The Department has published various pieces of additional information to support the ongoing public consultation on potential changes to the Nutrients Action Programme (NAP) which closes to responses on Thursday 24 July.

The most controversial issues set out in the current NAP consultation include plans to put in place phosphorus limits on intensive farms, as well as set new limits on the use of nitrogen (N) fertiliser.

The underlying science to support these proposals is included in the documents now online.

The original failure to publish this underlying science was one of the main criticisms levelled at DAERA when the NAP consultation was released on 1 May. There were also some errors throughout the document and inconsistencies with a draft regulation included in an Annex – those errors have now been amended by way of an addendum to the consultation on the DAERA website.

The addendum includes clarification that DAERA proposed banning the use of straight urea fertiliser from 1 January 2026 (not 2027 as indicated on the first page of the consultation).

In addition, links to other supporting documents have been updated and changes made to draft regulations. For example, written into the draft regulations are new P limits on intensive farms of 12kg/ha from 1 January 2027, while the actual proposal is a limit of 10kg.

Review of nitrogen fertiliser limits

At an AgriSearch event at the 2025 Balmoral Show, former scientist Dr Sinclair Mayne raised concerns about the lack of appropriate supporting scientific evidence underlying the DAERA NAP proposals.

In particular, Dr Mayne highlighted that no data was presented to support new fertiliser limits for grassland set out in the NAP consultation. He warned that if farmers are forced to apply less fertiliser, it will mean lower silage yields, which will have to be compensated for by higher meal feeding. It would be a perverse outcome given that concentrate feed is the main contributor to excess P in NI agriculture.

A paper has been published which summarises the scientific evidence provided by the Agri-Food and Biosciences Institute (AFBI) to inform new N fertiliser limits within NAP.

The document lists out a number of different research trials on grass yield response to N fertiliser done over the last 15 years at AFBI Hillsborough, on farm in NI and at other sites in the Republic of Ireland and Britain. According to AFBI, the research clearly supports the N limits set out in the NAP consultation.

N in slurry

Under current NAP rules, a dairy farm in NI can apply up to 272kg/ha of fertiliser N (8.25 bags/ac), while a beef farm can spread up to 222kg N/ha (6.75bags/ac).

The major changes would see the fertiliser limits for grassland set out in the NAP come into line with the UK fertiliser manual, RB209. In addition, the N in slurry is taken into account when setting new limits. The key assumption taken from RB209 is that 40% of the N in slurry is readily available for plant growth.

For a typical dairy farm currently operating under derogation, allowing it to spread 250kg manure N/ha, the change assumes there is 100kg N/ha coming from slurry (40% of 250kg).

With a total N requirement of 250kg N/ha to grow grass silage on the farm and 100kg coming from slurry, this creates a new fertiliser N limit of 150kg/ha, which is just 4.5 bags/acre of CAN.

A non-derogated dairy farm has less slurry (170kg N/ha), so slightly more would have to come from fertiliser N. When all the calculations are done, it equates to a new annual limit of 5.5 bags/ac of CAN.

On a typical beef and sheep farm operating at up to 120kg N/ha and growing two cuts of grass silage, fertiliser usage for grass silage would be limited to just 2.5 bags/acre.

There are also proposed limits set for grazing and on this typical beef and sheep farm, it would be limited to around four bags/acre of CAN. A typical dairy farm could apply up to 5.5 bags/acre. Only those growing really high yields of grass could apply more.

Officials worked together to produce new NAP

The controversial proposals to change the NAP from 2026 onwards came from a government working group tasked with reviewing the current requirements (the 2019 regulations).

The NAP Review Working Group had input from a NAP Scientific Working Group. While individuals are not named, the groups were comprised of officials from DAERA, AFBI, CAFRE and the NIEA.

The review of the 2019 NAP regulations extends to nearly 250 pages and covers issues from trends in water quality, through to farmer compliance with existing NAP rules.

Their analysis shows that both nitrates and phosphorus concentrations in NI rivers have been on a downward slope since the 1990s, however, recent data does not follow this trend. Nitrate levels are currently “showing signs of increasing concentrations” while phosphorus in rivers has been on “a general upward trend” since 2013, states the review.

Inspections

The document explores in detail, farmer compliance with current NAP regulations. Very high compliance was found with the likes of closed periods for spreading slurry and fertiliser. The most frequent areas of non-compliance relate to poorly managed or inadequate manure storage facilities.

Derogation

Other issues explored in the review include why farmers have been reluctant to apply for the nitrates derogation, even though it would benefit their business. That derogation allows farmers to operate at up to 250kg manure N/ha, rather than the standard 170kg. To stay below 170kg, many intensive farmers export slurry.

The report authors point out that farmers are often wary of the additional paperwork when in derogation as well as the higher risk of inspection (5% versus 1% rate).

However, the main issue is that derogated farmers must operate to an annual P balance limit of 10kg/ha.

“Many dairy farmers choose to export slurry or take control of additional land to reduce their N loading below 170kg/ha as they could not meet the nitrates derogation P balance limit of 10kg P/ha,” states the review.

NAP related research projects

Included within the review are summaries of the findings from various research projects related to the NAP.

It includes a study concluded in 2022 which compared CAN fertiliser with protected (or stabilised) urea for use in growing a crop of grass silage. No significant differences were found.

Other work reported in 2022 looked at phosphorus (P) loss after slurry spreading. It concluded that the current slurry closed period from 15 October to 31 January is “efficient” in reducing P loss.

This study also considered other options, including prohibiting slurry spreading when soil moisture is at or above field capacity. If that was implemented it would “considerably decrease” the number of days when spreading is possible, including for most of February.

Warning

A proposal that did make it into the on-going NAP consultation is for a system to be set up to provide a warning when heavy rain is forecast within 48 hours and conditions are unsuitable for slurry spreading.

However, a study to evaluate the feasibility of introducing temporary closed periods, shows there would be issues to resolve. In particular, the majority of recent yellow weather warnings tend to be issued within 24 hours of the event, not 48 hours. Also, the analysis found that over half of heavy rainfall events (greater than 4mm/hr of rain) do not come with a weather warning at all.

P balance

Near the end of the research papers is a summary of data around the problem issue of excess P within NI agriculture.

The intensification of agriculture over the last 10 years is highlighted as being to blame for more P getting into waterways, with the review report proposing the new annual P limits for intensive farms of 10kg P/ha in 2027, falling to 8kg P/ha in 2029.

It is clear that the report authors were well aware of the implications of these new P limits on many intensive farms. These farms will either need to process and separate slurry to export P or look to reduce feed inputs, production levels and/or livestock numbers, states the review.

However, on the issue of slurry processing, they note that it “is only in the early stages of development” and if it is to be used to get NI to a target P balance of 7kg/ha, around 6,000t of slurry would need to be processed annually from approximately 2,500 farms.

“This would be very challenging to achieve,” states the report.

High yielding

In dairying, five different systems were assessed. The work found that high yielding herds (over 10,000l per cow) could not meet a P balance of 8kg/ha by any means (including slurry separation) other than exporting a significant amount of raw slurry off the farm.

“Given their level of feed input and nutrient surplus, it is an understandable conclusion that they are farming at a level beyond their land base,” states the report.

Despite raising all these concerns, the authors describe their new proposed P limits as “ambitious, challenging, potentially achievable and appropriate for public consultation.”