The future of Overseer as a regulatory tool to limit farm nutrient losses could hang in the balance after a government-appointed panel identified weaknesses in its ability to capture nutrient loss and challenged its accuracy.
The review also reveals a gap between Overseer’s application as a long-term, strategic tool for farmers and the ability of councils to use it as a regulatory tool to cap nutrient losses.
The Overseer panel was appointed in response to a 2018 Parliamentary Commissioner recommendation that Overseer as the key tool for measuring nutrient losses be reviewed.
The review’s general assessment is that Overseer is not providing reliable results across the range of situations it is applied to. Recommendations include more “real-time” data on nutrient losses, particularly nitrogen.
While acknowledging it is not perfect, OverseerFM chief executive Dr Caroline Read has defended its use as a tool for monitoring trends and shifts in farm nutrient losses.
“Overseer is a tool to understand the direction of travel for the whole farm’s nutrient profile. But we need to keep it pragmatic and realistic for making long-term decisions, including issuing consents, without having to re-analyse data on a weekly or monthly basis,” Read said.
She says she was concerned the panel’s recommendations are pointing towards a far more precise real-time monitoring tool.
The panel recommended more real-time monitoring of water quality at a local level, including a call for more immediate climate data, rather than the long-term monthly averages used by Overseer.
“What is it we want to regulate farmers for? Is it the weather, or the direction of travel for the farm’s nutrient losses? Every year will be different, Overseer follows the long-term trends in nutrients,” she said.
Environment Minister David Parker says a new version of Overseer that incorporated risk categories was one possibility.
One recommendation made by the panel was to replace Overseer with a completely new nutrient loss model.
But any review and dumping of Overseer could set the scene for a litigious showdown between farmers, regional councils and central government.
Bay of Plenty Regional Council chair and regional representative for Local Government NZ Doug Leeder says some councils, including Horizons, Canterbury and Hawke’s Bay, have enshrined Overseer into their regional water management plans for setting nitrogen loss limits.
“Councils have always known of Overseer’s weaknesses. The issue is though, that the Environment Court and commissioners have determined it is fit for purpose (as a regulatory tool). But this review has put those judgements in question,” Leeder said.
Leeder’s concerns are supported by Federated Farmers.
Environment spokesperson Chris Allen says the review confirmed what the Feds had been pointing out for years.
The Feds estimate 6000 farmers are already strictly regulated by Overseer through regional council stipulations.
Allen says in coming months it would be vital to determine farmers’ legal status, given Overseer’s weaknesses raise issues on its accuracy in setting nutrient limits in catchments.
However, he did not want to see Overseer ejected entirely, rather it be kept out of setting regulatory limitations. His sentiments are also shared by DairyNZ and Beef+Lamb NZ.
B+LNZ chief executive Sam McIvor says there was no doubt OverseerFM was still a valuable farm management tool and he supported its use on-farm.
“What the review has identified is that the nitrogen aspects of the model, in particular, need improving,” McIvor said.
Leeder says there is no tool that will provide a “magic number” for setting nutrient limits.
He envisaged that if regulations are to include limits, then a suite of tools will be required, including real-time monitoring of water ways.
“But that is very expensive, not always practical, and the variables to measure are massive,” Leeder said.
Ballance research and environment head Warwick Catto says Overseer reflected NZ’s efforts to take an output approach to nutrient control, rather than a top-down input limit, as used in Europe.
“This is what keeps innovation to deal with nutrient losses alive,” Catto said.
“But Overseer is a model and models require good science to feed into them. Cropping farmers realised the weaknesses in Overseer five years ago and came on board with funding to improve the cropping aspect.
“Horticulture has not invested in nitrogen loss studies to apply into Overseer, despite knowing about nitrogen losses since the 1990s.”
Read confirmed OverseerFM had not directly received any of the $43 million from the 2019 budget allocated for upgrading it.
She says some funding had gone into soil mapping and freshwater research that she hoped would feed into Overseer.
