Contents & Foreword, Characterizing And ... - IRRI books

The availability of low-saline irrigation water to farms had a positive and statisticallysignificant effect on the intensity of land use applied by surveyed farms acrossall our land-use estimates. The magnitude of the effect of high-quality irrigation oncropping intensity was much greater than the effects of other explanatory variablesincluded in the model. Rainfall levels had mixed effects on the cropping intensity ofsurveyed farms. In years with normal to high rainfall, increased rain was associatedwith increased cropping intensity. In 1996, however, rains were particularly heavyand higher rainfall in that year was associated with significantly reduced levels ofcropping intensity among surveyed farms. The size of families’ landholdings relativeto their available labor had mixed signs across estimates and years, but generallysupported the hypothesis that the relative scarcity of land to labor leads to more intensiveland use. Results showed that rice variety selection was clearly linked to croppingintensity, with the adoption of modern short-duration rice varieties playing a keyrole in enabling more intensive rice cultivation. Farm-level investments in land levelingor dike construction were shown to increase the likelihood that farms adoptedintensive rice agriculture in the panel data-based land-use estimates. Other variablessuch as the level of education in the household, the age of the household head, or thefarming experience of the family did not have consistent statistically significant effectson land use in our estimates.Rice production and supply estimates were able to explain most of the observedvariation in the levels of rice output and marketed surplus across surveyed farms.Adjusted R 2 coefficient estimates across the production and supply models rangedbetween 0.70 and 0.93, with panel data estimators performing better than estimatorsusing only single years of the survey data. Variables estimated to have positive andstatistically significant effects on the level of output included farm size, the croppingintensity pursued by farms, the amount of hired labor used in crop cultivation, and thelevel of seed application. The use of modern versus traditional varieties did not havea consistent positive effect on rice production. The principal effect of the use of modern(usually short-duration) varieties appeared to be to enable farms to pursue moreintensive rice production. Other variables included in the production estimates suchas amount of fertilizer or pesticide applied on the crop had positive and statisticallysignificant effects on rice production in only a few of the production estimates. Theestimated price elasticity of supply ranged between 0.145 and 0.319 in year-aggregatesupply estimates. The rice price had a consistent positive and statistically significanteffect on rice marketed surplus, as did the quantity of urea applied to the crop.When estimates included the price of urea, occasional positive and statistically significantcoefficient estimates were obtained. The increasing price of urea during theyears of the survey appears to have been dominated by a broader trend toward increasingurea use among surveyed farms during these years.Simulation model for evaluation of investmentsThe implications of model estimates can be better understood by using them to formulatea simulation model to assess the effect of policy changes or investments ininfrastructure on land use and rice production. The results of a simulation modelIntegration of biophysical and socioeconomic constraints . . . 465