四川盆地耕地土壤pH空间变异特征及影响因素

基于四川盆地4362个耕地表层土壤（0~20cm）采样点数据，采用地统计学法、方差分析和回归分析法分析了该区域耕地表层土壤pH的空间分布特征及其不同影响因素对土壤pH空间变异的影响程度。结果表明：研究区土壤pH值在3.53~8.76之间，平均为6.54，以微酸性至中性为主；变异系数为18.89%，属于中等程度的空间变异。半方差分析表明，指数模型为该区域土壤pH变异的最佳拟合模型，块金效应为49.97%，属于中等程度的空间自相关性，受结构性因素和随机性因素共同影响。空间分布上，整体呈现北高南低、西高东低、中间高四周低的空间分布格局。回归分析结果表明，土壤pH的空间变异主要受到土壤类型、降雨量、地形和耕地利用方式的影响。其中，土壤类型和降雨量分别能独立解释14.6%和11.6%的土壤pH空间变异，是该区域土壤pH空间变异的主控因素。

Spatial Variability of Cropland Soil pH and Its Influencing Factors in Sichuan Basin

Based on 4362 topsoil samples (0~20cm) collected in the cropland, this study used geostatistical methods, variance analysis and regression analysis to evaluate the spatial distribution characteristics of soil pH and its influencing factors in the Sichuan basin, China. The results showed that the soil pH value in the study area ranged from 3.53 to 8.76, with an average of 6.54, mainly from slightly acidic to neutral; the coefficient of variation was 18.89%, suggesting moderate spatial variability. The semi-variogram analysis showed that the exponential model was the best fitting model for soil pH variation and the ratio of nugget to sill was 49.97%, which suggested that soil pH had moderate spatial dependence and its spatial distribution was determined by structural and random factors. Overall, the soil pH showed a trend of high in the north and low in the south, high in the west and low in the east, high in the middle and low in the surrounding area. Soil type, precipitation, topographical factors and cultivated land use pattern had significant impacts on the spatial variation of soil pH. Specifically, soil type and precipitation were the main controlling factors for the spatial variation of soil pH which could explanate 14.6% and 11.6% of soil pH variability respectively.