Decision-making strategies for the variable-rate application of compound fertilizers

The implementation of precision agriculture technologies is probably one of the greatest opportunities of the 21(st) century to expand the horizons for soil and plant analyses by converting the spatial variability of soil and crop characteristics into a spatially variable input of agro-resources in order to match the local demand in the field. Compound fertilizers have been developed in order to simplify fertilization, but with their use in precision agriculture the following major problems need to be faced: firstly, the spatial variability of optimum fertilizer rates between different nutrients are not correlated and secondly the nutrient ratio is constant during application and may lead to an undesired surplus or deficit in different zones of the field, which again is counter-productive to the aims of precision agriculture. In this paper, different decision-making strategies for variable-rate applications of compound fertilizers are presented which include a balanced fertilizer input over a three-year crop rotation.