Biochar and manure amendments mitigate chemical-fertilizer-induce negative effects on soil microbiomes, with implications for crop productivity gain

Co-applications of organic fertilizer and biochar have been demonstrated to have the advantages of improving soil fertility and food production while maintaining environmental benefits. However, the underground microbiological mechanism of the co-application-mediated crop production gaindescribed above were still insufficiently explored. Therein, a over decade-long field study was conducted to compare the effects of chemical-only fertilization and organic amendment on the microbial communities and functions of rhizosphere and non-rhizosphere soils as well as their production consequence. Findings indicated that long-term chemical-only fertilization notably reduced soil microbial diversity, whereas the loss of such diversity was mitigated by biochar and manureinputs. Additionally, biochar and manure inputs could enhance the complexity and stability of soil microbial community compared to no fertilizer or chemical-only fertilization. Interestingly, biochar and manure inputs replenished the certain microbiota involved in nutrient cycles that have disappeared as a result of long-term chemical-only fertilization, and meanwhile, reduced microbial pathogenic potentialin rhizosphere and non-rhizosphere soils. These positive shifts inmicrobial communities and functions were closely associated with the changed soil physicochemical propertiesinduced by organic amendment, which partly supported better crop growth and nutrient uptake. Overall, this study highlights the importance of incorporating biochar and manure into agricultural production to mitigate chemical-fertilizer-induce negative impactson soil biology, which will further solidify food production and security.