Keywords: Fertilizer spreaders, Spreading accuracy, Spreader testing, Environment.

This paper deals with today’s techniques in application of granular fertilizers in agriculture.

It is obvious that it is still difficult to predict the optimal fertilizer rate for a given plant-field-weather situation. Ecological demands and increased fertilizer prices have pursued a more efficient use of fertilizers.

In spite of several methods to measure the uniformity of fertilizer application there is still a need for better methods to relate the uniformity of spreading to the growth of the crop.

The spreading result of the broadcast spreader with spinning disc is dependent on a great number of factors and the calibration is difficult and time consuming. Due to wide overlapping its spreading width is not critical. The ability of the broadcast spreader to spread along borders without any fertilizer falling outside the field must be improved.

The pneumatic full width spreader is easier to calibrate and its spreading pattern is less dependent on high winds. Due to little overlapping its spreading width is critical and some kind of positioning is necessary.

Today, improvement in spreader design is more important than future systems with computers and satellite-location systems.

The influence of fertilizer use on environment must be seriously considered from the farmer's point of view as well as from society.

Prof. N Möller and J E T Svensson, Swedish University of Agricultural Sciences, Department of Agricultural Engineering, Uppsala, Sweden.

28 pages, 9 figures, 1 table, 14 references.