Yield-Controlling Factors in Rainfed Paddy Fields in Northeast Thailand

Abstract

To stabilize or increase yield in rainfed paddy fields in Surin province, northeast Thailand, the factors controlling yield were investigated. The undulating topography is characteristic of the region causing differences in soil properties and water availability at low and high elevations. Soil samples were collected at 52 plots from two selected sites with undulating topography in Surin province. Soil physico-chemical properties (e.g., texture, available phosphorus (P), and available potassium (K)) and hydrological conditions (e.g., hydraulic conductivity and available water capacity (AWC)) were determined. Rice grain yield and relative elevation at each plot were measured. The rice grain yield was 1.8–2.7 t ha^-1, which is in the range of the regional average. The soils were predominated by sandy texture and had low chemical fertility (e.g., low pH, available P and available K). Correlation analysis indicated that the most likely factor that limits yield of jasmine rice was AWC. Chemical properties did not correlate with the yield. The soils at higher elevations with courser texture had lower AWC and would be more vulnerable to drought. The first priority for management of rainfed rice production system to increase yield would be management of water availability.