Chisel Plough Cultivation Enhanced Soybean Growth and Yield due to Improvement of Soil Water Drainage in Upland Field Converted from Paddy Field in Mountainous Areas

Abstract

Stabilization and increase in soybean yield in three croppings (rice-wheat-soybean) in two years are important issues in cultivation on upland fields converted from paddy fields with poor drainage in mountainous areas. This study investigated the effects of improved drainage cultivation with a chisel plough on the soil physics and the growth and yield of soybean in local fields and fields in the research center in 2016 and 2017. The penetration resistance value in the plot of cultivation with a chisel plough (chisel plot) at a depth of 13 cm to 20 cm was lower than that of cultivation without a chisel plough (the plot without chisel), because the subsoil layer was soft. Decrease in the value of the soil matric potential at 15 cm depth in the chisel plot tended to be greater than that in the plot without chisel, especially in the wet soil. After using a chisel plough before sowing wheat, these effects such as superior soil drainage characteristics were succeeded to the next soybean cropping. Compared with the plot without chisel, soybean in the chisel plot had a higher establishment ratio, larger number of ripening pods and a higher yield. These results suggest that cultivation with a chisel plough would bring about superior soil drainage characteristics, an improved establishment ratio and higher yield of soybean in upland fields converted from paddy fields with poor drainage in mountainous areas.