|Kaspar, Thomas - Tom|
|Karlen, Douglas - Doug|
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2005
Publication Date: 11/14/2005
Citation: Schumacher, J.A., Venteris, E.R., Mccarty, G.W., Ritchie, J.C., Kaspar, T.C., Colvin, T.S., Jaynes, D.B., Karlen, D.L., Fenton, T.E., Schumacher, T.E., Lindstrom, M.J. 2005. Identifying spatial patterns of erosion for use in precision conservation. Journal of Soil and Water Conservation. 60(6):355-362. Interpretive Summary: Soil erosion is a serious threat to the productivity of our nation's soils. Water, wind, and tillage are the three primary causes of erosion in agricultural fields. These three causes of erosion affect different parts of fields to different degrees. If farmers and NRCS personnel knew which parts of fields were affected by which type of erosion, they would be able to assign specific erosion control practices to address the primary cause of erosion in that portion of the field. In this study, we found that in north central Iowa the summits and shoulders of hills were affected primarily by tillage erosion, whereas the backslopes and footslopes of hills were affected primarily by water erosion. Using elevation data we were able to map the areas of field affected primarily by tillage or water erosion. Using this information farmers and NRCS personnel will be able to tailor conservation plans for specific fields based on their terrain characteristics. For example, reduced tillage systems or no-till might be used on the summits and upper backslopes of hills to prevent tillage erosion, whereas winter cover crops might be used on footslopes or lower backslopes to prevent water erosion. The impact of this information will be reduced erosion, maintenance of soil productivity, and reduced sediment load to streams and lakes.
Technical Abstract: Water, wind, and tillage erosion of cropland in hummocky landscapes of the North Central United States is a well-documented problem. Evaluating spatial erosion patterns can provide information on crop production potential, soil properties, and problematic erosion / deposition areas. Our objective was to evaluate two methods of delineating soil erosion patterns in a west-central Iowa field. First, soil erosion was estimated using soil displacement of 137Cs, a radionuclide deposited from nuclear weapon testing in the 1950s and 1960s. Landscape erosion patterns were also generated using predictive models for tillage- and water-erosion. Topography-driven simulation modeling provided separate estimates of erosion and deposition rates due to water and tillage processes. Erosion pattern estimates were compared using qualitative and quantitative methods. The combined tillage-water erosion model was found to fit 137Cs patterns better than tillage or water erosion alone. Spatial maps reflecting past erosion could be used for planning precision conservation practices such as localized cover crops, supplemental carbon (e.g. manure, extra crop residue, or municipal sludge), reduced tillage, and other site-specific practices.