Arbuscular mycorrhizal fungus–induced decrease in phosphorus loss due to leaching in red soils under simulated heavy rainfall

Phosphorus (P) loss from the soil due to leaching is affected by plant roots and arbuscular mycorrhizal fungi (AMF). This paper aimed to (i) analyze the effects of plant roots and AMF on P concentrations in interflow and P loss from the soil due to leaching and (ii) explain whether there were interaction effects between plant roots and AMF on the loss of P from soils due to leaching. In this study, samples of red soil were collected from wasteland, farmland, and slopeland on the Yunnan Plateau. As a host plant, maize was cultivated in a dual-compartment cultivation system. There were mycorrhizal and hyphal compartments for the arbuscular mycorrhizal fungal inoculation treatment and root and soil compartments for the non-inoculation treatment. The maize biomass and P uptake, P concentrations in interflow within two soil layers (0–20 and 20–40 cm), and P losses due to leaching under simulated heavy rainfall (40 and 80 mm/h) were analyzed. Arbuscular mycorrhizal fungal inoculation significantly enhanced the biomass and P uptake of maize, but had little effect on P concentration in the interflow under 40 mm/h rainfall. In addition, Arbuscular mycorrhizal fungal inoculation resulted in a decrease of 37–65% in P concentration in interflow under 80 mm/h rainfall, and a decrease of 21–39% in the P loss from soils due to leaching under heavy rainfall (40 and 80 mm/h). Moreover, significant or highly significant positive correlations were observed between P concentrations in the interflow and the loss of P due to leaching from the red soil. Two-way analysis of variance indicated that AMF significantly or highly significantly decreased P concentrations in the interflow and decreased P loss from red soils due to leaching, whereas the root effects were insignificant. In addition, there was no interaction between AMF and maize roots. Our study indicated that the arbuscular mycorrhizal fungus–induced decreases in the loss of P due to leaching from red soils were caused by decreased P concentrations in the interflow. The potential for AMF to reduce P leaching from soils is an important ecological function.