Biochar – What’s good, not so good, and what’s not fully understood

SoilMatrix Newsletter No. 7

July, 2017

It’s mid-summer, so let’s enjoy it while it lasts.

This is how the SoilMatrix Garden looked on Thursday, July 27, 2017.

The romaine at the front corner is being consumed (by us). It is also being invaded by the zucchini (must remember not to plant so much of it next year).   Once again, this garden is receiving no chemical fertilizers, pesticides, or herbicides and as little city of Calgary water as possible. We are attempting to bring the soil health up to a level where all of these inputs are happening below ground level via our soil life food web friends.

In this newsletter we will provide a few links to research that indicates the various benefits of biochar soil amendments. I spent some time compiling these for your learning so you can read for yourself how biochar amendments make a difference to your flower and/or vegetable garden.

The concept of using biochar as a plant growth enhancing soil amendment didn’t really enter public awareness until the fall of 2008.   It was previously mostly an academic curiosity that was gaining attention in universities around the globe. Research has since expanded rapidly and today almost every university in every city has some form of biochar research taking place. Most of the papers written about biochar in these academic arenas are steeped in highly scientific language and, as such, are less accessible to the public. An exception to this is a well-researched book by Dr. Paul Taylor, which was written in 2010. A link to the book’s website is provided here:

where you will find free downloads of Chapter 1 as well as a recently written free download by Dr. Paul Taylor.

One of the co-authors of this book is a good friend and colleague of mine, Dr. Hugh McLauglin. Hugh wrote Chapter 7 “How Biochar Helps Soils”. One of the most informative compilations of the benefits, possible negatives, and unknowns of biochar in soils is referenced in this chapter:

“Biochar Application to Soils – A Critical Scientific Review of Effects on Soil Properties, Processes and Functions.” Report of the EU Joint Research Centre, Institute for Environmental Sustainability. Read more here:

To keep this Newsletter brief, I have summarized here the list of biochar’s possible benefits, disadvantages, and some unknowns that require further research:


  1. Biochar is a natural soil ingredient, which is found in soils in most parts of the world.
  2. The principle of improving soils with biochar has been tried successfully in many places over thousands of years.
  3. Plant production has been found to increase significantly after biochar additions to soils. In some cases negative effects have also been reported… see these in the “disadvantages” below.
  4. Biochar produces a “liming effect” to balance acidic soil towards a neutral pH.
  5. Biochar has an affinity for adsorbing contaminants and keeping them out of harm’s way for plants.
  6. Microbial habitat improvement and protection is offered by biochar’s presence.
  7. Moisture and nutrient retention improvements are evident as a result of biochar’s ability to both absorb moisture and adsorb nutrients and retain them longer.
  8. Increases in mycorrhizal fungi abundance is observed – these are fungi that are linked to plant productivity.
  9. Increases in earthworm abundance are observed.


  1. The use of biochar is well documented for only a few geographical locations. Much more research is needed to fully understand its benefits or disadvantages in soils around the globe.
  2. Soil loss by erosion can be an issue when top dressing biochar to soils. This occurs by wind and/or water transport of small, light biochar particles.  Proper incorporation into a soil blend is necessary.
  3. Risk of contamination of biochar exists (PAHs, heavy metals, dioxins) when contaminated feedstocks are used and/or the process conditions used to make the biochar are such that temperatures are greater than 500 C are used.
  4. Residue removal for use as a feedstock for biochar production could result in reduced incorporation of crop residues into soils and potentially lead to negative effects on soils. This would be the case if farmers were to use all of the straw produced in a field to make biochar, for example.
  5. Extremely high rates of biochar application could have negative effects on earthworm survival rates; however this would be in cases where application rates are greater than 67 kilograms per square meter of land – an impractical level of biochar application.


  1. Emperical evidence is extremely scarce (at this time) for many modern biochars in soils under modern arable management.
  2. The ability to sequester carbon in soils amended with biochar is still largely unquantified and requires further research.
  3. Biochar’s effects on the nitrogen cycle depend on many factors which have not yet been fully explored.
  4. Biochar benefits may be crop and soil dependent, which may be an issue given the irreversibility of biochar once applied to the soil.
  5. Distribution and availability of contaminants that are adsorbed by biochar (heavy metals, PAHs) require further research to assess the rate of bioavailability and toxicity of the contaminant depending on the biochar type, application rates, feedstock, production conditions, soil types, and environmental conditions.
  6. More research is needed to fully map the life cycles of biochar’s effects on soil organic matter.
  7. Issues of pore size and connectivity and the optimum particle sizes for biochar that is amended for soil enhancement still requires research.
  8. Soil water retention and availability requires further research for variations in soil type.
  9. Effects on larger soil organisms – such as contact of skin with biochar in soil for larger organisms.   This is still in the early days of research.
  10. Hydrophobicity of biochar in soils remains largely untested.
  11. Rate of decomposition of biochar as a function of agricultural management requires further research.
  12. There is a good potential that biochar can improve “Cationic Exchange Capacity” of soil – a facilitator of nutrient uptake by plants.   However, the effectiveness and duration of this effect after addition to soils remains poorly understood and requires long term experimentation.

