Litter chemical traits, microbial and soil stoichiometry regulate organic carbon accrual of particulate and mineral-associated organic matter

latw-2026-02-20_14_59_57-chenge-1.pdf

Litter chemical traits, microbial and soil stoichiometry regulate organic carbon accrual of particulate and mineral-associated organic matter.

Abstract

Plant litter quality considerably affects carbon accrual in soil organic matter. However, the chemical traits of litter that influence carbon distribution in soil organic matter fractions, such as particulate organic matter and mineral-associated organic matter, are not fully understood. Thus, we conducted a one hundred fifty-day incubation experiment with litter addition (poplar leaves, roots, grasses grown under the canopy, and a mixture of these three litter types). We analyzed the organic carbon concentration in the particulate organic matter and mineral-associated organic matter fractions and the stoichiometric ratios (carbon to nitrogen to phosphorus) of the soil and microbial biomass fifty, one hundred, and one hundred fifty days after the initial litter addition. Microbial residue carbon (amino sugar biomarkers) in soil organic matter fractions was registered at the end of decomposition. High-quality litter (i.e., leaf) increased mineral-associated organic matter carbon accrual, and low-quality litter (i.e., root and grass) contributed more to particulate organic matter carbon accrual. The mixed litter addition accumulated more carbon in the soil organic matter via high particulate organic matter carbon levels compared to single litter input, likely resulting from an antagonistic effect caused by different litter trait dissimilarity. Moreover, particulate organic matter carbon dynamics were dominated by litter chemical traits during litter decomposition, and mineral-associated organic matter carbon was controlled mainly by microbial and soil stoichiometry. Furthermore, the contribution of microbial residue carbon to soil organic matter (especially particulate organic matter carbon) was lower in the mixed litter than in the single litter. These findings highlight the direct or indirect impacts of litter types on the carbon dynamics of particulate organic matter and mineral-associated organic matter, and demonstrate that litter diversity is conducive to carbon accumulation in soil organic matter.