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土壤氮磷积累是引起农业面源污染的主要原因。为探讨土壤氮磷含量的分布状况及其对环境的影响,选取位于长沙县金井镇的小流域为研究区域,以表层土壤(0-20cm)为采样对象,按不同的土地利用方式共采集样品1 118个。以土地利用类型为分析单元,分析说明了土壤全氮、全磷的分布特征及其环境效应。结果表明:土壤全氮和全磷含量的平均值分别为1.66,0.54g/kg,变异系数分别为34.9%和46.3%,均属于中等变异。菜地土壤全氮含量主要分布在1.8～2.4g/kg区间,旱地和水田为1.2～1.8g/kg,林地和茶园为0.6～1.2g/kg;菜地土壤全磷含量主要分布在大于1.0g/kg区间,旱地为0.6～0.8g/kg,水田为0.4～0.6g/kg,林地和茶园为0.2～0.4g/kg。结合地下水氮磷含量分析表明,土壤氮素含量与地下水铵态氮含量增加有关,对地下水水质产生影响,其中水田的影响尤为突出;土壤磷素的淋失可能具有季节性差异,还有待进一步验证。
Soil nitrogen and phosphorus accumulation is the main cause of agricultural non-point source pollution. In order to explore the distribution of soil nitrogen and phosphorus content and its impact on the environment, a small watershed located in Jinjing Town of Changsha County was selected as the study area. Samples of surface soil (0-20cm) were sampled and collected according to different land use patterns 1,118. Taking the types of land use as the analysis unit, the distribution characteristics of total nitrogen and total phosphorus in soil and their environmental effects were analyzed. The results showed that the average contents of total nitrogen and total phosphorus in soil were 1.66,0.54g / kg and the coefficients of variation were 34.9% and 46.3%, respectively, which belonged to the medium variation. The total nitrogen content of vegetable soil mainly distributed in the range of 1.8-2.4g / kg, and the dry and paddy fields were 1.2-1.8g / kg, and the woodland and tea plantation were 0.6-1.2g / kg. The total phosphorus content of vegetable soil was mainly distributed over 1.0 g / kg, dry land was 0.6 ~ 0.8g / kg, paddy field was 0.4 ~ 0.6g / kg, woodland and tea garden was 0.2 ~ 0.4g / kg. Combined with the analysis of nitrogen and phosphorus in groundwater, it is indicated that the soil nitrogen content is related to the increase of groundwater ammoniacal nitrogen content, which has an impact on groundwater quality, especially in paddy fields; the leaching of soil phosphorus may have seasonal differences and remains to be further verified .