由于长期大量使用，进入土壤中的化肥，一部分未被作物吸收利用和未被根层土壤吸收固定，在土壤根层以下积累或转入地下水，成为污染物质。施入土壤中的氮肥不论是以氨盐的形式还是硝酸盐的形式进入土壤中后都被硝化和亚硝化细菌转变为硝酸盐。土壤中大量的硝酸盐会在蔬菜和饲料作物中积累，并通过食物链影响人体健康。
该技术能减少农药、化肥污染，节省灌溉用水和提高肥料利用率。
This technology can reduce pesticides and chemical fertilizer pollution, to save irrigation water and to raise the fertilizer efficiency.
苏州、扬州两地畜禽粪便污染、生活污染、化肥污染和精养鱼塘污染均占一定的比例。
Suzhou and Yangzhou were polluted corresponsively by animals' feces pollution, domestic living pollution, chemical fertilizer pollution and fish breeding pond pollution.
因此，在肯定施用化肥对农业增产有重要作用的同时，探讨预防化肥污染的方法和措施是十分必要的。
So, measures to control chemical fertilizer pollution are discussed in the paper on the basis on affirm the important role of chemical fertilizer in agriculture.
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