Frequently Asked Questions about Biochar

1. What is biochar?
2. What can biochar do?
3. How is biochar produced?
4. How do we know that biochar helps increase crop yields?
5. How can biochar help farmers?
6. How does biochar affect soil biology?
7. How does biochar affect soil properties like pH and CEC?
8. Can you add biochar to alkaline soils?
9. How long does biochar last in the soil?
10. How much CO₂ can biochar potentially remove from the atmosphere?
11. How does biochar work to reduce emissions of greenhouse gases other than CO₂?
12. Is biochar production sustainable?
13. Does IBI advocate adding carbon derived from coal, old tires or municipal solid waste to soils?
14. Could biochar impact climate through changes in soil albedo?
15. Could black dust from biochar have an impact on climate?
16. What are the costs and benefits of producing and using biochar?
17. Can biochar be patented?
18. Does the rise or fall of the biochar industry depend on comprehensive international agreements on climate change?
19. Can IBI provide more information on purchasing biochar?
20. How can I find help using biochar for my crops and the soils in my specific location?

Specific FAQs from the IBI Extension Directors

1. I live in a rural area in and want to make biochar to sell to local farmers. What type of biochar production equipment should I buy? Where do I buy it? How much does it cost?
2. At the recent sustainable ag conference in Black Mountain, at the workshop on  biochar, I heard people say that only activated charcoal would be beneficial  to soils. Can one produce activated charcoal with simple oil barrel burns?  Does 'ordinary' charcoal production produce activated charcoal - are the  temperatures high enough? Or does one have to use steam treatment on the  charcoal to 'activate' it? If so, how?
3. From my reading it appears that the biological component of "loaded" biochar is almost as important for utilization by plants as the qualities of the char. I am planning on harvesting wood vinegar while making char and using it and/or composted manure to "charge" the charcoal. Do you have recommendations or sources of information I might consult to decide what fungi might be good to inoculate it with before use?
4. I've heard that adding biochar "straight up" to soil initially robs the soil of nutrients as they are absorbed by the biochar. The recommendation was made to mix the biochar first with compost. Do you concur? If so, at what ratio?
5. I am interested in techniques for applying biochar in perennial pasture regimes. Is it feasible to grind biochar into fine enough particles that it could be applied at the same time as subsoil cultivation (i.e. keyline plowing)? Or you do have other recommendations for incorporation into the soil? And how much biochar does it make sense to add to a pasture?
6. Where can I get my biochar tested and analyzed?

1. What is biochar?

Biochar is the carbon (C) rich product when biomass, such as wood, manure or leaves, is heated with little or no available air. In more technical terms, biochar is produced by thermal decomposition of organic material under limited supply of oxygen (O₂), and at relatively low temperatures (<700°C). This process often mirrors the production of charcoal, which is perhaps the most ancient industrial technology developed by humankind. However, it distinguishes itself from charcoal and similar materials by the fact that biochar is produced with the intent to be applied to soil as a means to improve soil health, to filter and retain nutrients from percolating soil water, and to provide carbon storage.

See Chapter 1: Biochar for Environmental Management – an Introduction, Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

2. What can biochar do?

Sustainable biochar is a powerfully simple tool that can 1) fight global warming; 2) produce a soil enhancer that holds carbon and makes soil more fertile; 3) reduce agricultural waste; and 4) produce clean, renewable energy. In some biochar systems all four objectives can be met, while in others a combination of two or more objectives will be obtained.

See Chapter 1: Biochar for Environmental Management – an Introduction, Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

3. How is biochar produced?

Biochar can be made in many different ways, primarily using one of three dominant processes of thermal decomposition: pyrolysis, gasification and hydrothermal carbonization. Energy products in the form of gas or oil are produced along with the biochar. These energy products may be recoverable for another use, or may simply be burned and released as heat. In addition, biochar can be made from a wide variety of biomass feedstocks. As a result, very different biochar systems emerge on different scales. These systems may use production technologies that do or do not produce recoverable energy as well as biochar, and range from small household units to large bioenergy power plants.

