Effect of controlled-release nitrogen fertilizer on reducing nitrogen runoff loss and increasing nitrogen recovery efficiency of rice plant

The effects of controlled-release nitrogen fertilizer (CRNF) on nitrogen runoff loss, rice yield and nitrogen content in rice plant were studied under double rice cropping system in paddy soil of Dongting Lake Area using lysimeter simulation. The results showed that the amount of total nitrogen (TN) losses due to runoff in CRNF treatment and 70% CRNF treatment was reduced by 24.5% and 27.2% (P0.05) compared with urea treatment, because of great decrease of nitrogen concentrations in runoff water with CRNF application during the early growth stages of rice (within 10d after application). The total yields of early and late rice in two types of paddy soils were increased significantly in both controlled-release nitrogen fertilizer treatments than in urea treatment, especially in alluvial sandy loamy paddy soil, which was increased by 4.95%(P0.01) in the 70% CRNF treatment compared with the urea treatment. Applying CRNF could also increase N contents in rice plant and grain during late growth stage of rice compared with using urea. In Alluvial sandy loamy paddy soil, N contents in rice grain of early and late rice were increased by 9.4%(P0.05) and 23.3%(P0.01) in the 70% CRNF treatment as compared with the urea treatment. The nitrogen utilization efficiency was higher in the 70% CRNF treatment than in the urea treatment, especially in the alluvial sandy loamy paddy soil.