Groundwater and stream response times to fertility management changes in pastures

Authors: Owens, Lloyd; Shipitalo, Martin; Bonta, James - Jim

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2008
Publication Date: 9/1/2008
Citation: Owens, L.B., Shipitalo, M.J., Bonta, J.V. 2008. Groundwater and stream response times to fertility management changes in pastures. Journal of Soil and Water Conservation. 63(5):168A.

Interpretive Summary: To assess the effectiveness of best-management practices (BMPs), measurements need to be made to determine how the implementation of BMPs affect water quality and soil loss from the areas receiving the practices. For large watersheds (multiple square miles in area) this is a difficult, expensive, and multiple-year task. Although several years may be involved in assessments on small watersheds (a few acres), such measurements may give valuable insights for responses of BMPs on large watersheds. Small watersheds at the North Appalachian Experimental Watershed near Coshocton, Ohio were used to measure response time to changes in pasture management practices. Surface runoff was sampled on an event basis; subsurface flow was sampled monthly. Because of underlying clay layers, subsurface flow returned to the surface to contribute to continuously flowing streams. With different levels of nitrogen fertility being maintained for multi-year periods, changes in nitrogen movement could be measured when the N application rate was changed. These changes were also observed downstream at larger watershed sites (multiple acres). The response times indicated that several years are necessary to measure changes in management, and that response times in multi-square miles would be at least as long, probably longer. These results are of use to scientists and land managers who are trying to evaluate changes in management practices on soil loss and stream water quality.

Technical Abstract: To assess the effectiveness of best-management practices (BMPs), measurements need to be made to determine how the implementation of BMPs affect water quality and soil loss from the areas receiving the practices. For large watersheds (multiple square miles in area) this is a difficult, expensive, and multiple-year task. Although several years may be involved in assessments on small watersheds (a few acres), such measurements may give valuable insights for responses of BMPs on large watersheds. Small watersheds at the North Appalachian Experimental Watershed near Coshocton, Ohio were used to measure response time to changes in pasture management practices. Surface runoff was sampled on an event basis; subsurface flow was sampled monthly. Because of underlying clay layers, subsurface flow returned to the surface to contribute to continuously flowing streams. With different levels of nitrogen fertility being maintained for multi-year periods, changes in nitrogen movement could be measured when the N application rate was changed. These changes were also observed downstream at larger watershed sites (multiple acres). The response times indicated that several years are necessary to measure changes in management, and that response times in multi-square miles would be at least as long, probably longer. These results are of use to scientists and land managers who are trying to evaluate changes in management practices on soil loss and stream water quality.