Environmentally and economically sustainable phosphorus use in agriculture (VLM FOSFOR)

This research has determined the target phosphorus level in the soil at which no phosphorus deficiency for the crops occurs AND where the phosphorus losses to the environment are limited. In other words, the right balance. Further, ILVO studied which measurement technique best represents the phosphorus availability for the crop as well as the phosphorus losses. Based on the research outcomes, guidelines for sustainable phosphorus fertilization on soils in Flanders were drawn up. Many agricultural soils in Flanders contain high phosphorus contents. This phosphorus load is one of the contributors to the high phosphorus concentrations in water bodies in Flanders (eutrophication), which can lead to algae blooms, fish mortality and decreased water quality.

In a first part several methods for determination of phosphorus availability were tested. This was done by studying literature, performing pot trials, long term field trials and soil column experiments. The P-AL method (extraction of the soil sample in ammonium lactate), the standard soil test in Flanders, was selected as the best available method. In a second part the target zone for P-AL was set, meaning the phosphorus level that is acceptable for both agriculture (optimal crop yield) and environment (limited phosphorus losses). In part three, fertilization strategies were developed to reach this phosphorus level. This was done using literature study, lab and field experiments. Fertilization techniques as well as doses were evaluated.

At the end of this project, practical and useful results are now available. Methodological evaluation revealed that we can rely on the current method for soil phosphorus availability measurement in Flanders. Second, research-based recommendations for target soil phosphorus levels in Flanders are presented. The importance of an optimal soil pH is highlighted. Third, fertilization advice and a code of good agricultural practice to reach these target soil phosphorus levels have been issued. The societal relevance is that when farmers follow these recommendations regarding techniques and quantities, Flanders will have a more sustainable phosphorus use for both agriculture and environment.