In-field Static Spread Pattern of a Centrifugal Spreader by Considering Field Topography

For the application of granule fertilizer in site-specific farming, the performance of a centrifugal spreader is defined by the achieved application accuracy, which, in turn, is strongly influenced by the transversal distribution. The fertilizer distribution is not only affected by inaccurate positioning and the delayed response of the spreader to the rate changes at management zone boundaries, but also by field slopes. This study aims to investigate and estimate the influence of the field slope on the distribution of the fertilizer mass over the static spread pattern. To fulfill this aim, a mobile sensor frame was developed to acquire the 3D profile of a field. Further, a centrifugal disc spreader was equipped with the necessary sensors to obtain the georeferenced in-field position. With a mathematical model, the measured inputs were used to define each granule position with the corresponding mass over the acquired field profile. The transverse distribution of fertilizer granules resulting from static spread patterns for the flat field surface and the actual field surface were compared to evaluate the influence of the field topography on spreading. The comparison showed a root-mean-squared error of 27.8%. The absolute difference was equal to 22.2 kg/ha between the mean values and 5.9 kg/ha between the standard deviation of the best-fit distributions.