See Chapter 8: Biochar Production Technology and Chapter 9: Biochar Systems, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

4. How do we know that biochar helps increase crop yields?

There is a large body of peer-reviewed literature quantifying and describing the crop yield benefits of biochar-amended soil. Field trials using biochar have been conducted in the tropics over the past several years. All showed positive results on yields when biochar was applied to field soils and nutrients were managed appropriately. Large scale field trials have recently begun on highly fertile Iowa Mollisols by the US Department of Agriculture’s Agricultural Research Service (USDA-ARS).  First year results are positive, yet it will take several years before definitive results are available (Laird, D., 2009)

There is also evidence from thousands of years of traditional use of charcoal in soils. The most well-know example is the fertile Terra Preta soils in Brazil, but Japan also has a long tradition of using charcoal in soil, a tradition that is being revived and has been exported over the past 20 years to countries such as Costa Rica. The Brazilian and Japanese traditions together provide long-term evidence of positive biochar impact on soils. 

While the larger questions concerning overall biochar benefits to soils and climate have been answered in the affirmative, significant questions remain, including the need for a better understanding of some of the details of biochar production and characterization. Work is ongoing to develop methods for matching different types of biochar to soils for the best results. IBI is working with private and public researchers around the world to develop protocols to answer these questions.

For more information see IBI’s research summary: Soil Improvement from Application of Biochar

5. How can biochar help farmers?

Biochar provides a unique opportunity to improve soil fertility for the long term using locally available materials. Used alone, compost, manure or agrochemicals must be added at the same rate every year in order to realize benefits. Application rates can be reduced when nutrients are combined with biochar. Biochar remains in the soil, and single applications provide benefits over many years. Farmers can also receive an energy yield when converting organic residues into biochar by capturing energy given off in the biochar production process. In both industrialized and developing countries, soil loss and degradation is occurring at unprecedented rates, with profound consequences for soil ecosystem properties. In many regions, loss in soil productivity occurs despite intensive use of agrochemicals, concurrent with adverse environmental impacts on soil and water resources. Biochar can play a major role in expanding options for sustainable soil management by improving upon existing best management practices, not only to improve soil productivity but also to decrease nutrient loss through leaching by percolating water.

See Chapter 1: Biochar for Environmental Management – an Introduction, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

6. How does biochar affect soil biology?

Decades of research in Japan and recent studies in the U.S. have shown that biochar stimulates the activity of a variety of agriculturally important soil microorganisms, and can greatly affect the microbiological properties of soils. The pores in biochar provide a suitable habitat for many microorganisms by protecting them from predation and drying while providing many of their diverse carbon (C), energy and mineral nutrient needs. With the interest in using biochar for promoting soil fertility, many scientific studies are being conducted to better understand how this affects the physical and chemical properties of soil and its suitability as a microbial habitat. Since soil organisms provide a myriad of ecosystem services, understanding how adding biochar to soil may affect soil ecology is critical for assuring that soil quality and the integrity of the soil subsystem are maintained.

See Chapter 6: Characteristics of Biochar: Biological Properties, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

7. How does biochar affect soil properties like pH and CEC?

In most agricultural situations worldwide, soil pH (a measure of acidity) is low (low pH means acid soil) and needs to be increased. Biochar retains nutrients in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil (as does organic matter in general). Not only the pH of biochar but also the amount and nature of the ash it contains can have an effect on pH after soil application. In fact, ash added along with biochar can react in soil similarly to agricultural lime. Not all biochar materials have a high pH; it is also possible to control the pH of biochar by controlling the pyrolysis process. However, other desirable properties of the material such as surface area and CEC become greater as the temperature of the process (and the pH) increase.

CEC stands for Cation Exchange Capacity, and is one of many factors involved in soil fertility. “Cations” are positively charged ions, in this case we refer specifically to plant nutrients such as calcium (Ca²⁺), potassium (K⁺), magnesium (Mg²⁺) and others. These simple forms are those in which plants take the nutrients up through their roots. Organic matter and some clays in soil hold on to these positively charged nutrients because they have negatively charged sites on their surfaces, and opposite charges attract. The soil can then “exchange” these nutrients with plant roots. If a soil has a low cation exchange capacity, it is not able to retain such nutrients well, and the nutrients are often washed out with water. Biochar develops negative charges on the large surface area contained in its pores, and thus, when added to soil, provides more negatively charged sites for cations to be retained on and exchanged from.

