Don’t forget the need for soluble Phosphate

Many grassland farmers with a high stocking rate and significant feed inputs have moved away from using fertilisers containing P (Phosphate). But it’s important to know that even a maintenance application of P to keep soil indexes at target 2 can have an impact on grass yields.

The most recent data we’ve seen comes from trials at Reaseheath College, where they were using highly water-soluble fertilisers to add maintenance P (80kg P2O5/ha; 64 units/acre) on a P index 2 soil for a 3-cut silage system raised yields by 12% (1.2 t DM/ha).

• Where do we have P soil index 2 and below 2 on-farm?
• Can we cover this requirement with slurries and manures? (An application of 2,600 gals/acre dairy slurry adds about 54 units/acre) (that’s 29 m3/ha adding about 67 kg/ha)
• If not what fertiliser P do we need to buy-in?

• Make sure you need fertilisers containing P in the first place.
• Get a fertiliser grade that suits your needs.
• Make sure the P water solubility is 97%