Modeling Tractive Force Requirements of Wheel tractors For Disc Ploughing in Sandy Loam Soil

Tractive force models at different tillage speeds were developed using dimensional analysis, describing the tractor tyre - soil interaction. In this research study, disc ploughing on an experimental plot at twenty different soil moisture levels in loamy sand soil was carried out using trace tractor techniques. The independent variables: drawbar pull force, rolling (motion) resistance, wheel slip, moisture content, cone index, wheel numeric, contact pressure, speed, width of plough, depth of plough, and dependent variable (Tractive force) were measured and compared to computed values. High coefficients of determination R2 = 0.9492, 0.9555 and 0.9447 for ploughing at tillage speeds of 1.94m/s, 2.22m/s and 2.5m/s were obtained respectively. Standard errors of 0.3672552, 0.8628 and 0.8047 and the percentage (%) errors of -2.272608059 and 2.45655144,-2.304946155 and 2.523126085,-1.424947801 and 2.020155232 at minimum and maximum values, were obtained. These results are clear evidence of the test of goodness of fit of the models between predictive and measured parameters for ploughing at different tillage speeds. The models were verified and validated by comparing the predicted with the measured tractive forces, and shown to closely followed the experimental results.