亚热带小流域土壤氮磷分布及其环境效应

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。

Distribution of Soil Nitrogen,Phosphorus and Its Environmental Effects in a Small Subtropical Watershed

Accumulation of nitrogen and phosphorus is the main reason of agricultural non-point source pollution.To explore the distribution of nitrogen and phosphorus content and its impact on the environment,this study chose a small watershed of Jinjing town,Changsha county as the research area.There were 1 118 surface soil samples(0-20 cm) collected by different land use patterns to analysis the distribution of soil total nitrogen,total phosphorus and its environmental effects.The results showed that: The average contents of soil total nitrogen and total phosphorus were 1.66,0.54 g/kg,respectively,whereas the variation coefficients were 34.9% and 46.3%,both belonging to the medium variation.The contents of vegetable soil total nitrogen mainly distributed in 1.8~2.4 g/kg range,arid land and paddy fields were 1.2~1.8 g/kg,forest and tea plantations were 0.6~1.2 g/kg;the contents of vegetable soil total phosphorus mainly distributed in greater than 1.0 g/kg range,arid land was 0.6~0.8 g/kg,paddy fields was 0.4~0.6 g/kg,forest and tea plantations were 0.2~0.4 g/kg.Combining with the analysis of groundwater nitrogen and phosphorus content,it indicated that soil nitrogen content had relationship with the increase of groundwater ammonium nitrogen content,and impacted the quality of groundwater.Among which,paddy fields was particularly prominent.Leaching of soil phosphorus may have seasonal variations,which need to be further verified.