Helping farmers reach N targets
A DairyNZ programme to help farmers in two Canterbury catchments to reduce N loss has proved highly successful.
The Ministries for the Environment and Primary Industries jointly announced the review in early March, appointing eight independent experts to assess Overseer – their first task being the controversial question of its suitability as a regulatory tool.
“Having this review underway is an important milestone, and it’s great that the ministries have appointed such a comprehensive group of scientists to the task,” Overseer chief executive Caroline Read told Rural News.
“We’re looking forward to updating the panel on the OverseerFM tool and our science programme. We have recently expanded our science capability with the appointment of a chief scientist (Dr Jacquie Harper) and a senior modeller who will be able to engage with this group.”
Read says they’re also working on implementing the Parliamentary Commissioner for the Environment Simon Upton’s recommendations – including developing a more comprehensive understanding of the model’s uncertainties.
“We are also actively supporting projects including the development of formal guidance on the use of Overseer in regulation, as well as providing input into government investment in both calibration trials to achieve acceptable levels of calibration coverage, and data generation to provide an evidence base for on-farm mitigation.”
Read hopes the review could “put to bed” a lot of the criticisms of Overseer and identify a way forward to create an effects-based regulatory environment for New Zealand.
Read recently sparred with Taranaki Regional Council chief executive Basil Chamberlain in the pages of Rural News over Overseer’s suitability as a regulatory tool, but she downplays their disagreement. “We both agree, actually, that Overseer is a farm planning tool to help farmers on the ground, and how it is used in regulation needs careful consideration.
“We know they don’t want to use Overseer in regulation but I think it is really important New Zealand is given the opportunity to use a tool that allows farmers to have flexibility in the way that they act to improve water quality.”
Overseer staff had scheduled a meeting with the TRC to discuss their concerns and how they could support the council if the new freshwater policy requires them to use Overseer in regulation.
However, that meeting was postponed because of the COVID-19 emergency.
Part of Upton’s criticism was that Overseer was primarily developed around pastoral systems and it was less able to model other systems such as arable farming.
Read says Overseer models many systems including pastoral, arable cropping, permanent fruit crop systems and some vegetable systems.
“We are currently adding new crops, where we can get sufficient data to be able to add them, but it does cover a wide range of crops and there are alternative crops that can be used if the crop doesn’t exist [in the model].”
She says much of the criticism came down to needing to enter more information into Overseer for a more complex farm system.
“If you’re growing lots of different rotations of different crops, yes you do have to enter that into Overseer and that’s where people feel that it’s not as easy to use,” Reed explained.
“One thing that we are working on, at the moment and have been working on for the past year is assessing that we have data available through this big long-term fluxmeter programme delivered by industry and Government.
Asked if perceived inconsistency in results was the fault of the model or operator error, Read concedes that there was a problem with the old Overseer software in that updates came with a long list of changes and it wasn’t clear to farmers how changes in the models affected the changes in their results.
She says the new OverseerFM version completely changed the way this was done. It now puts into the software the specific change for each farm system, so farmers could understand the implications of the model updates.
