浙江宁海农用地土壤有机质和土壤养分空间变异分析

Spatial variability of farmland soil organic matter and soil nutrients in Ninghai County,Zhejiang Province

研究农用地土壤有机质和养分的空间变异,为农田管理和测土施肥提供依据,减少农民不必要的成本投入,有利于生态环境保护。以浙江省宁海县为例,采用地理信息系统(GIS)空间分析、地统计学和Kriging插值方法对耕层土壤的有机质、全氮、速效磷和速效钾等4种养分要素的空间变异特征及其影响因素进行了分析。结果表明:土壤有机质、全氮和速效钾变异函数曲线的理论模型符合指数模型,速效磷经对数转换后符合球状模型。土壤有机质、全氮、速效磷的块金值/基台值分别为50.5%,59.7%,50.5%,都具有中等的空间相关性,速效钾的块金值/基台值为77.3%,空间相关性较弱。利用Kriging插值方法,考虑趋势性各向异性,获得了各土壤养分质量分数的空间分布图,分析了空间分布规律,并对高程和土地利用类型对土壤养分空间分布影响进行了分析。研究区土壤养分的空间分布是自然和人为利用因素共同作用的结果。

Employing GIS （geographic information system） techniques and geostatistical analysis on farmland soils from Ninghai County,Zhejiang Province,China,spatial variability of soil organic matter （SOM）,total nitrogen （TN）,available phosphorus （AP）,and available potassium （AK） was determined with SOM,TN,AP,and AK contour maps obtained using ordinary Kriging interpolation. Results showed that an exponential model well fitted semivariograms for SOM,TN,and AK,whereas after a logarithmic conversion,a spherical model best fitted semivariograms of AP. The ratio of the nugget to the sill [C0 / （C0 ＋ C1）] for SOM（50.5%）,TN（59.7%）,and AP（50.5%） showed moderate spatial autocorrelation,whereas AK （77.3%） showed a slight degree of spatial autocorrelation. From the Kriging interpolation,elevation and land use type both strongly affected distribution of SOM,TN,AK,and AP. Thus,structural factors of parent material and elevation along with random factors,such as fertilization,soil management,and land use,jointly controlled spatial variability of soil nutrients in the study area.