Abstract
The specific fuel consumption (SFC) was measured for mouldboard ploughing, disc harrowing and rotavating a tropical loam soil and a clay loam soil, singly and in combination, at different soil moisture contents. Both soil types had the lowest SFC near their plastic limit. SFC for seed bed preparations using the disc plough only, the plough -t- h arrow, the plough + rotavator, and the plough + harrow + rotavator, and the yield of maize in response to these tillage methods, were measured. Although ploughing-only gave the highest yields on the loam soil, it did not produce a seedbed suitable for mechanical seeding. Plough + harrow was the most fuel-efficient of the tillage combinations and produced significantly higher yields of maize on the loam soil and yields similar to the other tillage combinations on the clay loam soil. Adoption of this method of seedbed preparation at the plastic limit of the soils can result in a saving in fuel costs. Measurement of changes in the micro-relief of the loam soil after tillage indicated that most of the changes occurred within the first 17 days and after a total rainfall of 112 mm.
