TEP: A Tillage Erosion Prediction model to calculate soil translocation rates from tillage

ABSTRACT:

Soil movement by tillage is a function of slope gradient. Tillage direction performed upslope and downslope in opposing directions over alternate years results in a net downslope movement of soil. The objective of this study was to develop a simulation model to describe soil redistribution along a billslope transect that can be used to explain observed erosion and deposition patterns in cultivated fields that result from tillage action. A diffusion-based conceptual model was used to represent soil redistribution by tillage, whereby the regression coefficient for the relationship between translocation and slope gradient was described by a diffusion coefficient, k′. Soil redistribution was calculated over a 50-yr period on a measured topographic transect in west central Minnesota using published k′ values for the moldboard plow. Additional simulations included the additive effects of secondary tillage (tandem disc) and an examination of hillsope segment lengths on soil redistribution rates. Results showed that 14.7% of the area from the measured transect would experience a loss or gain in soil that exceed 10 t ha⁻¹ yr ⁻¹ with moldboard plow using a k′ value of 2.34 kg m⁻¹ slope width. The loss or gain in soil that exceed 10 t ha⁻¹ yr ⁻¹ increased to 26% of the area with a k′ value of 3.30 kg m⁻¹. The addition of secondary tillage (two tandem disc operations) increased the area of excessive soil redistribution to 59%. The Tillage Erosion Prediction (TEP) model has the capability to identify areas based on landscape configuration of excessive soil loss (erosion) or gain (deposition) due to soil translocation by tillage.