologyin developing a dryland rice cropping systems testsite in the Philippines is analyzed here .

.'IETHODOLOCY DEVELOPMENTDryland rice is rice grown on unbunded, well-drainedfields w ithou t irrigation. It is grown on some 25%

of the world's rice land (De Datta 1972) and accountsfor nearly 20% of the total rice area of Asia (Barker1979). In the Philippines, dryland rice productionis widely distributed but is concentrated in severalzones (Fig. 1). Most farmers plant one dry land ricecrop a year, without a preceding or following crop(Dozina and Herdt 1974). Some farmers grow 2 crops,with dryland rice followed by corn 80% of the time.

Philippines

-6-N

Fig. 1. The distribution of drvtand rice by area planted. Each dot represents 300 ha.Source: 1971 cen-sus of agriculture.


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4 lRPS No. 33, July 1979

Previous analyses show that dryland rice environmentsare determined by three physical factors: the numberof months of continuous adequate rainfall, the slopeof the land, and the soil texture (Garrity 1976).The site selected for this study is in northeasternBatangas province at a latitude of 14N and longitude121oE. It is about 100 m above sea level and hasmean monthly temperatures between 26 and 34C. It isrepresentative of dryland rice-growing areas with 6to 7 months of rainfall exceeding 100 mm/month,gentle slopes 8%), and a medium soil texture. Thisenvironmental complex, a union of sites with the samevalues for the three environmental factors (Zandstra1976), is typical of the second largest dryland ricearea in the country (Fig. 2) and was particularlysuitable for intensive cropping systems.

S it e d es cr ip ti onThe earliest work at the site was in 1973. It con-centrated on understanding the existing croppingsystems and their relationships to the physical andeconomic conditions of the area (Frio and Banta 1974,Antonio and Banta 1974). The dominant characteris-tics of the site follow.

In northeastern Batangas nearly all drylandrice farmers grow a second crop -- usuallycorn -- after rice. Rice and corn fit intothe strongly unimodal rainy season, with theland fallowed for 2 months in the dry season(Fig. 3).

The soils are fertile (Eutrandolls, pH 6.0,loams), and nearly all tillage operations areby animal power.

Roads, transport, and markets are generallyadequate. Cash inputs crop to production are high fordryland farmers (about US$130/ha per crop). Most farmers are share-tenants, and farmsare generally less than 2.5 ha.

C ro pp in g p at te rn d es ig nAs information on the farmers' resources and theircurrent levels of crop technology accumulated, threetypes of alternative cropping pattern designs wereidentified:

Upland rice area (thousand hal62,----------------------------------------------------------------------.

Soil textural classes 0EntisolL = Light (sands) Mountain soilsM = Medium (loams)

~-(und ifferentiated)

H= Heavy (clays) Vertisol~ Alfisol: : ; : : : : : : 0. Inceptisolj ; ; ; j ; i i ~ .Ultisol

60 Slope classesGR = Gently rolling (0-8%)SR = Steeply rolling (8-30%)M = Mountainous (>30%)6

524844

4036322824

16

128

Soil textureSlope

Rainfall (>10U mill)

LMH LMHLMHf-G R-t--SR---t-M-if------ 6-7 --~-I----0-5---~

~~I ~~ ~~ ~~ ~n ~ ~

I ~~ ~Fig. 2. Dryland rice environmental complexes in the Philippines and the crop area found in each complex. The three determinants are rainfallpattern. slope, and soil texture (Garrity 1976).

LMH LMH LMHf-G R-t-- SR-+- M---jt------ 8- 10-------1

LMH LMHLMHJ-G R--r-S R-+ -- -- t- M--j~--11-1!2 -------j


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1. following rice with alternative field cropsthat may offer advantages over corn;

2. following rice with two crops, to extendcropping further into the dry season;3. following rice with intercrop patterns to

replace monoculture corn.

These designs were to test possible alternatives tothe local Tinumbaga corn variety that was commonlygrown after rlce. Three years of observation showedrice yields ranging from 2 to 2.2 t/ha.

The first year's cropping pattern trials were in the1974-75 crop season. Alternative crops selected tofollow rice were improved varieties of soybean,peanut, mung bean, and cowpea. The intercropsselected for the trials were sweet potato and glu-tinous corn. The three-crop-per-year patterns in-volved two crops following rice: sorghum followedby its ratoon, or glutinous corn followed by cowpea.Results of the trials were directly compared withthe existing rice-corn pattern.

