Soil bacterial and fungal microbiomes under cotton production are more sensitive to tillage and cover crops than irrigation level in a semi-arid sandy soil

Land managers in semi-arid regions experience challenging climatic conditions, such as variable rainfall, extreme temperature, and prolonged droughts that are expected to intensify over the next few decades. Conservation practices implemented to reduce erosion and restore degraded soils can alter soil properties that affect the composition and function of the soil microbiome. We compared microbiome responses to long-term (> 7 years) tillage and cropping management changes in bulk (0–10 cm, 10–20 cm) and root-associated soils under differing irrigation levels (High, Low) in sandy loam semi-arid soil. Cropping systems included a traditional system (Continuous tillage with continuous monocrop, CCCT) compared to two no-tillage systems that included a rye cover crop (NTCR) or a cotton/wheat rotation (NTCW). We found that microbiome structure was influenced more by management practices than irrigation across taxonomic levels. Drought-tolerant taxa also dominated bacterial communities, with no significant differences between high and low irrigation. Overall, the results from this sandy-textured soil show that tillage and vegetation management were stronger drivers of bacterial and fungal microbiome composition than irrigation level, demonstrating the efficacy of conservation management practices in semi-arid soils even under water-limited conditions.