Co‐Variation of Soil Chemistry, Bacterial Communities, and Functional Genes Under Different Tillage Systems in a Semiarid Agroecosystem

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ABSTRACT Tillage practices regulate soil functioning in semiarid agroecosystems, where moisture limits nutrient cycling and bacterial activity. This study evaluated soil physicochemical properties, bacterial community composition, and the abundance of functional genes linked to anaerobic metabolisms under long‐term conventional (CT), minimum (MT), and no‐tillage (NT) systems. Most soil physicochemical properties and diversity metrics remained stable across treatments, although multivariate analyses indicated moderate microbial and biogeochemical shifts. MT was associated with a higher relative abundance of phyla such as Actinobacteria, Chloroflexi, Planctomycetota, and Nitrospirota, suggesting increased microsite heterogeneity under moderate disturbance. NT favoured bacterial communities typical of stable, resource‐limited conditions, including Verrucomicrobiota, while CT was associated with copiotrophic groups such as Proteobacteria and Actinobacteria under more disturbed and oxidative conditions. Functional gene quantification showed higher potential for nitrogen and sulphur cycling under NT and MT, including genes associated with denitrification, iron reduction, and sulphate reduction. In contrast, methanogenic potential remained unchanged across treatments. Correlation analyses revealed consistent associations between functional genes, soil chemical properties and different responses of oligotrophic and copiotrophic phyla. Multivariate analyses indicated that MT is associated with changes in soil chemical properties and microbial functional potential, reflecting an intermediate condition between NT and CT. However, these effects did not provide improvements in crop yield across seasons, with NT generally showing more stable yield. Overall, long‐term MT influenced soil biochemical functioning, while NT may provide a more consistent balance between soil fertility and agronomic output.

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