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20年来,中国施用氮肥大大地增加了作物产量。但在陕西米脂县川道地区由于大量施用氮肥,导致饮水中的硝态氮含量已达到不可接受的程度。本项研究揭示,在川道地土壤水中硝态氮含量非常高,而在丘陵顶部和坡地上的土壤水中硝态氮含量比较低。在200～400cm土层中,川台地为272kg/hm~2,川滩地为172kg/hm~2。该区土壤剖面中水分入渗深度每年约为2m左右。假如在200cm深度以下的硝酸盐作物根系不能吸收,那么在土壤剖面中每年每公顷在川台地和川滩地上将要淋失的氮肥即分别相当于损失148美元和94美元。
China’s application of nitrogen fertilizer has greatly increased crop yields in the past 20 years. However, due to the large amount of nitrogen fertilizer applied in Chuan Road, Mizhi County, Shaanxi Province, the nitrate nitrogen content in drinking water has reached an unacceptable level. This study revealed that soil nitrate-N content in Chuandao soil is very high, while nitrate nitrogen is relatively low in soil water at the top of hills and on sloping land. In 200 ~ 400cm soil layer, Chuantai land was 272kg / hm ~ 2 and Chuantan land was 172kg / hm ~ 2. The water infiltration depth in the soil profile of this area is about 2m per year. If the root system of nitrate crops below 200cm depth can not be absorbed, the amount of nitrogen fertilizer to be leached on Chuantai land and Chuantan land per hectare per year in the soil profile is equivalent to a loss of 148 U.S. dollars and 94 U.S. dollars respectively.