In this trial, the effects of the reduction of nitrogen fertilizer application on the nitrogen absorption and utilization of crops and soil N balance were studied with the continuous two cycles of rice-wheat rotation. The results showed that based on traditional fertilizer recommendation (N 195 kg/hm2 in wheat, 210 kg/hm2 in rice, according to the effects of base fertilizer,tiller fertilizer and jointing fertilizer of 40 % , 30 % , 30 % three times applying) , and nitrogen amount were reduced by 20 % , combined with integrated control measures, the yield was not reduced, but apparent recovery rate, agronomic efficiency, nitrogen partial factor productivity and contribution rate were enhanced. The nitrogen accumulation in crops increased with the increase of nitrogen fertilizer application volume, also the same as the residue of soil inorganic nitrogen and nitrogen apparent losses. The nitrogen requirement amount of wheat was higher than that of rice for producing the same quantity of grain yield, but in the apparent loss of nitrogen, the rice was higher than wheat.%本试验采用连续两个轮作周期的稻麦轮作定位试验,研究了氮肥减施对作物氮素吸收、利用和土壤氮素平衡的影响.结果表明,在传统推荐施肥(小麦N 195kg/hm2,水稻210 kg/hm2,均按底肥40％、分蘖肥30％、拨节肥30％分3次施用)的基础上,氮量减施20％,并配合综合调控技术措施,产量并没有降低,而且氮肥表观利用率、农学利用率、氮肥偏生产力和贡献率均得到提高.氦素在作物体内累积随着施量的提高而提高,土壤无机氮残留量和氮素表观损失也有相同的规律.生产相同数量的籽粒产量的需氮量小麦高于水稻,而氮素表观损失,则水稻高于小麦.
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