Initial analysis of the potential phosphorus (P) balance on over a dozen farms operating as part of the AgriSearch Beacon Farm network suggests it will be “almost impossible” for any herd with cows yielding over 8,000l to achieve new limits proposed by DAERA.

The analysis, undertaken by AgriSearch Strategy Manager, Jason Rankin, looked at whether farms can get to a P balance of 8kg/ha, which is the limit proposed by DAERA from 2029 onwards.

In 2027, the P balance limit is 10kg/ha.

The work by Rankin plotted P balance against milk yield. All the herds with average yields over 8,000l had P balances well above the initial 10kg threshold, with some approaching a balance of 18kg.

Rankin said that the farms in the Beacon network are already among some of the most efficient in NI, calving heifers at two years, making good use of grass, so the figures should be seen “as the upper end of what is achievable”.

In addition, the figures relate to 2023, which was a “relatively benign year”.

However, in 2024, poor weather forced many farmers to feed an extra 0.5t of concentrate per cow, which would easily add 4 to 5kg P/ha onto the figures shown, said Rankin.

There is also the potential impact that an outbreak of TB or other disease would have, given the restriction this would put on sales, resulting in more stock being held and more concentrate being fed.

Land

Where farms are above the P limits, they will be faced with a choice of either cutting livestock numbers or exporting slurry. In one example quoted by Rankin, an 114ha farm with 200 dairy cows yielding 8,214 litres on 3.7t of concentrate, has a P surplus of 15.2kg/ha.

To get to a balance of 8kg, the farm either needs to cut stock numbers by 47.5% or find an extra 103ha of land to spread /export slurry.

“While there is the option to export slurry, the new rules mean that many of those beef and sheep farmers who had previously imported slurry would be extremely reluctant to do so given the increased bureaucracy,” warned Rankin.

At present, any farm can import slurry up to the 170kg manure N/ha limit, however, as part of the DAERA proposals, if the slurry imports push the farm to over 150kg manure N/ha, then the importing farm will have to comply with requirements around P balance.

Rankin also pointed out that as well as higher input dairy farms, many beef finishing units will be severely impacted by the proposed NAP changes.