Soil translocation with tillage tools
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A study of soil translocation by tillage tools was conducted in the soil bin facilities of the Department of Agricultural and Bioresourse Engineering, University of Saskatchewan. Initially a 300-mm wide sweep and a 14-mm Conserva-Pac knife opener (narrow tool) were used at three operating speeds with three soil moisture contents and three compaction levels. Soil translocation was measured by the movement of small plastic blocks positioned in the soil. The plastic blocks lad a density equal to the soil. New positions of the plastic blocks (x-y-z coordinates) after each test were measured with a special instrument developed for this study and the volume of translocated soil was determined. Effects of compaction level, moisture content, tool shape, and travel speed on soil translocation were studied. The results showed an exponential relationship between soil movement and depth, and the soil movement per travel unit area was higher for the narrow tool. Results also indicated that soil movement per unit width or per frontal area of the narrow tool was higher than for the sweep. Therefore, more experiments with different narrow tillage tools at higher speeds were conducted to determine the trend. Four narrow tools with shapes of 45° triangular, 90° triangular, flat and elliptical were used at four levels of speed (10, 15, 20, and 25 km h-1), three levels of compaction and three levels of soil moisture. A special device, using a simple pendulum principle, was used to provide the required speed levels. An instrumentation system was designed to measure the tool speed and the energy used during cutting. Soil profiles for each test were also measured by a laser soil profile meter fabricated for this study. Among the four tool shapes used in high speed experiments, the 45° and elliptical shaped tools in less soil movement and used less energy. Based on these data, a mathematical model for soil movement with speed of operation of the tillage tool was developed. Soil physical parameters were included to predict soil movement at different moisture contents, compaction levels, and tool shape factors. The predicted soil movement correlated well with experimental data. Since it is difficult to model soil parameters, the model needs further refinements.