If you are looking to update your farming practices, improve your soil, and preserve your margins, chances are you have heard of biochar. While it is not a recent discovery, some people are touting it as almost a miracle product. Its champions claim that it raises soil health, improves crop yields, offsets carbon emissions, and even improves the health of ruminants. But do the claims stack up? Sustainability Consultant Lucy Ross investigates the pros and cons.
What is biochar?
Biochar is produced through a process called pyrolysis, where organic matter (wood, plants, even manure) is burned in the absence of oxygen.
Typically, the oxygen-limited heating process takes place at temperatures between 300-700°C. The process creates a stable, carbon-rich material with a porous structure that resembles charcoal. This char is highly porous, with a surface area of approximately half a kilometre (550yds) per gram. This structure lends itself to the absorption of water, air, and small molecules, while providing a home for a variety of microbes.
Here’s a layman’s terms explainer video, from a small-scale farmer in the US, who shares his experiences.
What does biochar do?
Exponents of biochar claim that the product improves a farm’s soil in the short term, and that its effect continues for the long term.
It is claimed that biochar:
- Improves water retention – Biochar’s porous structure acts like a sponge, soaking up extra water during heavy rains and releasing it slowly during dry periods. This helps keep your crops hydrated and reduces the risk of drought stress.
- Acts as a nutrient magnet – Biochar’s surface is like a sticky pad, attracting and holding onto essential nutrients for your plants. This reduces nutrient leaching (washing away) and keeps them readily available for your crops.
- Is a haven for microbes – Biochar provides a home for beneficial soil microbes, the tiny organisms that break down organic matter and make nutrients even more accessible for plants. This thriving microbial community promotes overall soil health.
- Improves soil structure – Biochar helps bind soil particles together, creating a more stable structure. This leads to better drainage, aeration, and overall soil health.
One of biochar’s great benefits is that it remains in the soil, permanently stabilising its structure and microbiome, and continuing to serve as a nutrient reservoir, as observed in studies conducted on terra preta soils in the Amazon Basin.
It appears that as biochar ages in the soil, the rhizosphere develops in both complexity and stability, becoming more resilient to environmental fluctuations over time. However, this does rely on the presence of live roots to nurture the soil microbiome. - Promotes increased yields – With improved water retention, nutrient availability, and a thriving microbial community, biochar can potentially lead to increased crop yields and overall farm productivity.
In 2010, a three-year study in Quebec concluded that biochar improved forage plant biomass quantity and quality and this led to higher projected milk production. Notably, the study also recommended further research.
Biochar trials have given encouraging results
In trials, biochar appears to help reduce greenhouse gas emissions from crop production, and boosts yields. In fact, in a study reported by Nature Food, integrating biochar into crop production boosted crop yields by over 8%, while improving the environmental markers including carbon emissions, soil improvement, and fossil-fuel use.
Furthermore, using biochar as a livestock feed additive, in conjunction with solutions such as anaerobic digestion and other production efficiencies, could be successful for livestock producers.
Other enhancement approaches – including bokashi – may have a place, too, and could stand alongside biochar. The two processes offer different benefits to soil health that may be complimentary. Bokashi is more suitable for improving soil fertility and managing organic waste, while biochar is better for improving soil structure, water retention, and carbon sequestration. The choice between the two depends on specific soil needs and the goals of the user. (There is more about bokashi below.)
The challenge for biochar is that it is not a cheap or one-size-fits-all product. It can be made of many different plant materials, and pyrolyzed at lower or higher temperatures, all with different results. A type of biochar that is great for a specific soil, or a specific crop, may be little benefit to another. In general, biochar is better for poor, nutrient-depleted or acidic soils than healthy ones.
Biochar Explainer – Massachusetts Institute of Technology Climate Portal
Biochar and ruminants
Proponents of biochar claim that it is beneficial for ruminants, such as cows, sheep, and goats. Trials report that adding biochar to feed reduces gas production from the rumen, promotes animal growth, increases milk yield and quality, and produces a more stable, less emissions-laden manure, which composts more quickly.
This suggests that biochar has a place, and that it could be used alongside other additives that reduce methane production (such as 3-NOP and slurry inoculants).
As biochar’s stable nature unaffected by animal digestion, it may also result in a biochar-supercharged manure with additional soil health properties. Additionally, cattle often actively select biochar, leading many to suspect that it the animals may be using it for medicinal uses.
