Coupling effect of water saving irrigation and nitrogen application with different treatment in paddy fields

The yields of paddy rice and variation of N uptake in each component under two water-saving irrigation regimes (G1, G2) and three fertilization Levers (F0, F1 and F2) were experimented at Tuanlin, Hubei Province, China in 2008. Experiment had shown that the N uptake varied a lot among different organs, in which grain is the highest. The amount of N uptake in grains ranged from 216.4 to 290.9 mg/kg, accounting for 30.7-42.8% of the total nitrogen uptake. The combinations of G1F1 and G1F2 are better in terms of water use efficiency than other treatments. Considering indicators of nitrogen fertilizer use efficiency and yield, G1F1 combination has the highest rate of nitrogen recovery efficiency (NRE) and nitrogen production efficiency (NPF), which can increase 22.24 kg of rice per kilograms nitrogen fertilizer yield and save 45 kg nitrogen fertilizer per hectare. The regression relationships between yield, water use, N use were conducted to analyze the coupling effect of water saving irrigation and nitrogen application with different treatment in paddy fields. On the condition that the water input was fixed at 739.15 mm, nitrogen utilization was changed between 100 to 135 kg/ha, yield ranges from 8295 to 8578 kg/ha and nitrogen use efficiency ranges from 61.3 to 82.9 kg/kg as the regression curve presents.