Objective  the aims were to explore the spatial variation characteristics of soil pH value in the study area, and to provide a basis for local regional agricultural acid-base regulation.

  Method  Soil samples (0 - 20 cm, 150 - 200 cm) were collected and analyzed, and variance and regression analysis were used to quantify the influence degree of different factors on the spatial difference of pH value.

  Results  The top soil in the study area was mainly acidic, with an average pH of 5.66. The deep soil was mainly neutral, with an average pH of 7.07. Semi-variance analysis showed that spherical model was the best fitting model for soil pH value in the study area, and structural factors were the dominant factors affecting the distribution of pH value in the study area. In terms of spatial distribution, the low pH value area was mainly located in the northeast of the study area, which highly overlapped with the traditional agricultural distribution area, while the high pH value area was located in the southern mountainous area, which showed a pattern of high pH value in the south and low pH value in the north. Regression analysis showed that soil parent material was the main controlling factor of the spatial variation of surface soil pH value in the study area, and could explain 24.8% of the spatial variation alone. Secondly, land use type and soil type had the independent ability to explain 9.2% and 8.8% of the spatial variation of soil pH value, respectively. The explanatory power of geomorphic types was low (5.6%).

  Conclusion  Soil parent material and other structural factors have the greatest influence on the spatial distribution of surface soil pH value in the study area, which is similar to the results of semi-variance analysis. However, human factors also affect the spatial distribution of pH value in the region, and long-term unreasonable fertilization may be the main reason.