Ammonia
The pungent gas that comes off slurry, mostly while it sits uncovered or goes out through a splash plate. It's lost nitrogen and an air-quality problem — which is why covers and low-emission spreading matter.
Anaerobic digestion (AD)
Breaking slurry (often with crops) down in a sealed tank without oxygen to make biogas. What's left over is digestate.
Bund / secondary containment
A wall or bank around a store to catch the lot if it leaks or bursts. Required for many stores so a failure doesn't reach a watercourse.
Biosolids
The industry name for treated sewage sludge recycled to farmland. Governed by the 1989 sludge regulations plus the voluntary Safe Sludge Matrix — see the sludge guide.
Capital Grants
The English grant scheme for the physical kit — covers, separators, concrete, water gear. The 2026 round opened 30 July with £225m and went fast; see the grants guide.
Cesspool waste
The whole contents of a sealed tank, or a tanker load that's been mixed. Unlike residual septic tank sludge, it must not be spread on farmland — it goes to a treatment works.
Closed period
The stretch of the year when you're not allowed to spread slurry, to stop nitrate washing away over winter. The exact dates depend on nation, land use and soil type.
Cover (impermeable / floating)
A lid on a store — fixed, floating, or a tent — that cuts ammonia loss and keeps rain out. Increasingly expected, and already required for grant-funded and permitted stores.
Crust
The natural skin that forms on cattle slurry. It counts as a basic cover for cutting ammonia, though not as well as a proper fitted cover.
Cubic metre (m³)
The metric unit for slurry volume. One m³ is about 220 imperial gallons (roughly 1,000 litres).
Digestate
What's left after anaerobic digestion. Spread much like slurry, but usually higher in readily-available nitrogen, so it's stronger stuff.
Deployment
The permission an operator gets from the Environment Agency to spread a specific waste on a specific field under a landspreading permit. Not currently needed for sludge — but the proposed reform would change that.
Dirty water / clean water separation
Keeping rain off roofs and clean yards out of the slurry system — so you store less and free up capacity. Often the cheapest way to "make" more storage.
Dribble bar (trailing hose)
An applicator that lays slurry in lines on the surface through hanging pipes. Less ammonia loss than a splash plate, and counts as precision spreading.
Dry matter (DM)
How thick the slurry is — the solid fraction as a percentage. Cattle slurry is around 6%, pig around 4%. Thicker means more nutrients per m³ but harder to pump and stir.
FACTS adviser
A qualified nutrient-management adviser — the person to sign off your fertiliser and manure plan.
Farm limit (170 kg N/ha)
In an NVZ, the cap of 170 kg of nitrogen per hectare per year from livestock manure, averaged across the whole farm.
Field limit (250 kg N/ha)
In an NVZ, the cap of 250 kg of total nitrogen per hectare per year from organic manures on any single field.
Flexible tank (bladder / pillow tank)
A self-supporting above-ground store made of coated fabric. It's sealed, so inherently covered, and needs little groundwork. Different from an in-ground lined store, despite both being loosely called "bags".
Freeboard
The empty gap left at the top of a store so it can't overtop — about 300mm (12in) for steel or concrete, 750mm (30in) for an earth-bank store. The storage calculator adds it for you.
Farming Rules for Water (FRfW)
England rules saying you must spread to the crop and soil's need — not because the store's full — and never when the ground or weather make run-off likely.
Injection
Placing slurry into slots cut in the soil. The lowest ammonia loss and best nitrogen capture, but it takes more power and disturbs the ground.
Lagoon
A large earth-banked (usually lined) store. The cheapest per m³ at scale, but it needs suitable land, groundwork and normally a cover.
LESS (Low-Emission Slurry Spreading)
The family of precision methods — dribble bar, trailing shoe, injection — that cut ammonia loss versus a splash plate. Becoming the norm, and mandatory for every farm in Scotland from January 2027.
MANNER-NPK
The free tool that estimates the crop-available nutrients in your slurry. It replaced the old PLANET software for this job.
N, P, K (N / P₂O₅ / K₂O)
The three main plant nutrients — nitrogen, phosphate and potash. Slurry supplies all three, which is why it's a fertiliser, not a waste.
N-max limit
In an NVZ, the cap on total crop-available nitrogen from all sources for a given crop.
NVZ (Nitrate Vulnerable Zone)
Areas designated because of nitrate in water, where extra rules on storage, spreading and records apply. They cover a large part of the UK.
Nutrient Action Programme (NAP)
Northern Ireland's equivalent of the NVZ rules — but applying right across the country, not just in zones. The 2019 programme is still in force; a replacement for 2027–2030 is out for consultation.
Permitted farm
An intensive pig or poultry unit running under an environmental permit, with stricter rules — including covered slurry stores.
RB209
The Nutrient Management Guide — the standard reference for how much N, P and K each crop needs.
Readily available nitrogen (high-RAN)
Manures where over 30% of the nitrogen is immediately crop-available — all slurries, poultry manure and digestate. These are the ones the closed periods apply to.
Separator
Kit that splits slurry into a stackable solid and a liquid — easing storage and letting you place the nutrients where they're wanted.
Safe Sludge Matrix
A voluntary 1998 agreement between the water industry and the food chain setting which grades of biosolids may go on which crops. Not law — but the supply chain enforces it.
Septic tank sludge
The residual sludge from a septic tank or package treatment plant. Legally a separate thing from sewage sludge, and far less regulated — see the sludge guide.
Sewage sludge
Residual sludge from a sewage treatment works. Spread to farmland as biosolids under the 1989 regulations, with testing, metal limits and harvest intervals attached.
Slurry
The liquid or semi-liquid mix of dung, urine, washings and rainwater that comes off a livestock yard or building.
Slurry bag
A loose term for a flexible/bladder tank. Worth not confusing with an in-ground lined store — they're different products with different rules.
Slurry Wizard
AHDB's free storage-capacity calculator — and the one you need for a grant application.
Splash plate
The traditional spreader that fans slurry through the air. Cheapest, but the highest ammonia loss. Raised splash plates and rain guns have been banned in Scotland since 2023; the last exemption for low-level plates on smaller farms ends in January 2027.
SSAFO
The Storing Silage, Slurry and Agricultural Fuel Oil regulations — the rules for how stores must be built and how much storage you need.
Storage period
How many months' (or weeks') slurry your store must legally hold — 4–6 months in England, 22–26 weeks in Scotland, 5–6 months in Wales, 22–26 weeks in Northern Ireland.
SUiAR (Sludge (Use in Agriculture) Regulations 1989)
The rules for putting sewage sludge and septic tank sludge on farmland — nearly forty years old and now up for replacement. See the sludge guide.
Trailing shoe
An applicator that parts the grass and lays slurry at the base of the sward. Low ammonia loss and well suited to grassland.
Weeping wall
A store with slotted walls that let the liquid drain away, leaving a stackable solid behind.
No term matches that — try a shorter word, or ask us to add it.