农田大尺度土壤水空间变异试验研究

Experimental research on spatial variability of soil water at large-field scale

为了解半干旱地区农田大尺度土壤水空间变异性特征,文章利用传统统计学和地统计学方法对清水河平原105个土壤剖面的6个水平层面的土壤水分进行了分析。发现旱作农田土壤水垂向分布与灌溉农田有较大区别。同一置信水平和精度要求下,同一深度上旱作农田土壤含水量观测试验的合理取样数目明显高于灌溉农田;深层的合理取样数目明显高于浅层。区域土壤水具中等偏弱空间相关性,土壤水高值区与灌溉区具有一致性。结果表明:在半干旱地区,农田类型(灌溉与旱作)是影响农田大尺度土壤水空间变异的重要因素,多年灌溉农田土壤水空间变异性弱于旱作农田;区域土壤水空间变异性浅层弱于深层;土壤水空间分布与农田类型具有一致性。

In order to characterize the spatial variability of soil water content at large field-scale in a semi-arid zone, this paper analysed data of 6 layers in depth based on 105 profiles in the Qingshuihe Plain with classical statistics and geostatistic methods. Prominent differences exist in vertical distribution of soil water between rainfed farmland and irrigation field. For the same confidence level and precision, the reasonable sampling number of soil water content of the rainfed farmland is obviously much higher than that of irrigation field and sampling number of the deep layers is higher than that of the shallow layers at the same depth. Spatial relativity of regional soil water content is medium to weak, and high value area of soil water content is coincident with the irrigation area. The results show that in the semi-arid zone, irrigation is not a key factor influencing the spatial variability of soil water. The spatial variability of soil water of irrigation field is weaker than that of rainfed farmland, and the spatial variability of the shallow layers is weaker than that of the deep layers. The spatial distribution of soil water content is consistent with the farmland type.