A satellite-based positioning system is being developed to determine the location of farm equipment while working in the field. A satellite receiver mounted in a moving tractor or combine calculates position coordinates based on signals received from a selection of satellites in the Department of Defense Global Positioning System (GPS). The position coordinates are retrieved from the receiver by a computer and combined in a common data base with additional information collected by the computer such as yield, soil fertility, soil moisture, temperature, implement draft, and fuel consumption. There are a number of possible applications for this system. One is the automation of position information and data collection for research purposes. Comparison of results between years can be easily made. Another application is the optimized and automated application of manure, fertilizers and chemicals. Profits can be increased and environmental damage minimized.