土壤背景氮供应对水稻营养元素吸收和籽粒中营养元素含量的影响

 通过对前茬作物小麦设置施用氮肥与不施用氮肥处理研究它对土壤肥力及后茬作物水稻产量和氮肥利用率的影响。结果表明, 麦季氮肥的施用明显提高了稻季土壤全氮、铵态氮和硝态氮的含量，造成土壤背景氮偏高。与低土壤背景氮相比，在高土壤背景氮下水稻产量对氮肥的反应明显降低，氮肥利用率的各个指标均有不同程度下降。这些结果表明土壤背景氮过高是水稻氮肥利用率低的重要原因之一。在高土壤背景氮下，施用氮肥有使稻米品质变劣的趋势。

Effect of Indigenous Nitrogen Supply of Soil on the Grain Yield and Fertilizer-N Use Efficiency in Rice

The effect of applying N-fertilizer or not in wheat on soil fertility and grain yield and fertilizer-N use efficiency (FNUE) of rice in the wheat-rice cropping system were studied. N-fertilizer application in wheat significantly increased total N, ammonium-N and nitrate-N contents in paddy field, resulting in high indigenous N supply of soil (INS). Compared with low INS, the effect of N rate on the grain yield of rice was reduced significantly, and FNUE was also decreased to different extent under high INS. These results indicated that high INS was one of the main reasons for low FNUE in rice. Under high INS, rice grain quality tended to be worse.