However, it’s important to note that this remains a “good idea”, as reported in a study published in the Journal of Experimental Biology and Agricultural Sciences. The study is optimistic though, stating “…animal farmers are predicted to make greater use of biochar in the future.”
In short, more research is needed.
Biochar is attracting high-profile interest – and investment
According to a BBC Future article from 2021 entitled The regenerative revolution in food, “carbon farming promises a bold new agricultural business model – one that tackles climate change, creates jobs and saves farms that might otherwise be unprofitable.”
The technology certainly has a place in marginal farming land, and in places where substantial amounts of fast-growing forestry can be available for a grow-harvest-bury-grow cycle. However, that is a specific set of a circumstances – which may not be viable in UK settings.
Biochar is certainly luring investors. According to a recent analysis by Reuters, biomass carbon removal and storage (BiCRS) technologies are reckoned to have the potential to remove 5.5 gigatons of CO2 per year, globally. Biochar is the most mature of these technologies, accounting for over 90% of carbon credits and recognized by the Intergovernmental Panel on Climate Change (IPCC) for its carbon sequestration potential.
Biochar and carbon trading
So, as part of a carbon-trading model, biochar may become a lucrative technology. It depends on whether carbon sequestration and carbon trading become part of the mainstream mix of future farming.
For this to happen, a robust and standardised verification, measurement and monitoring processes will have to emerge. Without it, the market of carbon sequestration will be unworkable. The potential is there, but the technology and its management needs to mature, in a stable, nurturing environment.
And while proponents are optimistic about its future, scepticism remains due to the current lack of robust monitoring, reporting, and verification. The credibility and effectiveness of these markets depend on the ability to accurately verify and trade carbon credits.
Could biochar hinder emissions reduction?
Some studies point to a mitigation deterrence threat, an effect by which biochar’s hoped-for benefits create a complacency or a distraction, where carbon markets reduce the urgency for real emissions reduction.
While farming practices can help reduce pollution, they are not the only way to achieve decarbonization and should not allow other industries to avoid making changes.
The farming industry will need to make its voice heard, so that even-handed policy emerges which allows farming to flourish as it adopts productive and profitable methods that enhance carbon reduction. Forcing the farming sector to pursue carbon reduction on its own will not work. A holistic agri-industrial strategy is required.
What are the drawbacks of biochar?
Despite its promise, questions remain about biochar’s viability. At present, there are economic and technical drawbacks that must be overcome.
Expensive to buy
The cost of production versus selling price is a critical limitation, potentially restricting its widespread adoption. Furthermore, producing biochar on a larger agricultural scale requires substantial infrastructure investments.
However, there are companies who are seeking to rectify this, such as start-up company Capchar, as reported by Farmers Weekly. Capchar is working with the Royal Agricultural University to develop 2m3 kilns for use on farms, which it will provide on monthly subscription basis, along with carbon credit verification. This will mitigate the cost of investment for farmers, who would be reap the multiple productive benefits of biochar use.
For those looking to purchase the product, as biochar achieves scale then the wholesale price will fall.
Biochar application needs to be managed
Under heavy rainfall, biochar has washed off into watercourses, leading to potential pollution. Additionally, wind erosion has dispersed biochar dust, causing soil degradation. Producers argue that this dust can be reduced by careful production.
Meanwhile, run-off and wind-loss can be reduced or eliminated by tilling. However, this may make the process of including biochar less convenient and feasible for some farmers.
Quality control is important
Furthermore, as a Chinese study revealed, toxins can be produced during pyrolosis, which may affect crop growth, animal health, and even human health. So, the qualities of the materials that become biochar, and the process itself, is of vital importance.
Long-term effectiveness remains unproven
There is still a lack of comprehensive evidence on the long-term effectiveness of biochar on an agricultural scale. While studies suggest biochar’s potential benefits, more research is necessary to confirm these claims and understand its full impact in various agricultural settings.
More studies are necessary to assess these concerns.
Unknown negatives suspected
The potential for biochar to bring hitherto unknown negative effects remain. For example, it may be that the technology could result in reduced efficacy of soil-applied pesticides and herbicides, which could impact crop protection and waste resources and money.
Once proven, policymakers will have to adopt biochar
Biochar’s carbon capture and sequestration capabilities are increasingly interesting policymakers, who see it as crucial for the circular economy. They are also acknowledging its potential for enhancing farm production.
However, until more conclusive evidence is available, the broader adoption of biochar may remain limited, despite its promising potential.
