Nitrogen Use Efficiency of Wheat as Affected by Long-Term Fertilization in the Typical Soil of China

【Objective】The study was conducted to investigate the effect of long-term fertilization on nitrogen use efficiency(NUE) of wheat in various soil types of China,aiming to provide scientific references for establishing appropriate fertilization mode and improving NUE.【Method】 The NUE of wheat were examined in three treatments: chemical N fertilization(N),combined chemical fertilization(NPK),and combined chemical fertilization with manure(NPKM) in four typical soils(Aqui-cinnamon soil,AC;Fluvo-aquic soil,FA;Cumuli cinnamon soil,CC;and Red soil,RS) of China.【Result】 The NUE declined in the N treatments at all sites,with annual decreasing rate of 0.61%-2.32%.The averaged NUE was 6.5%-14.4% in the N treatments during the entire experiment periods.NUE in NPK treatments was significantly higher than that in N treatments,with averaged value of 20.5%-78.5%.Nitrogen use efficiency increase over time under long-term NPK fertilization at most sites.However,the NUE of NPK treatment showed a clearly decreasing trend in the red soil.Compared to the NPK fertilization,manure fertilization resulted in more stable NUE especially in the red soil where the averaged NUE value was 15.9% higher in the NPKM fertilization than in the NPK treatment.In addition,soil nitrogen,phosphorus,and potassium were lost under N fertilization but increased under NPK fertilization.The results indicated that balanced fertilization was beneficial to the improvement of NUE of wheat.【Conclusion】 Long-term fertilization with single N can result in a decrease NUE of wheat.The continuous manure fertilization could not only keep well capacity of sustainable soil nitrogen supply,but also prevent soil acidification in south China.