Cropping pattepn testingfour villages w ithin a 20-km radius were selectedfor the field trials, and 10 dryland rice farmersfrom each village participated in the study. Theiryland rice crop on the experimental parcel was.anaged entire l.y by the farmer with his usualva ricty and practices. After the rice harvest, thefarmer prepared three l,000-m2 plots. He plantedtwo to two of the test crops and one to his usualcorn variety (fig. 4). IRRl's support to the farmercovered the cost of fertilizer, se ed , and, whereusC'd, pC'sticidC's. The management practices werebased on experience at IRRI and included fC'rtiiizC'rat rates of 30 kg Nlha on the legumes and 80 kg N/haon all other crops, a single cultivation for weedcontrol, and low-level insect and disease control.No phosphorus fC'rtilizer was required.Several specific management components -- weedcontrol, insect control, and nitrogen responseswere studied for several of the crops included inthe alternative patterns to evaluate the validityof the management techniques that we r e used in thepatterns. The layout of the component technologyexperiments, which were conducted within the 1,000-m2 test plots, is shown in Figure 4,

The possible residual effects of the test crops andtheir management practices on the yield of thefollowing rice crop were also evaluated. Four 10-m2yield samples of the next rice crop (1975) after thepattern trials were taken from the plots where thetest crops had been planted, as well as from theadjacent plots previously planted to corn. Yieldsfrom the different crop treatments were compared bysplit-plot analysis.

Th'e performance of the test patterns was evaluatedthrough a two-step process.

IRPS No. 33, July 1979 5

1. The agronomic suitability of each pattern tothe test site was determined. The criteriafor agronomic adaptation of a test crop weregood stand establishment under highly variablesoil moisture conditions, good pest resistance,stable yields, and no adverse effect on thefollowing rice crop. Patterns with obviousagronomic deficiences were selected for fur-ther research on management technology ordiscarded as an error in design.

2. The test patterns were also subjected toeconomic analysis. The resource requirementsof labor and cash for the patterns were eval-uated. Each participating farmer kept adaily record, on specially prepared forms,of his operations on the experimental arca~,and of labor and material inputs used.

Rainfall (rnrn)

Planting period Harvest period+ ~+~~~~+~~+.~ Dryland rice ~

~ Field co rn ; : : : : : : : : = - - - -

Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb MarFig. 3. The growing seasonof the predominant dry land rice-based patterngraphed against the normal monthly rainfall for Tanauan. Batangas. Rainfall datasource: Climatological normals for the Philippines, Philippine Weather Bureau1951-1970.

It was hypothesized that the most important criteriaa farmer considers in selecting a pattern are relatedto four economic considerations:

1. Average retu~ns to th e farrn enterprise -- ameasure of the net income the householdderives from the crop. This measure was com-puted on a per-hectarC' basis as the grossreturns, less cash costs, less seed value ofthe pattern.

2. Average returns to Labor and manaq emen t: --computed per day of labor input as: grossreturns less cash costs less seed value lessland rent.


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6 IRPSNo. 33, July 1979

3. Ave~age net ~etu~s to cash inputs -- computedas gross returns, less cash costs, less seedvalue, less land rent, less value of all laborto cash costs.

4. Ch ance of negative returns -- computed as thepercentage of cases with negative returns tothe farm enterprise.

Technology changes that are likely to have thestrongest potential for farmer adoption are thosethat substantially increase the average returns toeach of the three resources - land, labor, andcapital - yet do not significantly increase theprobability of negative returns when compared withthe existing technology.

RESULTS AND DISCUSSION

A g ~o n om i c s u it a bi l it yA summary of the yields and the stability of the testcrops is shown in Table 1. Farmer interviews inquir-ing back 3 years indicated that corn yields for theseason were about average for the area (Garrity 1975).The test season could therefore be considered reason-ably normal. The yield potential for each crop

I 60m-~

Test crop: Test crop: Check crop: Farmer's corn cropmung sorghum farmer's outside the

corn experimental area

m

1--14 m- 1--14 m- I--14 m-'--

70

during that season was approximated as the averageyields of the two highest-yielding test farms.

