Effects of nitrogen fertilization on yield and nitrogen use efficiency of hybrid rice

The effects of different nitrogen applied levels on rice yield and nitrogen utilization were studied in fields of north of Zhejiang Province in order to get the optimal nitrogen application amount. The rice cultivar is hybrid “Zheyou 12”, and the soil is marinefluvigenic yellow loamy paddy soil. The results show that yield, nitrogen physiological efficiency(PEN)and recovery efficiency(REN)of rice are at their highest levels under the nitrogen application rate of N 210 kg/ha, and compared with the treatment without nitrogen fertilization, the yield, PEN and REN are increased by 54.4%, 34.1 kg/kg and 58.6%, respectively. The nitrogen use efficiency and rice yield are increased under the combined application of organic fertilizer and the nitrogen fertilizer at N 150 kg/ha, and compared with the treatment without nitrogen fertilization, the PEN, REN and yield are increased by 33.1 g/g, 50.6% and 61.2%, respectively. In the ecological conditions for the experiment, integrating three factors of rice production, ecological effects and economic benefits, the reasonable amounts of nitrogen application on rice are in the range of N 234.8-241.0 kg/ha, and the corresponding economic and ecological yields are in the range of 9796.4-9801.9 kg/ha.