Effect of Slow Release Fertilizer on Nitrogen Absorption and Fertilizer Nitrogen Recovery Rate in Chinese High-Yielding Rice Cultivars

The amount of nitrogen (N) absorbed from fertilizer before the young panicle formation stage in Chinese high-yielding cultivars, Yangdao 4 (YD) and Wuyugen 3 (WY) was increased significantly by applying a slow-release fertilizer. This resulted in a significant increase in fertilizer N recovery rate, and significantly increased the N content at the maturity stage in YD. The amount of N absorption from the young panicle formation stage to heading stage was significantly higher in YD than in WY, while WY absorbed a significantly larger amount of N than YD before the young panicle formation stage. This suggests that in YD, nitrogen is absorbed for a longer period from the slow-release fertilizer than in WY. The fertilizer N recovery rate in YD was higher in the sigmoid-type fertilizer than in the linear-type fertilizer, followed by the split application of ammonium chloride (C). It significantly increased with increasing amount of N fertilizer applied in C treatment, but not with linear or sigmoid-type fertilizers. These results show that the application of sigmoid-type slow-release fertilizer improves the fertilizer N recovery rate in these cultivars and the amount of N fertilizer to be applied can be decreased, thereby reducing the burden to the environment.