The yield stability of some test crops was estimatedas the standard deviation and as the percentage towhich average yields measured up to potential yieldsMung bean and cowpea yields were unacceptably vari-able because of severe insect and disease damage(Garrity 1976). Soybean and peanut had stable yieldbut from fewer replications. The remaining cropsshowed stability comparable with that of the localcorn varieties (Table 1).

Although stand establishment of soybean and sorghumduring a high rainfall period was poor, stable yieldwere obtained by revising the furrowing operation fshallower planting. No differences between riceyields following any of the test crops and thosefollowing corn were detected when the followingseason's rice crop was sampled (Table 2). The 2-3month fallow period appeared to have dissipatedpotential allelopathic effects or residual effects.If the dry season fallow period is eliminated, thethree-crop sequence pattern would be expected toexhibit the greatest potential to affect rice yieldsthrough nutrient depletion or biochemical products(Sikurajapathy 1974). However, even this patternshowed no adverse effects on yields (Table 2).

Test crop: mung

Crop-cut samplesfarmer management

Superimposed trials~ N response:~ 4 levels x 2 replica-

tions. Handweeded:

3 replicationsCarbofuran:2 replications

Fig. 4. Sample layouts of three cropping patterns in a cooperating farmer's parcel and of the superimposed trials in a croppingpattern test field.


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IRPS No. 33, July 1979

Table 1. Yield performance and yield stability of the test crops planted after rice,grown under farmers' management, eastern Ilatangas, Philippines, late wet season, 1974-75.a---------------___-----__--__----__-------_---_---

Crop Variety Farm(no.)

Av foral l

Yield (t/ha)Potential(av of 2

Measures of yieldstabilityAv as % Coeffi-of

potentialcientofvariation

Field corn

fields highestyielding_____ f ieJ.~),--__

Sorghum 1st cropSorghum ratoonMung beanCowpeaPeanutSoybeanGlutinous cornSweet potato-corn

intercrop

Orange flintUPCA varietyPopcornWhite flintCasar 3Casar 3CES 14EGI12CES 101TK 5Synthetic 22BNAS 51Synthetic 22

17482

104

141433555

1.743.051.461.362.721.450.413.11b0.82c0.92

26,000d7.20

l2,740d

2.423.522.151.363.551.880.985.92b0.88c0.99

30,580d9.18

15,350d

728768

261639

77684252939387

294873531114

81 35bGreen pods.Yield estimates are the average for three sample plots on each field.

cDry, unshelled. dMarketab1e ears/ha.

Table 2. Yields of dryland rice the year after the cropping pattern trials (test forpossible residual effects). Batangas, Philippines, 1974-75.

Test pattern Check patternFields(no. ) Yie~ Crop Yielda DifferenceCrop sequence (t/hal (t(halequence3 Rice-mung bean 2.13 Rice-corn 2.14 -0.015 Rice-cowpea 2.28 2.06 +0.223 Rice-sweet potato/corn 2.20 2.00 +0.203 Rice-sorghum-sorghum 2.29 2.13 +0.163 Rice-earn-cowpea 2.57 2.54 +0.03

aYield of the following rice crop.

The trials on component technology brought out anumber of cases where management practices designedfor the patterns could be substant~ally improved.They confirmed the importance of conducting such

trials in direct association with the pattern triaThere was strong evidence that levels of weed con-trol higher than those practiced by the farmerswould be uneconomical (Table 3) and that none of t


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8 IRPSNo33,JulyI979

legume crops responded sufficiently to nitrogen fer-tilizer application to justify the use of nitrogenfor legumes (Fig. 5). Response to carbofuran side-dressed during early vegetative growth was signifi-cant for the cowpea and glutinous corn crops, indi-cating the need for more appropriate insect controlpractices. Soybean and mung bean yields were nothigher in carbofuran-treated plots, probably becauseof their low yield potential.

Yield (t/ha)

The cost of labor and chemicals for crops rangedfrom US$35 to $105/ha (Fig. 7), with the legumeshaving the lowest costs. Each farmer's resourcelimitations influence the crop alternatives fromwhich he can select. A matrix of resource stateswas developed to illustrate which group of croppingpatterns was likely to be adopted, given differentlevels of cash and harvest labor availability (Fig.8). The amount of cash required for each crop alter-native is varied along the vertical axis, and thelabor requirement is varied along the horizontal axis.

