The rules, and how much storage you need
Two sets of rules, doing different jobs
Storage is governed by two things that often get run together.
- The SSAFO regulations - Silage, Slurry and Agricultural Fuel Oil - which govern how a store is built and how it must perform.
- The NVZ rules, which govern how much storage capacity you must have. In England that means land inside a designated zone. In Wales the equivalent rules apply across the whole country. Our NVZ guide covers the rest of what a zone brings with it.
A store can be built exactly to the SSAFO standard and still be too small for the NVZ capacity requirement, so check it against both.
How much storage you need
Two different numbers get quoted, and they answer different questions.
The general SSAFO expectation is that you'll normally need at least four months' slurry storage, judged on your own circumstances.
The NVZ requirement is more specific, and it's expressed as a period you must be able to store right through:
- Pigs and poultry - 1 October to 1 April, so six months.
- Cattle and other livestock, including sheep, goats, deer and horses - 1 October to 1 March, so five months.
Pigs and poultry need the longer period.
What has to go into the calculation
Everything that ends up in the store counts, not just what the animals produce:
- Slurry and washings from the parlour.
- Rainfall on any uncovered store or dirty yard that drains into it.
- Silage effluent, where it goes to the same place.
- Any bedding or feed waste that adds volume.
Roofing a store or diverting clean yard water away from it is often cheaper than building more capacity.
