Improving animal drawn tillage system in Ethiopian highlands

In most smallholder farms in Ethiopian highlands, farmers still use the wooden ard plough (Maresha). This study was undertaken to understand and optimise the traction forces provided by the draught animals. An ard plough equipped with three load cells (one on the beam and one on each side of the yoke) was implemented to measure traction forces required for tillage of four Vertisol fields under wet and dry conditions. Tillage was performed at three different depths of shallow (0–5 cm), medium-deep (5–10 cm) and deep (10–15 cm). The interpretation of force measurement was done for equally and unequally strong pair of oxen. After tillage, soil samples were taken for the determination of bulk density and moisture content. The cross-section area of furrow profile (CSAFP) and depth were also measured.With the measurement of equally strong oxen, each ox provided 50% of the total traction force required for tillage. However, with unequally strong oxen, different contributions of each ox to the total traction force were found. The stronger ox moved faster than the weaker ox, creating an asymmetric position of the yoke. In this situation, the weaker ox had to work harder to overcome the force transferred from the strong ox and correct the asymmetric position of the yoke. Thus, the weaker ox had to provide a larger force to the total traction force compared to the stronger ox. A larger traction force was measured with the yoke asymmetric position for smaller depth, speed and CSAFP. Therefore, farmers in the Ethiopian highlands can improve the tillage efficiency of the Ethiopian ard plough by using equally strong pairs of oxen. However, with unequally strong oxen the weaker ox should be enhanced to walk a head of the stronger ox, allowing the latter to provide the larger required traction force.