Using the agricultural emissions Calculator

The calculator enables any farmer, grower or small-block holder to get a quick initial estimate of their farm’s emissions. It is especially useful for farms with many different livestock types, some of which are not covered by sector-specific tools. Knowing your land's greenhouse gas emissions and where they come from is the first step towards reducing them.

The He Waka Eke Noa - Primary Sector Climate Action Partnership has committed to the goal of every farmer knowing their greenhouse gas emissions number by the end of 2022. This calculator is a starting point towards that goal.

The calculator uses emissions factors derived from New Zealand’s National Inventory for methane and nitrous oxide emissions.  These factors are national averages.  The factors for forests are based on our Land Use and Carbon Analysis System (LUCAS) national sample.  The method has been accepted by the He Waka Eke Noa – Primary Sector Climate Action Partnership as suitable for achieving its 2022 milestone of every farmer knowing their emissions number.  More details of the method can be found here Detailed Guide (MfE Guidance for Voluntary GHG Reporting – 2020).

Because the approach used to calculate emissions is very simple, the calculator will give you a ball-park estimate of emissions and sequestration.. For example, it does not account for livestock and tree ages, and management practices which could reduce or increase emissions such as bought-in feed and manure management. It also relies on national average default values for emissions factors. If you want a more accurate estimate, or want to test the effect of different management practices, you should use one of the other tools included in the GHG tools and farm planning factsheet [hewakaekenoa.nz].

The data you enter, and the results the calculator generates will only be visible to you. No record is kept of the data and results, so you will need to save or print them if you want to keep a copy.

The calculator is focused on the emissions being considered by the He Waka Eke Noa -Primary Sector Climate Action Partnership. This includes:

• methane and nitrous oxide from livestock and nitrogen fertiliser
• carbon sequestered in vegetation. 

However, users can obtain estimates of farm emissions from wider sources such as transport and waste using our measuring emissions interactive workbook.

The term agri-soils in the calculator refers to the nitrous oxide lost from dung and urine in soil, rather than soil carbon. The nitrogen in dung and urine is used by soil micro-organisms such as bacteria and fungi, and as a result, some is released as nitrous oxide into the atmosphere. Nitrogen from fertiliser can also be converted to nitrous oxide, and this is accounted for in the fertiliser section of the calculator. The He Waka Eke Noa - Primary Sector Climate Action Partnership is investigating whether soil carbon can be recognised.

The He Waka Eke Noa - Primary Sector Climate Action Partnership will provide a recommendation on the recognition of forests and other vegetation in 2022. In the meantime, you should use the Emissions Trading Scheme definition of a forest which is: at least 1 hectare of trees that are capable of reaching 5 metres in height at maturity, and at a stocking density that will provide canopy cover of more than 30% on each hectare.

It does not include shelterbelts (unless their average width is at least 30 m), trees primarily for fruit and nut production, and pre-1990 forests.

In the calculator, tall natural forests (such as mature native trees) are assigned a zero value for sequestration. This is in line with the approach taken in New Zealand’s Greenhouse Gas Inventory. The zero value may change in the future (either up or down), as we discover more about sequestration in New Zealand’s forests through the monitoring programme managed by the Ministry for the Environment.

For farms where livestock numbers fluctuate widely over the year, an average will need to be estimated. For example, a rough average can be calculated by summing the monthly numbers and dividing by 12. Where this information is not available, an estimate will need to be made.

The calculator requires that nitrogen fertiliser data is entered as kilograms of fertiliser, not as kilograms of nitrogen, to enable different emissions factors to be applied. For non-urea nitrogen fertilisers, you will need to enter each type that you use separately, along with the percentage of nitrogen in each. However the calculator has the percentage of nitrogen in urea (with and without urease inhibitor) built into the calculation, so all you need to enter is the total kilograms of urea applied.