Agronomy Advice
March 11, 2024

Pay close attention to your Phosphate applications this Spring

Phosphate (P) is a key nutrient for grass. Its role in energy supply, root growth and tillering make its availability crucial for grass growth in the spring.

Image of Grass

The plants requirement for P is small in volume when compared to nitrogen BUT its availability is essential. For grazing, the key period of application runs from March to May, due to soils being cold and wet, but also an increasing grass P demand, as grass growth rates increase in April and peak in May.

Typically, the P in fertiliser is 100% water soluble; this however creates its own problems. As soon as you apply water soluble P to a soil, this soluble P becomes slowly fixed by iron and aluminium. The P contained in YaraMila ExtraGrass (27-5-5+6% SO3) and YaraMila 52 S (20.6-8.2-11.6+6.5% SO3) is a mix of water-soluble phosphate and Di-Calcium Phosphate (DCP). This DCP is not fixed by the soil but becomes available as it is triggered by weak acids from grass root exudates.

The maintenance requirement for P on grazed swards is 20 kg/ha, however if your grazing platform is growing 13-15 t of dry matter with 80% utilisation, then your maintenance will be closer to 30 kg/ha. We shouldn’t underestimate the importance of fertiliser quality when it comes to applying the P & K in NPK fertilisers, and using a uniform compound is one sure way of ensuring spreading uniformity and maximising the number of P & K landing sites.