Given these point form benefits, negatives, and unknowns, there seems to be much more in the “unknown” category, which is the reason for the huge interest in this topic at leading research institutions around the globe.   Much more will be discovered about biochar in the coming years. It could makes for an exciting career for budding agronomists, biologists, and soil scientists.

We hope to keep you informed as the results from all this research becomes available.

Thank you for your interest in this topic. We will see you again at the end of August.

Copyright ©_2017 AirTerra, All rights reserved.

Dr. David Montgomery’s Videos and Books… a must listen and read…

Welcome to our June 2017 SoilMatrix Newsletter – “Dr. David Montgomery’s Videos and Books”

It’s amazing how the summer months fly by!  This SoilMatrix Newsletter will be very short, I promise.

Here is what the SoilMatrix Garden looked like on June 29, 2017.

As you can see, we have a relatively good start with the romaine lettuce, kale, swiss chard, green and yellow beans, and peas.   The potatoes are developing very nicely in the back and the zucchini is doing well next to the romaine. All in all we are quite happy with this year’s experimental use of compost only for nutrients. This garden is receiving no chemical fertilizers, pesticides, or herbicides and as little city of Calgary water as possible. We are attempting to bring the soil health up to a level where all of these services are happening below ground level via our soil life food web friends.

In this newsletter I only will introduce to you a person who has become my favorite author — Dr. David Montgomery. Last month I told you that I had just skimmed his most recent book, “Growing a Revolution – Bringing our Soil Back to Life”. Now I have taken the time to really read it and watch a couple of videos where David gives a summary of his most recent books.

The first lecture by Dr. David Montgomery is about the soil food web specifically.   You can find it here (warning, it is just over one hour in length…)

The full book on this topic is available here:

The second lecture is about a revolution in farming and gardening methods where the use of three principle practices are regenerating farm and garden soils back to life with higher soil organic carbon content that is stimulating beneficial microbes back into making soils more highly productive and resilient to drought, pests, and disease. You can find it here (again, you will need about an hour to listen to this entire lecture…)

This book can be found here:

Given these two informative videos, the books they summarize, and the time it will take you to digest them — that is all I have to share for this month.

There will be a lot more to share as the garden progresses into producing fruit through the summer. July will probably see the most significant change in the appearance of the garden, and then August will see most of the fruit being filled and ripened… if all goes well. The raspberry bushes in our back alley are seeing their best season ever.

See you at the end of July.

Copyright ©_2017 AirTerra, All rights reserved.

A Growing Revolution – Two Great Books about Soil Life!

Welcome to our May 2017 SoilMatrix newsletter – A Growing Revolution – Two Great Books about Soil Food Web and Healthy Soil Function!

This month’s newsletter contains some valuable revelations gained from two books and two different authors who have keen insights into how to bring soils back to vibrant life and health through building into the “Soil Food Web”.  I will share these with you after I describe and show you what is happening in the SoilMatrix Garden right now!

Soil preparation and seeding are complete for this year. I went out on a limb and purchased a couple of totes of good garden soil and a tote of Hop compost to blend along with about 25% (by volume) SoilMatrix Biochar.   The additional soil was needed to expand the number of raised beds and I became impatient with attempting to do this out of my own soil stock. Here is what the seeded raised beds looked like at the end of the May long weekend (May 22, 2017).  See photo above:

There are now five (5) three foot wide beds. The wooden box at the far corner is a bee hive. A rhubarb patch is in the right hand corner, the downspout from the house goes into one of the swales to store water during large rain events. The swales connect with each other and work nicely to create a bottom wicking function to keep the beds moist during longer dry periods.

