Effects of cattle-lagoon slurry on a soil microbial community can be observed until depths of 50Â m

► Cattle-slurry infiltration can affect microbial community in 30-m-deep vadose zone. ► Soil microflora under a slurry lagoon show adaptation to aromatic carboxylic acids. ► Soil layers under a slurry lagoon have higher microbial functional diversity. ► Vadose-zone microbial activity can be a bioindicator of anthropogenic activities.