Deciphering Biotic and Abiotic Mechanisms Underlying Straw Decomposition and Soil Organic Carbon Priming in Agriculture Soils Receiving Long-Term Fertilizers

Straw-related carbon (C) dynamics are central for C accrual in agro-ecosystems and should be assessed by investigating their decomposition and soil organic carbon (SOC) priming effects. Our understanding of biotic and abiotic mechanisms underpinning these two C processes, however, is still not sufficiently profound. Soils that had received organic and mineral fertilizers for 26 years were sampled for a 28 day incubation experiment to assess ¹³C-labeled straw decomposition and SOC priming effects. On the basis of analyzing physicochemical properties, fungal taxonomic (MiSeq sequencing) and functional (metagenomics) guilds, we quantified the contributions of biotic and abiotic attributes to straw decomposition and SOC priming. Here, we propose two distinct mechanisms underlying straw decomposition and SOC priming in agriculture soils: (i) accelerated straw mineralization in manure-treated soils was mainly driven by biotic forces, while (ii) larger SOC priming in NPK-amended soils was through abiotic regulation.