“Overseer” and dairy farming have been in the news a lot lately. ("Govt to assist development of next-gen waterways protection tool", Radio NZ, 11 August 2021, "Hawke's Bay farmers 'frustrated' by review of regulatory tool Overseer", NZ Herald, 11 August 2021 and "Major tool for managing farm pollution gets a fail from reviewers", Stuff, 11 August 2021)
What is Overseer?
According to a Government media release of 11/08/21;
"Overseer and its predecessors have been used for 30 years by many New Zealand (dairy) farmers to estimate nutrient budgets and understand how nutrients are cycled on-farm. Recently, it has been used by a number of Regional Councils as part of their plans and consents to manage nutrient loss to rivers and groundwater.“
An independent expert peer review of Overseer has just been completed and it’s conclusion is that Overseer is not fit for purpose and is unfixable.
The Review conclusion (pages 95 and 96) is;.
"...we do not have confidence that Overseer’s modelled outputs tell us whether changes in farm management reduce or increase the losses of nutrients, or what the magnitude or error of these losses might be."
Why was there an independent expert peer review?
Because the Parliamentary Commissioner for the Environment Simon Upton wrote a report asking for a review in 2018.
What was the original concern of Simon Upton?
“This investigation is about Overseer’s fitness for purpose in a regulatory context. Can we be confident that its estimates of nutrient loss provide regional councils with a basis for making regulatory decisions, notwithstanding the simplifications and approximations that are inevitable in having recourse to models?”
Upton was also concerned that privately owned proprietary software was not transparent and neither it’s model structure or results had been independently verified.
So what’s the big issue now this independent peer review has been released?
Well the answer is “No” to Simon Upton’s question; can there be confidence in Overseer’s estimates of nutrient losses when regulating agricultural intensification under the RMA?
However, the Government response is to fudge the issue. In the Beehive media release they down play the peer review conclusion in bullet points.
- Report finds shortcomings in Overseer nutrient management tool
- Overseer will be supported while a next generation of the tool is developed and/or additional tools are made available
Minister for the Environment David Parker states;
“Despite its shortcomings Overseer has been a useful tool to build awareness and influence practices to manage nutrient loss at the farm and catchment level”
Minister for the Environment David Parker is minimising and therefore denying the peer review's conclusion. Parker in an interview with Radio NZ stated that Overseer isn't fatally flawed. Look for my underlining
"The Overseer tool has been used by Regional Councils to estimate what the nutrient pollution coming from a farm into water ways and it turns out there's some problems with it. That doesn't necessarily make it fatally flawed but those problems are significant."
And he states that Overseer can indicate the relative change in nutrient flows after a change of farm practise:
"We need to look at whether its still got really sound utility as a regulatory tool on say on a flat dairy farm on which it probably is quite accurate on and lets face it that's where most of our dairying is on flat land but there are some councils who instead of using it just to measure the relative performance of a change on farm because even if its not accurate as to the absolute number it does give you an indication if you change your practice of things getting better or worse and that's very useful."
What’s wrong with what David Parker is saying?
The peer review gave a black and white answer. Overseer can't give reliable estimates of either relative or absolute nutrient losses from farms. Yet David Parker made a 180 degree contrary statement to Radio NZ that Overseer can usefully estimate relative nutrient losses from farms.
Parker and the Government need to accept that Overseer is fatally flawed. It isn't fit for purpose for regulating agricultural intensification. Parker is treating the issue as shades of grey. There are problems, but these can be addressed, work can be done, and Overseer can be supported and improved.
Parker's assertions completely fly in the face of the peer review's conclusions. I don't see how any sufficiently informed reader of the peer review could possibly see the Government work program and Parker's statements as logical and valid responses to the peer review's conclusion.
So how does this fit in with the context of resource consents and RMA regional plans?
In terms of the regulatory context that Simon Upton was concerned about, I draw three conclusions;
- Any resource consents that have Overseer conditions - those conditions are now unenforceable on the consent holder.
- The regional council process that led to the granting of consents for agricultural intensification relied for their conclusion of "adverse effects mitigated" on the inappropriate use of a fatally flawed model.
- Any regional plan rules (i.e. Manawatu Whanganui Regional Council’s One Plan) where Overseer was used to manage and therefore allow intensification were based again on the inappropriate use of a fatally flawed model.
What are the environmental organisations saying?
I agree with Greenpeace who said that Overseer had supported dairy conversions and intensification. Overseer was an excuse for allowing too much synthetic nitrogen fertiliser and too many cows to be crammed onto the land, despite worsening freshwater quality and drinking water contamination. Overseer justified the over-application of synthetic nitrogen fertiliser and had been embedded in resource consents.
“From the start, Overseer has been peddled by fertiliser companies as a means to sell more fertiliser – the very thing that is wrecking rivers and driving intensive dairying.”
“That’s no surprise given that Overseer is managed by the fertiliser companies that make a killing off farmers dumping synthetic nitrogen fertiliser onto the land,”
Overseer has been unequivocally unmasked as not just an imperfect tool used inappropriately in the RMA context to justify more intensive horticulture and dairy farming, but as propaganda for environmentally damaging agricultural intensification.
David Parker’s statements and intentions to continue with Overseer with incremental improvements show he is just a cheerleader for agricultural intensification and it’s ensuing adverse nutrient pollution of our freshwater bodies.
Well that sucks. What should be done about it?
I think the environmental NGOs need to get a declaration from the Environment Court that Overseer is unusable in any consenting or planning context. The Government needs to be stopped from propping Overseer up with incremental fudges so it can still act as a fig-leaf of faked mitigation for agricultural intensification.
An appendix on the independent peer review of Overseer
The citation for the independent peer review is Overseer whole-model review Assessment of the model approach, MPI Technical Paper no: 2021/12 Prepared for the Ministry for Primary Industries and the Ministry for the Environment by the Science Advisory Panel ISBN No: 978-1-99-100936-4 (online) ISSN No: 2253-3923 (online)
Here are the relevant conclusions from the independent review.
On page 90 in para 10.2.3 "The limitations of the overarching structure of Overseer notably impair the ability of the model to produce trustworthy absolute or relative predictions (see 10.2.1). These challenges with the overarching model structure are likely to overshadow any appropriately modelled behaviours represented by the model microstructure."
On page 93 "As highlighted in 10.2, Overseer’s structure, data, and behaviour suggest predictions of absolute and relative nutrient losses are likely inaccurate."
On pages 95 and 96 a summary of the panel's findings and conclusion.
"Our core concerns are that Overseer:
- Is a steady state model attempting to simulate a dynamic, continually varying system;
- Uses monthly time-steps;
- Uses average climate data and, therefore, cannot model episodic events, or capture responses to climate variation;
- Does not balance mass;
- Does not account for variation in water and nutrient distribution in the soil profile;
- Does not adequately accommodate deep-rooting plants;
- Focuses on nitrate and omits ammoniacal nitrogen and organic matter dynamics; and
- Lacks consideration of surface water and nutrient transport, as well as critical landscape factors.
As a result of these concerns, we do not have confidence that Overseer’s modelled outputs tell us whether changes in farm management reduce or increase the losses of nutrients, or what the magnitude or error of these losses might be."