Manure storage for stables under the EU Nitrates Directive
The Nitrates Directive sets the frame for every EU member state, but the numbers that bind you are written in national law. Here is the shape of the obligation and how to size storage for a stable.
Horses are livestock, and their manure falls under the EU Nitrates Directive (91/676/EEC) like any other livestock manure. The Directive itself sets principles: impermeable storage with enough capacity to cover the longest period when spreading is banned, closed periods for application, and a ceiling of 170 kg of nitrogen per hectare per year from livestock manure in nitrate vulnerable zones. The binding numbers — how many months of storage, which dates, what distances — are set by each member state in its national action programme.
The Nitrates Directive is written for agriculture and communicated through farm advisory services, which is why a great many equestrian businesses first hear about it during an inspection. A riding school is not obviously a farm, but a horse is unambiguously livestock. This guide sets out what the Directive requires of a stable, how to size storage, and where to find the numbers that actually apply where you are.
Who is covered
The obligation attaches to anyone keeping livestock and producing manure, regardless of whether the holding sells anything agricultural. A competition yard, a stud, a riding school and a livery on the edge of a town are all in scope. Nothing in the Directive exempts horses kept purely for sport or recreation.
What varies between member states is the geographical scope. Some states designate nitrate vulnerable zones and apply the action programme only there; others — Austria, Denmark, Finland, Germany, Ireland, Lithuania, Luxembourg, Malta, the Netherlands, Poland, Romania and Slovenia among them — apply it across the whole territory. Check which model applies to you before assuming you are outside the rules.
This guide describes the common frame. The figures that bind you sit in your national action programme, published by the ministry responsible for agriculture or water, and usually explained by the regional agricultural advisory service. Ask them for: required storage months, closed periods for solid manure, minimum distances from watercourses and boreholes, and the record-keeping you must maintain.
Storage capacity and how to size it
The Directive requires storage capacity that exceeds the amount produced during the longest prohibition period, unless you can demonstrate the excess will be disposed of without harm to the environment. In practice, national programmes turn this into a fixed number of months — commonly between five and eight, and longer in northern states with long closed periods.
Sizing is straightforward once you have the volume. One horse produces roughly 25 m³ of manure with bedding per year, or about 2.1 m³ a month.
| Horses | Per year | 5 months | 8 months | Slab at 5 months |
|---|---|---|---|---|
| 5 | about 125 m³ | about 52 m³ | about 83 m³ | about 26 m² |
| 10 | about 250 m³ | about 104 m³ | about 167 m³ | about 52 m² |
| 20 | about 500 m³ | about 208 m³ | about 333 m³ | about 104 m² |
| 30 | about 750 m³ | about 313 m³ | about 500 m³ | about 156 m² |
Add edges, falls and room to manoeuvre a loader or tractor to the working area. Building exactly to the table leaves you with a slab you cannot drive onto with a full bucket. A practical allowance is 30–40% on top of the calculated figure.
What the storage has to do
The Directive specifies an outcome rather than a technology: no leachate reaching groundwater or surface water. National rules translate that into requirements that in practice mean:
- an impermeable base, usually a concrete slab laid to falls;
- collection of leachate into a sealed tank, sized in its own right;
- retaining walls on at least three sides where manure is stacked to any height;
- protection from clean water running in from surrounding ground and roofs.
Deep-litter housing on an impermeable floor is accepted in many member states as storage in its own right, which for yards keeping horses in open systems is often cheaper than building a separate slab.
Field heaps
Temporary storage of solid manure directly on farmland is permitted in most national programmes, but hedged with conditions, and it does not replace the permanent storage you are required to have. Conditions typically cover:
- a maximum period on one site, often six months;
- a minimum distance from watercourses, drains and water abstraction points — 25 metres is a common figure, but it varies;
- flat ground with a limited gradient, away from hollows and land liable to flooding;
- a waiting period before the same spot can be used again, often two or three years.
The last condition is the one most often breached without anyone noticing. Yards carry manure to the same convenient corner behind the building year after year — and that is exactly what an inspector can demonstrate from successive years of aerial imagery.
Spreading: closed periods and the nitrogen ceiling
Two limits apply when manure goes onto land. The first is the closed period, a window during which spreading is banned; dates differ by member state, soil type and manure type, and typically cover late autumn and winter. The second is the ceiling of 170 kg of nitrogen per hectare per year from livestock manure in nitrate vulnerable zones, with derogations available to some states under conditions.
For a stable this is usually good news rather than a burden. Horse manure carries real fertiliser value: the 8.5 tonnes one horse produces in a year contains roughly 46 kg of nitrogen, 20 kg of P₂O₅ and 35 kg of K₂O. At 170 kg N per hectare, one horse’s annual output covers about a quarter of a hectare. That turns the conversation with a neighbouring farmer from asking for a favour into negotiating a price.
Enforcement
Enforcement sits with national environmental or agricultural inspectorates, and penalties are set nationally — administrative fines in most states, with breaches also capable of affecting agricultural support payments through cross-compliance and conditionality. Inspections look at the physical facility and at paperwork: records of manure movements and applications, and, where required, a nitrogen fertilisation plan.
A riding centre that grows nothing and passes all its manure to an outside taker still needs compliant storage. The contract with the taker governs what happens after collection; it does not remove the obligation to hold manure safely until then. Keep that agreement in writing, together with records of what left the yard and when.
Pre-inspection checklist
- Does the storage have an impermeable base and leachate capture?
- Is the capacity sized for your current herd, not the one you had five years ago?
- Is the leachate tank sealed and adequately sized?
- Do field heaps meet the distance, gradient and return-interval conditions in your national programme?
- Are records of manure movements and applications being kept?
- Is there a written agreement with whoever takes the manure away?
If the answer to the second question is “not sure”, start by measuring the actual volume — the method is in our guide to what manure costs your stable.
Frequently asked questions
Does the Nitrates Directive apply to horses?
Yes. Horses are livestock and their manure is livestock manure under Directive 91/676/EEC. The rules apply regardless of whether the holding is a commercial farm, a stud, a riding school or a livery yard.
How many months of manure storage are required?
The Directive requires capacity exceeding production during the longest prohibition period. National action programmes usually fix this at five to eight months, with longer requirements in states that have long closed periods. Check your national programme for the exact figure.
What is the 170 kg N per hectare limit?
In nitrate vulnerable zones, the amount of livestock manure applied each year may not exceed the equivalent of 170 kg of nitrogen per hectare. Some member states hold derogations allowing a higher figure under specified conditions.
How much nitrogen is in horse manure?
The 8.5 tonnes of manure one horse produces annually contains roughly 46 kg of nitrogen, 20 kg of P₂O₅ and 35 kg of K₂O. At the 170 kg N per hectare ceiling, one horse’s yearly output covers about a quarter of a hectare.
Can a riding school without farmland avoid building storage?
No. The requirement for compliant storage follows from keeping livestock, not from farming land. Passing manure to an external taker regulates what happens after collection but does not remove the obligation to store it safely beforehand.
This guide is informational and reflects the framework of Directive 91/676/EEC as at September 2026. It is not legal advice, and it does not reproduce the national rules of any specific member state. Before investing, confirm the requirements with your national or regional competent authority.
Sources
- Council Directive 91/676/EEC concerning the protection of waters against nitrate pollution — EUR-Lex
- Horse Stable Manure Management — Penn State Extension
- Nitrates programme — Polish Ministry of Infrastructure (national implementation example)
Last updated: 2026-09-20. Prepared by the team at Clever Equine Solutions sp. z o.o..