NVZ Compliance Check
Storage balance · N loading · 170 kg/ha compliance · All calculators updated 2026
NVZ Compliance Tools
Annual N Excretion
N Loading Calculator
Calculate total annual nitrogen excretion from your livestock using RB209 2024 data.
Production Volume
Slurry Storage Required
Calculate slurry production volumes in m³ based on livestock numbers and housing period.
Available Storage
Tank Capacity Calculator
Record tank dimensions and calculate available winter storage capacity in m³ and gallons.
Quick Compliance Check
Enter your farm figures below — no account needed.
Your Farm Figures
Annual organic N excretion from livestock
NVZ Rules England 2026 — What Farmers Need to Know
Nitrate Vulnerable Zone (NVZ) regulations require farmers in designated areas to limit the amount of organic nitrogen applied to land and to maintain adequate slurry storage. The rules are enforced by the Environment Agency and non-compliance can result in unlimited fines, loss of subsidy payments and, in serious cases, prosecution.
The core requirement is that total organic nitrogen from livestock manure — including slurry, farmyard manure and poultry manure — must not exceed 170 kg N per hectare per year across your whole holding. Farms that hold a derogation, typically intensive dairy operations, may apply up to 250 kg N/ha but must meet strict additional conditions including a soil nitrogen supply assessment and a nutrient management plan.
The rules also require a minimum of 4 months of slurry storage capacity for cattle and pig enterprises, along with closed periods during which organic manures with high readily available nitrogen (slurry, digestate and poultry manure) cannot be spread. All applications must be recorded and records kept for at least 5 years.
NVZ Key Figures at a Glance
| Requirement | Standard | Derogation |
|---|---|---|
| Organic N limit | 170 kg N/ha/year | 250 kg N/ha/year |
| Min slurry storage | 4 months | 4 months |
| Slurry closed period (grassland) | 15 Oct – 31 Jan | 15 Oct – 31 Jan |
| Slurry closed period (tillage) | 1 Oct – 31 Jan | 1 Oct – 31 Jan |
| Solid FYM closed period (tillage) | 1 Nov – 31 Jan | 1 Nov – 31 Jan |
| Record keeping | 5 years minimum | 5 years minimum |
| Nutrient management plan | Required | Required |
Closed periods for shallow or sandy soils may start earlier — check the Environment Agency NVZ guidance for your soil type. Source: Nitrate Pollution Prevention Regulations 2015 (as amended).
How to Calculate Your Farm's Nitrogen Loading
Your whole farm N loading is calculated by dividing your total annual organic nitrogen excretion by your total spreadable area in hectares. The excretion figures must come from the DEFRA standard values table — the same figures used in the AgriOps N Loading Calculator, sourced from RB209 2024.
For example, a mixed farm with 150 dairy cows (6,000–9,000 litre yield) and 50 beef suckler cows on 200 ha of spreadable land:
- 150 dairy cows × 1.923 kg N/week × 52 weeks = 15,010 kg N
- 50 suckler cows × 1.000 kg N/week × 52 weeks = 2,600 kg N
- Total N = 17,610 kg N
- N loading = 17,610 ÷ 200 ha = 88.1 kg N/ha — well within the 170 kg/ha limit
The N excretion figures above are from RB209 2024 and represent total nitrogen — this is the figure used for NVZ compliance, not the available nitrogen figure used for fertiliser planning. Use the N Loading Calculator to check your full herd automatically.