Phosphorus and Potassium are essential to maximize grass yields therefore adequate supply of these nutrients in the soil is critical. Build up and maintenance requirements should be taken into account when deciding what levels of P and K are needed for a productive crop of silage. For target index 3 soils, 20 units of phosphorous and 100 units of potassium will be sufficient, however if soils are deficient in these nutrients, then a higher fertiliser input is needed.
Organic manures like cattle slurry and farm yard manure are an effective source of N, P & K and can provide a large proportion of crop P and K requirements at relatively low cost. 1,000 gallons of cattle slurry at 7% DM has a similar value of one bag of 5-5-30 fertiliser. Organic manure and chemical fertiliser application should be kept one week apart. Contact the Drinagh Advisory team for further fertiliser plans and information.