Department update stocking rate rules

Changes to the good agricultural practice (GAP) regulations were signed into law by the Minister for Housing, Local Government and Heritage James Browne in early December 2025.

While most of the updates to the regulations were outlined in the draft document circulated in October, there has been one key change to the rules around nutrient distribution.

In the draft GAP regulations, higher-stocked dairy farmers were required to move a certain percentage of slurry off their milking platform based on their nitrates band and milking platform stocking rates.

In the new regulations signed into law, how much slurry to move is set out in volume terms rather than percentages and the nitrates band that the herd is in is no longer being considered.

The changes have the effect of simplifying the regulations compared to what was being proposed, but there are still a lot of moving parts.

The first step is to work out the chemical nitrogen (N) allowance on the milking platform. This is how much nitrogen fertiliser or bag nitrogen a dairy farmer spreads on the milking platform. The Irish Farmers Journal understands that the Department views this as a sort of voluntary decision by each farmer as to how much N they apply on the milking platform.

So while the overall chemical N allowance is determined by stocking rate, it is the farmer that decides where that chemical N is applied such as on the milking platform or on the other lands, if any.

For example, while most farmers operating within a nitrates derogation will have a maximum allowance of either 214kg N/ha or 241kg N/ha, most farmers do not use up all of their allowance. Many have used clover or multispecies to fix biological N and so don’t need to use up all their chemical N allowance.

By declaring what they plan to spread on the milking platform in 2026 and from then on using the previous years actual application rate, farmers and their advisers can work out what category they are in based off Table 14 in the amendments to the GAP regulations 2025.

The next piece of information that is required is the milking platform stocking rate. This is determined by kg of organic N per hectare. To work out the stocking rate from this, multiply the nitrogen excretion rate per cow by the number of cows kept on each milking platform hectare.

The nitrogen excretion rate is based off banding, so is typically either 80kg, 92kg or 106kg of N per cow annually. However, these rates are reduced where low-crude protein concentrates are fed. For example, where the average crude protein in concentrate fed throughout the year is 13% or lower, then the nitrogen excretion rate for each band reduces to 76kg, 87kg and 98kg for herds in band one, two and three respectively.

There are four stocking rate categories under each chemical N application rate.

For example, where the chemical N on the milking platform allowance is 214kg N/ha the milking platform stocking rate ranges are:

At 92kg N of a nitrogen excretion rate per cow, these ranges correspond to a milking platform stocking rate of <3.1 cows/ha, 3.1-3.33 cows/ha, 3.3-3.54 cows/ha and 3.54 cows/ha. The higher the stocking rate, the more slurry needs to be moved off the milking platform.

The amount of slurry to be moved off the milking platform is now a based on the equivalent of kg of organic N per hectare rather than a percentage of all slurry produced on the holding.

Based on the above example, milking platforms with a stocking rate <3.1 cows/ha will have no requirement to move slurry. Where the stocking rate is between 3.1 and 3.3 cows/ha, then 20kg N/ha of slurry needs to move off the milking platform.

Where the stocking rate is between 3.3 and 3.54 cows/ha then up to 40kg N/ha of slurry needs to move off the milking platform. At >3.54 cows/ha, over 41kg N/ha of slurry needs to move off the milking platform.

There are 2.4kg of N in every 1t, 1m3 or 1,000l of slurry. So to move 20kg of organic N per hectare, a farmer would be required to move 8,333l per hectare. This is the equivalent of 742 gallons for every acre on the milking platform.

To move 40kg N/ha, a farmer would need to move 16,666l per hectare, which is the equivalent of 1,486 gallons for every acre on the milking platform. The thing to remember is that these are not actually application rates, but a guide as to how much slurry needs to be moved off the milking platform.

For example, if 20kg N/ha needs to be moved and the milking platform extends to 50ha, then over 416,000l or almost 92,000 gallons needs to be moved.

Let''s say there are 160 cows on the farm and each cow produces 0.4m3 of slurry per week over a 16-week period corresponding to annual slurry production of 6.4m3 per cow.

To move 416m3 of slurry would mean moving over 40% of all slurry produced by the cows.

More slurry needs to be moved at higher stocking rates but there is also more slurry produced at higher stocking rates. Using the same example, at 3.4 cows/ha there would be 170 cows on the farm and 40kg N/ha would need to be moved.

This would be a total of 1,088m3 to be moved which is about 77% of all slurry produced by the cows.

These new rules are complex, but ultimately correspond to good farming practice and where most farmers already move slurry to outside land they should have nothing to fear from them.

It is likely that farmers will need to report slurry movements along the same lines as they do for exporting.