A 10-year field experiment proves the neutralization of soil pH in Chinese hickory plantation of southeastern China

Purpose Stable soil pH is the key property to maintain soil biogeochemical balance, structure, and function stability of the terrestrial ecosystem. Understanding the soil pH change and its influencing factors is critical for maintaining soil quality and the sustainability of agricultural resources. Materials and methods In our study, 215 soil samples were collected using a paired comparison method from a typical hickory plantation region between 2008 and 2018 in southeastern China. The geostatistics and kriging interpolation method were used to evaluate the change in pH (CIP). The structural equation model (SEM) was combined to quantify the contribution of driving factors to CIP. Results and discussion The results suggested that the pH value of the soil had a significant neutralization effect which was manifested by increased pH value of the relatively acidic soil but decreased pH value of the relatively alkaline soil. The soil pH threshold (pHτ, the point at which the soil pH changes from positive to negative) was 5.96. The spatial distribution trend of pH between 2008 and 2018 was similar, while the local variation was different. Soil initial pH (IpH) was the most critical negative driving factor influencing CIP, while the mean annual temperature (MAT) and the mean annual precipitation (MAP) had positive effects on CIP. In addition, soil organic matter content (SOM) and bulk density were also important factors affecting CIP. Conclusions Our results indicated that long-term management could increase, decrease, or remain the soil pH value, with CIP mainly dependent on IpH, climatic factors, soil organic matter content, and bulk density. Lime, sod cultivation, and organic fertilizers are recommended to increase soil pH.