Phosphorus content and its spatial heterogeneity in paddy soil with different parent materials at Jianghan Plain—Taking Jingzhou District in Hubei Province as an example
[Objective] The phosphorus content (P) and spatial distribution of paddy soils developed from different parent materials in the Jianghan Plain were analyzed to provide a reference for the strategic application of phosphorus fertilizer in rice-planting areas. [Methods] Jingzhou area in the hinterland of Jianghan Plain was taken as an example to determine the phosphorus content of paddy soil developed from different parent materials and evaluate its grade. A survey was conducted on the farmland in Jingzhou area, focusing on paddy soils developed from three parent materials, namely, alluvial deposits, secondary loess, and lacustrine deposits. A total of 600 soil samples were collected, and total phosphorus (TP), organic phosphorus (OP), available phosphorus (AP), and water-soluble phosphorus (WSP) contents were measured and evaluated. [Results] The average TP contents in paddy soils developed from alluvial, secondary loess, and lacustrine deposits in Jingzhou area were 0.881, 0.427, and 0.579 g/kg, respectively. The OP content was 0.104, 0.058, and 0.066 g/kg, respectively. The AP content was 24.418, 11.339, and 17.043 mg/kg, respectively, and the WSP content was 21.157, 13.421, and 22.600 mg/kg. The phosphorus content in various forms was higher in the southern part of Jingzhou area along the Yangtze River, where paddy soils developed from alluvial and lacustrine deposits. Meanwhile, phosphorus was lower in the central and northern regions, where paddy soils developed from secondary loess on the hilly uplands. According to the phosphorus grading standards from the second national soil survey, the TP content in the paddy soils of Jingzhou area was at a medium or higher level, whereas AP was mainly at a medium level. The phosphorus content in paddy soils developed from alluvial and lacustrine deposits was higher than that in soils developed from secondary loess. Redundancy analysis and spatial interpolation showed that the zonal distribution of paddy soils developed from different parent materials in Jingzhou area was closely related to the locations of the Yangtze River, lakes, and hills, significantly influencing the spatial heterogeneity of soil phosphorus. [Conclusion] In Jingzhou area, it is advisable to moderately control phosphorus fertilizer application in areas with alluvial and lacustrine deposits along the Yangtze River and around lakes while appropriately increasing phosphorus fertilizer application in hilly areas with secondary loess to enhance soil fertility and maintain crop productivity.