Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2007
Publication Date: 1/1/2008
Citation: Li, S., Lobb, D.A., Lindstrom, M.J., Papiernik, S.K., Farenhorst, A. 2008. Modeling tillage-induced redistribution of soil mass and its constituents within different landscapes. Soil Science Society of America Journal. 72(1):167-178. Interpretive Summary: Soil movement by tillage (tillage erosion) is recognized as a major force in redistributing soil in cultivated landscapes. The redistribution of soil constituents is affected by soil movement by tillage and mixing of subsoil into the tilled layer. Tillage erosion affects soil productivity and environmental quality by redistributing soil mass and soil constituents in the landscape. In this study, a model (TillTM) was developed to simulate the tillage erosion process. The TillTM model is a diffusion model, which is conceptually simple. This model was used to describe the redistribution of soil mass and soil organic carbon (an example of a soil constituent) on landscapes with different topographic features. We determined that the rate of soil movement by tillage is mainly dependent on topography; whereas, the redistribution of soil constituents was primarily affected by landscape topography, tillage direction, and time. The TillTM model was tested against field measurements. It was shown that the TillTM model can precisely estimate the pattern of soil constituent redistribution by tillage, but may require detailed field measurements to accurately represent the changing contents of soil constituents in the landscape. These results will enable land managers, extension personnel, consultants, and agricultural researchers to predict the effects of tillage erosion on the movement of soil mass and soil constituents in landscapes and to better describe landscapes affected by tillage erosion. These results will be useful in designing and evaluating cropping practices to reduce soil erosion.
Technical Abstract: Tillage is a driving force of soil movement in cultivated fields. Soil constituents, together with the mass of soil, are redistributed over landscapes by tillage. The pattern of soil constituent redistribution by tillage is not determined by the pattern of soil mass redistribution alone because the extent of soil translocation and mixture with subsoil also strongly affect soil constituent redistribution. In this study, we used a convoluting procedure and developed a model (TillTM) to simulate the tillage translocation process, which was used to describe the tillage-induced redistribution of soil mass and soil organic carbon (as an example of a soil constituent) on four hypothetical landscapes: plane slope, symmetric hill, asymmetric hill, and irregular hill under different tillage patterns and over different temporal scales. The model was validated against field data collected at a site near Cyrus, Minnesota, USA. We determined that the local tillage erosion rate is mainly dependent on topography; the effects of tillage pattern and temporal scale on tillage erosion are relatively minor. The redistribution of soil constituents in the till-layer is mainly determined by the number, location, and size of soil loss positions in the landscape and the intensity of soil loss occurring on these positions. Net loss of soil organic carbon occurs in the till-layer across the landscape and this loss increases over time. In contrast, soil organic carbon content in the sub-layer increases at soil accumulation positions. The application of the TillTM to the field data demonstrated that the model could precisely estimate the pattern of soil organic carbon and inorganic carbon redistribution. These results indicate that a simple diffusion model can accurately assess the pattern of the soil constituent redistribution through the estimation of tillage erosion.