Biochar Study Highlights Efficacy in Global Drawdown

This amazing ancient material can sequester carbon and improve soil quality.

bags of biochar

Jessica Suarez / Getty Images

Biochar could be an important solution in our fight against global warming. It is an amazing material with a long history that can sequester carbon and reduce the carbon footprint of modern food production, while also boosting yield and improving plant growth in poor soils. A recent study adds to the evidence that this material can contribute significantly to tackling our climate crisis and overhauling the agricultural industry. 

“Biochar can draw down carbon from the atmosphere into the soil and store it for hundreds to thousands of years,” lead author Stephen Joseph, visiting professor in the School of Materials Science and Engineering at UNSW Science, said. “This study also found that biochar helps build organic carbon in soil by up to 20 per cent (average 3.8 per cent) and can reduce nitrous oxide emissions from soil by 12 to 50 per cent, which increases the climate change mitigation benefits of biochar.”

What Is Biochar?

Biochar is a stable charcoal created from waste biomass. Sustainable home gardeners and small-scale food producers have long been espousing its creation and use. The processes of making and adding fertility to the charcoal produced in these ways on a small scale have been refined to minimize emissions to a remarkable degree. Growers on many small farms and gardens around the world have discovered the benefits of using biochar for their crops and yields. 

Biochar is not a new idea. Pre-Columbian peoples of South America produced biochar, creating rich fertile soils called "terra preta" by European settlers. And biochar has also long been used in crop production by indigenous peoples in Africa, Australia, and elsewhere. 

Biochar is a material that can be created in a range of rudimentary ways by home gardeners and growers. It can be created in a pit in the ground, in a clay charcoal oven, or in a DIY furnace, and is made by heating organic materials such as wood chips, animal manures, sludges, green wastes, and compost in an oxygen-starved environment through a process called pyrolysis. 

It is in larger industrial-scale production, however, that biochar has the most potential to help us really tackle the climate crisis. A 2008 paper highlighted how biochar pyrolyzation not only produces valuable biochar but also generates bio-oil and syngas, which could provide the energy needs of the pyrolyzer.

biochar in a farmer's hand
Jeff Hutchens / Getty Images

Biochar Benefits

A new study from the University of New South Wales, Sydney, and published in the journal GCB Bioenergy, adds to the findings of the IPCC's recent Special Report on Climate Change and Land, which estimated that biochar has significant mitigation potential. The IPCC found that biochar could mitigate between 300 million to 660 million tonnes of carbon dioxide per year by 2050. 

This recent meta-analysis, a synthesis of 20 years of research, has found that biochars can remain in the soil for thousands of years. They increase phosphorus availability in soils by 4.6 times, decrease plant tissue concentrations of heavy metals by 17-39%, build soil organic carbon by 3.8%, and reduce greenhouse gas emissions by 12-50%. 

Furthermore, the study found that crop yield upon application of biochar could increase by 10-42%, with the greatest increases in the low-nutrient acidic soils of the tropics, and dryland sandy soils. 

The conclusions drawn demonstrate how, when used wisely, biochars mitigate climate change and support food security and the circular economy. 

This study also details for the first time how biochar improves the root zone of a plant. During the first three weeks, as biochar reacts with the soil, it stimulates seed germination and seedling growth. Over the next six months, reactive surfaces form on biochar particles, improving nutrient supply to plants. Over the subsequent three to six months, the biochar ages and forms micro-aggregates in the soil that protect organic matter from decomposition. 

Biochar is already being used around the globe on various smaller-scale projects and even on a larger scale in some regions. But commercializing and upscaling biochar production could be an important part of the transition to a more sustainable way of life and in tackling the existential threats we face. Biochar needs to be produced on a much larger scale and needs to be readily integrated with existing farming operations and demonstrated to be economically viable. 

The global biochar market accounted for US$1.5 billion in 2019 and is expected to reach US$3.7 billion by 2026. But we need to produce more biochar—and use it wisely—to take advantage of all the benefits outlined in this fascinating study. Governments and authorities need to step up and take note of this useful negative emissions technology.

View Article Sources
  1. Joseph, Stephen, et al. "How Biochar Works, and When it Doesn't: A Review of Mechanisms Controlling Soil and Plant Responses to Biochar." GCB Bioenergy, 2021, doi:10.1111/gcbb.12885

  2. Laird, David A. "The Charcoal Vision: A Win–Win–Win Scenario for Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, While Improving Soil and Water Quality." Agronomy Journal, vol. 100, no. 1, 2008, p. 178., doi:10.2134/agrojnl2007.0161

  3. "Climate Change and Land." Intergovernmental Panel on Climate Change, 2021.