小尺度农田土壤有机质的空间变异性

采用10m×10m高密度网格设计,在面积为10.24hm²农田内取耕层土壤样本1 024个,测定土壤有机质(SOM)含量。分析该取样尺度下土壤耕层(O～20 cm)有机质空间变异性,运用地统计学方法量化土壤有机质的空间变异特征。研究结果表明10.24hm²取样区内,土壤有机质空间分布呈弱变异性,CV为1.84%,但整体含量偏低,SOM≤1.04%。剔除趋势的土壤有机质变异函数具有较小的块金值0.000 05、块金基台比0.135和较大的变程145.5 m,Kriging插值的估计标准差仅为0.009 43%,表明该取样尺度下取样区土壤有机质空间分布的结构性变异比例高,土壤有机质具有高度空间相关性和较大空间相关范围。

Spatial variability of soil organic matter in small scale across a cropland

Data of 1024 samples (0-20 cm) collected from a 10.24 hm~2 cropland in a dense grid of 10 m×10 m were used to analyze and quantify spatial variability of soil organic matter(SOM) by geostatistical method. Within the study area, soil organic matter had weak variability as CV = 1.84%, but it was entirely low in the content no more than 1.04%. The semi-variogram of soil organic matter after eliminating the trend had low nugget variance 0.00005, small ratio of nugget to sill 0.135 and long range 145.5 m. The standard variance of Kriging estimation 0.00943% was also extremely low. Our results showed soil organic matter had strong spatial dependence across the cropland and the spatial correlation range was very large.