上海市郊旱作农田土壤养分资源状况

研究了上海市郊旱作农田土壤养分特征,结果表明：自80年代以来经过近20年的土壤耕作演替,上海市郊蔬菜、瓜果旱作土壤总体养分状况表现为有机质、氮素、磷素和钾素含量均很丰富。土壤氮、磷养分积累明显,较80年代第二次土壤普查有大幅度增加,一方面施用过多肥料造成浪费,另一方面带来潜在的非点源污染,对周围的环境造成威胁。各区域由于受土壤质地、土壤类型、气候条件、作物种类、耕作方式等不同土壤养分有所差异。不同耕作方式对农田土壤养分的含量影响较大,其水平高低依次为：大棚土壤、露天菜地土壤、传统自留地土壤。大棚瓜、菜地土壤有酸化趋势,菜园土壤有效磷含量远高于稻麦田土壤,这主要和施肥水平有关。

Nutrient Content of Farmland Soil in Shanghai Suburb

Nutrient content of farmland soil in Shanghai suburb was studied in the paper.The result show that in the past about 20 years' succession cultivation from 1980s,nitrogen and phosphorus nutrient of dry farmland soil in Shanghai suburbs increased greatly with fertilization increase.Employing too much fertilizer causes waste and increases dry farmland N,P potential losses possibility.Nitrate content in vegetable of greenhouse cultivation is significantly higher than that of soil open in air.The effects of different cropping systems on content of nitric nitrogen in soils and vegetable were studied.Soil nutrient level of different cultivation mode from high to low in turn is: greenhouse vegetable,melon and fruit soil,open vegetable soil,traditional vegetable soil,rice and wheat dry farmland.The results indicated that,there is more Olsen-P in vegetable soils than in paddy soil.It depends on fertilization level.