Establish farm nitrogen allowance first
Fertiliser records must be prepared annually, and maintained on the farm for five years; this is a cross-compliance requirement.
Select fertilisers on the basis of a recent soil test report, and crop nutrient requirements.
Aim for a soil pH of 6.5.
Many growers are under-fertilising for yield potential, and are thus depleting soil reserves of P and K.
A 7.5t/ha spring barley crop requires 28kg of P/ha (23 units/ac) and 86kg of K/ha (69 units/ac), or the equivalent of 3.4 50kg bags per acre of 13:6:20, to match crop offtakes of nutrient.
Research results from Teagasc at Oak Park show high fertiliser prices have little effect on the economic optimum N rate.
Assuming a soil N Index 1, and a CAN price of €340/t with a grain price of €180/t (dry), the economic N optimum is 227 kg of N/ha for winter wheat, and 137 kg of N/ha for spring barley.
Organic Manures
To maximise the nutrient value of organic fertilisers, and reduce nitrogen losses, ensure slurry is well agitated before even and accurate application at 2,000 gallons/acre. Incorporate it within six hours to maximise N recovery.
Fertiliser cost can be reduced by €50/acre with 2,000 gallons/acre of pig slurry.
A bag of 19-7-20 is equivalent to 1,000 gallons of pig slurry, which can add other soil benefits such as increased soil organic matter and improved micronutrient levels.