Biochar vs. bokashi
People often mention biochar and bokashi together as soil amendments. If you’d like to find out more about bokashi, and how it compares to biochar, follow this drop-down guide.
-
What's bokashi?
Bokashi is a fermented organic material that can be used as a soil amendment. It is created through a process of anaerobic fermentation, which involves preserving organic waste in a controlled environment.
-
Bokashi – production, uses, drawbacks, comparison with biochar
Bokashi production process
- Organic waste such as food scraps, yard trimmings, and lesser amounts of animal manure are collected.
- The collected waste is mixed with a proprietary microbial inoculant, often made from beneficial bacteria and fungi.
- The mixture is placed in a container and covered to create an anaerobic environment. The microbes break down the organic matter, producing a fermented material that has a slightly acidic odor.
Bokashi’s proven uses
- Soil Amendment – Bokashi can be added to soil to improve its structure, nutrient content, and water retention.
- Compost Accelerator – It can speed up the composting process by providing beneficial microorganisms.
- Odour Control – Bokashi helps to reduce unpleasant odours associated with organic waste.
- Pest and Disease Management – The acidic environment created by bokashi can help to suppress pests and diseases in plants.
Bokashi is a sustainable and environmentally friendly way to manage organic waste while producing a valuable soil amendment.
Bokashi drawbacks
- Initial Investment – Setting up a bokashi system may require an initial investment for containers, inoculant, and other materials.
- Odour Control – While bokashi can help reduce odours, it may still produce a strong smell during the fermentation process, especially if not managed properly.
- Maintenance – Bokashi requires regular maintenance, including turning the mixture to ensure proper fermentation and preventing mold growth.
- Limited Use Cases – Bokashi is primarily suitable for small-scale organic waste management. It may not be practical for large-scale operations or industrial waste.
- Nutrient Limitations – While bokashi can improve soil fertility, it may not provide all the necessary nutrients for certain plants, especially those with high nutrient demands.
- Potential Pathogen Concerns – If not handled properly, bokashi can harbor pathogens from the organic waste, which could pose a risk to plants or humans.
Despite these drawbacks, bokashi remains a valuable tool for sustainable waste management and soil improvement, especially for individuals and small-scale operations. Innovative farmers, including Greg and Rowan Pickstock, are using it.
Key differences – bokashi vs. biochar
- Production – Bokashi is produced through fermentation, while biochar is produced through pyrolysis.
- Nutrient Content – Bokashi provides nutrients from the organic matter, while biochar primarily improves soil physical properties.
- Carbon Sequestration – Biochar is known for its ability to sequester carbon, while bokashi’s carbon sequestration potential is limited.
In summary, bokashi and biochar offer different benefits for soil health. Bokashi is more suitable for improving soil fertility and managing organic waste, while biochar is better for improving soil structure, water retention, and carbon sequestration. The choice between the two depends on specific soil needs and the goals of the user.
Combining biochar with other soil additives
Biochar slurry
Combining biochar and slurry can potentially increase organic carbon sequestration in agricultural soil by promoting aggregate formation. However, soil moisture conditions influence this effect. While biochar alone does not significantly improve aggregate formation, its combination with slurry can enhance it. However, this effect might be less pronounced in soils that experience frequent drying and wetting cycles.
Biochar compost
Biochar-compost is a promising method for improving problem soils. It can help mitigate various issues, including high mineralization rates, phosphorus deficiency, aluminium toxicity, and soil contamination with heavy metals or organic pollutants. This combination often outperforms biochar or compost alone. While biochar-compost has shown positive results in tropical, temperate, and saline soils, its adoption remains low.
Biochar-based fertilisers
Biochar enrichment techniques can improve the nutrient content of biochar, making it a more effective soil amendment. Studies show that biochar-based fertilizers (BCFs) produced using these techniques can enhance soil properties and crop yields compared to pure biochar or other fertilizers. The post-pyrolysis method is the most common for enriching biochar. Future research should focus on the long-term effects of BCF application.
Biochar and AD
According to studies, biochar’s beneficial role as an additive in anaerobic digestion (AD) looks promising.
- Improved nutrient retention –Biochar’s porous structure appears to help retain nutrients like nitrogen and phosphorus, preventing their loss from the digester. This can enhance the overall efficiency of the AD process.
- Enhanced microbial activity – Evidence suggests that biochar can provide a suitable habitat for beneficial microorganisms involved in AD. This can lead to increased microbial activity and improved organic matter degradation.
