县域农田土壤有机质空间变异及其影响因素分析

研究县域农田空间变异特征可以为培肥地力，增加作物产量提供指导。本文运用地统计学和 GIS相结合的方法，研究了四川省双流县土壤有机质的空间变异特征及其影响因素。结果表明： ①研究区域土壤有机质含量处于中等偏高水平，平均值为 29.72 g/kg，变异系数为 30.11%，属中等变异强度。②有机质变异函数的理论最佳模型为球状模型，块金值与基台值之比为12.67%，表明有机质含量具有强烈的空间相关性，空间相关距离为 91.10 km，普通Kriging插值表明土壤有机质含量呈现北部向东南部减少的趋势。③影响有机质空间变异的主要因素为土壤类型、地貌类型等结构性因子，而土地利用方式、施肥等随机性因子也对有机质空间变异产生重要影响，其中秸秆还田是有机质含量普遍升高的原因。

Spatial variability of soil organic matter and its influencing factors at county scales

Study on the spatial variability of soil organic matter can provide useful information for promoting land productivity. In this investigation method of geostatistics combined with GIS was used to analyze the spatial variation characteristics of soil organic matter and its influencing factors in Shuangliu County of Sichuan Province, China. The results indicated that soil organic matter was 29.72 g/kg which was more than middle level, and its coefficient of variation was 30.11%. The spherical variogram model fitted the sample variograms very well, and it was highly spatial correlated, the spatially dependent range was 91.10 km, C0/(C0+C) was 12.67%. Through ordinary Kriging interpolation, the soil organic matter in the north was highest and was reducing towards the southeast. SSR test indicated that the soil organic matter was significantly different depending on soil types and terrain conditions. The land use and fertilization application rate strongly affected soil organic matter, and its increasing trend was attributed to straw manure.