Maize/soybean intercropping improves stability of soil aggregates driven by arbuscular mycorrhizal fungi in a black soil of Northeast China

Abstract Background and Aims Studies verify that intercropping influence the soil aggregates and arbuscular mycorrhizal fungi (AMF), but the characteristics and relationships of AMF communities and soil aggregates at different soil depths have not been fully understood. Methods A long term positioning experiment starting in 2017, including two-factor experiment of N application level and cultivation. The N application level including N0 (0 kg·hm−2) and N2 (240 kg·hm−2 and 80 kg·hm−2 for maize and soybean, respectively). The cultivation, including monoculture maize, monoculture soybean, and maize/soybean intercropping (intercropping maize, intercropping soybean). Soil aggregates and AMF were collected and analyzed from the difference depths soil. Results Results showed that intercropping can improve the macro-aggregate (>5 mm) content of maize soil at 0-15 cm and 15-30 cm depth under N0 level. Also, the intercropping can only improve the macro-aggregate content of soybean soil at 0-15 cm depth. Likewise, the results also proved that increasing the N fertilizer application rate can significantly decrease the macro-aggregates in intercropping soil at 0-15 cm and 15-30 cm depths. Moreover, intercropping treatment can significantly improve the AMF diversity of maize and soybean soil at different depths, while the application of N fertilizer significantly reduced the AMF diversity of soil at different depths. Conclusion The Structural equation modeling indicated that the intercropping system could influence and participate in the formation of soil aggregates by changing the soil AMF community and relative abundance, thereby contributing the soil stability. These results reveal the mechanisms of improvement of soil quality through diversity planting patterns.