19 Sep 2014

A window into Overseer

As interest in water quality and nutrient management has increased in recent years, so too has the use of Overseer, a nutrient budgeting tool owned and supported by the fertiliser industry, government (Ministry of Primary Industries) and AgResearch Limited. Caroline Read was appointed the General Manager for Overseer in November last year.  We had a chat to Caroline this week to find out a little bit more about the increasingly important role of Overseer in New Zealand’s land and water management and the challenges for the future.

What attracted you to the role of General Manager of Overseer?
As Overseer’s role in nutrient management in New Zealand has become increasingly important I could see there was a big challenge in ensuring the Overseer model continues to be fit for purpose and I always enjoy a good challenge. I was previously working on the water reforms and saw this as an excellent opportunity to work with those implementing these reforms on the ground.

For those who might not be so familiar with Overseer, can you summarise what the model is and what it is used for?
Overseer is a nutrient budgeting tool that enables farmers to make decisions about their nutrient use on farm. The model looks at all the nutrient flows (inputs and outputs) in the farm system and tells you what your nutrient budget is, where nutrients are being lost and what your maintenance fertiliser requirements are. You can also scenario test different farm management practices that affect nutrient flows to identify possible solutions that will work for your farm system. Overseer has the double benefit of enabling farmers to make decisions about optimising production and reducing environmental impacts.

Overseer was originally developed as a nutrient budgeting tool for pastoral farmers and has evolved more recently into an integral part of land & water regulation in New Zealand, such as the Canterbury Land and Water Regional Plan. What do you see as being the biggest challenge in this transition?
Continuing to develop the model to be fit for purpose. We need to make sure Overseer can be calibrated for the various soils and climates we encounter in New Zealand and can cover the broad range of farming systems. We also need to enable various mitigation options for reducing nutrient loss to be included. To achieve this requires a lot of investment and building capability in science and systems and this will be critical to meet the growing needs.

There is always a lot of work in keeping these types of tools up-to-date. How do you prioritise what to work on first?
An important part of my role has been setting up advisory groups that provide advice to the Overseer owners on what is most important and what to prioritise. We have set up an experts group (users from regional councils, fertiliser representatives and farm advisors), a technical group (our scientists and modellers) and a stakeholder group that includes a wide range of people interested in how Overseer is evolving (farmers, agriculture industry groups, IT companies and government). All these groups are helping to identify the priorities for improving Overseer in the future and supporting the development process.

There has been some concern from some quarters about the accuracy of Overseer, particularly when used in a compliance situation. How have the Overseer owners been addressing this?
We have been working on this in various ways. The advisory groups we have set up help to review the model and identify any areas for improvement. We have work underway to better understand the uncertainty in the drainage model. We are increasing our engagement with people to communicate what the model can and cannot do. But the biggest bang for increasing the reliability of the Overseer budgets has been the release of the best practice data input standards late last year. Because there is a lot of farm-specific information needed to run Overseer and this information can come in various ways, the standards ensure that users are using the best quality data available to get a more representative and repeatable nutrient budget.

What are the key outcomes you are hoping to achieve with Overseer over the next year?
Building better relationships with Overseer users, continuing the development of Overseer, particularly around irrigation practices, and working with partners to support the growing science and knowledge base needed to develop this world class tool.


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