Evaluating the impacts of tillage on sediment production and yield

Soil erosion is identified as the primary cause of soil degradatgion due to the unsustainable agricultural practices, leading to severe threat worldwide for soil health and water quality problems. Therefore, quantifying soil erosion under various conservation practices is important for watershed management and a framework that can accurately estimate the spatio-temporal dynamics of soil erosion is required. In this paper, a modeling framework that coupled physically based models, Water Erosion Prediction Project (WEPP) and MIKE SHE/MIKE 11, was presented. Daily soil loss in field scale was determined using WEPP and the transport processes of the eroded soil were simulated using an advection-dispersion equation in MIKE SHE/MIKE 11 models. The framework facilitated the physical simulation of sediment production at the field scale and transport processes across the watershed. The coupled model was tested in an intensively managed agricultural watershed in Illinois. The impacts of no-till practice on both sediment production and sediment yield were evaluated using scenario-based simulations with different fractions of no-till and conventional tillage combinations. The results indicated that if no-till were implemented for all fields throughout the watershed, 76% and 72% reductions in total soil loss and sediment yield, respectively, can be achieved. In addition, if no-till practice were implemented in the most vulnerable areas to sediment production across the watershed, a 40% no-till implementation can achieve almost the same reduction as 100% no-till implementation. Based on the simulation results, the impacts of no-till practice are more prominent if implemented where it is most needed.