THE ACCURACY OF FARM MACHINERY FOR PRECISION AGRICULTURE - A CASE FORFERTILIZER APPLICATION

Work quality, capacity and reliability are important criteria for desi gn and evaluation of farm equipment. With the introduction of precisio n agriculture, the ability to adapt to spatially variable soil and cro p conditions, becomes an additional aspect. A calculation method is de veloped to find the precision of site specific fertilizer application. The variance between the required rate, RR, and the applied rate, AR, is used as a measure for precision. The theory of gee-statistics is u sed for variance calculation. Spreading patterns are evaluated for dif ferent levers of field variability, positioning accuracy and resolutio n of the required application rates. The shape of spreading patterns h ad small influence. The effect of the accuracy of positioning systems depends on the resolution of the required application rates and of the working width of independently controlled sections of the spreaders. The study shows how machine design depends on the resolution of field information.