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.
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.
How the economics of such an approach evolve depends on the commitment of the international community to attain such sustainable and environmental goals. There has been a substantial global investment in agricultural mechanization and automation by governments, industry, farmers and international agencies. In general, the return on investment has been spectacular.
The harvesting of delicate fruits (strawberries, raspberries, grapes, plums) and vegetables (tomatoes, mushrooms, lettuce) for the fresh market has not been successfully completed despite a substantial investment in crop breeding and mechanization research. Machines that can harvest such delicate biological tissues, generally inflict too much damage on a product destined for the fresh market but have been successful with product destined for processing.
Selective harvesting is another substantial challenge facing researchers in the fruit and vegetable sector in particular.