The North American landscape has been profoundly altered to promote agricultural
development since European settlement (“settlement”) at the end of
the nineteenth century. More than 98% of the North American prairie and vast
areas of forest have been replaced with croplands. Bringing much of this land
into production under modern agricultural systems has been associated with
extensive modifications to natural drainage networks. Extensive networks of
surface ditches and subsurface drains (“tiles”) have been constructed to remove
excess water from the field soil surface or soil profile (Spaling & Smit,
1995). By 1987, the most recent year for which survey data were collected,
more than 17% of U.S. cropland (up to 30% in the Upper Midwest) had been
altered by artificial surface or subsurface drainage (Pavelis, 1987).
Blann, Kristen, L.; Anderson, James, L.; Sands, Gary, R.; Vondracek, Bruce.
Effects of Agricultural Drainage on Aquatic Ecosystems: A Review.
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