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Most of the conventional lime spreaders available in the Brazilian market distribute lime at a fixed rate without considering the particular features of the field. The purpose of this research was to design and build a variable rate lime application system. The system calculates the geographic coordinates of the lime spreader position obtained by a Differential Global Positioning System. These coordinates, the information on the machine velocity and a prescription map of the quantity of lime for each field point, are transferred to a computer. The program in the computer automatically adjusts the position of the machine metering device using a step motor driven by electric impulses generated by an electronic interface. The metering device position was checked through potentiometric sensors. The C++ programming language was used to write the systems control program. The metering system was tested and the results indicate that the total error of the opening of the metering device is 0.18x10 -2 0.60x10 -2 m. This can be considered acceptable for lime application systems.