Analysis of Draft Force Requirement of a Compact Disc Harrow and Model Development for Future Predictions

Abstract

During tillage operations, draft force contributes hugely to the operational cost. Accurate knowledge of draft force (DF) requirement for tillage implements is a useful tool for machinery selection, matching of implements to tractor, etc. The goal of this research was to measure the draft force of a compact disc harrow and analyze the effect of soil moisture content (SMC) and machine speed on draft force. Also, another aim is to develop a model equation to predict draft force requirement of compact disc harrow. A EWX 10000F winch was used to provide the draft (pull) force which was powered by a 24 V DC battery. The draft force was measured using a load cell which transmitted the measured values to an AND ad 4532B indicator. The draft force of the compact disc harrow was measured at three different levels of SMC: low SMC (5–7%, 9–11%, 13–15%); medium SMC (25–27%, 29–31%, 33–35%); and High SMC (40–42%, 44–46%, 48–50%) with machine speed (MS) of 0.06 m/s, 0.09 m/s, and 0.12 m/s. The results obtained were statistically analyzed and it showed that the lowest draft force occurred at 26% SMC with a force of about 658 N. A multi-variable regression equation was developed after the regression analysis. The regression equation DF = 466.91 + 6.25*(SMC) + 2952.1*(MS) was selected as the best model for predicting draft force. This equation was verified using the Bland–Altman plot, the t test analysis, and the standard error analysis. The results of the verification methods proved that the suggested model can be used for predicting draft force requirement of a compact disc harrow.