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Targeted use of biochar is essential


Photo: Anette Tjomsland Spilling

Biochar has many positive qualities that make it a potentially important tool for carbon neutral farming systems. However, according to one researcher, it is important to target the application to achieve the desired effect.

Charred biomass in the form of Biochar can help to improve the soil quality and reduce greenhouse gas emissions when added to the soil. Unlike untreated organic material such as leaves or compost, Biochar remains largely in the soil. This is because the biochar has a chemical structure that makes it hard for micro-organisms to break it down.

The carbon, of which the biochar is made, is therefore not released as carbon dioxide into the atmosphere, but instead helps to increase the carbon content of the soil.

In his doctorate (PhD), Simon Weldon investigated how biochar might be used to improve nitrogen use by retaining more mineral nitrogen and reducing nitrous oxide (N2O) emissions in compost and soil.

He discovered, among other things, that biochar that is produced at high temperatures contributes the most to reducing N2O emissions.

He also discovered that the ability of fresh biochar to store nitrogen is limited, something that may have significance for the production of biochar-enriched fertiliser.

“Our results both confirm and challenge existing knowledge on biochar function. We argued that production and application of Biochar needs to be targeted to maximise the potential benefits across a range of soil types, climates and applications,” explains Weldon.

Nevertheless, he is clear that biochar is a valuable technology for the future bioeconomy.

“Biochar clearly has the potential to reduce greenhouse gas emissions from both compost and soil. It is also one of the few effective measures we have to increase soil carbon while also reducing N2O emissions.” he says.

It is important to be realistic about biochar so that the technology finds the most economic and effective use.