Selenium combined with chitin reduced phosphorus leaching in soil with pomelo by driving soil phosphorus cycle via microbial community

Phosphorus leaching is severe in the orchard of Fujian province, especially in Pinghe where 'Guanximiyou' Pomelo is extensively grown. It triggers decreased phosphorus fertilizer utilization efficiency and causes eutrophication of waterways. Microorganisms can promote plant growth, mineralize organic phosphorus and solubilize inorganic phosphorus in soil. Here, metagenomics was used to explore the effects of selenium combined with chitin inputs on genes and microorganisms related to the soil phosphorous cycle. Phenotypic approaches were used to explore phosphorus accumulation in plants and the leaching of soil phosphorus from leaching column experiments. The results showed that compared with the control, the combination of selenium and chitin could significantly promote phosphorus accumulation in leaves by 33.3% and reduce the leaching of phosphorus from soil by 29.11%. Addition of selenium and chitin also changed the composition of microbial community, thus affecting the relative abundance of genes and microorganisms involved with phosphorus cycle. For example, the PstSAC protein which mediates phosphorus transport in soil phosphorus cycle increased in the current study. And it may promote microbes to immobilize more phosphorus in their biomass. These findings provide a strategy to reduce the loss of phosphorus from soil and lower the risks of eutrophication of waterways, which would contribute to a sustainable and environmental friendly agriculture.