桐柏山北麓土壤pH值空间分布特征及其影响因素

  目的  探明研究区土壤pH值空间变异特征，为当地区域农业酸碱调控提供基础依据。  方法  通过对土壤样品（0 ~ 20 cm、150 ~ 200 cm）分析，利用方差以及回归分析量化了不同因素对pH值的空间差异的影响程度。  结果  研究区表层土壤以酸性为主，pH均值5.66；深层土壤以中性为主，pH均值7.07。半方差分析表明，球状模型为研究区土壤pH值的最佳拟合模型，同时结构性因素为影响区域内pH值分布的主导因素。空间分布上，pH低值区主要位于研究区东北部，与传统农业分布区高度重合，高值区位于南侧山区，总体上呈现南高北低的格局。回归分析显示，成土母质是研究区表层土壤pH值空间变异的主控因素，可以单独解释24.8%的空间变异；土地利用类型和土壤类型分别有9.2%和8.8%的独立解释土壤 pH 值空间变化的能力。地貌类型的解释能力较低（5.6%）。  结论  土壤母质等结构因素对研究区表层土壤pH值的空间分布影响最大，与半方差分析结果相近；人为因素同样影响着区域内pH值的空间分布情况，长期不合理的施肥可能是主要原因。

Spatial Variation Characteristics and Influencing Factors of Soil pH Value at the Northern Foot of Tongbai Mountain

  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.