Severe drought conditions modify the microbial community structure, size and activity in amended and unamended soils

► A long period of severe drought can affect the growth and activity of the soil microbial population. ► The physiology and structure of the soil microbial communities are affected by long drought periods. ► Organic amendments might influence on soil resistance to this severe drought. ► A 6-months drought seems to be insufficient to destroy the native soil microbial biomass. ► The new microbial biomass provided by organic amendments is more sensitive to water stress.