Tillage practices can alter the microbial resistance and resilience to drought

An aspect of ‘soil health’ can be assessed by evaluating the microbial responses to soil rewetting after a period of drought. In general, those microbial communities that had been frequently exposed to extreme moisture fluctuations exhibit a faster recovery of their functions after rain than communities not used to severe droughts. However, whether and how changes in land-use management alter these short-term responses remains unresolved. To investigate this issue, we sampled soils from permanent pastures and tilled croplands, exposed them to a cycle of drying-rewetting, and compared their responses –bacterial growth, fungal growth, and respiration– over soil depth (top 30 cm). Results showed categorically different response patterns across land uses that were noticeable down to the ploughing depth, exhibiting significant differences in the microbial resistance and resilience to drought. When ploughing cancelled soil stratification, the exposure and adaptation of soil microorganisms to conditions of water stress increased, which caused contrasting shifts in the bacterial vs fungal response to drying-rewetting. These results confirmed the capability of land-use management to alter soil health and agroecological functioning.