2023 Volume 58 Issue 2 Pages 49-58
This study compared a work system consisting of deep plowing （plowing depth: 20 cm） with a chisel plow （deep plowing→wheat→shallow tillage→soybean→shallow tillage→rice: chisel deep plowing system） with a conventional system consisting of shallow tillage （depth of tillage: 10 cm） with a rotary tiller （shallow tillage→wheat→shallow tillage→soybean→shallow tillage→rice） to investigate the effects of pre-crop soil chemical property, soil hardness at rice transplantation, work speed and accuracy for rice transplantation, water requirement in depth during rice cultivation, yield, and grain quality, in a paddy upland rotation field with three-crop rotation of rice, wheat, and soybean in two years. The chisel deep plowing system resulted in lower soil hardness （11–20 cm below the surface） at rice transplantation, and the rice transplanter sank deeper, increasing the slip rate, resulting in slower work speed compared to the conventional system. In the same system, the unevenness of the plow sole slightly reduced the driving of the rice transplanter, but this was within the range that could be handled by steering wheel controls by the operator, and planting accuracy was equivalent. The water requirement in depth during rice cultivation was the same as for the conventional system, because the lower layer of subsoil became the layer limiting permeability. In the chisel deep plowing system, deep plowing before wheat cropping caused the subsoil with low T-C, T-N, and available N to mix into the plow layer, resulting in a reduction of straw weight in some areas, but there was no effect on yield or grain quality. The results suggested that deep plowing before wheat cropping with a chisel plow had little practical effect on rice transplantation and no effect on planting accuracy, water requirement in depth, yield, or grain quality, and can be managed in the same way as conventional cultivation.
