Submitted to: Soil & Tillage Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/22/2006
Publication Date: 4/1/2007
Citation: Papiernik, S.K., Lindstrom, M.J., Schumacher, T.E., Schumacher, J.A., Malo, D.D., Lobb, D.A. 2007. Characterization of Soil Profiles in a Landscape Affected by Long-term Tillage. Soil & Tillage Research. 93:335-345. Interpretive Summary: Soil loss by erosion is recognized as a factor limiting crop production and plant growth throughout the world. Research has consistently demonstrated yield reductions in response to topsoil loss by erosion. Soil movement by tillage (tillage erosion) can be a dominant force in redistributing soil in a landscape. In this study, we evaluated the impact of long-term cultivation on the properties of the different layers (horizons) in the soil and their arrangement with depth. We determined that at this site in west central Minnesota, cultivation for the past 100 years has resulted in a pattern of soil redistribution within the landscape such that topsoil has been removed from upper hillslope positions and accumulated at lower slope positions. Tillage erosion, the primary erosive force at this site, has altered the characteristics of the soil across the landscape. Substantial incorporation of subsoil material has occurred in eroded landscape positions, giving the surface soils in these areas properties that impart lower productivity than soils in lower slope positions. Comparing the properties of the surface soil in cultivated areas (regardless of erosion status) with those in an adjacent uncultivated area indicated that intensive tillage and cropping has significantly depleted the surface soil organic matter in this landscape. Extension personnel, growers, crop consultants, regulatory agencies, and other scientists can use this information to better predict crop yield responses to soil properties and landscape position in eroded areas, to develop precision agriculture approaches to increase the productivity of eroded soils, and to design methods to remediate or restore eroded landscapes.
Technical Abstract: Soil movement by tillage redistributes soil within the profile and throughout the landscape, resulting in soil removal from convex slope positions and soil accumulation in concave slope positions. Previous investigations of the spatial variability in surface soil properties and crop yield at a till-derived study site in west central Minnesota indicated that wheat yields were decreased in upper hillslope positions affected by high soil erosion loss. In the present study, soil cores were collected and characterized to indicate the effects of long-term intensive tillage on soil properties as a function of depth and tillage erosion. Soil profiles in areas subject to high soil loss by tillage erosion were characterized by truncated profiles with a shallow depth to the C horizon, which was overlain by a calcic subsoil and a tilled layer containing significant amounts of inorganic carbon. Profiles in areas of soil accumulation by tillage exhibited thick sola with a large depth to the C horizon. Organic carbon, total nitrogen, and extractable phosphorus contents were lower throughout the profile in eroded landscape positions than in areas of soil accumulation. The high carbonate content of subsoil material in upper landscape positions results in high pH throughout the profile in areas of soil loss by tillage erosion. Deep accumulation of topsoil material in areas of soil deposition resulted in inorganic carbon contents that were lower throughout the profile than those found in an adjacent uncultivated area. The mean surface soil organic carbon and total nitrogen contents in cultivated areas (regardless of erosion status) were less than half that measured in the uncultivated area, indicating that intensive tillage and cropping has significantly depleted the surface soil organic matter in this landscape.