- Buffering effect – Biochar can help to stabilise the pH of the digester, preventing fluctuations that can negatively impact AD performance.
- Reduced ammonia inhibition – Ammonia can inhibit the AD process at high concentrations. Biochar can help to adsorb ammonia, reducing its toxicity and improving overall system performance.
- Enhanced methane production – By improving microbial activity and nutrient retention, biochar can contribute to increased methane production, the primary goal of AD.
- Improved digestate quality – Biochar can enhance the quality of the digestate produced by AD, making it more suitable for use as a soil amendment or fertilizer.
Overall, biochar can be a valuable additive to AD processes, offering a range of benefits that can improve efficiency, sustainability, and product quality.
However, as a 2020 University of Edinburgh review concluded, “…systematic investigation of the correlations linking BC [biochar] physico-chemical characteristics and AD performances… is highly needed for a deep understanding of BC role as additive in AD processes.”
The importance of knowing your soil, and your goals
Essentially, choosing biochar will depend on three essential elements:
- Your farming circumstances – these will include your land type, analysis of your soil composition and condition, and the type of farming you undertake.
- Your farming goals,
- Your access to biomass.
You must make any decision about incorporating biochar into your farming practice based on scientific and economic evidence and as part of a strategic approach, not a whim or fashion.
At Promar, we are experts at helping farmers form a practical, no-nonsense understanding of their business, and a plan of action for short, medium, and long-term goals. If you would like to talk to us about this, why not contact us for an initial discussion?
Summing up…
Biochar clearly has potential to enhance soil health, increase crop yields, and contribute to carbon sequestration. However, its effectiveness depends on specific farm conditions, including soil type, crop needs, and available resources.
Farmers should approach biochar as part of a broader strategy for sustainable farming, assessing both the benefits and costs, and considering it alongside other soil amendments like bokashi. Participation in ongoing research and trials can provide valuable insights into its long-term viability on individual farms.
Checklist for farmers considering biochar
Here’s a checklist to help you make an informed decision about whether biochar could be right for your farm, that could contribute effectively to both your productivity and sustainability goals.
Assess your soil and land conditions
• Conduct a soil test to determine nutrient levels, pH, and structure.
• Identify whether your soil is poor, nutrient-depleted, or acidic, as biochar is most beneficial in these conditions.
Define your farming goals
• Determine your primary objectives (e.g., improving soil structure, enhancing water retention, increasing crop yields).
• Consider whether carbon sequestration and participation in carbon markets align with your farm’s sustainability goals.
Evaluate biochar’s economic feasibility for your business
• Analyse the cost of biochar, including production or purchase, and evaluate it with regard to your potential benefits such as increased yields, carbon credits.
• Explore partnerships or subsidies that might offset initial investments.
Consider your access to biomass
• Assess the availability of suitable organic material for biochar production, for instance wood, and crop residues).
• Determine whether you have the infrastructure or resources to produce biochar on-site, or if you will need to purchase it.
Research biochar application methods
• Identify the best method for applying biochar to your fields, for example tilling, combining with compost or slurry.
• Understand the potential risks of runoff or wind erosion and plan mitigation strategies.
Compare with other soil amendments
• Evaluate whether biochar should be used alone or in combination with other amendments like bokashi, depending on your soil’s needs.
• Understand the complementary benefits of biochar and other amendments, such as improved soil fertility and water retention.
Monitor and measure results
• Start with small-scale trials to assess the impact of biochar on your crops and soil.
• Track changes in soil health, crop yields, and greenhouse gas emissions over time.
Stay informed and engage in research
• Keep up with the latest studies and findings on biochar’s effectiveness in agriculture.
• Consider participating in research projects to contribute to and benefit from collective knowledge.
Consult experts
• Seek advice from agricultural consultants or soil scientists to tailor biochar use to your specific farm conditions.
• Use expert guidance to develop a strategic, evidence-based plan for incorporating biochar into your farming practices.
Would you like to take part in a biochar research project?
Furthermore, and despite the obvious promise of biochar, research is still needed to help farmers decide how much of a place it has in UK farming, and in general carbon-reduction policy. That is why we are looking to work with farmers on a biochar study.
If you are interested in taking part, then please call me, Lucy Ross, on 07815 978362, or email me at lucy.ross@genusplc.com. Alternatively, fill in this form:
Special thanks to Samuel Olegnowicz at Oxford Biochar for technical information and advice during the writing of this article.
About The Author
07815 978 362
lucy.ross@genusplc.com