Subsurface Drains on Agricultural Land in the Conterminous United States, 1992: National Resource Inventory Conservation Practice 606

This data set represents the estimated percentage of the 1-km grid cell that is covered by or subject to the agricultural conservation practice (CP606), Subsurface Drains (SD) on agricultural land by county. Subsurface Drains are described as "a conduit, such as corrugated plastic tubing, tile, or pipe, installed beneath the ground surface to collect and/or convey drainage." (U.S. Department of Agriculture, 1995) This data set was created with geographic information systems (GIS) and database management tools. The acres on which SD's are applied were totaled at the county level in the tabular NRI database and then apportioned to a raster coverage of agricultural land within the county based on the Enhanced National Land Cover Dataset (NLCDe) 1-kilometer resolution land cover grids (Nakagaki, 2003). Federal land is not considered in this analysis because NRI does not record information on those lands.