Effects of Slope-related Soil Properties on Upland Rice Growth and Yield under Slash-and-burn System in South Konawe Regency, Southeast Sulawesi Province, Indonesia

This study examined how slope-related soil physicochemical properties affect the growth and yield of upland rice subjected to slash-and-burn. The yield survey and soil analysis were performed at a hillside farm in Southeast Sulawesi Province, Indonesia. Organic-C, total-N, available-P and exchangeable-Ca, Mg, and K tended to increase further down the slope, leading to greater rice growth and yield. The resultant yield increase was mainly attributable to higher spikelet number per square meter. Total-N explained variation in spikelet number per panicle, but not variation in grain yield. Among the tested soil physicochemical parameters, only organic-C was significantly and positively correlated with rice growth and yield. In addition, most other parameters increased with soil organic-C. These findings indicate that organic-C in the soil is important to the growth and yield of upland rice cultivated with slash-and-burn systems, although other complex relationships may exist between rice productivity, the environment, and agricultural management factors. Moreover, our results imply that position on a slope affect rice growth and yield.