34. We argued earlier in this paper that the most appropriate stage for introducting animal traction is the late bush-fallow or the grass-fallow stage. The question we now ask is: can we go directly to tractors at this stage without the intermediate animal traction stage? We looked at 17 projects in Africa that tried to make this direct jump and found that only two had succeeded. All the failures were located in areas of bush-fallow and early grass-fallow. The quality of destumping required for tractors is much higher than for animal draft, because in the former case all stumps and roots have to be removed to avoid damage to tractor implements. In the latter case, the animals can be used in partially destumped fields working their way around the stumps. In a few years the stumps decay and clear fields are available for cultivation with animals or tractors. Moreover, areas in which plow use is emerging have a variety of field conditions, some of which are permanently cultivated while bush fields are still periodically fallowed. Having animal drawn plows allows the farmer to till both his permanently cultivated fields as well as his bush fields.
35. It is very rarely that one sees a complete shift from one power source to another. In parts of India and Philippines, where tractors do tillage and transport, interculture continues to be done by animal draft power while harvesting is done by hand. In low wage conditions, tractors and animals are complements, with tractors concentrating on operations which require high levels of power while animals are used to work on operations that require a greater degree of care and judgement, such as weeding. If a direct transition is made to tractors this complementary would be lost.
36. Finally, economies in the early stages of mechanization are often characterized by capital scarcity and poor infrastructure facilities. It would therefore be easier for farmers to obtain and maintain animals and animal drawn equipment rather than tractors which require a more sophisticated network of repair and spare parts facilities. We would therefore argue that in most cases it would not be cost effective to make the direct transition from handhoes to tractors.
37. In the two cases where the transition was successfully made, both of them were in areas which were stump free, such as the grassy savannas of central Sudan and floodplain areas such as those in northern Ghana. Both these cases had the following characteristics: destumping costs were low; soils required deep tillage; they were not cultivated prior to the advent of tractors; the growing period was very long due to the water retention capacity of the soils; a government sponsored and subsidized tractorization program was in place; a government parastatal marketed the output.
