Microbial residues as indicator for inorganic carbon transition to
organic carbon in coastal saline soils
Although autotrophic or chemotrophic microorganisms can assimilate CO2
or carbonate, it is still unclear how microorganisms convert soil
inorganic carbon (SIC) to organic carbon (SOC), owing to the lack of a
microbial indicator between SIC and SOC. Herein, we hypothesized that
carbonate-rich saline soils are a potential source that contribute to
the SOC pool through the transformation of microbial necromass. SIC
levels linearly decreased with an increase in salinity, while SOC and
microbial residues exponentially declined. A structural equation model
verified the causality of SIC-microbial residues-SOC, suggesting that
microbial residues can serve as an indicator of SIC transition to SOC.
This study highlights the regulation of microbial necromass in SIC
cycling, thus enhancing the application of SIC for C biogeochemical
cycles and enriching organic C reservoirs in global saline or dry lands.