What is the 190 kg nitrogen cap?

A limit of 190 kilograms of synthetic nitrogen a hectare a year on pastoral land, set by the National Environmental Standards for Freshwater. It applies both as an average across the farm and to each individual hectare, so a farm can meet the average and still breach the cap on a block that was pushed harder than the rest. The nitrogen year runs from 1 July to 30 June.

What fertiliser counts towards the nitrogen cap?

Synthetic fertiliser containing more than 5 percent nitrogen by dry weight, which covers urea, DAP and sulphate of ammonia among others. Biological sources are excluded, including compost and untreated dairy effluent. What matters is the kilograms of nitrogen applied rather than the kilograms of product, so a tonne of urea is not a tonne of nitrogen and the conversion has to be done before anything is compared with the cap.

When is the nitrogen return due?

By 31 July each year, to your regional council, covering the nitrogen year that ended on 30 June. That leaves a month after the year closes to pull the records together. The reporting obligation is separate from the cap itself: a farm can be comfortably under 190 kilograms and still be in breach of its obligations by not reporting.

Nitrogen Cap Compliance Calculator NZ

Pastoral land in New Zealand is capped at 190 kilograms of synthetic nitrogen a hectare a year, and the detail that catches farms out is that the cap applies two ways at once. It is a farm average, and it is also a limit on each individual hectare. A farm can sit comfortably under 190 across the whole property and still be in breach on the block that got pushed harder than the rest, which is why this page checks every block you enter separately as well as working out the average. The other thing worth being careful about is units. The cap is on kilograms of nitrogen, not kilograms of product, so a tonne of urea is nothing like a tonne of nitrogen and the conversion has to happen before anything is compared. Urea is about 46 percent nitrogen, so the same weight of product lands very differently depending on what it was. Enter either and this converts for you. Only synthetic fertiliser above 5 percent nitrogen by dry weight counts. Biological sources are outside the cap entirely, including compost and untreated dairy effluent, so they do not need to go in here at all.

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The nitrogen year is 1 July 2026 to 30 June 2027, and the return is due to your regional council by 31 July 2027. The reporting obligation is separate from the cap: a farm can be well under 190 kilograms and still be in breach by not reporting. Some regional councils have additional or stricter rules of their own, so check your regional plan as well as the national standard. This is a compliance check, not compliance advice.

Blocks, and what went on each

Block	kg N a hectare	Against the cap
Milking platform	164.6	25.4 to spare
Support block	212.8	over by 22.8
Runoff	73.6	116.4 to spare

Enter the product weight and its nitrogen percentage, and the page converts. Urea is about 46 percent nitrogen. If you already have kilograms of nitrogen rather than kilograms of product, enter that figure and set the percentage to 100.

162.4

kilograms of nitrogen a hectare, farm average

Cap190 kg N/ha

Nitrogen applied25,990 kg N

Area160 ha

Headroom on the average27.6 kg N/ha

The farm average passes at 162.4 kg N a hectare, but 1 block is over the cap. Averaging does not fix that: the block that is over is over. The cap applies as a farm average and to each hectare. Both tests have to pass.

How it works

For each block, the product weight is multiplied by its nitrogen percentage to give kilograms of nitrogen, then divided by the hectares to give the rate a hectare. That rate is checked against the 190 kilogram cap on its own. The farm average adds the nitrogen from every block and divides by the total area, and is checked against the same cap. Both tests have to pass, and the page says which one failed rather than giving a single verdict, because they fail for different reasons and are fixed in different ways.

Why the per hectare test is the one that bites

Averaging is forgiving. A milking platform run hard at 220 kilograms can be pulled back under the average by a runoff that got almost nothing, and on the farm average alone that farm looks compliant. The per hectare limit exists precisely to stop that, since the environmental effect happens where the nitrogen lands rather than across a title. So the block that is over is over, whatever the rest of the farm did, and the fix is to reduce that block rather than to spread the paperwork differently.

Worked example

A farm with a 95 hectare milking platform, a 40 hectare support block and a 25 hectare runoff, applying 34,000 kilograms of urea to the platform, 18,500 to the support block and 4,000 to the runoff, at 46 percent nitrogen, has applied 15,640, 8,510 and 1,840 kilograms of nitrogen respectively. That is 164.6 kilograms a hectare on the platform, 212.8 on the support block and 73.6 on the runoff. The farm average is 162.4 kilograms a hectare, comfortably under the cap, and the farm is still in breach: the support block is 22.8 kilograms a hectare over the limit and no amount of averaging fixes it.

Related calculators

Stock Units: the stocking the nitrogen is feeding.
Effluent Storage: the other freshwater compliance line.
Farm Lease Rate: what the blocks cost to hold.
Knapsack Spray Mix: the same per hectare arithmetic for spray.

Data sources: the 190 kg N per hectare per year cap, its application as both a farm average and a per hectare limit, the 1 July to 30 June nitrogen year, the 31 July reporting deadline and the scope covering synthetic fertiliser above 5 percent nitrogen by dry weight all come from the Ministry for the Environment National Environmental Standards for Freshwater. Verified 10 August 2026 and reviewed each 1 July.