Modeling Landscape Evolution Due to Tillage: Model Development

Abstract

Tillage erosion has been identified as an important contributor to the modification of agricultural landscapes. A two-dimensional, grid-based model has been developed to compute soil redistribution and morphological changes of complex landscapes due to tillage operations. Soil movement along and perpendicular to the directions of tractor movement are computed as a function of local slope gradients and of characteristics of the tillage implement. A control volume approach is employed to determine terrain elevation changes after each tillage pass. The model explicitly considers the presence of internal and external field boundaries, simulating their influence on the development of erosion and deposition patterns. GIS layers are used to provide terrain elevation data, actual tillage directions, field borders, and the location of other features, such as vegetated strips, trees, or fences. The model was verified against an analytical solution for the development of bench terraces due to tillage between vegetated strips. The model's capability of considering variable tillage directions was tested with a simulation of tillage erosion over a synthetic, undulating surface and was used to investigate how an implement's forward and lateral soil displacement characteristics influence erosion patterns as a function of tillage direction relative to slope. The model's stability, computational efficiency, and ability to simulate fields with complex boundaries and varying tillage directions allow its use as a practical tool within a comprehensive conservation planning system.