How does biochar reduce soil greenhouse gas emissions?
Not only is biochar carbon negative but it also has the ability to reduce green house gas emissions from soil 🥳
As part of Lottie’s PhD, we visited an 800 hectare farm to talk with the farm manager about how we can add biochar into UK agriculture.
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During the visit we had the chance to see a state of the art green house gas analyser. This machine measures the methane, carbon dioxide and nitrous oxide emissions that are released from soil.
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Overuse of nitrogen fertiliser causes billions of tonnes of GHG emissions to be released each year. Biochar has been found to significantly reduce emissions (results range from 28-40%, more detail below).
This makes biochar a vital tool in helping farms reduce their carbon footprint. As part of the PhD we will be using a machine like this to quantify this for ourselves.
We now know that biochar actually sequesters carbon twice. Once through converting wood into biochar and again when used in soil. Further GHG reductions are seen when added to compost or when used to increase gas output from anaerobic digesters.
How does this work? It’s all about pores.
Biochar acts as a filter. So as gas passes through it, it can get trapped inside the biochar preventing it from being released into the air. This is due to biochar’s vast surface area and porosity which is the mechanism behind many of biochar’s benefits. Through adsorbing the gasses, biochar prevents the release of GHG emissions from soil.
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In scientific literature the results are promising, but more work needs to be done.
A review of multiple studies looking into biochar’s effect on N2O emissions showed biochar reduced soil N2O emissions by 28% (± 16%) in field trials. This is a stark contrast to the lab results, where biochar was able to reduce the emissions by 54% (± 3%). The variation in the field trial results, although averaging at 28%, was due to variable climate and application rates. The experiments used less biochar in the field trials vs the lab tests (Fidel et al. 2019).
These are promising results but more work needs to be done — the field trials only tested biochar in one cropping system and measured the change in N2O emissions within 12 months of application. We need to find out what happens as the biochar ages? Does it continue to absorb GHG emissions? What about under different types of farming practices and different climates?
If you’re interested in learning more, click the link in our bio and sign up to receive a free biochar guide and a recording of our most popular webinar.
Read more about what we’re doing with biochar at www.earthlybiochar.com
We share what we learn about biochar on our Instagram which you can check it out here: https://www.instagram.com/earthly.biochar/
You can speak to either Connor or Lottie by emailing us at connor@earthlybiochar.com or lottie@earthlybiochar.com
Effect of Biochar on Soil Greenhouse Gas Emissions at the Laboratory and Field Scales: https://www.mdpi.com/2571-8789/3/1/8/pdf
