南四湖流域农田土壤养分空间变异特征研究

Spatial Variation Characteristics of Farmland Soil Nutrients in the Nansi Lake Basin

土壤碳(C)、氮(N)、磷(P)是农业生产的主要养分,但农田土壤氮磷营养元素的流失也是导致区域水体富营养化的重要因素,因此,明确流域农田土壤N、P的空间分布特征对农业生产及其面源污染控制具有重要意义。本研究在野外采样调查分析的基础上,利用地统计学和经典统计学相结合的方法对南四湖流域农田土壤有机碳(SOC)、总氮(TN)和总磷(TP)空间分布特征及影响因子进行分析。结果表明,研究区土壤肥力处于中等偏下水平,其SOC、TN和TP平均含量分别为7.37、3.66 g·kg^(-1)和0.70 g·kg^(-1);其化学计量比C∶N、C∶P、N∶P平均值分别为2.34、13.20、6.68,土壤C∶N∶P平均值为10.53∶5.23∶1,说明P是该区域土壤主要的限制因素。进一步的分析表明,土壤C、N、P及其化学计量比的空间分布特征是土地利用类型和环境因子相互作用的结果,同时也受到人为因素的干扰。总之,长期的不科学施肥方式和耕作模式导致南四湖流域的氮磷负荷较大,具有较大的流失风险,是流域的农业面源污染管理需要关注的问题。

Soil carbon(C),nitrogen(N)and phosphorus(P)are the main nutrients in agricultural production,but the loss of nitrogen and phosphorus nutrients in farmland soil is also an important factor leading to regional water eutrophication.Therefore,it is of great significance to agricultural production and non-point source pollution control to determine the spatial distribution characteristics of N and P in farmland soil in the Nansi Lake watershed.On the basis of field sampling,investigation and analysis,the spatial distribution characteristics and influencing factors of soil organic carbon(SOC),total nitrogen(TN)and total phosphorus(TP)in farmland of the Nansi Lake basin were studied by using the method of geostatistics and classical statistics.The results showed that the soil fertility in the research area was at lower middle level,and the average contents of SOC,TN and TP were 7.37,3.66 and 0.70 g·kg^(-1),respectively;the average values of stoichiometric ratios of C∶N,C∶P and N∶P were 2.34,13.20 and 6.68,respectively,and the average value of soil C∶N∶P was 10.53∶5.23∶1,indicating that P was the main limiting factor in this area.Further analysis showed that the spatial distribution characteristics of soil C,N and P and their stoichiometric ratios were the results of interaction between land use types and environmental factors,and also the interference of human factors.In a word,long-term unscientific fertilization and farming patterns led to large nitrogen and phosphorus loads in the Nansi Lake basin,which had greater risk of loss and was a problem that needed attention in agricultural non-point source pollution management in the basin.