INFLUENCE OF SOIL WETNESS AT TIME OF TILLAGE AND TILLAGE IMPLEMENT ONSOIL PROPERTIES AFFECTING WIND EROSION

Surface soil properties such as wetness, bulk density and dry aggregat e size distribution (DASD) affect wind erodibility. The degree to whic h these properties are changed by tillage depends largely on the soil wetness at the time of tillage and the type of tillage implement used. The new Wind Erosion Prediction System (WEPS) seeks to simulate these changes to allow better prediction of wind erosion losses. The object ive of this study was to quantify the effect of soil wetness at the ti me of tillage on soil erodibility parameters for three commonly used i mplements in southern Alberta. Three soil wetness treatments (dry, mid and wet) were established on a clay loam soil and then cultivated by three tillage implements (Noble blade cultivator, rototiller and tande m disc). Soil wetness, bulk density and DASD were characterized pre- a nd post-tillage. Tillage on all nine treatments decreased bulk density ; the drop ranged from 0.11 to 0.35 Mg m-3. Significant positive linea r relationships were found between soil wetness at time of tillage and geometric mean diameter of aggregates for the blade and rototiller tr eatments. This relationship was non-linear for the tandem disc. To ach ieve maximum protection against erosion, the blade and rototiller shou ld be used in moist soil conditions and the tandem disc in dry soil co nditions.