[Spatial Variation and Influencing Factors of Soil pH in Anshun City]

Exploring the spatial distribution characteristics and variation law of soil pH and analyzing the impact of environmental factors on the spatial differentiation of soil pH are of great significance to the accurate management of soil pH and the sustainable utilization of soil resources in the complex mountainous environment of Anshun City. Based on 22 851 field sampling points, using the methods of global Moran's I index, cold and hot spot analysis, semi-variance function, and Kriging interpolation, the spatial structure characteristics and distribution law of soil pH in Anshun City were revealed from different angles, and the influence of environmental factors on its spatial differentiation was analyzed with the help of geographic detectors. The results showed that:① the variation range of topsoil pH value in Anshun City was 3.56-8.61, the mean value was 6.28, and the coefficient of variation was 16.33%. ② In the global space, soil pH showed aggregation distribution; in the local space, the west and northwest were hot spots, whereas the east and south were cold spots. The nugget coefficient (40.19%) showed that the spatial variability in soil pH was determined by both structural and random factors, but the role of structural factors was greater. ③ In terms of spatial distribution, soil pH mainly presented a patchy mosaic distribution pattern, in which slightly acidic soil (57.14%) was concentrated in the east, northeast, and south of Anshun City; neutral soil (30.13%) was concentrated in the west, northwest, and southeast; and strongly acidic soil (6.12%) and alkaline soil (6.45%) were embedded in slightly acidic soil and neutral soil, respectively, in a block structure. ④ The geo-detector analysis showed that the explanatory power of various environmental factors to the spatial variation in soil pH was ranked as soil type (9.4%)>soil forming parent rock (7.9%)>altitude (2.1%)>land use (1.8%)>slope (0.1%), in which the q value of the interaction between soil type and parent rock type and other factors was large. Therefore, soil type and parent rock type were the main controlling factors of soil pH spatial variation in Anshun City.