See Chapter 14: Biochar effects on soil nutrient transformations; Chapter 15: Biochar effects on nutrient leaching; and Chapter 16: Biochar and Sorption of Organic Compounds, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

8. Can you add biochar to alkaline soils?

Most biochar trials have been done on acidic soils, where biochars with a high pH (e.g. 6 – 10) were used. One study that compared the effect of adding biochar to an acidic and an alkaline soil found greater benefits on crop growth in the acidic soil, while benefits on the alkaline soil were minor. In another study, adding biochar to soil caused increases in pH which had a detrimental effect on yields, because of micronutrient deficiencies which occur at high pH (>6). Care must be taken when adding any material with a liming capacity to alkaline soils; however, it is possible to produce biochar that has little or no liming capacity that is suitable for alkaline soils.

See Chapter 5 Biochar: Nutrient Properties and Their Enhancement, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

9. How long does biochar last in the soil?

The stability of biochar is of fundamental importance in determining the environmental benefits of biochar. There are two reasons why stability is important: first, stability determines how long carbon (C) applied to soil as biochar will remain sequestered in soil and contribute to the mitigation of climate change; and secondly, stability will determine how long biochar can provide benefits to soil and water quality. Biochar is not a single material, and its characteristics vary depending upon what it is made from and how it is made. Most biochars have a small labile (easily decomposed) fraction in addition to a much larger stable fraction. Scientists have shown that the mean residence time of this stable fraction is estimated to range from several hundred to a few thousand years. Generally, in temperate regions, organic matter decomposes more slowly than in the tropics, so we would expect longer residence times there.

For more information see IBI’s research summary: Biochar Recalcitrance in Soil

See Chapter 11: Stability of Biochar in Soil, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

10. How much CO₂ can biochar potentially remove from the atmosphere?

The IBI promotes the use of waste biomass for the production of biochar. Large amounts of agricultural residues, municipal green waste and forestry biomass are currently burned or left to decompose and release CO₂ and methane back into the atmosphere.

IBI has produced a preliminary analysis of several different carbon offset scenarios titled, “How Much Carbon Can Biochar Systems Offset--and When?” based on using only biomass from waste streams. Even a conservative scenario, using only 27% of the world’s crop and forestry wastes for biochar, could sequester 0.25 gigatons (Gt) of carbon a year by 2030 with biochar alone. If the energy co-product of biochar production is used to offset fossil fuel use, then the carbon offset potential of biochar more than doubles to 0.6 Gt of carbon a year by 2030.

A more optimistic scenario shows that by the year 2050, approximately 2.2 Gt of carbon could be stored or offset on an annual basis. The assumptions used that produced the high end figure are as follows:

• Assumes 80% of all crop and forestry residues (assuming current agricultural and forestry production levels) are available to be converted to biochar and energy.
• Assumes energy produced in pyrolysis was used to replace energy that would have come from coal.
• Assumes significant decreases in N₂O emissions resulting from biochar use.
• Assumes an increase in Net Primary Production accrues from use of biochar in soils.

11. How does biochar work to reduce emissions of greenhouse gases other than CO₂?

Recent studies have indicated that incorporating biochar into soil reduces nitrous oxide (N₂O) emissions and increases methane (CH₄) uptake from soil. Methane is over 20 times more effective in trapping heat in the atmosphere than CO₂, while nitrous oxide has a global warming potential that is 310 times greater than CO₂. Although the mechanisms for these reductions are not fully understood, it is likely that a combination of biotic and abiotic factors are involved, and these factors will vary according to soil type, land use, climate and the characteristics of the biochar. An improved understanding of the role of biochar in reducing non-CO₂ greenhouse gas (GHG) emissions will promote its incorporation into climate change mitigation strategies, and ultimately, its commercial availability and application.