0.2 Soybean (multivar 80~7I I

6.0 I-

Green ::~~:~~~~~~ _..----~ - - - - - - - - - - . - -

Av of all fields

4.0

Ec~nomic perfonmanceC o mp ar at i ve r e so ur ce r eq ui re me n ts . The resourcerequirements of the alternative crops differed.Labor requirement ranged from a low of 32 days/hafor glutinous corn to a high of 194 days/ha forgreen-harvested cowpea (Fig. 6). The major differ-ence was in harvest and postharvest operations. Asshown in Figure 6, a switch from corn to any of theother crops would require more available labor duringharvest time.

2.0 r-: =1.0 r- Peanut (CES 101)~ _ - - - ......-._-_."".....-. - r=:---- Soybean (TK 5)r- _._---7-'___. ..--. Mung bean (CES 14)0.6

o 15 30 45Applied N (kg/ha)

Fig. 5. Yield response to applied nitrogen by legume field cropsgrown under farmers' management in fields in 4 barrios of norneastern Batangas, late wet season, 1974-75.

Table 3. Comparison of yield using farmers' weeding practices with yields fromadditional hand weeding for 9 test crops. Batangas, Philippines, 1974-75.

Yield (t/ha) Repl icat ionsCrop, variety Farmers' Farmers' Differenceb (no. )practice practice +handweedinga

Orange flint corn 1.,71 1.88 0.17* 48Popcorn (local) 2.98 2.93 -0.05 15UPCA var. corn 3.06 2.85 -0.21 12Sorghum (Cosor 3) 2.98 2.93 -0.05 33Soybean '(TK-5) 0.92 0.83 -0.09 9Cowpea (EG 2) 3.69 4.31 0.62 18Peanut (CES 101) 0.84 0.96 0.12 9Glutinous cornc SUd 14,381 18,1,55 3,774 12Sweet potato (BNAS 6.15 5.79 -0.36 12

~Hand weeded when weeds grew 5 cm tall betweenplant'illg and canopy closllre.Significant at the 5% level. Clntercropped with sweet potato, yields inmarketable ears/ha. dlntercropped with glutinous corn, yields in mae kerabLe

tubers/ha.


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SoybeanField corn

Preharvest labor~ Harvest and~~ postharvest labor

Farmers presently grow corn after rice and utilize,latively high levels of cash inputs and a moderate

~evel of harvest labor. Adopting legume crops wouldentail a downward shift to the right -- lower cashinputs but higher harvest labor. Producing sorghummight entail moving upward to the right -- increasingboth labor and cash needs. Thus, the availableresources for each cropping pattern in relation totheir supply may limit farmers' adoption, in spiteof the potential for increasing profits.

Glutinous corn

SorghumMung bean

Peanut .-.~.-.~eturns to Y'esources. The test crops used followingrice were ranked according to their returns toresources and the chance of negative returns (Table4). Two -- sorghum and soybean -- were consistentlysuperior to orange flint corn and showed no negativereturn. Sorghum gave higher returns to the farmerthan corn, and its returns to labor and cash wereabout the same as those of corn.

Sweet potato/cornCowpea

o 20 40 60 80 100 120 140 160 180 200Days/ha

Fig. 6 . Average labor requirements of test crops, Batangas. Philippines, late wet season,1974-75.

Three other crop patterns -- peanut, sweet potato-corn intercrop, and cowpea -- showed attractiveaverage returns per hectare, but their high laborrequirements caused poor returns to labor and cash.The profitability of the last crops in the three-crop sequence also was promising (Table 4).

Table 4. The rank of each test crop with respect to four economic criteria ofprofitability and acceptability. Av for all fields of each crop, Batangas,Philippines, late wet sea son, 1974-75.

Returns Returns to Net returns Chanceto the farm labor a nd to ofenteq,rise management cash inI2uts n eg at iv e r et ur ns

Rank (US$/ha) R an k ( US $/ da y) Rank (US$/ha) Rank %

Second cropCowpea (EG 2) 1 298 8 1. 20 7 56 7 35Soybean (TK 5) 2 260 2 3.50 1 322 1 0S we et p ot at o/ co rn

crop 3 256 5 1.70 6 72 5 17Peanut (CES 101) 4 218 6 1. 50 5 79 6 33UPCA field corn 5 217 1 4.00 2 156 1 0Sorghum 6 202 4 2.10 3 101 1 0O ra nge f lin t corn 7 169 3 2.50 4 97 1 0Mung bean (CES 14) 8 163 9 1.10 8 46 8 47Popcorn (local) 9 136 6 1. 50 9 44G lu tin ous co rn

