2022 Volume 57 Issue 4 Pages 201-214
This study was performed to establish a deep plowing system using a chisel plow to improve soil compaction in the subsoil and poor drainage in the plow layer, both of which are related to low yield of wheat and soybean in an upland field converted from paddy field with three-crop rotation of rice, wheat, and soybean in two years. The depth of plowing and frequency of deep plowing were examined under three-crop rotation in two years. The results showed that deep plowing with a chisel plow after rice harvest （before wheat） under this rotation system improved soil compaction of the subsoil and poor drainage of the plow layer throughout the wheat and soybean growing periods. The optimal plowing depth for deep plowing with a chisel plow should be about 22 cm, taking into account drainage of the plow layer, operating accuracy of seeding, reduced rate of work associated with deep plowing, and other risks. Furthermore, the effects of deep plowing on soil physical properties in the subsoil were comparable between deep plowing before both wheat and soybean cultivation and deep plowing only before wheat cultivation, indicating that when rice was subsequently planted, deep plowing had little effect on the succeeding crop of wheat. Therefore, in an upland field converted from paddy field with three-crop rotation of rice, wheat, and soybean in two years, it was considered reasonable and effective to use a chisel plow after rice harvest （before wheat） at a plowing depth of about 22 cm, which was beneficial for both wheat and soybean crops.
