Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/1999
Publication Date: N/A
Interpretive Summary: The effects of tillage translocation due to cross-slope moldboard plowing on hillslopes in the Palouse region have heretofore been described primarily in a qualitative manner. The results of this study provide quantitative evidence from controlled experiments that tillage translocation due to downslope-directed moldboard plowing is an important geomorphological process on Palouse hillslopes. The experimental data also indicate that tillage translocation can be described using a diffusion-type equation and that a single number, the diffusion constant (k), can represent the rate of tillage translocation. Statistical analysis of tillage translocation indicated no significant correlation between mean soil displacement and bulk density and moisture content. Mean soil displacement was significantly correlated with tillage direction. These results provide additional impetus for reduced and no-tillage management practices.
Technical Abstract: Most of the erosion research in the Palouse has focused on quantifying rates and patterns of water erosion for conservation planning. Tillage translocation and tillage deposition, however, are frequently overlooked but significant geomorphic processes on steep Palouse hillslopes, and have resulted in severe soil degradation. Unfortunately, few controlled experiments have been conducted to quantify these processes in the Palouse This field study was conducted to quantify tillage translocation due to moldboard plowing parallel to the contour, and to compare this movement with measured long-term tillage deposition. A multivariate statistical model was developed expressing mean soil displacement distance as a function of gravimetric moisture content, soil bulk density, slope gradient, and direction of furrow slice displacement. Analysis of variance (ANOVA) revealed a weak correlation between soil displacement and both bulk kdensity and moisture content. Soil displacement was, however, significantly correlated with direction of furrow slice displacement. Tillage translocation rates were expressed in terms of the diffusion constant (k) and ranged from 105 to 113 kg m/1 per tillage operation. Measured tillage deposition rates ranged from 54-148 kg m/1 per tillage operation. The rates of tillage translocation and deposition are not completely in balance; however, these rates suggest that soil tillage is a significant geoporphic process on Palouse hillslopes and could account for some of the variations in soil physical properties and crop yield potential at the hillslope and farm-field scale in the Palouse region.