Fenlong-ridging promotes microbial activity in sugarcane: a soil and root metabarcoding survey

Fenlong-ridging (FL) is a new conservation tillage technique that has been shown to increase crop yields without additional fertilization. Little is known about the role that microbes play in medi-ating the growth-promoting effects of FL, and this restricts further application and improvement of FL. Here, we characterized variation in the soil and root microbial diversity of sugarcane (GT44) under FL and traditional turn-over plough tillage (CK) by conducting 16S RNA and ITS metabarcoding surveys; we also measured several phenotypic traits to determine sugarcane yields and analyzed the physical and chemical properties of soil. We found that (i) the height of sugarcane plants was 9% greater under FL than under CK at six months of growth, suggesting that FL increased sugarcane yield; (ii) the content of organic matter, total nitrogen, available phosphorus, and available potassium was lower in soil under FL than under CK, suggesting that the utilization of soil nutrients was greater in FL soil; (iii) FL promoted the activity of endophytic microbes in the roots, and these diverse microbial taxa might have an effect on sugarcane yield and soil chemical properties; and (iv) Sphingomonas, Rhizobium, and Paraburkholderia and Tala-romyces, Didymella, and Fusarium were top three most abundant genera of bacteria and fungi, re-spectively, in soil and root samples. Strains from Rhizobium and Talaromyces were isolated to veri-fy the results of the metabarcoding survey. Overall, our study provided new insights into the role of microbes in mediating the growth-promoting effects of FL, and these findings could be used to further improve applications of this novel conservation tillage technology.