Adaptive evaluation of green manure rotation for a low fertility farmland system: Impacts on crop yield, soil nutrients, and soil microbial community

Green manure-based rotations have been shown to be an effective sustainable farming practice and were considered a dual solution to resource conservation and crop productivity maintenance. However, our understanding of the adaptations of green manure rotation to the regional agricultural environments lags significantly behind other farming practices. Here, a 6-year field experiment with four green manure cropping treatments and one conventional treatment has been conducted in a typical low fertility farmland in the arid land. Maize yield was significantly increased after green manure was planted, and on a 6-year average, maize grain yield in the green manure intercropping system was 11.7% higher than that in the conventional cropping system. Green manure rotation or intercropping with maize can significantly increase SOM (soil organic matter), TN (total nitrogen), and TP (total phosphorus) in the surface soil layer. Perennial alfalfa planting significantly increased SOM and TN, but significantly decreased TP. Continuous maize planting had no significant effect on TN and TP, but significantly decrease SOM. Green manure planting promoted shifts in soil bacteria composition, with increased the relative abundance of Actinobacteria but decreased the relative abundance of Chloroflexi and Acidobacteria. For fungal abundance, green manure intercropping with maize increased the relative abundance of Ascomycota, but green manure rotation decreased the relative abundance of Mortierellomycota. In summary, our study elucidated that green manure planting especially intercropping with maize can be adopted as the most effective cropping system in the future to decrease environmental stress and enhance agricultural production conditions through improving the crop productivity, increasing soil fertility and nutrients, and regulating soil microbial communities in the low fertility farmland.