Microbial residues as the nexus transforming inorganic carbon to organic carbon in coastal saline soils

Soil inorganic carbon (SIC), including mainly carbonate, is a key component of terrestrial soil C pool. Autotrophic microorganisms can assimilate carbonate as the main or unique source, how convert SIC to organic (SOC) remains unclear. A systematic field survey (n = 94) was performed evaluate shift in components (i.e., SIC, SOC, and microbial residues) along natural salinity gradient (ranging from 0.5 ‰ 19 ‰), further explore necromass an indicator converting into SOC Yellow River delta. We observed that levels linearly decreased with increasing salinity, ranging ?12 g kg?1 (salinity < 6 ‰) ?10 >6 ‰). Additionally, concentrations residues exponentially ‰, decline 39% 70%, respectively. Microbial tightly related variations SIC. The structural equation model showed causality on explanation through residues, which contribute 89% variance storage combined Taken together, these two statistical analyses support serve transition SOC. This study highlights regulation cycling, enhancing role playing biogeochemical cycles enriching reservoirs coastal saline soils.