A thesis submitted in partial fulfillment of the requirements for the degree of master of science, School of Environment, Resources & Development

Thesis (M.Sc.) - Asian Institute of Technology, 1994

The aim of this research is to appraise a sustainable way for agricultural development, through land u se planning, in Sa and Nan districts, Nan province, Thailand. The whole research processes included assessment of existing land use, analysis of problems, evaluation of land suitability and formulation of a land use plan . Three main problems for land use in the study area were identified and further discussed emphatically . They are soil erosion, forestry encroachment and unbalance (negative balance ) in soil nutrients . Based on the assessment of land suitability for paddy and upland crops, a new land use plan for the study area was made 1 and relevant recommendations to dissolve thes e problems in land use were also proposed as the result of the study . GIS ARC/INFO and ERDAS were used as tools for spatial data analysis. Linear factors combination and matrix model were used to identify land suitability for different crops and in turn, to formulate a map for land use plan. A satellite TM imagery was used to get update data for present land use pattern. The findings in the research demonstrated that the problem of degradation. of land quality was mainly resulted from the traditional behavior of shifting cultivation . Lack of agricultural land in the study area constituted a obvious limitation for agricultural development, while inappropriate land uses, if compared with land suitability, had become one of the main reasons for existing unsustainabil i ty in agricultural development. Low fertilizer input and poor land management led to a decrease of nutrients in soil . As a measurement to deal with these problems, mixed farming system was suggested to tbe as a direction for agricultural development in future. In the direction, promotion of agroforestry, adjustment in land use according to land use suitability, and diversification in rural economic development would be helpful to approach for the goal of sustainability in agricultural development .