Phosphorus Application during Rapeseed Season Combined with Straw Return Improves Crop Productivity and Soil Bacterial Diversity in Rape-Rice Rotation

Abstract

Rape-rice rotation uses large amounts of phosphate fertilizers with low utilization rates and large amounts of straw. Therefore, it is necessary to establish a suitable phosphorus fertilizer application mode for straw-returning in a rape-rice rotation system. The treatments were: P application with straw return (T2) and without straw return (T1), no P application in either rapeseed season (P1), application of 120 kg·ha−1 P2O5 on rapeseed and 90 kg·ha−1 P2O5 on rice (P2), application of 120 kg·ha−1 P2O5 only on rapeseed (P3), and application of 90 kg·ha−1 P2O5 only on rice (P4). The results showed that the maximum rapeseed grain yields of T2P3 were increased by 15.57% and 21.05% in 2019 and 18.02% and 32.69% in 2020 compared with those of T2P2 and T2P4, respectively. In the rice season, the maximum yields of T2P3 increased by 17.31% and 6.67% in 2019 and 16.42% and 5.23% in 2020 compared to those of T2P2 and T2P4, respectively. Meanwhile, soil bacterial diversity reached its highest under the T2P3 and T2P2 treatments, but the difference was not statistically significant. Straw return combined with phosphorus application of 120 kg·ha−1 during rape season increased crop productivity and diversity of the soil bacterial community structure during rape-rice rotation.