Thesis Abstract of AGS Students
Upland rice cultivation practices for sustainable production on the steep land
Sanan Peukrai (1990)
An increase in intensive cultivation on upland and highland areas under rainfed conditions, using improper practices and cropping systems, is leading to serious erosion problems. This is coupled with the degradation of both soil structure and fertility resulting in unacceptable decline in soil productivity. One possible solution to these problems should be an introduction of appropriate agronomic practices which would provide better ground cover. Social and economic facets of farmers should also be taken into considerations. An approach for research towards the above conditions is to study on soil subsystems, crop-ecosystems, farmers and their managements that may affect soil erosion.
The experiment was conducted on an area of 46% slope to examine the effects of crop management with emphasis on planting date and residue management on soil erosion in upland rice fields. Fifteen farmers were selected as cooperators. Three of their fields were used for intensive investigations on two planting dates and four types of residue management. The rest of farmers' fields were used to monitor crop cover, soil loss and cultural practices.
It was found that, early planting date did not significantly reduce top soil loss and did not significantly alter upland rice yield comparing with regular planting. Mulching with residue of corn relay cropping with lablab and residue of upland rice reduced soil loss by more than 50% comparing to the traditional practices. The average top soil loss from mulched plots was 111 t/ha or equivalent to 1 cm/yr while average soil loss resulting from non-mulched plots was 165 ton/ha or 1.46 cm/yr. The average yields of upland rice of 2.2 t/ha and 2.0 t/ha were recorded from experimental fields and observed fields, respectively. The study indicated that apart from appropriate crop management, soil conservation and soil amelioration for improving soil productivity in the long run should be considered in order to sustain the upland rice yield on the steep land of northern Thailand.