The phosphorus (P) buildup allowance, which was introduced in 2018, has been renewed under the new Nitrates Action Programme (NAP). This measure allowed farmers with low soil P to apply additional phosphorus fertiliser in order to improve soil fertility.

Only grassland farmers stocked at greater than 130kg organic nitrogen per hectare are permitted to apply for P buildup, but it is open to derogation and to non-derogation farmers.

Farmers wishing to avail of increased P buildup levels must submit a nutrient management plan prepared by a Farm Advisory Service (FAS) adviser. Soil analysis is required, including for soil organic matter content. This is to ensure that the P buildup is not being applied to organic soils, eg peat soils.

All peat soils are classified as being at index three for P, so no buildup is permitted on these soils. The FAS adviser can certify the soil type.

Only parcels at soil fertility index one and two for phosphorus are allowed to get the additional phosphorus allowance.

The purpose of the scheme is to enable farmers to improve their soil fertility. In its submission to the fourth review of the NAP, Teagasc stated that low overall soil fertility provides a poor return on fertiliser other than that which is deficient, especially nitrogen.

It said that where strategies to improve N use efficiency, such as the adoption of grass-clover swards, low P soil fertility levels are a major limiting factor to maximising the opportunity for clover establishment and persistence.

It also stated that where nitrogen is applied to soils at P index three, nitrous oxide (N2O) greenhouse gas emissions are lower compared to soils with sub-optimal soil P fertility levels.