“…However, they also produce negative effects, acknowledged by a few researchers, but ignored by most. Earthworm burrows increase bypass flow and rapid movement of surface-applied contaminants to groundwater (Cohen, 1997;Edwards et al, 1989Edwards et al, , 1992Edwards et al, , 1993Ehlers, 1975;Hall et al, 1989Hall et al, , 1991Isensee et al, 1990;Tyler and Thomas, 1977;Shipitalo et al, 1994;Steenhuis et al, 1990;Trojan and Linden, 1992;Zachmann et al, 1987;Zachmann and Linden, 1989). In rainfed agriculture, earthworms help reduce runoff and erosion.…”