秸秆还田下氮肥用量对玉米产量及土壤无机氮的影响

研究连续2年秸秆还田下氮肥用量对玉米产量、氮肥利用率及土壤硝态氮的影响，结果表明，玉米产量随着施氮量的增加逐渐增加，施氮量达到216 kg·hm^-2时，产量最高，施氮量超过216 kg·hm^-2时产量有降低的趋势。相同施氮处理玉米产量年际变化明显，2010年较2009年产量提高0.69％~4.75％。氮肥利用率、氮肥农学利用率和氮收获指数随着秸秆还田年限的增加，均有不同程度的增加。2年0~100 cm土层土壤硝态氮含量均以施氮240 kg·hm^-2最高，且有向土壤深层迁移的趋势，对浅层地下水构成潜在的威胁。与施氮240 kg·hm^-2相比，施氮168、192 kg·hm^-2和216 kg·hm^-2处理0~100 cm土壤无机氮残留量2年平均减少39.87％、35.84％和29.38％。相同施氮处理，0~100 cm土壤无机氮累积量2010年较2009年略有降低。综合考虑玉米产量、氮肥利用率与生态环境效益，该地区最适施氮量200 kg·hm^-2左右。

Effect of Different Application Rate of Nitrogen Fertilizer Under Straw Return on Maize Yield and Inorganic Nitrogen Accumulation

We investigated the influences of different nitrogen fertilizer rate on maize production, nitrogen use efficiency and soil nitrate ni-trogen at straw return farmland for two years. The results showed that maize production increased with the increment of nitrogen fertilizer. The maize production was the highest at 216 kg·hm^-2（N216）of nitrogen use and began to decrease when the amount of nitrogen use was beyond 216 kg·hm^-2. There were significant interannual differences on maize production in the same treatment. The maize production in 2010 in-creased 0.69%~4.75%compared with that in 2009. Nitrogen use efficiency, nitrogen agronomic efficiency and nitrogen harvest index im-proved with the year of straw return. The highest nitrate nitrogen accumulation was found in the treatment of 240 kg·hm^-2（N240）in 0~100 cm soil layer. Soil nitrate content increased with the depth of soil. This may potentially increased the risk of nitrate pollution on shallow ground-water. Compared with N240, the nitrate nitrogen accumulation of N168（168 kg·hm^-2）, N192（192 kg·hm^-2）and N216（216 kg·hm^-2）were e-qually reduced by respectively 39.87%, 35.84%and 29.38%in 0~100 cm soil layer. Considering the maize production, nitrogen use efficien-cy and ecological environmental benefits, the optimum amount of nitrogen use should be 200 kg·hm^-2.