ICT Bill
09-17-2008, 10:15 AM
I was doing a little research and came on this, it had never crossed my mind actually. This a USDA article and about farming but I would assume the same thing would happen in turf and landscape. bottomline, its better to have them than not
Earthworms may have undesirable impacts if they remove too much surface residue and leave the soil surface unprotected, or if their burrows open into surface irrigation furrows. There is also some concern that earthworms may enhance the “preferential flow” of herbicides and other pollutants down burrows and into groundwater, causing water to pass too rapidly through the soil matrix. When their total effect is considered, however, earthworms are unlikely to have a significant negative impact on water quality. Where they are active, earthworms may bury herbicide-tainted residue before it has a chance to leach down through burrows. Earthworms may act as plugs in their own burrows, and, in the case of the herbicide atrazine, earthworm-feeding activity may actually change the chemical to reduce its mobility (Farenhorst et al., 2000). In addition, earthworm activity improves soil structure and therefore reduces runoff of chemicals into surface water. Another concern is that fresh earthworm casts on the surface are unstable and may lead to higher soil erosion and nutrients in runoff. Earthworm casts stabilize as they age so that the risk of erosion is greatly reduced. In summary, earthworms affect soil function in multiple ways. In specific situations they may have undesirable effects, but predominately they contribute to improved soil quality and are a sign of a healthy, properly functioning soil.
http://policy.nrcs.usda.gov/scripts/lpsiis.dll/TN/tn_ecs_11_02_A.rtf
Earthworms may have undesirable impacts if they remove too much surface residue and leave the soil surface unprotected, or if their burrows open into surface irrigation furrows. There is also some concern that earthworms may enhance the “preferential flow” of herbicides and other pollutants down burrows and into groundwater, causing water to pass too rapidly through the soil matrix. When their total effect is considered, however, earthworms are unlikely to have a significant negative impact on water quality. Where they are active, earthworms may bury herbicide-tainted residue before it has a chance to leach down through burrows. Earthworms may act as plugs in their own burrows, and, in the case of the herbicide atrazine, earthworm-feeding activity may actually change the chemical to reduce its mobility (Farenhorst et al., 2000). In addition, earthworm activity improves soil structure and therefore reduces runoff of chemicals into surface water. Another concern is that fresh earthworm casts on the surface are unstable and may lead to higher soil erosion and nutrients in runoff. Earthworm casts stabilize as they age so that the risk of erosion is greatly reduced. In summary, earthworms affect soil function in multiple ways. In specific situations they may have undesirable effects, but predominately they contribute to improved soil quality and are a sign of a healthy, properly functioning soil.
http://policy.nrcs.usda.gov/scripts/lpsiis.dll/TN/tn_ecs_11_02_A.rtf