Effects of Fenlong Tillage and Green Manure Returning on Soil Nutrients and Microbial Community Structure in Continuous Cropping Sugarcane Fields

Purpose To investigate the effects of Fenlong tillage and green manure returning on the soil nutrients and microbial communities in long-term continuous sugarcane fields.

Methods Four treatments were established: traditional rotary tillage with sugarcane monoculture (TCK), Fenlong tillage with sugarcane monoculture (FLCK), Fenlong tillage with sugarcane/soybean intercropping and returning green manure into the root zone (FLG), and returning to wide rows (FLK). A two-year field experiment was conducted. Soil samples from the roots and wide rows were collected for analyzing microbial community structure and nutrient changes using high-throughput sequencing.

Results 1) Compared with TCK, Fenlong tillage and green manure returning increased the contents of soil organic matter (SOM), alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), and total potassium (TK), with increments ranging from 16.1% to 76.7%. 2) Fenlong tillage and green manure returning significantly increased soil bacterial diversity, while the increase in fungal richness and diversity was most pronounced in the roots of FLG treatment. 3) The dominant bacterial phyla across all treatments were Chloroflexi, Proteobacteria, Acidobacteriota, and Actinobacteriota, while the dominant fungal phyla were Ascomycota, Basidiomycota, and Mucoromycota. Fenlong tillage and green manure returning increased the relative abundance of Chloroflexi, Acidobacteriota, and Ascomycota, while reducing that of Proteobacteria, Actinobacteriota, and Mucoromycota. 4) Redundancy analysis showed that the soil microbial community at the phylum level was primarily influenced by SOM, total nitrogen (TN), and AN. Pearson correlation analysis showed significant correlations between microbial genera and SOM, TN, AN, AP, and TK.

Conclusion The combination of Fenlong tillage and green manure returning effectively improves soil nutrients, optimizes microbial community structure, and enhances microbial diversity, providing a scientific basis for soil improvement and efficient cultivation of continuous sugarcane fields.