Abstract:
objectives Understanding the spatial variation characteristics and influencing factors of soil available phosphorus in cultivated land is of great significance for determining the amount and application mode of phosphorus fertilizer and preventing and controlling non-point source pollution.
methods Based on the data of 4409 topsoil samples (0−20 cm) in Sichuan Basin, the spatial distribution characteristics of topsoil available phosphorus and the effects of different influencing factors on the spatial variation of topsoil available phosphorus were analyzed by geostatistical method, correlation analysis, variance analysis and random forest model.
results The results showed that the average content of available phosphorus in the study area was 20.98 mg/kg, which was generally in the secondary (high) level. Semi-variance analysis showed that the spherical model was the best fitting model for soil available phosphorus variation in this region, and its bullion effect was 0.776 and coefficient of determination was 0.923, indicating that available phosphorus was mainly affected by random factors.The spatial distribution of soil available phosphorus showed a pattern of low in the middle and high in the surrounding area, and the high-value areas were mainly located in the Chengdu-Ya'an area and along the Fuling-Wanxian area.The random forest model showed that soil pH, annual average rainfall, root phosphorus input, annual average temperature, and soil-forming parent rock were the main influencing factors for the spatial variation of soil available phosphorus in this region, and their relative importance was 14.54%, 8.03%, 7.76%, 7.37%, and 7.27%, respectively.
conclusions The spatial distribution pattern of soil available phosphorus content in cultivated land in this region is still mainly controlled by soil pH, climate and patient material, and the influence of soil pH, climate and patient material needs to be mainly considered in the future. For areas with high soil available phosphorus content, such as the Chengdu Plain, attention should be paid to controlling phosphorus input.