Position control is a system whereby the position of a fully mounted implement (sprayer or fertilizer distributor, whose weight is completely supported by the tractor) is automatically maintained in a constant position (e.g. operating height over the ground) despite leakages in the hydraulic system tending to lower the position of the implement.
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.
Precision farming practices including the use of global positioning systems (GPS) and geographic information systems (GIS) are applicable not only to harvesting operations but to other farm mechanization operations including precision application of agrochemicals i.e. applying a pesticide or a crop nutrient where it is required and at the appropriate concentration rather than using blanket coverage.Researchers in California have demonstrated the feasibility of a selective field lettuce harvester where mature lettuce heads are identified by an X-ray signal through the lettuce head, which then instructs the harvester accordingly.Agricultural mechanization has involved the partial or full replacement of human energy and animal-powered equipment (e.g. plows, seeders and harvesters) by engine-driven equipment. Most of this is tractor driven and to a lesser extent self-propelled equipment (including harvesters, sprayers, fertilizer applicators, planters and seeders). Agricultural mechanization has been pioneered in North America and Europe and more recently in Japan, and is now spreading rapidly throughout the world. Notwithstanding such progress, a significant element of human and animal powered mechanization remains, particularly in the poorer regions of the world.
While much remains to be done on small farms in the poorest regions, sufficient progress has been made to accelerate food production in line with population growth (contrary to the Malthusian prediction). In this theme, farm machinery is considered with primary emphasis on engine and motor driven machines and implements and a lesser emphasis on human or animal powered equipment.