The importance of enhancing and upgrading such mechanization practices prior to the almost inevitable transition to engine-driven equipment is now well recognized. Automation of agricultural mechanization is an intensive area of research and development with emphasis on enhancement of food quality, preservation of operator comfort and safety, precision application of agrochemicals, energy conservation and environmental control. At first glance, renewable fuels are attractive from an environmental and sustainability perspective and cogent arguments have been made that such considerations justify the generous tax remission protocols necessary to commercialize these products. For example, the use of renewable fuels in urban vehicles may be justified if the emissions are much cleaner than those from conventionally fuelled vehicles.
It is thus no accident that rental markets for threshing machines were well established in the nineteenth century in the United States and are now common all over Asia (Gardezi and others 1979; Walker and Kshirsagar 1981). The contract-hire system for combines in the United States illustrates the problem of synchronized timing. The contractors achieve higher rates of machinery utilization by migrating to follow the harvest from the TexasOklahoma area to the northern states, where harvesting takes place months later. Wages are so low in South Asia that, except for tea plantations, it is still cheaper to weed by hand than to use herbicides (Binswanger and Shetty 1977). Mechanical weeding between the rows with animals becomes feasible only when line seeding is practiced. Inter-row cultivation also tends to be performed by animals long after tractors are used for tillage.