The Big Biochar Experiment is a UK-wide initiative and is the largest study on the use of biochar on British allotments to date. The Experiment aims to gather data to assess the effects of biochar on plant productivity and soil health of widely used fruit and vegetable varieties in the UK. The team is comprised of members of Oxford Biochar Ltd, Earthwatch, the Environmental Change Institute (Oxford University), and the UK Biochar Research Centre. Project partner Dr. Dan Bebber of Earthwatch said, “Biochar holds great potential for addressing some of our greatest challenges, including climate change and food security. This novel experiment will provide important insights on biochar’s applicability to the UK farming industry, and allow people to get involved in real science.”

Believing that biochar could be a solution to safely and permanently sequester carbon in the soil, the Big Biochar Experiment is looking for hundreds of UK residents to enroll in the program and participate in citizen-powered science. Biochar will be provided free of charge. The participants will investigate whether biochar will work for their gardens and plants, and receive instructions and support on how to record the data from their plots and send it in to the experiment. Participants agree to set up two small fruit or vegetable plots of approximately 1m x 1m in size in their garden or allotment. One plot will be treated as usual with compost, while the other will have biochar applied with compost. Participants receive detailed instructions on how to apply biochar and how to plant seeds (to ensure similar experimental set up). Application rates should be at least 10% of the top 30 cm of soil (1 kg of biochar for a 1m x 1m plot). After harvest, they are asked to separate leaves, stems, and roots and weigh them to allow the project team to determine the plant’s net primary productivity and how biochar affects allocation of plant biomass to different components. Results will be drawn from all over Great Britain and are set to be published later this year.

One of the project leaders is Dr. Cécile Girardin of Oxford Biochar Ltd. Oxford Biochar Ltd is a non-profit organization that aims to promote the sustainable deployment of biochar. Girardin is an ecosystems scientist who focuses on carbon cycling in tropical forest ecosystems. Her work includes a strong focus on above and below ground carbon dynamics and provides important insights on the highly fertile Amazonian soils. Girardin said, “The benefits of biochar on plant productivity have been frequently documented on relatively infertile soils of the southern hemisphere. We would like to investigate the potential for biochar on more fertile soils of Great Britain. Once we have the preliminary results from this first round of data gathering (over 250 sampling points so far), we would like to focus the research on specific plant species and eco-physiological responses.”

Initial Participant Feedback
The project’s preliminary results indicate a significant improvement in yield, root production, and leaf color for radishes, garlic, onions, lettuces and pak choi/bok choy. The pak choi/bok choy seedlings (see photo) were grown from seeds by participant Chris Goodall, author of the blog Carbon Commentary (Guardian Environment Network). Goodall said, “I planted pak choi seeds in 20 small pots with your biochar (10% by weight) and New Horizon compost. It is probably not clear from the photographs but the difference to the naked eye is very substantial indeed. The germination rate was higher in the biochar pots compared to the control and the average size of the biochar seedlings is much greater. The biochar seedlings often had main roots 40 cm long, while the normal seedlings’ roots did not extend out of the pots. The leaf color of the biochar seedlings looks much better. Overall, the difference is really striking and I will always plant in biochar enriched soil in the future.”

So far, no participant has reported a negative or no significant change. The team is hoping to get as many reports as possible, including negative results. They do not yet have a big enough dataset to provide conclusive results and are still seeking more participants at this time. The Big Biochar Experiment still has 100 free bags of biochar to give away. For more information on the project and to participate, register at or contact Dr. Cécile Girardin. The Oxford Times recently ran an article on this project at:….

Dr. Cécile Girardin of Oxford Biochar Ltd with biochar, courtesy of Dr. Girardin.

Plot pre-planting; courtesy of Dr. Girardin.

Left: biochar pots; right control. Note the larger root mass in the biochar amended samples; courtesy of Chris Goodall.