Thesis Abstract of AGS Students

Size efficiency in rice based multiple cropping systems in the Chiang Mai valley

Zhang Rentian (1991)

In order to study farm size efficiency of rice based multiple cropping systems in the Chiang Mai Valley, four common rice based cropping systems of the study area are chosen from Nong Han subdistrict, San Sai district of Chiang Mai province. The systems are rice-soybean, rice-potato, rice-tomato and rice-garlic. Cross section data of 193, 70, 60, 67 and 60 observations for rice, soybean, potato, tomato and garlic farmers, respectively, are collected by using structured questionnair interview. Data cover the cropping period of rainy season 1989 to dry season 1990. The appropriate method of Ordinary Least squares (OLS) or Generalized Least Squares (GLS) is employed to estimate the homogeneous Cobb-Douglas production function of the individual crops. Tests of returns to scale show that there are constant returns to scale in all the five crops concerned.

In order to investigate technical efficiency of crop production, stochastic frontier production functions are estimated. Two error terms are specified, i.e., a random error with normal distribution and a one-sided error with half normal distribution. The later error term is to capture the production inefficiency of the sample. Such frontier production functions are only obtained for rice, tomato and garlic crops. It was found that on average, there are 92.6, 95.1 and 95.6 percent technical efficiency for the sampled farmers of rice, tomato and garlic, respectively. However, in the case of soybean and potato, the frontier production functions and the OLS estimators yield the same estimates, and the one-sided error term is therefore zero.

A logit model is employed to estimate factors associated with technical efficiencies of each crop production. Because of small variations of the technical efficiencies across farmers, the logit models are not statistically significant when overall F tests are used. All the coefficients are quite close to zero, although in the case of rice, larger farmers are slightly less technically efficient than the smaller ones.

Since there are constant returns to scale in crop roduction and technical efficiency is not affected by land size. Given the present technology and physical environment in the irrigated area of

Chiang Mai Valley, the rice-based farmers cannot raise their technical efficiency by increasing the farm size. Technical efficiency or production improvement may be derived from other factors. Further studies should be extended to the larger study areas with more heterogeneity of the technical and environmental background of the farmers. So that the determinants of the technical efficiency can be verified.

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