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Plantekongres 2022 – Perennial crops as a climate remedy

Perennial biomass crops have a moderate emission of nitrous oxide compared to annual crops despite a high supply of nitrogen. At this year's virtual Plant Congress, you have the opportunity to learn about how perennial grass for biorefining can be cultivated with moderate emissions of nitrous oxide.

At this year's virtual Plant Congress, you have the opportunity to learn about how perennial grass for biorefining can be cultivated with moderate emissions of nitrous oxide. Photo: Colourbox

It is good for both the climate and the environment when grass is grown instead of cereal crops in the fields. Grass also has the advantage that it is more robust to prolonged drought or rain. At a webinar in connection with Plantekongres 2022, Poul Erik Lærke, senior researcher at the Department of Agroecology at Aarhus University, will explain how perennial crops such as grass can help reduce nitrous oxide emissions, and how perennial crops can help change the carbon content of the soil.

Below the IPCC value of one percent

According to guidelines from the IPCC (International Panel on Climate Change), one percent of the added nitrogen becomes nitrous oxide. But if you can document measurements of actual greenhouse gas emissions, you can use them instead of the IPCC's one percent. In a long-term experiment, the Department of Agroecology has investigated the annual emission from a number of crops, which Poul Erik Lærke will present at his webinar on Tuesday 18 January 2022 at 13.00-13.45.

Moderate emissions even with a high supply of nitrogen

A challenge with high-performance perennial grass crops is that they require a large supply of nitrogen, which could cancel out the climate benefits of producing grass for biorefining, at least if one has to use the IPCC's value of one percent as measurement.

"In our experiment, we found that the annual emission factors for both perennial grass and maize were below the IPCC's value of one percent," says Poul Erik Lærke.

The perennial crops are good at absorbing the fertilizer, and when there is no nitrate available in the soil, no nitrous oxide is emitted either. Even during the conversion period, where there is a great risk of large emissions of nitrous oxide, measurements from the experiment at the Department of Agroecology have shown that they were well below one percent.

"Overall, it is still our conclusion that conversion from annual to perennial crops, which can also be used for biorefining, will be able to reduce the agricultural climate footprint, but it is important to convert grass in the right way so that subsequent crops can use the nitrogen that is in the ground," explains Poul Erik Lærke.

Hear much more at the webinar "Perennial crops as a climate tool" on Tuesday 18 January 2022 at 13.00 - 13.45.

Virtual Plant Congress

This webinar is part of the Plant Congress 2022. Again this year, the Plant Congress is being held virtually due to the Covid-19 pandemic. But the content is still the same, now you can just follow the many exciting presentations at home from the living room when they are held as webinars. In addition to this webinar, you can hear about:

  • Biochar's effect on agricultural soil - In pyrolysis, the carbon of the biomass is converted into very stable C-compounds. This means that it is not a food base for the micro and macro life of the field. On the other hand, biochar has potential as a carbon storage, and it has positive effects on both the soil's physics and chemistry.
  • Effect of catch crops and plant residues on nitrous oxide - Plant residues can release nitrous oxide when mulching. But catch crops can also reduce nitrous oxide emissions by absorbing nitrogen and preventing leaching. Hear about the possibilities and complications of plant debris and catch crops to reduce nitrous oxide emissions.
  • Cereals of the future - The climate has become more unstable and extreme, and therefore the future offers new requirements and challenges for cereal production. The grain must be climate-tolerant and at the same time have a high health and nutritional quality.

Read more about the Plantekongres 2022 here www.plantekongres.dk (in Danish)

Additional information


Senior Researcher Poul Erik Lærke, Department of Agroecology, Aarhus University. Tel. +45 22401844 or mail: poule.laerke@agro.au.dk