Associations between soil microbiomes and carbon stabilization under long-term no-till farming systems in the Argentine Pampas

Abstract

Soil microbial communities play a key role in carbon (C) cycling inagroecosystems; however, their long-term responses to contrastingmanagement practices remain poorly understood in agricultural soils.In this study, we evaluated the effects of more than 20 years of no-tillfarming (NTF) and conventional tillage (CT) on soil physicochemicalproperties, bacterial and fungal community composition, and inferredfunctions related to C and nutrient cycling in the Argentine Pampas.We show that NTF increased total organic carbon (TOC) stocks insurface soils and promoted edaphic conditions associated with Cstabilization, including higher cation exchange capacity and structuralstability. Bacterial communities exhibited high functional redundancyand were primarily structured along sodium-related parameters,whereas fungal communities were more sensitive to management,with NTF favoring ligninolytic and symbiotic fungi that contribute tonecromass formation and long-term carbon stabilization. In contrast,CT enriched opportunistic fungal guilds associated with disturbanceand short-term nutrient turnover. Phylogenetic analyses revealedcommunity assembly dominated by environmental filtering in bothmicrobial domains. Overall, these results highlight the central role offungi as mediators of soil C stabilization and suggest that conservationpractices such as NTF enhance microbiome contributions toecosystem services and climate change mitigation in intensivelymanaged agroecosystems.