See Chapter 13: Biochar and emissions of non-CO₂ greenhouse gases from soil, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

12. Is biochar production sustainable?

Of all the key factors that will support the fastest commercialization of the biochar industry, feedstock supply and sustainable yield issues are by far the most important, from both a broad sustainability perspective and from the financial and commercial points of view. This will require the sources of biomass selected for biochar production to be appropriate and be able to withstand a comprehensive life cycle analysis. Biochar can and should be made from waste materials. These include crop residues (both field residues and processing residues such as nut shells, fruit pits, etc), as well as yard, food and forestry wastes, and animal manures. Large amounts of agricultural, municipal and forestry biomass are currently burned or left to decompose and release CO₂ and methane back into the atmosphere. Making biochar from these materials will entail no competition for land with any other land use option.

Biochar can be a tool for improving soils and sequestering carbon in soil. However, this technology as any other must be implemented in a way that respects the land rights of indigenous people and supports the health of natural ecosystems. The goal of biochar technology as IBI envisions it is to improve soil fertility and sequester carbon, taking into consideration the full life cycle analysis of the technology. Properly implemented, biochar production and use should serve the interests of local people and protect biodiversity.

See Chapter 20: Socio-economic Assessment and Implementation of Small Scale Biochar Projects; and Chapter 21: Taking Biochar to Market: Some Essential Concepts for Commercial Success, , in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

13. Does IBI advocate adding carbon derived from coal, old tires or municipal solid waste to soils?

No. Coal is not a renewable resource. Biochar refers specifically to materials made from present-day biomass, not fossil carbon. Tires and other potentially toxic waste materials are not appropriate as sources of biochar for soil improvement.

14. Could biochar impact climate through changes in soil albedo?

After centuries of agriculture, soils globally have become depleted of carbon, compared to pre-agricultural conditions. Agricultural development goals include restoring carbon to carbon-depleted soils. Unavoidably, adding carbon to soils darkens them, changing their albedo (a measure of sunlight reflectance). Fortunately, darker, carbon-rich soils are more fertile and will be more easily re-vegetated. Vegetation has a lighter albedo, so the albedo problem is very temporary in nature and is not a significant issue.

15. Could black dust from biochar have an impact on climate?

Small particles of black carbon are produced from the incomplete combustion of fossil and biomass fuels. When deposited on snow and ice, they are able to absorb heat and energy. The smallest black carbon particles associated with biochar production and application are much larger, in the millimeter range, than the particles associated with global warming, in the nanometer range. Thus application of biochar would result in little opportunity for long-range transport and deposition into the sensitive Arctic and mountain regions.

Dust is a certainly a concern with biochar application, but best practices require that biochar applications be done during periods of low wind to prevent the blowing of fines. Agricultural techniques already exist to apply powdered fertilizers and other amendments. Several techniques are available to help keep wind losses to a minimum: biochar can be pelleted, prilled, mixed into a slurry with water or other liquids, mixed with manure and/or compost, or banded in rows. The optimization of biochar application to soil is important, and the farm technology and methods are available to do the job.

16. What are the costs and benefits of producing and using biochar?

The benefits that potentially flow from biochar production and use include waste reduction, energy co-production, improved soil fertility and structure, and climate change mitigation. Not all of these benefits are accounted for under current economic systems, but under the carbon constrained economies of the future, the climate mitigation benefit is likely to be accounted for as an economic benefit. Biochar benefits are partly offset by the costs of production, mainly hauling and processing feedstocks. Profitability of biochar systems will be especially sensitive to prices for energy and for greenhouse gas reductions and offsets.

We do not have good data on the cost of various biochar production systems, because most of these are in development or are purely experimental. One of IBI’s principal objectives is to improve our understanding of the cost of producing biochar from various feedstocks.

See Chapter 19: Economics of Biochar Production, Utilisation and Emissions, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

17. Can biochar be patented?

While some biochar producers may be able to patent a specific biochar production process or method, there exist a number of open-source, low-cost, clean technologies that can make biochar at the home or village level, and more are being developed.

18. Does the rise or fall of the biochar industry depend on comprehensive international agreements on climate change?

Biochar offers direct, present day benefits to farmers of all sizes in the form of greater crop productivity, and efforts are underway to promote widespread testing of biochar in many different types of soils. Financial instruments that would lead to direct benefits for farmers in the form of carbon trading, for example, would certainly provide more incentives for biochar technology adoption. This has been and is being promoted by IBI at a number of UN events through the UN Framework Convention on Climate Change (UNFCCC). 

