How Much Slurry Storage Do I Need?
Your slurry store has to hold everything your stock produce over the winter storage period — plus the rain and washings that end up in it. Here is what the rules say in Northern Ireland and England, how much slurry each type of animal produces, and how to work out your own figure.
The Rules
The Quick Answer
| Northern Ireland | England (inside an NVZ) | |
|---|---|---|
| Most livestock | 22 weeks | 5 months — 1 October to 1 March |
| Pigs and poultry | 26 weeks (enterprises over 10 sow / 150 finishing / 500 poultry places) | 6 months — 1 October to 1 April |
| Must also hold | Rainfall and washings over the period | Rainfall, washings and other liquid over the period |
| Freeboard | 300 mm tanks, 750 mm earth-banked | 300 mm tanks, 750 mm earth-banked (SSAFO) |
In Northern Ireland the rules apply to every farm under the Nutrient Action Programme Regulations (NI) 2019. In England they apply to land inside a Nitrate Vulnerable Zone under the Nitrate Pollution Prevention Regulations 2015. Both also expect you to have regard to extra capacity for long spells of wet weather or frozen ground, when slurry can’t be spread.
Standard Figures
How Much Slurry Your Stock Produce
Both regulations set standard volumes per animal. They cover excreta only — washing water is extra. Here are the most common types, with the volume one animal produces over the storage period.
Northern Ireland (NAP Regulations Schedule 2, Table 6)
| Livestock | m³ per week | m³ over 22 weeks |
|---|---|---|
| Dairy cow | 0.37 | 8.1 |
| Suckler cow / cattle over 2 years | 0.23 | 5.1 |
| Cattle 1–2 years | 0.18 | 4.0 |
| Calf 6–12 months | 0.09 | 2.0 |
| Calf 0–6 months | 0.05 | 1.1 |
| Adult ewe or ram | 0.03 | 0.7 |
| Dry or lactating sow (26 weeks) | 0.08 | 2.1 |
| Finishing pig 35–105 kg, meal fed (26 weeks) | 0.03 | 0.8 |
England (Nitrate Pollution Prevention Regulations Schedule 1)
| Livestock | Litres per day | m³ over 5 months |
|---|---|---|
| Dairy cow, under 6,000 litres | 42 | 6.3 |
| Dairy cow, 6,000–9,000 litres | 53 | 8.0 |
| Dairy cow, over 9,000 litres | 64 | 9.7 |
| Beef cattle 12–24 months | 26 | 3.9 |
| Breeding female over 24 months, over 500 kg | 45 | 6.8 |
| Ewe 60 kg or more | 5 | 0.8 |
| Sow incl. litter to 7 kg (6 months) | 10.9 | 2.0 |
| Finishing pig 66 kg+, dry fed (6 months) | 5.1 | 0.9 |
Slurry Storage Required Calculator
Enter your stock and it works out the full figure, including rainfall, washings and farmyard manure.
Example
A Worked Example: 100 Dairy Cows in Northern Ireland
| Calculation | m³ | |
|---|---|---|
| Slurry from the cows | 100 × 0.37 m³ × 22 weeks | 814 |
| Parlour washings | 100 × 0.13 m³ × 22 weeks | 286 |
| Rain on 400 m² of open tank and yard | 400 m² × 25 mm × 22 weeks | 220 |
| Total storage needed | 1,320 (about 290,000 gallons) |
The same herd in an English NVZ, at 6,000–9,000 litres, produces about 800 m³ over the 5-month period before washings and rain. Notice how much the extras add: washings and rainfall make up almost 40% of the Northern Ireland total. That is why covering open tanks and keeping clean roof water out of the store are often the cheapest way to free up capacity.
The Extras
Rainfall, Washings and Freeboard
- Rainfall. DAERA uses 25 mm a week as the Northern Ireland winter average — about 550 mm over 22 weeks — on every open area that drains to the store: uncovered tanks and lagoons, unroofed yards, and any roofs or clean areas that drain in. In England, gov.uk guidance says to allow for a wetter than average (1 in 5) year for your area.
- Washings. DAERA’s standard for dairy parlour washings is 0.13 m³ per cow per week. Add any other wash water that goes to the store.
- Freeboard. A store can’t be filled to the brim — leave 300 mm in concrete or steel tanks and 750 mm in earth-banked lagoons. Use the tank capacity calculator to see what your stores really hold.
Options
Ways to Reduce the Storage You Need
Northern Ireland
- Stock on straw: manure collected as farmyard manure doesn’t need slurry storage (only half, if they can reach a slatted or solid area).
- Separation: removing solids can cut the volume of cattle slurry by up to 20% (not pig slurry).
- Rented storage, with a written rental agreement.
- A contract to export manure to a processing facility such as an AD plant.
- Out-wintered stock at low stocking rates.
England
- Slurry exported off the holding during the storage period.
- Spreading on suitable low run-off risk land during the period, keeping one extra week of storage.
Each of these needs records you can show an inspector. If you are relying on one, it is worth getting it checked as part of your nutrient management plan.
FAQs
Frequently Asked Questions
Q.How much slurry storage do I need in Northern Ireland?
At least 22 weeks of storage for slurry, rainfall and washings. Pig enterprises (more than 10 breeding sow places or 150 finishing pig places) and poultry enterprises (more than 500 places) need at least 26 weeks for that enterprise’s manure.
Q.How much slurry storage do I need in an NVZ in England?
Enough to hold everything produced from 1 October to 1 March (5 months) for cattle, sheep and other stock, or from 1 October to 1 April (6 months) for pigs and poultry — plus rainfall, washings and any other liquid that enters the store over that period.
Q.How much slurry does a dairy cow produce?
Northern Ireland’s standard figure is 0.37 m³ a week — about 53 litres a day. England’s standard depends on milk yield: 42 litres a day under 6,000 litres, 53 litres a day for 6,000–9,000 litres and 64 litres a day over 9,000 litres. These figures exclude washing water.
Q.How much slurry does a beef animal produce?
In Northern Ireland, 0.23 m³ a week for a suckler cow or cattle over 2 years, 0.18 m³ for cattle aged 1–2 years and 0.09 m³ for calves of 6–12 months. In England, 26 litres a day for beef cattle aged 12–24 months and 32–45 litres a day for cattle over 24 months, depending on type and weight.
Q.How do I convert slurry storage from m³ to gallons?
One cubic metre is about 220 UK gallons (219.97). So a 1,000 m³ tank holds roughly 220,000 gallons.
Q.Can I count farmyard manure towards my storage?
In Northern Ireland, manure from stock on straw collected as farmyard manure doesn’t need slurry storage — but if bedded animals can get onto a slatted or solid area, only half their manure can be treated as FYM. Run-off from a midden counts as slurry and must be collected.
Short of Slurry Storage?
We help farms across Northern Ireland and the UK work out their storage position, plan new or covered stores, and set up export agreements — before an inspection finds the gap.