Soil Phosphorus Forms in Saline Soil after the Application of Biomass Materials

Abstract

Although the application of biological materials has shown potential in improving the environment of salinized soil, the impact on the transformation of soil phosphorus forms in salinized soil, especially when combined with B. mucilaginosus (BM), has rarely been studied. Therefore, this study investigated soil’s properties and phosphorus forms, as well as their relationship, in salinized soil after the application of different biological materials, including rice straw (RS), biochar (B), acidified biochar (AB), BM, RS+BM, B+BM, and AB+BM. A sequential extraction procedure was employed to determine the soil organic/inorganic phosphorus forms (Po/Pi). In our study, the contents of the soil’s resin-P, NaHCO3-Pi, NaOH-Pi, and HCl-P increased by 50–341.66%, 4.08–184.63%, 37.45–163.45%, and 10.19–38.29%, respectively, with the application of the biological materials compared to with conventional fertilization (CK1). However, the contents of the soil’s NaHCO3-Po, NaOH-Po, and residual-P significantly decreased in comparison to with CK1, particularly in the soils that received a combined application with biological materials and BM. Furthermore, the results from the statistical analysis revealed that the application of biological materials could increase the level of soil stable phosphorus, facilitate the transformation from soil stable phosphorus and soil unstable Po to soil unstable Pi, and enhance the effectiveness of soil phosphorus, especially when combined with BM, particularly in soil with AB+BM.