Getting the job dung

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Henrik Moller and Emma Curtin with a sample of beetles and their dung creations. PHOTOS: GERARD O...
Henrik Moller and Emma Curtin with a sample of beetles and their dung creations. PHOTOS: GERARD O’BRIEN
A humble beetle could be the catalyst that brings town and country together to create better farms and cleaner waterways, Henrik Moller tells Tom McKinlay.

"A single dung pat can vanish without trace in less than 10 minutes," David Attenborough observes in trademark hushed tones.

"Without this help from dung beetles the daily dose of 5000 tonnes would soon swamp the plains."

And indeed, the time lapse action that accompanies his commentary shows a busy team of glossy black scarab beetles demolish a fresh pat with remarkable efficiency.

Attenborough is telling the story of the Serengeti, but the point he makes about the beetles’ vital ecosystem service is part of an increasingly animated conversation here too. In Africa they clean up after vast herds of wildebeest. Here they could do similar work on farms.

We have imported the dung doers — cows, sheep, deer, pigs — without the traditional operators of the waste system, with predictable impacts on waterways, says ecologist Henrik Moller.

It’s time we addressed that, he says. And, importantly, it’s a job we should take on together, as a community.

"Dung beetles are the missing group out there," Moller says of Aotearoa’s farming ecosystems, "because we brought all these herbivores over and we didn’t bring with them the things that normally disperse their dung — or bury their dung."

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The tidy product of dung beetles’ endeavours.
The tidy product of dung beetles’ endeavours.
The ecological impact of the missing critters has been huge.

New Zealand does have native dung beetles, but they are forest dwellers. Pasture is not for them. The beetles Moller advocates for are a small number of exotic species approved for release, having been vetted to check it is safe to do so.

"Why I am so fascinated by them is partly, as an ecologist, they are something called an ecosystem engineer — so they create a matrix or a habitat for a whole lot of other things to live. In forests we can think of a kereru as an ecosystem engineer, because they spread seeds that keep forests regenerating."

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The Onitis alexis, another of the beetles approved for release.
The Onitis alexis, another of the beetles approved for release.
Dung beetles and earthworms are examples of ecosystem engineers in our paddocks. Indeed, University of Otago zoology department PhD candidate Emma Curtin is researching the benefits of dung beetles, including their interactions with earthworms.

Not only do the beetles tidy up, but they build soils by burying the dung, gently tilling the soil in the process to spread nutrients. They disperse organic matter that glues soil particles together and create tunnels and pores to let air and water into the soil.

"Lots of people think of soils as dirt, or as a test tube where you pour in nitrogen and phosphorus and it produces things," Moller says. "But the key to completing ecological cycles and leading to more efficient production is the biological health of the soils.

"And there’s a huge array of things in there — the fungae, bacteria and invertebrates that are important for healthy soils. We now need to add dung beetles to the mix."

Moller is part of a wider Beef + Lamb New Zealand- and MBIE-supported project, the Hill Country Futures Programme, which is looking for systems and strategies for smart farming. Its work involves a dung beetle trial on the East Coast’s Mahia Peninsula.

"As an ecologist, it’s like repairing or reassembling a complete ecosystem so it can cycle more efficiently in the way that would normally happen," he says.

The beetles have been introduced to farms in other places around the country too, from Southland to the Far North. And indeed, in the Kaipara are already well established and filling their ecological niche.

Moller says those efforts now need to be monitored to provide the systematic ecological science farmers require to inform decisions on whether to invest themselves.

On the other hand, the environmental issues dung beetles could help address are pressing, and the case for giving them a go is already strong, so Moller believes there is an argument for a broader coalition to come in behind the effort.

At the moment a farmer is up for $6000 a year for a dung beetle innoculation on their property, without any guarantees about how long it might take for benefits to accrue or just how significant those gains will be. It is estimated a successful introduction could begin to show results in three to five years, and be humming within a decade.

"We are asking the farmers to carry all that risk whereas I hope that all New Zealanders will step forward to share that risk and cost," Moller says.

It’s an opportunity for the wider community, Rotary groups, Lions clubs, environmental groups and NGOs, to add another element to the work they are already doing on waterway health, he says.

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The 22mm Copris hispanus, or Spanish dung beetle, is nocturnal and builds burrows up to 40cm deep...
The 22mm Copris hispanus, or Spanish dung beetle, is nocturnal and builds burrows up to 40cm deep to sequester dung.
Moller calls this the "social ecology" — every bit as important as the biological kind.

Commonly, those public good actors — the service clubs and green groups — work with farmers on habitat restoration along streams and rivers; planting natives to protect and improve water quality.

It’s good worthwhile work, Moller says, but also the last line of defence to stop sediment and nutrients entering waterways. Dung beetles can cut off some of those threats at their source, in the paddocks themselves.

"Why don’t we club together to buy dung beetles and get them out as quickly as we can, as widely as possible within New Zealand’s landscapes, to help farmers and us all out?"

The effort is beginning to mobilise.

The Otago Regional Council’s Eco Fund recently granted $5000 to the Soil Your Undies Otago project, a sum that will in part support looking at the role of dung beetles in soil functioning.

It will be used to buy dung beetles, boxes and traps for schools and participating farms in East and North Otago.

It’s just the kind of coalition of farmers and wider community members that Moller is hoping for. It is led by the North Otago Land Management Group, with help from Beef + Lamb New Zealand, Enviroschools, AgResearch and the Curious Minds Otago Participatory Science Platform, a next-level citizen science initiative.

"If we are going to benefit from healthy and productive and environmentally friendly farming, then we all have a role to play in meeting some of the costs," Moller says.

Not only can dung beetles contribute to swimmable rivers, clear of pathogens, but they can help mitigate climate change by building carbon stocks in soils, he says.

"We desperately need a conversation in New Zealand about sharing costs and benefits. The pompous way of saying it in the literature is ‘common but differentiated responsibilities’."

It’s the idea that we all share in the benefits of environmental care and climate-smart agriculture, so we all should help create the solution, even if farmers carry most of the cost for the dung beetles.

Leaving these sorts of solutions to the market alone won’t cut it, he says.

"It never has and never will."

"Small amounts of smart money at the beginning of these innovations is, in my view, a public responsibility — spending a bit now, like on kick-starting dung beetle populations, returns its investment in spades later."

Of course, there are also voices raised in favour of reducing farm stock numbers as a solution to the accumulation of dung and run-off.

Moller says we’d most certainly all pay the cost of that approach in lost economic activity.

He hopes we can find many ways to farm profitably that have less impact on ecological landscapes and the rural communities.

"In some places that could require destocking or reduced stocking, but there could be other places where it could be increased."

With the help of the scarab beetle other opportunities might present themselves.

"It could be one of the ways that we can keep farming profitable at the same time as reducing the environmental footprint, and even using it to restore environmental health. And if we all club in to help, we’ll also build trust and respect between town and country."


 

Comments

Unfortunately the dung beetle is not the silver bullet this pair claim it to be. Our waterways are polluted through agricultural leaching, leaching is the loss of water-soluble plant nutrients from the soil, a cowpat is relatively solid and as it slowly breaks down, the soil is able to absorb it's nutrients, like when it's put around roses. However urine and effluent are the real problem as these are in a liquid form and able to pass through the soil quickly without their nutrients being absorbed before they enter the water table.

This is a very one side article and I encourage readers to do their own research before investing in the introduction of another non native species. With over 10 million cows in this country and a farming system that relies heavily on pesticides, herbicides and artificial fertilizers, it's going to take more than a bettle to fix the damage they cause.

 

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