Alongside the primary nutrients (N, P and K), sulphur is the most important secondary nutrient (Mg, Ca and S). However, sulphur fertilization is a relatively new topic. Following a sharp reduction in atmospheric fallout and other sources of supply (through plant protection products or animal manure), the application of sulphur through mineral fertilization has become crucial. Soil microbial activity (mineralisation) releases sulphur in available form. Mineralisation depends on soil temperature. Like nitrogen, it is mobile and sensitive to the risk of leaching in its plant available form (sulphate, SO42-) due to winter rainfall. Therefore, the first application of sulphur should occur after wintertime when vegetation restarts, in a balanced ratio together with nitrogen.