19. Can IBI provide more information on purchasing biochar?

The IBI receives frequent requests from gardeners, farmers and landscapers for information on reliable sources of biochar.  At this time, IBI is unable to make these recommendations, primarily for two reasons:

• There is not a system for classifying biochars in terms of their suitability for use in specific agricultural applications; and
• There is not a system for certifying sustainable biochar production systems or producers of biochar.

In other words, we are unable to say without specific evaluation whether a certain biochar will perform the soil improvement or carbon sequestration that a user anticipates, or whether it has been produced in a sustainable manner under full life cycle accounting. Developing these systems is a key priority for IBI, but until they are in place, along with the necessary data to back them up, we cannot responsibly make recommendations. Given the extremely promising research on the benefits of biochar, this is frustrating to us all, but we believe patience and due diligence are advisable, rather than haste.

20. How can I find help using biochar for my crops and the soils in my specific location?

A good place is the IBI’s Extension service. Since testing biochar in soils is just beginning in many climates and soil types, you will initially be an experimenter yourself! Any data you produce and share widely will be welcome. IBI has a field trial registry that you are welcome to join.

Extension Director Questions

1.  I live in a rural area in and want to make biochar to sell to local farmers. What type of biochar production equipment should I buy? Where do I buy it? How much does it cost?

The biochar production (pyrolysis) equipment chosen for a particular project will depend on project specific requirements such as: the feedstock (biomass) and its characteristics (size, moisture content, etc); the amount of feedstock available to convert to biochar and its source; the amount/hr of feedstock to be processed based on amount of feedstock available and plant downtime; and specific environmental conditions (eg high humidity, rainfall, etc) which may affect the materials chosen to manufacture the plant.

IBI is not a supplier of technologies so is therefore not able to provide a quotation or recommend a particular technology or supplier. However there are many technologies available, with different units being suitable for different requirements of throughput, feedstock properties, budget, etc. It is a good idea to spend some time becoming familiar with available technologies to see what best suits your needs.

The following websites provide a very good starting point to gather this information.

The International Biochar Initiative Member Directory: Go to the home page: http://biochar-international.org/; click on ‘Member Directory’ under ‘IBI Member Services’ on left of page; search according to your needs (in this case it may be appropriate to search by ‘Project Type’ and choose ‘District/farm scale’).

The following website provides a list of biochar producers:
http://terrapreta.bioenergylists.org/company

The Biochar Production group is also a good place to join the discussions on biochar production.
http://tech.groups.yahoo.com/group/biochar-production/

If you are able to provide us with further information on your project, as outlined above, we are better able to direct you to technologies we are aware of that may suit your needs.

2.  At the recent sustainable ag conference in Black Mountain, at the workshop on  biochar, I heard people say that only activated charcoal would be beneficial  to soils. Can one produce activated charcoal with simple oil barrel burns?  Does 'ordinary' charcoal production produce activated charcoal - are the  temperatures high enough? Or does one have to use steam treatment on the  charcoal to 'activate' it? If so, how?

The fact is that activated charcoal and biochar are quite different, and research shows that biochar is beneficial in soils. Activated charcoal is basically biochar that has been activated, by submitting it to exposure to steam or some chemicals, for example. But again, whenever you see the word "biochar" on IBI's website or in serious literature, what is referred to is NOT actiavted charcoal. I think that, due to the extra step required to "activate" biochar, activated charcoal would likely not be economical to use as a soil amendement.

Having said this, biochar straight out of the pyrolysis unit might take some time to reach its full potential in soil, because it needs it's surfaces to "open up", or "weather". This happens naturally in soil, but the process can be sped up by mixing biochar with compost, for example. Keep in mind that this is not the same as actual "activation", the industrial processes that create "activated charcoal".

3.  From my reading it appears that the biological component of "loaded" biochar is almost as important for utilization by plants as the qualities of the char. I am planning on harvesting wood vinegar while making char and using it and/or composted manure to "charge" the charcoal. Do you have recommendations or sources of information I might consult to decide what fungi might be good to inoculate it with before use?

