PREFARM system works with a lot of information that are important for the precise determination of the fertilizer doses. The aim is to develop a fertilization plan and application maps for the optimised application of fertilizers.
The elaboration of the fertilization plan is based on the crop rotation design. The doses of fertilizers are determined with respect to the main crop, pre-crop and yield level of crops grown. Additionally, corrections are made based on the soil grain composition, nutrient inputs in the form of organic fertilizers and post-harvest residues and other factors affecting the determination of the correct fertilizer dose. The result is a clear plan of fertilization with application maps that determine the optimal dose of nutrients for each site.

The fertilization plan serves as the basis for discussion with the management of the farm, especially the agronomist. The recommended doses resulting from the fertilization plan may be corrected based on the site specific needs and precise knowledge of the particular localities. The economic situation in less successful years must be also taken into account. The resulting corrections are projected into the fertilization plan with a sensitive consideration of the observed soil variability. Eventhough  the total amount of fertilizer is limited, it is always possible to prefer sites that are most in need of nutrients and are the best most efficient in their use. This system optimizes the use of fertilizers.