Abstract
<title>Abstract</title> <p>Purpose Coal particles entering cropland soils introduce coal-derived carbon into the soil organic carbon pool, but whether this geogenic carbon reshapes microbial potential for coupled carbon (C), nitrogen (N) and phosphorus (P) cycling remains unclear. Methods An outdoor controlled experiment was established with coal-free soil (CFS) and four coal accumulation levels (CCSL, CCSM, CCSH and CCSEH). Soil physicochemical properties, coal-derived carbon, metagenomic sequencing, KEGG functional annotation, differential abundance analysis and multivariate statistics were integrated to link functional genes, functional taxa and environmental drivers. Results Coal accumulation significantly altered the whole-community KO functional profile and the compositions of C, N and P cycling genes. Total abundances of C and N cycling genes increased significantly with coal-derived carbon, whereas P cycling genes showed a positive but nonsignificant trend. Responsive genes were mainly related to C degradation, C fixation, methane metabolism, hydroxylamine oxidation, denitrification, nitrate/nitrite reduction, P solubilisation, organic P mineralisation and P transport. Proteobacteria, Candidatus_Rokubacteria and Nitrospirae were important classified responders, and coal-derived carbon indicators, pH, available P, total N, available N and microbial biomass were closely associated with functional shifts. Conclusion Coal-derived carbon is not a passive component of total soil organic carbon; it can act as a persistent pressure reshaping microbial functional potential and multi-element cycling in coal-cropland overlapping regions.</p>