That is a good question. It is likely that biochar effects on microbes in the soil is important for providing benefits for crop growth, however very little work has been reported on this. The scientific literature that I am aware of concerns only mycorrhyizal fungi and nitrogen-fixing symbiotic bacteria. One study so far looked at biochar effects on N-fixation, and found it was better with biochar presumably due to greater availability of some micronutrients. For mycorrhizae, several Japanese studies reported better inoculation root with biochar, and increases in pH might be responsible for this. Another pot study made with less acidic soil showed varying effects of biochar on mycorrhyizae activity. As you can see, people have observed effects of biochar on beneficial biotic factors of soil, but it seems that what the biochar actually changes are abiotic soil factors (e.g. micronutrient availability, pH). Changes in these abiotic factors in turn provide advantages to biotic factors. In a chapter of the book "Biochar for Environmental Management: Science and Technology", Thies and Rillig suggest several mechanisms by which biochar could directly benefit microbes, such as by providing surfaces for colonization that predators cannot access. Here, inoculation would help, but the properties of the actual biochar material (i.e. surface area and porosity) would be key.

I'm not familiar with the composition of wood vinegar, but my sense is that it might function as an energy sources for soil biota (and that can be good and bad, since it can lead to N immobilization). Compost is a good idea for mixing with biochar. It is generally understood that biochar improves plant nutrition more after its surfaces have "weathered", or become more reactive in the soil. Time will make that happen, but mixing with compost can accelerate the process, on top of providing nutrients which the biochar lacks but can help retain against losses.

Since little information is available to date on biochar formulations with other ingredients (although many people are experimenting), I encourage you to try out several options and grow plants in your formulations. As for the scientific understanding, lots remains to be determined, but as I say above, what has been demonstrated are biochar effects of the availability of nutrients and pH. I attach our field trial guide which you might find helpful in testing biochar and biochar formulations.

4.  I've heard that adding biochar "straight up" to soil initially robs the soil of nutrients as they are absorbed by the biochar. The recommendation was made to mix the biochar first with compost. Do you concur? If so, at what ratio?

The initial part of your question is not entirely accurate. Biochar tends to hold on to nutrients, and likely helps to reduce their loss by leaching, for example. So, the nutrients remain available for plants to use. Furthermore, many biochar materials also contain ash, which can serve as a fertilizer in itself. I don't think that the concern you mention above is justified. One exception might be for nitrogen. If the biochar contains lots of volatile carbon compounds (and a good biochar for soil application would not, but no standards have been developed yet), you might get N limitations early on, but this effect would not be long-lived. Actually, nutrient retention with biochar is thought to improve with time, along with crop benefits. Mixing biochar with compost is a great idea, since apart from the ash (and there might only be small amounts of it in biochar), biochar is not a fertilizer in itself so the compost can provide nutrients which the biochar can help retain. You'd have to do some testing to establish the optimal ratios in your situation. 

5.  I am interested in techniques for applying biochar in perennial pasture regimes. Is it feasible to grind biochar into fine enough particles that it could be applied at the same time as subsoil cultivation (i.e. keyline plowing)? Or you do have other recommendations for incorporation into the soil? And how much biochar does it make sense to add to a pasture?

You can definitely grind biochar up very fine (and some commercial biochar products are very fine). I have heard of folks using deep banding and pressure injection systems. Biochar can be mixed with liquid manures also for incorporation by these techniques....folks all over are experimenting with this, but not many reports are out yet. In terms of amounts, I have not seen any data for pasture applications of biochar. You might find that actual application techniques (not to mention obtaining biochar) limit how much you can put on initially. But upper limits have not been really established, and these would in any case be specific to your soil and cropping system. Bottom line: we need your data!

6.  Where can I get my biochar tested and analyzed?

Today, no standard tests for biochar exist, nor are there standards to determine the desired properties of a biochar for use in a specific soil type. Some basic characteristics of biochar can be obtained by analyzing it as soil (e.g. available nutrients, pH, CEC, total carbon, total nitrogen contents). This testing can be done at any soil testing lab, and some labs offer proximate analyses (fixed carbon, volatile carbon, ash content) that were developed for analyzing fuel charcoal. Remember, however, that at this time only testing biochar under specific soil conditions will provide information as to its usefulness in the field. Some quick tests can and should be carried out before experimenting with crops; see Box 1 in IBI’s “Guide to Conducting Biochar Trials”.