Manure substitution improves maize yield bypromoting soil fertility and mediating the microbial community in limeconcretion black soil

Syntheticnitrogen (N) fertilizer has made a great contribution to the improvement ofsoil fertility and productivity, but excessive application of synthetic Nfertilizer may cause agroecosystem risks, such as soil acidification,groundwater contamination and biodiversity reduction. Meanwhile, organic substitution has receivedincreasing attention for its ecologically and environmentally friendly andproductivity benefits. However, thelinkages between manure substitution, crop yield and the underlying microbialmechanisms remain uncertain. To bridgethis gap, a three-year field experiment was conducted with five fertilizationregimes: i) Control, non-fertilization; CF, conventional synthetic fertilizerapplication; CF1/2M1/2, 1/2 N input via syntheticfertilizer and 1/2 N input via manure; CF1/4M3/4,1/4 N input synthetic fertilizer and 3/4 N input via manure; M,manure application. All fertilizationtreatments were designed to have equal N input. Our results showed that all manure substituted treatments achieved highsoil fertility indexes (SFI) and productivities by increasing the soil organiccarbon (SOC), total N (TN) and available phosphorus (AP) concentrations, and byaltering the bacterial community diversity and composition compared with CF. SOC, AP, and the soil C:N ratio were mainlyresponsible for microbial community variations. The co-occurrence network revealed that SOC and AP had strong positiveassociations with Rhodospirillales and Burkholderiales, while TN and C:N ratiohad positive and negative associations with Micromonosporaceae,respectively. These specific taxa areimplicated in soil macroelement turnover. Random Forest analysis predicted that both biotic (bacterial compositionand Micromonosporaceae) and abiotic (AP, SOC, SFI, and TN) factors hadsignificant effects on crop yield. Thepresent work strengthens our understanding of the effects of manuresubstitution on crop yield and provides theoretical support for optimizingfertilization strategies.