Soil Erosion Problems In Northeast Thailand: A Case Study from the View of Agricultural Development in a Rural Community Near Khon Kaen

摘要

We uncovered relations among soil erosion problems, farming practices and agricultural landscape in the study site. The introduction of cash crops in the upland starting in the 1970s caused a drastic change to the agricultural landscape, i.e., the former landscape, which was composed of forest-covered uplands and lowlands occupied by rain-fed paddy fields for cultivation of subsistence rice, has completely changed into the new landscape formed by the replacement of forests with crop fields in the upland. Agricultural development from the introduction of cash crops resulted in the birth of a new village from a mother village in the study site. Such agricultural development also caused soil erosion problems in rain-fed paddy fields of the lowland as well as crop fields of the upland. Soil erosion of crop fields, which were converted from forests to sustain the population growth of the rural community, was caused by the modification of site hydrology by decreasing the infiltration capacity, coupled with a strong intensity of rainfall in the rainy season and sandy soil. On the other hand soil erosion of rain-fed paddy fields resulted from culverts in the road that crossed the valley of rolling hilly land. This unique erosion could be caused by the imbalance between the road improvement due to the development of rural community and farming systems of rain-fed paddy fields that remained unchanged in spite of the development of rural community. In conclusion, agricultural development of the study site caused not only the typical soil erosion in crop fields of the upland, but also the unique soil erosion in rain-fed paddy fields of the low land. Both types of soil erosion depend on underlying factors such as agricultural development, rural community transformation, and population growth as well as by direct factors such as rainfall intensity, topographical features, farming systems and road culverts.