A Novel Approach to the Prediction of Tillage Tool Draught using a Standard Tine

Abstract

An investigation was conducted to develop and validate a novel approach to the prediction of the draught required by primary tillage implements op- erating in field conditions. A methodology was developed based upon an existing force prediction model which describes the draught of a standard tine as the product of two factors, related to soil strength and tool geometry respectively. The methodology results in a two-step prediction procedure, which consists of (1) establishing, in a reference soil condition, some comparative draught relationships (tool index I) be- tween the standard tine and each tillage implement and, (2) measuring the draught of the standard tine in the field. The tool index relationships were determined under laboratory conditions for a number of single tillage tools over a range of working depths, and the methodology was validated in four field conditions, namely: two friable sandy-loams, a compact clay and a plastic clay soil. Predicted draughts were on average within 18% of the measured values. In the friable soil conditions, the average prediction errors for the tine tools, mouldboard body and disc tool were 14%, 16% and 30% respectively. The corresponding errors for the same tools in the plastic clay were 18%, 26% and 26% respectively.