Long-term farmyard organic residue amendments shape the resistance and resilience of soil microbial communities to simulated drying and heating-drying disturbances under a changing climate in the Senegalese groundnut basin

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Introduction Soil hosts a rich diversity of microorganisms essential to ecosystem functioning, but the droughts and high temperatures projected under future climate scenarios, particularly in Senegal, may significantly disrupt these processes. This study aimed to assess the effects of projected drying and combined heating-drying stress on the resistance and resilience of soil microbial communities, and to evaluate how these properties are shaped by contrasting farming practices, home-fields, which receive regular organic inputs, versus out-fields, which receive low or no organic inputs. Methods Soils sampled from home-field and out-field plots were subjected to five cycles of drying and heating-drying disturbance under controlled conditions. The effects on carbon mineralization, β-glucosidase activity, and microbial biomass and abundance (PLFA profiles) were assessed. Results Both drying and combined heating-drying significantly reduced microbial activity and biomass, regardless of farming practice, with soils exposed to drying alone less affected than those subjected to combined heating-drying stress. Long-term organic amendments in home-fields markedly enhanced soil microbial communities and improved resistance compared with out-fields receiving low organic inputs. Resilience patterns diverged sharply among microbial parameters: biomass and β-glucosidase activity showed low resilience, whereas carbon mineralization showed high resilience. Discussion These results are consistent with reports that organic inputs enhance microbial resistance to drying-related stress, while the divergent recovery of carbon mineralization versus biomass and enzyme activity supports the view that functionally redundant processes remain buffered even when community structure does not fully recover. This underscores the value of long-term organic management for building drought resilience in Sahelian farming systems, and points to a need for field-scale, multi-cycle studies under recurrent climate extremes.

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