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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%。
In order to understand and evaluate the soil fertility and the nitrate and ammonia nitrogen content of the groundwater in the greenhouse in Taihu Lake Area, taking the Zhichuang small watershed as the research area, 192 and 54 soil samples were collected from the canopy and the open ground vegetable, And 10 soil available nutrients, total nitrogen and organic matter content, soil pH and EC value, groundwater nitrate and ammonia nitrogen content. The results showed that available nitrogen content in topsoil was 255 mg / kg, which was 2.6 times of that in open-air vegetable field. Available phosphorus and potassium in topsoil of greenhouses were 188 mg / kg and 203 mg / kg, respectively, which were not significantly different from those in open field. The contents of available N, P, K in topsoil of greenhouses were all higher than the highest standard of the second national soil census classification, and the N, P and K nutrient tables were serious. Soil organic matter content in the topsoil was 13 / kg lower than that in the greenhouse. Soil pH value in the topsoil of the greenhouse was 5.6, which was weakly acidic. Soil pH value in 37% of the planting area in the vegetable garden in this area was lower than the critical value of crop physiological disturbance. The soil EC of 16.4% vegetable planting area exceeded the critical value of crop growth retardation. According to the evaluation of drinking water health standards in our country, the results showed that the exceeding standard rate of groundwater nitrate in the shallow groundwater around the vegetable shed in Zhijinhu small watershed was 35%, and the exceeding rate of ammonia nitrogen was 8%.