New rules for rural landowners nationwide take effect soon, and the most important covers nitrogen loss.
Why you need to know your (nitrogen) limit
Nitrogen is one of the key nutrients that landowners need to keep on their property and out of their waterways. No matter where you live, it will be measured under soon-to-be-introduced regional council regulations.
These regulations are being developed in response to the National Policy Statement for Freshwater Management. While timing and details will be different depending on where you live, all regional councils will be setting limits for allowable nitrogen loss and will measure that loss.
Most councils are leaving it up to individual farmers and block owners as to how they manage the nutrients on their land. However, Farm Environmental Management Plans will be required by most properties 4ha and larger. These will establish a limit on the amount of nitrogen which can be lost from an individual property, known as the nitrogen loss limit.
Even if your region hasn’t set limits yet, it’s important to understand how the process works. It will be vital to get your nutrient budget right once one is set. If you go over your nitrogen loss limit, it might trigger the requirement to apply for a resource consent. Nitrogen loss limits might also become relevant in determining the saleable value of your property.
But how will the allowable levels be set and how will the nitrogen loss be measured?
This sounds warm and fuzzy, but it’s a way of setting nitrogen limits. However, this type of grandparent will have favourites.
For example, in Waikato, the nitrogen limit will be set on a reference year in the past that provides a baseline. Ideally, this baseline will be historic enough to avoid people trying to ‘game’ it. They could do this by artificially inflating their leaching with unusually intensive practices in order to establish a higher loss allowance.
Comparable properties might receive different limits depending on their history. Unfortunately, in some cases it might be seen to reward poor historical environmental practices.
Whatever happens, this level will be the upper allowable limit of nitrogen loss for that land in the future. This will mean it won’t be possible to transition from a less intensive land use (like forestry) to a more intensive land use (like dairying).
The other system currently used for setting nitrogen limits is the Natural Capital approach. Hawke’s Bay Regional Council are using this for the Tukituki region.
This method uses the Land Use Capability (LUC) classification. LUC is
a system developed in the 1950s-1970s. It helps farmers to understand the production potential of New Zealand’s agricultural land. It takes into account the gradients, climate and erosion risks of an individual property. These factors give a good guide to the type of land use sustainable for that area.
LUC 1 is the best land, with good longterm production potential. LUC 1-4 can be cropped, 5-7 is generally for pastoral farming, and LUC 8 is really only for conservation.
Each LUC class has been assigned a leaching limit, on the assumption that better land is used more intensively and so gets a slightly higher allowance. The LUC system allows similar properties to be treated in a similar way.
In some cases, it will be worth investing in a paddock-scale remap of a farm, where the national-level LUC map is not accurate enough for the property.
A specialist nutrient calculation software (OVERSEER® or another approved model) can be used to work out the limit for a property in a grandparented region, and to model losses against the property limit. These model annual nutrient losses from farms based on farm inputs such as fertiliser, stock and supplementary feed, and specific individual production information.
OVERSEER® updates as scientific studies provide more information about nutrient flows in farm systems, so it is always improving.