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  Council » Policies and Plans » Plans under development » PROPOSED WAIKATO REGIONAL PLAN CHANGE 1 » Frequently asked questions (FAQ) and infosheets » Nitrogen reference points

Nitrogen reference points

What's a Nitrogen Reference Point (NRP) and who needs one?

‘Nitrogen Reference Point’ (NRP) refers to information on a property’s nitrogen leaching losses, calculated using OVERSEER®, or another approved model. Under the proposed plan change, properties with an area (or cumulative area) greater than 20ha and all commercial vegetable growers will generally be required to calculate an NRP. This includes:

Commercial vegetable production properties

Average annual nitrogen leaching losses from 1 July 2006 to 30 June 2016 and associated data, including the OVERSEER output file.

The NRP will be provided to council at the time the resource consent application is lodged.

Farming activities on properties or enterprises greater than 20ha

Highest annual nitrogen leaching loss in eather the 2014/15 or 2015/16 financial year for the property and associated data, including the OVERSEER output file. Records will need to be kept and produced on request.

These properties or enterprises will have from 1 May 2020 to 30 November 2020 to provide council with their NRP. 


How will Waikato Regional Council use the Nitrogen Reference Point information provided?

Waikato Regional Council will use NRP information from dairy farms to determine the 75th percentile nitrogen leaching value. This will be calculated by looking at the kilograms of nitrogen leached per hectare/ per year in each Freshwater Management Unit (FMU), using the values provided by dairy farming properties and enterprises.

All farming activities whose NRP is above this value, not just dairy farming activities, will be required to reduce their discharges to the 75th percentile, by July 2026. All other properties must not exceed their nitrogen discharge levels. For example, if the 75th percentile NRP in your FMU is 40kg/ha, and your NRP is 45kg/ha, you will be required to reduce your nitrogen levels to 40kg/ha.

Waikato Regional Council will also use NRP information:

  • When considering actions and mitigations in a Farm Environment Plan
  • When considering land use changes, to ensure there are no increases in nitrogen discharges from exisiting land uses
  • In future plan changes to identify catchment nitrogen loads and inform future policy

How is this different to 'Grandparenting?'

FAQ NRPClick here [PDF, 276 KB] to download

The Collaborative Stakeholder Group (CSG) recommended the use of NRPs in order to prevent any increase in nitrogen loads over the next 10 years, quantify existing nitrogen loads to help inform future policy, and require the highest NRPs to come down to the 75th percentile.

Grandparenting locks everyone into their pre-existing level of nitrogen. The CSG didn’t want to reward those properties with a high NRP by allowing them to maintain their nitrogen losses going forward. They wanted to require properties with the highest nitrogen losses to reduce these, and the remaining properties to not exceed current nitrogen losses. The NRP was the metric chosen to achieve this.

What information will I need for a NRP?

The proposed plan change requires that farmers do not increase their nitrogen leaching beyond their NRP. It also states that those leaching more nitrogen than the 75th percentile in each FMU, based on NRPs submitted for dairy farms, will have to reduce nitrogen losses to below this level.

OVERSEER uses a range of farm management and geographical parameters to predict NRPs and you will need to retain these records if council requests them for verification. These records might include:

  • Evidence of stock numbers (as represented in annual accounts) together with stock sale and purchase invoices. Additional information may include grazing invoices and transport receipts.
  • Dairy production data (e.g. milk supply company receipts)
  • Records for fertiliser applied to the land, preferentially in the form of invoices and/or fertiliser proof of placement data
  • Invoices for feed supplements sold or purchased
  • Water use records for irrigation averaged over 3 yars, including irrigated area, in order to determine irrigation application rates
  • Records of crops grown and grazed, including cultivation and sowing invoices where available e.g. harvest contractor and/or seed company receipts
  • Horticulture crop diaries and NZGAP records for vegetable growers
  • Any soil test data available
  • A map detailing the property boundaries, including the different management units of the farm (e.g. effluent block, farm forestry non-productive areas)
  • Certificate of title and legal description information
  • Soil type maps and related data

If records are not available, the proposed plan change states that default values for NRP will be used. Generally this will be input values that represent 75 per cent of the average for that farm system type within each Freshwater Management Unit. You may already have a nitrogen assessment, however this information is only indicative of nitrogen leaching on the property and may not be adequate as an NRP.

What does 75th percentile mean?

A 75th percent nitrogen leaching value will be calculated for every FMU based on the NRPs from all dairy farms in that FMU. The 75th percentile means that if you were to calculate the nitrogen leaching value from 100 dairy farms, and then put those numbers in order from lowest to highest, the 75th percentile would be the nitrogen leaching loss from farm number 75. All farms that have a NRP above the 75th percentile will need to take steps to reduce their nitrogen leaching. 

Will I need to provide a NRP every year?

No, you will not need to calculate an NRP every year; however, you will need to provide an OVERSEER file each year in order to determine your five-year rolling average. This number represents the average nitrogen leaching losses on your property over the past five years. 

How does OVERSEER work?

OVERSEER uses information about the soils, climate and farm system to calculate what happens to nutrients on a farm. Because the programme ‘knows’ how much nitrogen is applied to the soil from all sources, and how much is leaving as product (eg, milk, meat or crop), it can calculate how much is likely to be found in the soil, atmosphere or washed through the soil by rain.

Farms are complex, and because of the natural variability in these systems, OVERSEER gives an average annual output that represents the likely nitrogen leaching for any one year.

Want more information about how OVERSEER works? Visit link).

What are the benefits to having a nutrient budget and NRP?

OVERSEER was originally developed as a decision support tool to improve productivity on farms and it still delivers on that purpose. The process of developing an NRP provides an opportunity to better understand nutrient flows within the production system and that can help you improve productivity on your farm and minimise your environmental impact.

To make the most of this opportunity it’s important to take an active part in the development of the OVERSEER file and discuss management options with your CFNA. Similar to a financial plan, a nutrient budget, tells you how much is coming in, how much is going out and where it’s going. You can use this information to:

  • Understand how nutrients are being used on farm
  • Select the best fertiliser and schedule for your soil type
  • Minimise nitrogen leaching into waterways 

How do I get an NRP?

In order to get an NRP you will need to work with a Certified Farm Nutrient Advisor (CFNA). CFNAs are individuals with experience and qualifications in nutrient management who are certified by Waikato Regional Council to calculate an NRP for Plan Change 1.

Council is currently working on a certification program for nutrient advisors. Once approved, there will be contact information on our website for all CFNAs in your area. Be sure to check here to find out more information about CFNAs.


This information has been provided based on Waikato Regional Council’s interpretation of the proposed plan. The proposed plan is subject to change through the hearings process.

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