Biochar and lime improve soil health and mitigates disease index in acidic field of sugarcane

Soil acidification is one of the main problem facing worldwide leading to a decrease in soil fertility and an increase in the occurrence of diseases. Therefore our study explores the effects of lime and biochar on soil functionalities, rhizosphere microbial community, and pokkah boeng disease (PBD) in acidic rhizosphere sugarcane fields. Two sugarcane varieties Guitang 42 (GT42) and Zhongzhe 9 (ZZ9), resistant and susceptible to PBD were selected. Treatments were arranged in a randomized complete block design such as G (GT42) and Z (ZZ9) a control group; GB, and ZB (Biochar, 15 t ha-1 B); GL, ZL (Lime, 1.5 t ha-1 L); GLB, and ZLB, combined application of 1.5 t ha-1 of lime and 15 t ha-1 of biochar with triplicates, and samples were collected at three different growth stages (seedling, jointing, and maturity) of sugarcane. Application of lime significantly increased soil pH value, and the combined application of lime and biochar increased the contents of soil organic carbon (SOC), nutrients and nitrate nitrogen (NO3--N), and soil catalase (S-CAT) activity. While lime significantly increased soil urease (S-UE), and decreased soil acid phosphatase (S-ACP) activity, and beta-glucosidase activity was lower in the treatments than in the control. The application of lime and biochar alleviates soil acidification, improves soil fertility and caused the substantial changes in the community structure and population abundance of rhizosphere bacterial and fungal communities. Redundancy analysis showed that soil pH, SOC, and AP were the key edaphic factors that altered the microbial community composition. Beneficial bacteria (Filomicrobium, OLB13, Arenimonas) and fungi (Redeckera) were enriched with the combined use of lime and biochar. Results of FUNGuild function prediction showed that combining lime with biochar reduced the relative abundance of plant pathogens, absolute content of soil pathogen (Fusarium), and disease index of sugarcane pokkah boeng, and thus laid a theoretical foundation, however more field experiments verifications are needed for alleviating of further degradation in acidic sugarcane fields and reducing sugarcane fungal diseases.