( Sy nt he ti c 2 2) 10 79 10 0.50 11 -29 9 60G lut ino us cor n

(local) 11 76 10 0.50 10 -26Third crop

S or gh um r at oo n 39 1.30 20 33Cowpea following

glutinous corn 183 2.30 158


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10 lRPS No. 33, July 1979

aSoybean

Mung bean

Peanut

CowpeaField corn

Glutinous corn

Sorghum

Sweet potato/corn0

25US$/ha

50 75 l O a

100 200 300 400Pesos/ha

500

Amount of cashrequiredduringlatewet season

(US$/ha)

Glutinouscorn (120)aGlutinouscorn (80, 120)followedby cowpea (30)

Glutinouscorn (80)Glutinouscorn (10)followed by cowpea (30)

Corn (UPCA) (40)Glutinous corn (10, 40)

Corn (Orange flint)10)Corn (UPCA) (10)

CONCLUSIONSThe initial cropping pattern trials showed that theadoption of an improved corn variety could increaseproductivity in the dryland rice-corn system studied.Soybean and sorghum appeared to be outstanding alter-native crops. Because neither is presently g rown inthe area, however, their adoption would represent amore substantial change in the system. New infra-structural support, markets, and threshers would berequired (Nicholas et al 1976).Corn is presently grown by itself. Intercropping itshows promise of substantially raising land produc-tivity but labor appears to be a potential constraint.More intercrop studies should be conducted, withspecial attention to labor requirements. Croppingpatterns with 3 crops/year were shown to be feasibleand profitable. Adoption of 3-crop patterns willultimately depend upon a shortening of turnaroundperiods between crops and the forthcoming release ofea rl ier -ma turin g dryl and rice va rieties.

600 700

ig. 7. Total cash cost per hectare of test crop. Batangas, Philippines,late wet season, 1974-75.

Very high(>100)

High(60-100)Moderate(30-60)

Lo w(0-30)

800

No variety trials were conducted on the test crops,but the need for incorporating such trials as asegment of on-site component technology trials be-came evident in this study.Experience in building a research program at thissite has uncovered several promising ways by whichdryland rice farmers may increase the productivityof their rice-corn cropping patterns. It has alsoconfirmed the usefulness of the cropping systemsresearch methodology that was being tested.

Popcorn (120)Sorghum (120)S or gh um ( 80 ,120)followedbysorghum (80)

Sweet potato/corn(80)Sweet potato/corn(80)

Corn (Orange flint)120)Corn (UPCA) (120)

Moderate (12-24)ow 12)

Corn (Orange flint)(80)Popcorn (80)Corn (UPCA) (80)

Sorghum (80)Sweet potato/corn (40)Cowpea (30, 45)

Peanut (75)

Sweet potato/corn (10)

Mung bean (15, 30,45)Cowpea (0,15)Cowpea (15)Cowpea (15,30,45)

Peanut (25, 30)orn (Orange flint)40)Popcorn (40)Sorghum (40)

Popcorn (10)Sorghum (10)

Mung bean (0)S oy be an ( 0)

Peanut (10,25)

High (25-42) Very high (43-66)Amount of laborrequiredduringharvestweek? (davs/ha)

Fig. 8. The crop management level combinations that are possible within eachof the resource statesof labor and cashavailability,

aFigur es in parentheses a re nitr ogen leve l in kilograms per hecta re . Multiple ra tes indica te acceptable management a lte rnatives. bit is assumed that the crop must be harvested in 1w eek except forcowpea (2 primings or 1/5 of harvest/week) and mung bean (1/2 of ha rves t during the fir st ha rvest week) .


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REFERENCES CITED

Antonio, E. V., and G. R. Banta. 1974.presented at a Saturday seminar, 29Los Banos, Philippines. (mimeo .)

Multiple cropping in a Batangas barrio, PaperJune 1974, International Rice Research Institute,

Barker, R. 1970. Green revolution. Curro Affairs Bull. 45:66-79.De Datta, S. K. 1972. Variety and cultural practices for upland rice. Paper presented

at a Saturday seminar, 22 July 1972, International Rice Research Institute, LosBanos, Philippines. (mimeo.)Dozina, G., and R. Herdt. 1974. Upland rice in the Philippines. Paper 74-25, Dep. Agric.

