Preliminary study on effects of rotational tillage on soil physical properties and rice yield

Conservation tillage for paddy is very common in Southern China. However, problems such as bulk density and compaction increasing occurred for paddy fields with long-term conservation tillage, which was not favorable for paddy rice growth. In order to solve those problems, rotational tillage was introduced in this study. No-tillage(NT), rotary tillage(RT), and conventional tillage(CT) were conducted in the paddy field with seven years no-tillage in double rice cropping region, Hunan Province. And treatments were NT-NT, NT-RT and NT-CT, respectively. The tillage methods were the same of early rice and late rice. Results showed as follows: NT-RT and NT-CT treatments showed lower soil bulk density and higher water storage than NT-NT during the rice-growing stage. The soil saturated mass water content and bulk density showed inverse proportion under tillage treatments. The capillary porosity at 0～5 cm soil layer was significantly higher for NT-RT and NT-CT than that for NT-NT at the 5% level, but it was not significant in deeper soil during late rice harvest. The situ soil saturated hydraulic conductivity at 0～5 cm soil layer was significantly higher under NT-CT than those under NT-NT and NT-RT at the 5% level, but the difference was not significant at 5～10 cm soil layer during drying field periods for both early rice and late rice. Yields from the highest to the lowest were NT-RT, NT-CT, NT-NT in order for both early rice and late rice, and the key of yield components was effective panicles of rice.