Effects of municipal solid waste composting on solubilization of insoluble phosphate and soil phosphorus sorption characteristics

There are a lot of organic acid substances during municipal solid waste(MSW) composting that can transform insoluble phosphate. Ground phosphate rock was mixed into MSW composting; the effects of composting on ability of insoluble phosphate solubilization and the effects of composting production (P-enriched MSW composting) on soil phosphorus sorption characteristics after being amended for two years were studied. The authors observed that by mixing ground phosphate rock into composting, the active organic phosphate, middling active organic phosphate, middling stable organic phosphate and high stable organic phosphate were increased by 212.83%, 80.36%, 61.21%, 62.74%, 157.89%, respectively. At the final stage of composting, scanning electron microscopy revealed cavities of phosphate rock powder surface. After composting productions have amended soil for two years, the results showed, in comparison with the treatment of chemical fertilizer, amending with P-enriched MSW composting could influence phosphorus sorption characteristics of the soil. Maximum phosphorus sorption capacity(Q_m), maximum buffer capacity(X_m·K) decreased by 8.76%, 13.58%, and the degree of phosphorus saturation(DPS) and equilibrium phosphorus concentration at zero sorption(EPC₀) increased by 98.52%, 7.13%, respectively. This study suggests that P-enriched MSW composting could provide a biological approach to the problem of phosphate resources shortage and limited availability rate of phosphorus fertilizer in China.