Fungal necromass carbon contributes to organic carbon sequestration within soil macroaggregates under manure application combined with plastic film mulching

Microbial necromass carbon (C) is a major contributor to soil organic C (SOC) sequestration. Soil aggregates are key functional units in regulating SOC dynamics. Fertilization and plastic film mulching, as common agricultural management practices, affect soil aggregation and microbial activities. However, how microbial necromass C is accumulated and contributes to organic C sequestration within soil aggregates remains poorly understood, especially under fertilization combined with plastic film mulching. We set the mulching and no-mulching sub-treatments under three long-term (28 years) fertilization treatments (no fertilization, NF; inorganic fertilization, IF; manure application, MF) and conducted a 900-day field mesocosm experiment. We quantified the proportion of microbial necromass C in organic C within soil aggregates using amino sugar biomarkers, and investigated the effects of fertilization combined with mulching on the dynamics of microbial necromass C within soil aggregates. Microbial necromass C accounted for 28.2–42.9