Efficiency of Nutrient Utilization of Controlled-release Nitrogen Fertilizer for Rice at Different Soil Fertility Levels

Field experiments were conducted in Changsha and Hengshan county of Hunan province. Yield increase efficiency and nutrient utilization of controlled-release nitrogen fertilizer in different paddy soils was studied. Results showed that it could be profitable to determine rate of controlled-release nitrogen fertilizer according to the basic fertility level of paddy soil. It was recommended that the amount of rice controlled-release nitrogen fertilizer should be increased in paddy soils of low fertility. The amount should be decreased in paddy soils of high fertility. The Yield of rice by controlled-release N fertilizer application (90 kgN/ha) was 4.9%-16.4% higher than the urea treatment of equal N amount, was 13.8%-60.9% higher than no N plot among different basic soil fertility level. Nitrogen recovery of rice controlled-release nitrogen fertilizer was changed in the ranged from 69.7%～86.9%, and was 37.5% higher than that of urea treatment with 90 kgN/ha by early rice and later rice in different basic soil fertility level. N recovery of controlled-release nitrogen fertilizer was related with soil fertility level. One time application of controlled-release nitrogen fertilizer had higher physiological and agronomic efficiency.