Measurement of Tillage Translocation and Modeling Tillage Erosion in Southwest Manitoba, Canada

摘要

Tillage erosion is the redistribution of soil within a landscape caused directly by tillage. There is a growing recognition that tillage erosion is a major contributor to the total soil erosion that occurs on cultivated land and, therefore, can affect a variety of biophysical processes within landscapes, such as pesticide fate and greenhouse gas emissions. In 2003, a total of 36 plots were established at a field site located near Deerwood, southwest of Winnipeg, to examine tillage translocation caused by 3 different tillage implements, deep tiller, spring-tooth harrow, and air seeder. Dyed stone chips were placed into the soil in plots located over a range of topographic conditions in two areas in the field. The distribution of these plottracers after tillage was used to measure soil translocation. Regression analysis was performed to examine the effect of both slope gradient and slope curvature and to calibrate a tillage erosion model. The calibrated model was then used to predict tillage erosion in the whole field for a full tillage sequence. For all three tillage implements, translocation was highly variable. However, regression analysis shows that there is a significant relationship between tillage translocation and slope gradient. Slope curvature has also been found have strong effect on tillage translocation and was recommended to be used as a second factor in the model. Compared to the other two implements, deep tiller has been found moves much more soil and has more potential of tillage erosion. Air seeder moves more soil than spring tooth harrow, but the potential of tillage erosion for the two implements are almost the same. According to the model prediction, soil loss occurs typically on crest and up-slope area and soil accumulation occurs typic ally on down-slope and depression area. It ranges from 22.3 ton·ha{sup}(-1)·y{sup}(-1) soil loss to 16.7 ton·ha{sup}(-1)·y{sup}(-1) soil gain. The high variability of tillage translocation indicates that it cannot be explained by slope gradient alone. Slope curvature, tillage speed, tillage depth and soil properties may also have strong effects. Further study is being carried out to cover more tillage implements, to confirm the effect of slope curvature found in this study and to examine the effect of other factors.