Integrated Soil-Crop System Management Increases Phosphorus Concentrations and Bioavailability in a Primosol

In recent years, integrated soil-crop system management (ISSM), i.e., using crop modeling and advanced nutrient management to redesign the cropping system, has been successfully used to improve crop yield and nutrient-use efficiency in China. However, the effects of ISSM on the properties of soils are not yet clear. Based on a seven-year (2009–2016) field plot trial with continuous corn monoculture, this study compared the effects of ISSM with improved practice (IP), high-yield practice (HY), and current farming practice (FP) on phosphorus (P) forms in an Alluvic Primosol of Northeast China by using chemical and spectroscopic (31P NMR) analyses. The concentrations of total P and Olsen P were in the order FP < IP < HY < ISSM; the order for inorganic and organic P fractions obtained by chemical analysis was also the same except for Ca10-P that showed an opposite order. 31P NMR spectroscopy showed that inorganic orthophosphate, pyrophosphate, orthophosphate monoesters, and orthophosphate diesters were all higher in the surface soil in ISSM treatment than in HY, IP, and FP treatments. Our results suggest that ISSM has a positive effect on the availability of P in soil.