Effect of cutting edge thickness and state of wear of ploughshare on draught force and heart rates of Sanga oxen in Ghana

In this study, draught forces and heart rates of oxen were measured during ploughing to assess ploughshare cutting edge performance. The main objective of the study was to examine the effect of cutting edge thickness and state of wear of animal-drawn mouldboard ploughshares on the draught force and the heart rates of oxen pulling the implement and to determine the optimum cutting edge that gives the least draught force and lowest heart rates when pulled by animals. To minimise soil variability, a field was ploughed, harrowed and left to consolidate for 4 weeks before field experiments started. A pair of Sanga oxen was used during the field test. Analyses of variance showed there were significant differences (p < 0.05) in the mean draught forces and the corresponding oxen heart rates for the cutting edges. The field test results indicated the draught forces and heart rates of the animals increased with increasing cutting edge thickness from 2 to 8 mm, but also increased slightly for the I rum edge. The draught forces of the other cutting edges relative to the 2 mm were 9%, 1%, 29%, 35% and 65% higher for the 1, 4, 8 mm, Reversed and double-sided, respectively. The heart rates induced by the other cutting edges relative to the 2 mm varied from under 1 to 12%. The draught of the cutting edges was between 6 and 10% of the body weight of the animals used for the experiment. The lowest draught force and heart rate were obtained for the 2 mm cutting edge. Since the 4 mm cutting edge generated draught forces and heart rates values as low as the 2 mm, it was considered potentially more durable under field conditions and could be the recommended cutting edge thickness for animal-drawn shares in similar soil conditions used for the experiment. (C) 2007 Elsevier B.V. All rights reserved.