SUSTAINABLE AGRICULTURE ON SLOPES: THE EFFECTIVENESS OF INTERNATIONAL DEVELOPMENT PROJECTS IN FOSTERING SOIL CONSERVATION IN NORTH THAILAN

This study evaluates the performance of three international assistance projects in controlling soil erosion, increasing sustainable yields, and improving farmer welfare in hilly lands of Chiang Mai and Nan Provinces, Thailand. A team of seven researchers gathered primary data on 138 project-treated fields and 82 non-project controls. Interviews with each farmer provided information on yields and project participation, perception of erosion and conservation, and household welfare. Staffs and managers of assistance projects supplied information on project goals and activities. The study hypothesized that (a) soil conservation leads to improved sustainable yields, and (b) projects effectively transfer soil conservation technology to farmers.;The main findings are: (1) Projects have succeeded in reducing erosion rates 33 to 75 percent using control structures, but they have failed to teach farmers agronomic conservation methods necessary to limit soil degradation on project-treated fields. Mean erosion rates exceed creation rates in all sample villages. (2) Exposure of subsoil during construction of bench terraces has led to declining yields and reduced farmer acceptance of soil conservation. (3) Lack of maintenance limits the effective life of structures and indicates limited commitment by farmers to conservation. (4) Projects tend to use only one type of conservation method, regardless of site conditions and prevailing agricultural practices. (5) Yield levels do not correlate well with conservation, erosion rates, or project participation. However, sustainable production correlates with high yields and with agronomic conservation benefits such as increased organic matter and reduced sheet erosion. (6) Projects have succeeded in replacing swidden cultivation with settled farming in project villages, although most farmers still favor exploitive rather than conservative farming techniques. (7) Sustainable production is close to being achieved on farms practicing agronomic conservation. Swiddens (which are rarely tilled more than 4 years) and fields using only structural conservation display declining yields. Optimally, a combination of structural and agronomic conservation should be used. (8) Success of assistance projects varies according to farmer involvement, project design and organization, and integration of social and technical aspects of soil conservation.