When structure means conservation: Effect of aggregate structure in controlling microbial responses to rewetting events

► Aggregates showed the importance of the physical mechanism in driving the Birch effect. ► Intact aggregates have lower respiration rates upon rewetting than crushed ones. ► Aggregate crushing increases biomass upon rewetting. ► Exposure of carbon through aggregate crushing is not enough to convert it into “bioavailable C”. ► Nitrification rate depends on aggregate structure being higher in intact aggregates.