Aarhus University Seal / Aarhus Universitets segl

Methods to reduce nitrous oxide emissions

Greenhouse gases from agriculture has to be reduced. This can be done in many ways, here researchers from the Department of Agroecology introduce two ways to reduce the emission of nitrous oxide from agricultural soil.

[Translate to English:] Kalkning af mark på forsøgsstation Aaskov. Foto: Henning Carlo Thomsen.

The climate is changing and part of the problem is the emission of greenhouse gases. Agriculture accounts for a large proportion of GHG emissions, but there are methods by which one can try to reduce emissions as much as possible. E.g., research shows that liming of acidic soils has an effect, just as certain plant species can reduce emissions from flooded grasslands. 

Liming on acidic soils reduces nitrous oxide emissions and increases yields

When farmers lime their soil, they will not just increase crop production, they will also reduce nitrous oxide emissions. In addition, the soil capacity to oxidise methane will also increase. In other words, liming of acidic soils helps to mitigate climate change. 

“We saw that the rate of liming that ensured the maximum crop yield also increased CO2 emissions and reduced the oxidation of methane compared to lower liming rates. However, we also saw that the nitrous oxide emissions were the same at all liming rates, but was greatly reduced compared with the unlimed reference. Therefore, our field experiment suggests that targeting a pH at 6.39 for crop yields seems to be the most appropriate option to balance crop production and mitigation of climate change,” concludes Diego Abalos.

Read more here

Plants can reduce nitrous oxide emissions from flooded grasslands

Climate change is causing extreme weather, and it is affecting the earth's ecosystems in various ways. One consequence of climate change is increased amounts of rain and thus the risk of floods. And it negatively affects the agricultural grasslands. Plant mortality is increased and field yields are reduced.

Emissions of nitrous oxide increase markedly when grasslands are repeatedly flooded. But it turns out that certain plant species can help limit the increased emissions. E.g. it turned out that the nitrous oxide emissions from tall fescue grown in monoculture are 54% lower than the other monocultures tested.

“This shows us that when faced with extreme weather events, tall fescue will be an important plant species to include in the mixture of plants to grow in the grasslands. It can cope with large temperature differences, as well as both flooding and drought, while it at the same time reduce the emission of nitrous oxide,” says Diego Abalos.

Read about the results for the other plant species, as the researchers' conclusions here.