Overseer models the flow of nutrients on a farm, and produces nutrient analyses and greenhouse gas footprint reports.

Overseer farm analysis calculates the flow of all seven major farm nutrients – nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium (Ca), magnesium (Mg) and sodium (Na) – as well as acidity for pastoral blocks - to provide a full picture of the farm’s nutrient health. It also delivers greenhouse gas emissions and energy reports.

Nutrient cycling on farms and Overseer

A farm is a complex living system; made up of soil, plants, water and often animals – which all contain nutrients. The changing nature of a farm adds to the complexity of modelling nutrient flows, because different farming practices and preferences affect how nutrients cycle around the farm.
To create a farm analysis, Overseer captures information about how a farm is run and models it through a series of complex sub-models that mimic the known bio-physical processes operating across a farm system.

There is a full technical description of how Overseer works in the Overseer Technical Description.

Greenhouse gas reporting with Overseer

Agriculture contributes almost half of New Zealand’s greenhouse gas (GHG) emissions (49% of emissions were from agriculture in 2014).

Overseer helps users identify the major sources of GHG losses on farms. It models farm-level emissions, based on the New Zealand Greenhouse Gas Inventory methodology, reporting on a per-hectare and per-product basis.


OVERSEER supports Kiwi farmers and growers as producers of world-class food who care for our land, water and air.

Download a copy of the OVERSEER brochure to find out more.

Taking care of our land, water and air


Overseer's integrated nutrient budgeting and greenhouse gas reporting tool allows New Zealand to demonstrate a country-wide commitment to our environment.

Farmers and farm consultants have been using Overseer since the 1980s to help them understand the nutrient needs of their farm.

Seven regional councils now also use Overseer to help them manage water quality. And the GHG function ensures New Zealand is ready to meet any future requirements for agriculture emissions reporting and improvements too. Having the same tool to measure nutrient leeching and GHG emissions is efficient for users and imperative for consistency of reporting.

Empowering farmers to innovate 


With growing scrutiny on the impact of farming on the environment both here and abroad, many countries have placed restrictions on stock numbers and fertiliser use in an effort to protect fresh water and reduce greenhouse gas emissions.

Overseer's effects-based modelling means New Zealand farmers can make science-backed decisions for their farm based on their unique situation, rather than facing blanket restrictions.

OVERSEER’s value to New Zealand

Overseer can deliver significant benefits to New Zealand by allowing our agriculture sector to show we are leading the world in sustainable farming.

In an independent report, agricultural economist Phil Journeaux estimated the benefits for the New Zealand agricultural sector from using Overseer to be valued at $271 million (per year). 

The benefits include significant cost and time savings in improving farm fertiliser application, farm nutrient management and agricultural research.