中国北方土壤硝态氮的累积及其对环境的影响

Nitrate accumulation and its implication to environment in north China

运用统计资料和调查研究资料,揭示中国氮肥用量在地区之间和作物之间分配的不平衡现象.经济发达的东南部地区和城郊地区氮肥施用量远高于西北部地区,经济作物远高于粮食作物,氮肥短缺和过量施用并存.中国北方某些地区土壤剖面硝态氮的大量累积对水体环境构成了某种程度的威胁.由于大田作物获得较高产量的'平均适宜施氮量(N 150~180 kg/hm2)'与氮素环境安全指标尚有一定距离,中国完全可以实现水体环境安全和农业高产优质的双重目标.氮肥对水体环境的影响主要是由不合理大量施用氮肥造成的.因此,中国应制定施肥技术标准和法规,鼓励农民降低氮肥用量.

This paper pointed out that the rate of nitrogen fertilizer application was variation largely among districts and among crops because of unevenly economic development in China based on statistics data and research data. The nitrogen application rate in southeast regions was far higher than that in northwest regains, and economic crops far higher than cereal crops, which leaded nitrogen fertilizer shortage and excessive usage both exist. No-point pollution in agriculture is becoming serious owing to excessive nitrogen fertilization rate and the continuously descending of recovery rate. Because the “average proper nitrogen fertilizer rate “( N 150~180 kg/hm2 ) reaching higher yield in field crops still remain certain distance with safe environment index. Therefore, we can realize the dual targets completely for water environment protection and high yield, superior quality agriculture. But China needs to take into account of formulating relevant policy and laws in order to encourage farmers in economically developed area to reduce applying nitrogen fertilizer rate, meanwhile China needs to develop conventional fertilization recommendation techniques for small scale disperse farming systems and strengthen to formulate fertilization technique standard on economic crops such as vegetable, fruit trees and flower etc.