Arbuscular Mycorrhizal Fungi and Rhizobium Facilitate Nitrogen and Phosphate Availability in Soybean/Maize Intercropping Systems

Abstract

This study aimed to assess the impacts of the inoculation of arbuscular mycorrhizal fungi (AMF) and rhizobium on soil nitrogen (N) and phosphate (P) availability in monoculture and soybean/maize incorporating systems. We designed a greenhouse experiment as follows: Three planting patterns, including soybean/maize intercropping, maize monoculture, and soybean monoculture; Four microbial treatments, including inoculating with AMF, inoculating with rhizobium, dual inoculation (both AMF and rhizobium), and non-inoculation as a control. The results showed that intercropping of soybean/maize significantly promoted maize and soybean growth, and increased concentrations of soil available N and P concentrations compared to monoculture. Dual inoculation of AMF and rhizobium further promoted plant growth and enhanced soil available N concentration compared with that non-inoculated or only inoculated with AMF or rhizobium in the soybean/maize intercropping system. The redundancy analysis showed that dual inoculated with AMF and rhizobium in soybean/maize intercropping was most conducive to the concentrations of ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), and available phosphorus (AP) in the soil. The overall correlation analysis indicated that AP was positively related to AMF symbiosis, while NH4+-N and NO3−N were positively correlated with plant biomass. Inoculating with both AMF and rhizobium in the soybean/maize intercropping system improved the soil available N and P, improving the advantages of legume/graminaceous intercropping.