GPS Use in Agriculture:
Tractor Guidance: Farmers can not put their tractors on auto-pilot. If they plow their fields with a recording GPS system the tractor can then be programmed to follow the same route – for cultivating, fertilizing, pest control and harvesting. The programming of tractor routes has the potential to save a lot of money.
Cropduster Targeting: Insects don’t attack a field with a uniform distribution. Instead outbreaks of insect activity are concentrated in certain areas. Workers strolling the crops can use a GPS to record the locations of insect problems. The data can then be used by cropduster pilots to selectively target the problem areas instead of treating an entire field. This method results in a savings of time, fuel, insecticide and crop exposure to chemicals.
Tracking Livestock: The location of valuable animals on a large farm can be monitored by GPS transmitters attached to the animals collar. When the animals are sent to market GPS transmitters can also be used to track their location.
Yield Monitoring: Estimates of yield variations across a property can be made using GPS. To do this the property is divided into zones and the yield of each zone is estimated and plotted on a map. The map can then be used to better understand the property and for decision-making in regard to the next planting.
Soil Sampling: Collecing soil samples across a large property can be organized using GPS and mapping software. The sample locations can be waypointed in the field and those waypoints marked on the mapping software. Then, when the laboratory results are returned the data can be plotted on the maps and decisions for soil treatment can be made for various parts of the property. The locational information can save money and time by allowing variable rate applications and treating only those areas with a documented need.
(Source – http://www.mapwatch.com/gps/gps-agriculture-farming.shtml)