Mapping
the
CO2
landscape
Over the summer, COWI
interns took 9,000 soil
samples to help register
CO2 emissions from
Denmark's agricultural
wetlands
Skagerrak
North
Sea
Sweden
Denmark
Kattegat
River Guden
Copenhagen
1 The core sampler is loaded onto an all terrain vehicle,
which can make it past even the toughest obstacles.
Baltic
Sea
2 Once the soil cores are drilled, it takes more hand
power to pull them out of the sampler.
Germany
3 The cylinder-shaped soil core after it comes out of
the sampler.
1
2
3
By Henrik Olsen
The tell-tale drone grows louder as the ATV bounces its
way over the bumpy terrain along the river, zigzagging
between grazing cows. The four-wheeler stops, and the
driver turns off the engine. After ripping off the helmet
and shaking out a mane of blonde hair, he scans the
horizon.
We are standing on the banks of the River Guden in
eastern Jutland, what many consider to be Denmark’s
most beautiful natural area. With the drone of the
motor gone, the larks resume their song. Meanwhile,
the grazing cattle meander closer to inspect the fireengine red ATV.
But it is not the lark or the view that Nielsen is here
to admire. He and 25 other cowi interns are spending
their summer break collecting soil samples from 9,000
locations in agricultural wetlands from all across Denmark. The samples, being collected for Aarhus University, will show how much carbon is stored in the peat, and
how much CO2 it releases into the atmosphere.
The amount of CO2 released from peat soils depends
on the content of the organic materials in the ground
and its land use. In order to find out just how much CO2
COWI intern Kristoffer Nielsen collects soil
samples from around Denmark using
hand-powered core samplers. Photos:
Niels Åge Skovbo
the peat soils contain, a team of scientists from Aarhus
University has undertaken a project mapping existing
occurrences of peat throughout Denmark. Once the
team has compared carbon levels with farming methods,
they will be able to come up with a precise calculation of
how much CO2 is released, as well as ways to cut CO2
emissions by planting other crops.
Potato — part of the high CO2 diet
“If you want to get the most out of our mapping, one
example would be to stop planting potatoes in peaty
soil. Potatoes have an effect deep down in the soil, and
you till the soil more than just once,” says Mogens H.
Greve, who is leading the study for Aarhus University.
When the peat is tilled, large quantities of oxygen
make their way into the soil. The oxygen mineralises
the organic material producing CO2 which is released
into the atmosphere contributing to climate change. If
farmers switched from potatoes to grass or grains, the
negative effect on the climate would be reduced.
The results of the study will be included in the
national CO2 account, which will be used to show
International news magazine from cowi • 13
4 Drill site locations are measured precisely using
GPS units.
5 Soil make-up, lime content and pH value are measured before the sample is packed for shipping to the lab
where the organic content will be measured.
6 Yellow stakes mark the spot where the sample was
taken.
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whether the country is meeting its Kyoto obligations. By
2012, Denmark needs to cut its emissions by 21 per cent
on 1990 levels. The current mapping programme will
probably show that the country is closer to meeting its
goals than previously thought.
But Denmark is not the only country that could
benefit from such a study. Even though mapping is
expensive, the financial benefits could far outstrip the
costs. If the study can document a reduction in CO2
emissions from farmlands, it means fewer CO2 quotas
need to be bought in order to live up to Kyoto Protocol
obligations.
“Documenting that we can save EUR 200 million on
quotas by spending EUR 9 million on the project is the
kind of return on investment we like,” Greve says.
Three more samples
Back on the banks of the River Guden, Nielsen packs his
drilling equipment and hammers a little yellow stake
into the ground in order to mark the spot where he sampled. The ATV roars to life, and its drone drowns out the
larks as it speeds off towards the horizon. It has gotten
late, and there are still three more locations to sample
today.
@
@
Kerim Martinez, Project
Manager, [email protected]
Mogens H. Greve, Research
Unit Head, Aarhus University,
[email protected]
14 • International news magazine from cowi
When peat is ploughed, oxygen
(O2) penetrates deep into the soil,
causing organic material to
decompose and release CO2.
Illustration: COWI