The Country 11/03/25: Peter Almond talks to Jamie Mackay

The Associate Professor at the Department of Soil and Physical Sciences at Lincoln University on the Enhanced Rock Weathering Research, which is developing an innovative method of absorbing large amounts of CO2 through rock deposits on pastoral land.

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Episode Transcript

Speaker 1 (00:00):
So we have committed to being net zero by twenty fifty.
How are we going to get there? Well, Lincoln University
has a good idea. Rather than planting forests and reducing
the amount of productive farming land available, Lincoln University's rock
weathering research aims to absorb CO two while not inhibiting

(00:21):
our agricultural production. And they're going to do it by
putting rock on pasture. How does this work? Let's ask
doctor Peter Ahmand, Associate Professor of Soil and Physical Silent Science.
Should I say at Lincoln and you're about to start
a new trial next week in Southland?

Speaker 2 (00:39):
Peter, good afternoon, Yes we are, Jamie, thanks for having
me on your program. Yes, we're starting our trial next
week and essentially what we're going to be doing is
applying crushed rock and crushed bassalt source from a quarry
in Dunedin to pasture land in Outahuti in Southland, and

(01:01):
over the next few years measuring the amount of carbon
dioxide that is absorbed by the weathering of that material.

Speaker 1 (01:08):
So how do we know? I mean, there's obviously scientific
proof that weathering basalt rock reduces CO two emissions or
absorbed CO two? How does that work.

Speaker 2 (01:18):
Well, It is quite simple thing. Fortunately. It's when CO
two dissolves in water in the atmosphere, water, vapor and rain,
it produces an acid, carbonic acid, it's called it's the
same sort of acid that you get in soft drinks
and sparkling water, and it reacts with minerals within rocks,

(01:41):
and the carbon dioxide that's dissolved into the water ends
up remaining in the water as another chemical form called bicarbonate,
and the bicarbonate leaches off the land, accompanied by some
of the rock weathering products and ends up in the ocean.
A very long term and one hundred thousand year store

(02:03):
of carbon dioxide.

Speaker 1 (02:05):
Is this like the silver bullet, the El Dorado to
fight climate change? Potentially?

Speaker 2 (02:11):
No, No, it is just one tool in the toolbox. Really,
it can probably We've done some of the numbers and
I think conservatively it might be able to pull about
four million tons of carbon dioxide or the atmosphere in

(02:32):
New Zealand, depending on how widespread it is. And that's
you know, that's in the context of a budget of
something like eighty million tons or I would say net
sixty million tons from New Zealand emission, so it's part
of it's part of the solution.

Speaker 1 (02:46):
Will there be any pollution issues You talk about this
stuff going into our waterways eventually being a carbon sink
in the ocean, there must be negatives to that.

Speaker 2 (02:55):
Potentially, the best rock for this technology is volcanic rocks
like basalt. They're quite reactive, the minerals weather quickly and
this process is sped up relative if we used other
common rocks, say like gray wacky, which our mountains are
made out of. But yes, basalt can have some contaminants

(03:18):
like chromium and nickel in it, but generally the calculations
we show the it's a long time before those contaminants
build up to any toxic levels and soils and they're
quite strongly fixed, so we don't expect them to be
leaching into our waterways.

Speaker 1 (03:37):
In terms of the trial on the Southland farm you
mentioned Otahutia. I know Southland reasonably, well, I'm the born
and bred Southlander. Well, it's got to be a dairy
farm around that area.

Speaker 2 (03:48):
No, it's actually a sheep farm. And we had a
research project on the farm previously and we were looking
specific at the drainage network in the farm and the
quality of the water that was coming out of the drains,
and then we realized after we instrumented a catchment had

(04:11):
a lot of infrastructure in the ground, that there was
the ideal set up to investigate in halfsrock weathering, because
one of the best ways of quantifying the amount of
CO two being sucked out of the atmosphere is to
look at the chemistry of the water coming out of
the landscape. So we had all the time we had
tile drains monitored with flow meters and auto samplers to

(04:35):
take water and allow us to do the chemistry on it.
So that's why we stuck on this particular farm, very
co opative landowner and the ideal set up for our experiments.

Speaker 1 (04:50):
So this trial begins I think next week. How long
until you get some sort of meaningful data in terms
of a result.

Speaker 2 (05:00):
Good question and not one I can give you answer to.
It's really it's part of the experiment. We've been monitoring
the waternow really solidly for a year up to the
point that we apply the rock, and so we've got
a good baseline, a very accurate baseline. So I'm hoping
that we will be able to detect the change and

(05:22):
I don't know. If I had to put money on,
i'd say within maybe within a couple of years. If
something's going to happen, we should be seeing it by then.

Speaker 1 (05:31):
So there you go. A field scale experiment putting crushed
basalt rock on pastures to reduce CO two emissions. Exciting.
We'll keep an eye on this one. Doctor Peter Armand
out of Lincoln University, Associate Professor of Soil and Physical Science,
Thanks for your time today on the country. I've learned
something with a pleasure.

Speaker 2 (05:50):
Thank you. Jamis