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作 者 ：杨宪龙 路永莉 同延安 林文 梁婷

期 刊 ：植物营养与肥料学报 2013年 19卷 1期 页码：68-77

关键词：长期施氮；秸秆还田；作物产量；累积氮肥利用率；无机氮残留；氮平衡；

Keywords:long-term N application, straw returning, crop yield, NUE, residual Nmin, N budget,

摘 要 ：在陕西关中小麦-玉米轮作区，通过4年田间定位试验研究了长期施氮和秸秆还田对作物产量、 氮肥利用率、 0—100 cm土层无机氮残留及体系氮平衡的影响。结果显示，施氮能显著提高作物产量，小麦、 玉米4年平均产量增幅分别为64.1%和48.8%，均随施氮量的增加先增加后减小。优化施肥小麦、 玉米氮肥用量较农民习惯施肥分别减少了27.3%和55.6%，但连续4年作物产量没有显著降低。秸秆还田随种植年限的推移其增产效果逐渐明显。轮作体系作物累计氮肥利用率逐年升高，前8季作物达33.3%~56.6%，说明氮肥后效明显。施氮增加了0—100 cm土层无机氮残留，且NO₃^--N残留明显高于NH₄⁺-N，并与年施氮量表现出显著的正相关关系，秸秆还田对无机氮残留影响不明显。体系氮平衡表明，随施氮量增加，作物累计氮素吸收先显著增加后增幅不变，而残留Nmin和表观损失均显著增加。秸秆还田措施下，作物累计氮素吸收和氮肥利用率分别增加了13.0% 和26.2%，氮素表观损失和损失率均降低了22.9%，但对残留Nmin和表观残留率的影响不显著。

Abstract:In a 4-year field experiment, effects of the longterm N application and straw returning on crop yield, NUE, residual Nmin and N budget are studied under wheatcorn rotation system in the Guanzhong Plain. The results show that the N application significantly increase the crop yields of winter wheat and summer maize with averages of 64.1% and 48.8% respectively, and the trends are increased at first and then decreased with N application rate increasing. The yields are not decreased in the 4-year successive harvests, though the nitrogen application rates are reduced by 27.3% for winter wheat and 55.6% for summer maize. The crop yields under the straw returning on are increased gradually with planting years. The accumulative NUEs of crops are increased with the increase of cropping rotation time and the NUEs in the four years are from 33.3% to 56.6%, which shows that the N fertilization has a carryover effect. The nitrogen application significantly enhances the residual Nmin in which the residual nitrateN is apparently larger than the residual ammoniumN. The residual nitrateN in 0-100 cm soil layer shows a positive relationship with the annual N fertilizer inputs. The straw returning shows no effects on mineral N residual in this experiment. The results of N budget show that the N accumulative uptakes by the crops are firstly increased and then declined, while the residual Nmin and apparent N loss are increased significantly. The straw returning has strong influences on nitrogen budgets of the rotation system, N accumulative uptakes by the crops, and the NUEs are increased by 13.0% and 26.2%, respectively. Both the apparent N loss and apparent N loss efficiency are decreased by 22.9%, while the apparent fertilizer N is kept in soil (Nmin  residual) and its percentage in the straw returning treatment is not affected significantly compared with the treatment without straw returning.

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