Significant increases in concentrate feed use this year could push many farmers above their phosphorus limits for next year.

Farmers who complete a nutrient management plan will have received a total chemical phosphorus allowance for their farm based on their stocking rate, soil fertility status and how much meal they feed.

However, in many cases the amount of meal being fed is between two and three times more than expected, meaning the farm will have exceeded its phosphorus allowance.

At high feeding levels, the phosphorus deduction in feed is penalising. For every tonne of feed used, the default figure is 5kg of phosphorus brought on to the farm.

A typical 40ha farm feeding 0.5t of meal per cow per year would have a chemical phosphorus allowance of around 1t per year. But if meal feeding increased to 1.5t per cow, the chemical allowance for phosphorus would halve to 500kg per year.

Nitrates Regulations

A spokesperson for the Department of Agriculture told the Irish Farmers Journal that the Nitrates Regulations set maximum fertilisation allowances for both nitrogen and phosphorus for grassland and crops.

“Concentrates fed to grazing livestock in the previous year must be taken into account when calculating how much phosphorus can be applied.

Nutrient management planning will allow farmers to calculate how much fertiliser can be applied in 2019

“Concentrates fed to grazing livestock in 2018 will be taken into account in the calculation of 2019 phosphorus allowances.

“Nutrient management planning will allow farmers to calculate how much fertiliser can be applied in 2019, and farmers are advised to consult with their advisors on this matter in the near future,” the spokesperson said.

Soil samples

Using soil sample results for planning will be a significant benefit to farmers, the Department spokesperson said.

“Results from Teagasc show there has been a significant improvement in soil pH in 2017 compared to 2016 with 55% of soils with a pH >6.2 compared to 38% in 2016.

“There is still a percentage of soils below the optimum pH 6.3 and 6.5 for grassland and tillage soils, respectively. All farmers should aim to have their soils at optimum pH in order to make maximum use of any fertilisers applied.”