不同施氮水平对春玉米氮素利用及土壤硝态氮残留的影响

过量施用氮肥造成的环境问题日益严重，氮肥合理使用成为了人们研究的热点。通过研究不同施氮水平对春玉米氮素利用及土壤硝态氮残留的影响，为氮肥的合理利用提供依据。通过在北京市通州区农业技术推广站进行田间小区试验，研究了不同施氮量（0、50、100、200和300kg·hm^-2）对春玉米产量及氮素利用效率、氮平衡和土壤硝态氮累积量的影响。结果表明：（1）春玉米在施氮量为200kg·hm^-2时达到最高产量，为9006．4kg．hm^-2，不同氮肥水平的氮肥利用率在19．7％-25．8％之间，在100kg·hm^-2时的利用效率最高，达到25．8％。（2）作物吸氮量随输入量的增加而增加，氮盈余主要以土壤残留为主，表观损失在氮盈余中的比例虽小，但随施氮量的增加而增加的趋势更加明显。（3）硝态氮在180cm土层中的累积量随氮素输入量的增加而显著增加，在300kg·hm^-2时达到最高值，为195kg·hm^-2，在施氮水平为100kg·hm^-2时作物生长的需要就基本上能够得到满足，而在高施氮水平下（200和300kg·hm^-2）时土壤中的硝态氮出现富集现象，对环境形成一定的威胁。

Effect of Different Nitrogen Rates on Nitrogen Utilization and Residual Soil Nitrate of Spring Maize

The environmental problem caused by excessive use of nitrogen fertilizer is becoming a very important issue and rational use of nitrogen fertilizer has become the focus of concern＇increasingly. In order to provide evidence for reasonable use of nitrogen fertilizer, this paper analyzed the effects of nitrogen level on spring maize nitrogen utilization and soil nitrate nitrogen residual. With 5 level of nitrogen rates（0, 50, 100, 200 and 300 kg.hm-2）, this experiment were conducted at Tongzhou District, Beijing. The effects on spring maize production, nitrogen use efficiency, nitrogen balance and nitrate-nitrogen accumulation in soil were discussed in this paper. The results show as following： （ 1 ） the highest spring maize yield reached to 9 006.4 kg·hm^-2; the nitrogen use efficiency ranged from 19.7% to 25.8% under different rates of nitrogen fertilization, which reached the highest 100 kg·hm^-2 when 100 kg·hm^-2 was applied; （2）the nitrogen uptake by spring maize increased with the nitrogen fertilizer increasing and surplus nitrogen in soil profile dominated the residual N. Despite apparent nitrogen loss was a small part of nitrogen surplus, the apparent nitrogen loss significantly increased with the nitrogen fertilizer increasing; （3）The residual Nmin accumulated increased significantly with the nitrogen fertilizer increasing in 180 cm soil profile, which reached to the highest value 195 kg.hm^-2 at the rate of 300 kg-hm^-2 level. The nitrogen at the rate of 100 kg.hm^-2 could satisfy the spring maize demand. The environment would be threatened when the nitrate was cumulated in the soil at the rate of 200 and 300 kg. hm^-2.