The aim here is to use the magnesium from kieserite and the ammonium and phosphorus from the slurry to grow struvite crystals in the slurry belt.
Struvite has a sand-like structure with a typical nutrient composition of 5%N, 23%P2O2 and 12%MgO. Struvite is a magnesium ammonium phosphate (MAP), which has the efficiency-improving advantage that part of the nitrogen from the slurry is bound as ammonium in struvite and is protected from nitrification and leaching losses. Furthermore, the phosphate from the liquid manure in the new Struvit compound has very good citric acid solubility and thus plant availability via root exudates, on a par with triple superphosphate. The phosphate is thus protected against ageing and remains readily available to plants. Due to its relatively high weight (bulk density 1,380 kg/m³), Kieserit fine is difficult to mix homogeneously into a 20 m³ slurry tanker, for example. The "just-in-time" introduction of Kieserit fine into the distribution head has the advantage that an exact mixture can be produced and that crystallization only begins in the soil and no sand-like deposits can occur in the spreading vehicle. The media can no longer segregate until they enter the soil.
