太湖地区大棚菜地土壤养分与地下水水质调查

为了解和评价太湖地区大棚菜地土壤肥力及其周边地下水硝酸盐和氨氮含量状况,以直湖港小流域为研究区域,采集大棚和露天菜地土样192和54个,浅层地下水样26和10个,分析土壤速效养分、全氮和有机质含量,土壤pH和EC值,地下水硝酸盐和氨氮含量。结果表明,直湖港小流域大棚菜地耕层土壤速效氮含量为279 mg/kg,是露天菜地的2.6倍。大棚菜地耕层土壤速效磷、钾含量分别为188 mg/kg和203 mg/kg,与露天菜地无显著差异。大棚菜地耕层土壤速效氮磷钾含量均高于全国第二次土壤普查分级的最高标准,且氮磷钾养分表聚严重。耕层土壤有机质含量偏低为13/kg;大棚菜地耕层土壤pH值为5.6呈弱酸性,37%的该区大棚菜地种植面积土壤pH值低于作物生理障碍的临界值,该区16.4%的大棚蔬菜种植面积土壤EC值超过作物生育障碍临界值。参照我国生活饮用水卫生标准评价,结果表明,直湖港小流域大棚菜地周边浅层地下水硝酸盐超标率为35%,氨氮超标率为8%。

Investigation of soil fertility and quality of ground water in greenhouse vegetable fields of Tai Lake region

In order to find out and evaluate soil fertility and pollution status of nitrate and ammonia N in ground water in greenhouse vegetable fields of Tai Lake Region, 192 and 54 soil samples, 26 and 10 groundwater samples were collected from the greenhouse and no-covered field respectively in the watershed of Zhihu harbor, and then the contents of mineral N, olsen-P, exchangeble-K, total N, organic matter, the values of pH and EC of soil samples and the contents of nitrate N and ammonia N in the ground water were analyzed. The results revealed that the mineral N content was 279 mg/kg in greenhouse plow layer soil, which was 2.6 times of no-covered. The Olsen-P and exchangeable-K contents were 188 mg/kg and 203 mg/kg respectively in greenhouse plow layer soil, which showed no significant difference between greenhouse and no-covered vegetable fields. N, P and K were easily accumulated in the surface layer of the greenhouse vegetable fields. Organic matter content was 13 g/kg in plow layer soil, which was lower than the classification standard of soil fertility. pH value was 5.6 in greenhouse plow layer soil and 37% of the total cultivated area was below the critical value of the vegetable physiological barrier. 16.4% of the total cultivated area was above the critical value of the vegetable inbreed EC barrier. According to the national sanitary standards in drinking groundwater, the exceeding standard rate of nitrate N and ammonia N reached 35% and 8% respectively.