Page 29 - Green knowledge 2025

Photo: Jørgen Lervik
Cover crops are the key to healthier soils
A new study shows that cover crops with vigorous root systems improve soil structure,
increase nutrient cycling and enhance carbon storage – without compromising yields.
Cover crops strengthen soil health and contribute to
carbon sequestration, but until now little has been
known about how these processes function under
Nordic conditions.
but the effects on carbon storage take longer to mate-
rialise.
A study led by NIBIO research scientist Dr Thiago
Inagaki shows that the roots of cover crops are cru-
cial for building stable organic matter in the soil,
known as mineral-associated organic matter
(MAOM). This forms when carbon from plant resi-
dues binds to minerals in the soil. When carbon is
bound in this way, it breaks down more slowly and
can be stored for many years – an important contri-
bution to slowing climate change.
Trials at the Tuv experimental farm in Steinkjer
show that cover crop mixtures with high root bio-
mass, such as ryegrass and clover, store the most
MAOM. More complex mixtures with species such as
chicory and birdsfoot trefoil improve soil structure
and support a greater abundance of microorganisms,
“Instead of only measuring carbon content, we
should promote biological activity that forms stable
types of organic matter,” says Dr Inagaki.
The study showed that cover crops did not reduce
barley yields, which may reassure farmers concerned
about competition for nutrients.
Biochar had no noticeable effect on soil quality or
yield but did not cause any negative effects.
The work continues in the AgroMixNorth project,
which examines how mixed cropping systems affect
the nitrogen cycle and plant development. The aim is
improved soil health and more sustainable cultiva-
tion systems in Nordic agriculture.
“We hope our findings can change the way we think
about soil management in the Nordic region,” says
Dr Inagaki.
Purpose: Funding: Contact: Investigate how cover crops affect soil quality under Nordic conditions.
NordForsk (via The Research Council of Norway) and the Norwegian Agriculture Agency
Research Scientist Thiago M. Inagaki, Division of Environment and Natural Resources.
Email: thiago.inagaki@nibio.no | Telephone: +47 922 65 448
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