A system for spatially variable rate fertiliser application

The crop yield can be spatially variable within the same field, because of spatially variable soil characteristics (slope, texture, pH, etc.), influencing the soil nutrient content (of nitrogen, phosphorus, potassium, etc.). Because of this within-field spatial variability, in the precision agriculture cycle, the targeted fertiliser spreading can be highly profitable for both environment protection and cost saving. For this aim the yield and, then, the soil nutrient content must be measured on a localised basis and, therefore, mapped. Relying on the yield map and on the map of each nutrient available in the field it is possible to produce the fertiliser application map, which must be stored on a portable computer, in order to perform the spatially variable rate fertiliser spreading. For this aim an electronic system able to apply fertiliser rates proportionally related to the machine forward speed is also needed; this system can be mounted not only on any pneumatic spreader but also on any centrifugal spreader with setting up system working by gravity. Yet, the fertiliser spreaders produced by different manufacturers, which are equipped with systems able to apply not only rates proportionally related to machine forward speed but also spatially variable rates, are very expensive. Therefore, the I.T.A.F. Department designed, developed and set up a system for spatially variable rate fertiliser application, compatible with most DGPS and spreaders able to apply rates proportionally related to the machine forward speed. The system is constituted by a data sensing system (DGPS and Doppler radar), a data processing system (portable computer, with a specifically developed software called Precision Agriculture Controller) and an active and control system (Land Manager of DICKEY-john with built-in display and keyboard), able to apply rates proportionally related to machine forward speed, by varying the size of the two hopper openings. The software is able to: receive and interpret DGPS position data and compare them with the fertiliser application map, in order to identify the rate related to the actual machine position; transmit commands to Land Manager; log the machine track and the applied rates.