Econ., International Rice Research Institute, Los Banos, Philippines. (mimeo.)Frio, A. L., and G. R. Banta. 1974. Socioeconomic factors affecting cropping systems in

selected Batangas barrios. Paper presented at a Saturday seminar, 22 June 1974,International Rice Research Institute, Los Banos, Philippines. (mimeo.)

Garrity, D. P. 1976. A test of potential cropping patterns for an upland rice-growingregion of the Philippines. Unpublished MS thesis, University of the Philippines atLos Banos, Philippines.

Garrity, D. P., B. O. Buenaseda, R. R. Harwood, and E. C. Price. 1975. Evaluatingalternative field crop patterns for upland rice areas. Paper presented at aSaturday seminar, 28 June 1975, International Rice Research Institute, Los Banos,Philippines. (mimeo.)

IRRI (International Rice Research Institute). 1975. Report of the cropping systemsworking group. Los Banos, Philippines.Nicholas, J., D. Galang, D. P. Garrity, G. Huelgas, A. Garcia, and E. C. Price. 1976.

Removing the constraints that limit the adoption of the rice-sorghum pattern inTanauan, Batangas. Cropping Systems Program. (mimeo.)

Sikurajapathy, Mervyn.succeeding crops.Philippines.1974. The effect of the previous crop on the performance ofUnpublished MS thesis, University of the Philippines at Los Banos,

Zandstra, H. G. 1976. Cropping systems research for the Asian rice farmer. Pages 11-30in International Rice Research Institute. Symposium on cropping systems researchand development for the Asian rice farmer. Los Banos, Philippines.


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Other papers in this seriesNo.No. 2

No. 3No. 4

No. 5No. 6No. 7

No. 8No. 9

No. 10No. IINo. 12

No. 13No. 14No. 15No. 16No. 17

No. 18

Recent studies on the rice tungro disease at IRRISpeci fic soil chemical characterist ics for r ice production inAsiaBiological nitrogen fixation in paddy field studies by in situacetylene-reduction assaysTransmission of rice tungro virus at various temperatures: Atransitory virus-vector interactionPhysicochemical properties of submerged soils in relation tofertilityScreening rice for tolerance to mineral stressesMulti-site tests environments and breeding strategies for newrice technologyBehavior of minor elements in paddy soilsZinc deficiency in rice: A review of research at theInternat ional Rice Research InstituteGenetic and sociologic aspects of rice breed ing in IndiaUtilization of the Azolla-Anabaena complex as a nitrogenfer til izer for riceScientific communication among rice breeders in 10 AsiannationsRice breeders in Asia: A lG-country survey of theirbackgrounds, attitudes, and use of genetic materialsDrought and rice improvement in perspectiveRisk and uncertainty as factors in crop improvement researchRice ragged stunt disease in the Phil ippinesResidues of carbofuran applied as a systemic insecticide inirrigated wetland rice: Implications for insect controlDiffusion and adoption of genetic materials among ricebreeding programs in Asia

No. 19

No. 20No.21No. 22

No. 23No. 24No. 25No. 26

No.27

Methods of screening rices for varietal resistance toCcrcospora leaf spotTropical climate and its influence on riceSulfur nutrition of wetland riceLand preparation and crop establishment for rainfed andlowland riceGenetic interrelationships of improved rice varieties in AsiaBarrier s to efficient capi tal inves tment in Asian agricultureBarriers to increased rice production in eastern IndiaRainfed lowland rice as a research priority - an economist'sviewRice leaf folder: Mass rearing and a proposal for screeningfor varietal resistance in the greenhouse

No. 28 Measuring the economic benefits of new technologies tosmall r ice farmers

No. 29 An analysis of the labor-intensive continuous rice productionsystem at IRRI

No. 30 Biological constraints to farmers' rice yields in threePhilippine provinces

No.31 'Changes in rice harvesting systems in Central Luzon andLagunaNo.32 Variation in varietal reaction to rice tungro disease: Possiblecauses

The International Rice Research InstitutePO. Box 933, Manila, PhilippinesStamp

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irps 33 determining superior cropping patterns for small farms in a dryland rice environment: test...

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