Rotation with oilseed rape as the winter crop enhances rice yield and improves soil indigenous nutrient supply

Crop yield and soil fertility are significantly influenced by crop rotation practices and plant nutrition management. A 3-year field experiment testing different fertilizer inputs under oilseed rape-rice (OR), wheat-rice (WR), and fallow-rice (FR) rotations was performed to investigate the effects of different rotations on rice yield and soil indigenous nutrient supply. Rice yield under the OR rotation was significantly higher than yields under the other two rotations, especially when no fertilizer was applied (control treatment) or when the applied fertilizer lacked N (no-N treatment). The rice grain yields of the control and no-N treatments under OR rotation exceeded those under the WR and FR rotations by 20.5 % and 14.5 % (control), and by 16.2 % and 14.9 % (no-N), respectively. The increase in rice yield was significantly related to the soil indigenous nutrient supply. Linear regression analysis showed that for every 1.0 kg increase in soil N supply, the rice yield increased by 86.2-136.8 kg ha-1. The indigenous N supply in the rice season under OR rotation was 22.0 % and 19.5 % higher than supplies under WR and FR rotations, respectively. The indigenous P and K supplies under OR were 21.9 % and 12.8 % higher, respectively, than those under WR. The highest N and P surpluses and lowest K deficits occurred under OR rotation. These effects were significantly correlated with the soil indigenous nutrient supply. Thus, a surplus of 1.0 kg N ha-1 increased the soil indigenous N supply by 0.04-0.29 kg N ha-1. Consequently, the use of oilseed rape as a previous crop in a rotation protocol could significantly increase rice yield and soil indigenous nutrient supply capacity. Inclusion of this rotation practice into agronomic systems that currently use wheat-rice and fallow-rice rotations should bring significant benefits.