Livestock Nitrogen Loading: The 170 kg N/ha Limit Explained
Every farm in Northern Ireland, and every holding in an English Nitrate Vulnerable Zone, has to keep the nitrogen from livestock manure to 170 kg per hectare. Here is how the figure is worked out, the standard figures for each type of stock, and your options if you are over.
The Rule
What the 170 kg N/ha Limit Is
The total nitrogen in livestock manure applied to the farm — what grazing animals deposit themselves plus any slurry or manure you spread — must not exceed 170 kg N per hectare per year, averaged over the farm’s agricultural area.
| Northern Ireland | England | |
|---|---|---|
| Where it applies | Every farm | Land inside a Nitrate Vulnerable Zone |
| Counts | Livestock manure and digestate containing livestock manure | Livestock manure |
| Area used | Agricultural area — excluding roads, yards, buildings, woods, water and scrub | NVZ land, excluding surface water, hardstanding, buildings, roads and ungrazed woodland |
| Rules | Nutrient Action Programme Regulations (NI) 2019 | Nitrate Pollution Prevention Regulations 2015 |
The sum is: average stock numbers × the standard nitrogen figure for each type, plus nitrogen in any manure brought in, minus any exported, divided by the agricultural area.
Standard Figures
How Much Nitrogen Your Stock Produce
Annual nitrogen per animal, from the regulations. Count the average number on the farm over the year.
Northern Ireland
| Livestock | kg N per head per year |
|---|---|
| Dairy cow | 100 |
| Beef suckler cow (over 2 years) | 52 |
| Cattle over 2 years | 45 |
| Cattle 1–2 years | 39 |
| Bull beef 0–13 months | 30 |
| Calf 0–1 year | 19 |
| Ewe or ram (over 1 year) | 9 |
| Breeding sow (incl. piglets to weaning) | 16 |
England
| Livestock | kg N per head per year |
|---|---|
| Dairy cow, over 9,000 litres | 115 |
| Dairy cow, 6,000–9,000 litres | 101 |
| Dairy cow, under 6,000 litres | 77 |
| Breeding female over 24 months, over 500 kg | 83 |
| Beef cattle 12–24 months | 50 |
| Ewe under 60 kg (incl. suckled lambs to 6 months) | 7.7 |
| Sow incl. litter to 7 kg | 16–18 |
England’s figures are the Schedule 1 daily figures × 365.
Livestock Nitrogen Loading Calculator
Every livestock type for NI and England, with imports, exports and the derogation check.
Example
A Worked Example
A Northern Ireland dairy farm with 80 ha of agricultural area:
| Stock | Calculation | kg N/yr |
|---|---|---|
| 120 dairy cows | 120 × 100 | 12,000 |
| 80 dairy heifers (1–2 years) | 80 × 39 | 3,120 |
| 70 bull beef (6–13 months) | 70 × 23 | 1,610 |
| Total | 16,730 |
16,730 ÷ 80 ha = 209 kg N/ha — well over 170. To comply without a derogation the farm needs about 98.4 ha, or to export around 3,130 kg of nitrogen (roughly 1,200 m³ of 6% cattle slurry at 2.6 kg N/m³). With a derogation, the area needed falls to about 67 ha, so it would be within the limit.
Going Above 170
The Grassland Derogation
Both Northern Ireland and England allow grassland farms to go up to 250 kg N/ha from grazing livestock manure with a derogation. Manure from pigs and poultry stays at 170.
| Northern Ireland | England | |
|---|---|---|
| Grass | At least 80% of the area available for manure | At least 80% of the agricultural area |
| Applying | Each year, 1 January to 1 March | In the autumn, for the following year |
| Key conditions | Fertilisation plan by 1 March; soil sampling every 4 years (1 per 4 ha); phosphorus surplus no more than 10 kg P/ha; half the slurry spread by 15 June, and low-emission spreading after that | Fertilisation plan and account (by 30 April the next year); other conditions in the derogation guidance |
Options
If You Are Over the Limit
- Export manure to tillage farms or an AD plant, with records. In Northern Ireland, exports must be recorded online with DAERA by 31 January (1 March for derogated farms) or they don’t count.
- Take on more land that is available for manure — rented or conacre ground.
- Apply for a derogation if you are a grassland farm and can meet the conditions.
- Adjust stock numbers or the timing of sales across the year.
It all comes together in a nutrient management plan, which also covers your slurry storage — see our slurry storage guide.
Northern Ireland
Changes Coming in Northern Ireland
DAERA consulted from June to September 2026 on a new Nutrients Action Programme for 2027–2030. The proposals include replacing the single dairy cow figure of 100 kg N with bands by milk yield — from 77 kg for herds under 5,000 litres up to 149 kg for herds over 12,000 litres — and replacing the derogation with a two-tier Nutrient Stewardship Programme open to farms with at least 70% grass.
FAQs
Frequently Asked Questions
Q.What is the 170 kg N/ha limit?
The total nitrogen in livestock manure applied to a farm — by grazing animals and by spreading — must not exceed 170 kg N per hectare per year, averaged over the farm’s agricultural area. It applies to every farm in Northern Ireland and to land inside a Nitrate Vulnerable Zone in England.
Q.Does chemical fertiliser count towards the 170 kg limit?
No. The 170 kg limit only covers livestock manure (and, in Northern Ireland, digestate containing livestock manure). Chemical fertiliser is controlled separately — in Northern Ireland by limits of 272 kg N/ha on dairy grassland and 222 kg N/ha on other grassland, and by crop maximums for cereals.
Q.How much nitrogen does a dairy cow produce?
In Northern Ireland the standard figure is 100 kg N per cow per year. In England it depends on milk yield: about 77 kg under 6,000 litres, 101 kg for 6,000–9,000 litres and 115 kg over 9,000 litres.
Q.How many dairy cows can I keep per hectare?
At 100 kg N per cow, 170 kg N/ha works out at 1.7 dairy cows per hectare of agricultural area — before counting followers, other stock or manure imports. With a derogation (250 kg N/ha from grazing livestock) it rises to 2.5 cows per hectare.
Q.What happens if I am over 170 kg N/ha?
You are in breach of the regulations and need to bring the figure down — by exporting manure under a recorded agreement, taking on more land, applying for a derogation if you qualify, or reducing stock. In Northern Ireland, exports only count if they are recorded with DAERA by the deadline.
Close to 170 kg N/ha?
We help farms across Northern Ireland and the UK check their loading, set up manure exports and prepare derogation applications and nutrient management plans.