Carbon addition reduces labile soil phosphorus by increasing microbial biomass phosphorus in intensive agricultural systems
Zhen Xu, Mingshan Qu, Shenglin Liu, Yisheng Duan, Wang Xiao, Lawrie K. Brown, Timothy George, Lin Zhang, Gu Feng
Abstract
Abstract Accumulation of inorganic and labile organic phosphorus (P) in intensive agricultural systems leads to P loss from soil which can cause serious environmental problems. Soil microbes are important in mobilizing soil non‐available P, however, little is known about the role of soil microbes in immobilizing P to reduce P loss. Here, we test whether stimulating microbial biomass to immobilize P could reduce the amount of labile P available for leaching. The distribution characteristics of Olsen P, organic P and microbial biomass P were determined in three intensive agricultural systems. In addition, we conducted a pot experiment with three P and four carbon (C) levels. CaCl 2 extractable P was measured and used to indicate the risk of P leaching. We found that there was a positive relationship between soil organic C and microbial biomass P. Carbon addition drove the process of P immobilization and reduced CaCl 2 extractable P. Microbial biomass P increased by 64% ( p < .05) with the addition of C, and Olsen P and CaCl 2 extractable P decreased by 28% and 17%, respectively. Our results show that C addition increased microbial immobilization of P and reduced forms of labile P susceptible to leaching. Stimulating microbes to immobilize P by adding C to soils may have the potential to reduce P loss from intensive agricultural systems, reducing their environmental impact.