I don’t cultivate or rototill the soil and it is usually covered with either wood chips or other organic material, but I prefer to seed into bare soil and wait until the seedlings begin to sprout before reapplying the mulch cover. However, this is a practice I plan to change after reading the first book I’ll mention this month – Jon Stika’s “A Soil Owner’s Manual”.   In fact — Jon sent a reply to the SoilMatrix website last week to suggest that readers of The SoilMatrix Newsletter may be interested in his book.   What an understatement! I read the book in about three or four sittings and plan to re-read it several times. This book is a thought changer for me. It describes in plain language how to restore soil’s capacity to perform all of its intended functions. Jon Stika is one of America’s soil health pioneers (we will learn from a number of these pioneers in future newsletters) and in simple terms he describes how to restore soil to its full potential by working with nature instead of relying on expensive inputs to maintain yields. I highly recommend this book and encourage you to read it carefully. It is available as a download from Amazon:

So at this point you must be scratching your heads thinking, what is the SoilMatrix Biochar guy saying here. Isn’t biochar a soil amendment? And didn’t he just say that a full 25% of the soil he just blended is SoilMatrix Biochar? Well yes, that is what I just said. And the truth is, if you do all the things suggested in Jon Stika’s book, you probably don’t need any biochar in your soil to make it healthy and productive.   My hypothesis, however, is that soil can be made more healthy and resilient by adding biochar to the soil up to between 20 to 30% by volume.   After that there is a significant diminishing return on adding any more biochar.   Moreover, once you have this amount of biochar in a soil, it remains there for a long time — no further additions are necessary.

The second part of my hypothesis is that given the evidence from experiments where biochar is amended into soils in ways that work with nature and the soil food web, yields increase and nutrient input requirements reduce. How does this happen? It happens by biochar’s ability to stimulate microbial growth and then protect these beneficial microbes. Furthermore, biochar has the ability to make nutrients more bio-available for both microbes and plants. Future SoilMatrix Newsletters will share the results of numerous experiments that provide evidence of this. For now, let me just say that Jon Stika’s book has significantly changed the way I think about the soil and how the soil food web needs to be nurtured to perform as intended.

Let me demonstrate! After reading Jon’s book I have become more acutely aware of the function of earthworms in the soil. Earthworms are prolific in the SoilMatrix Garden. In the early mornings I have noticed something amazing appearing at the surface of our freshly seeded garden:

These earthworm burrows are literally all over. They also extend deep into each garden bed and serve to infiltrate water deep into the garden soil to preserve moisture and make it available to all of the soil matrix and roots. They also serve to keep the soil pliable and aerated so that the soil food web can breath and have much needed oxygen to function. But I have realized something else by observing these earthworm burrows… I need to replace the mulch cover as soon as possible to make sure my earthworms are properly fed. I am sure they come to the top of the soil for a reason. They are seeking organic debris to feed on and since I have removed most of it for seeding, it is missing. This photo shows what I have done to remedy this problem (see below).
Not so pretty anymore, but it is far better for the soil to have a covering to protect it from the heat and heavy rains – to conserve moisture and to protect it from compaction. I am still careful to allow the seedlings to come through all this cover.

I hope to replace the mulch on the rest of the garden beds as soon as possible. This is a stretch for me because I am concerned about making sure the seedlings get a good start as well. In sum — it is an experiment for this year.

In the future, possibly starting this fall, I will be experimenting with cover crops on the SoilMatrix Garden. Based on Jon Stika’s book and based on the learning of thousands of no-till farmers, this is an even better option to loose organics on top of the soil. Why? Because of the additional benefit of roots for the soil. You will need to read the book to learn how cover crop roots add even more health to the soil.

Speaking of seedlings, here is an example of a zucchini seedling that I had to remove to thin the rows this morning:

Notice the small flecks of biochar attached to the root hairs.   This zucchini seedling was getting quite friendly with the biochar in the soil, but it’s not only the roots that benefit from the presence of biochar — have a look at a typical earthworm in The SoilMatrix Garden:  

These are a set of my large work gloves to give you an idea of the size of these animals. I don’t need a rototiller with these guys working 24×7 to generate burrows all through the garden.

As of May 31, 2017 the garden appears as shown below. I’ll keep you posted as the summer progresses.

The second book that I am looking forward to reading more carefully ( I have scanned it quickly) is “Growing A Revolution, Bringing our Soil Back to Life” (May 2017) by Dr. David Montgomery. I have enjoyed two of his previous books:

“Dirt, the Erosion of Civilizations”


“The Hidden Half of Nature, the Microbial Roots of Life and Health.”

These two books were game changers for me! They opened the door to understanding soils as living organisms (virtually the sum total of billions of mutually beneficial microbes and insects (arthropods, earthworms, etc.). However neither of these books discussed the potential for biochar amendments to further stimulate soil life and benefit plants. I chalk this up to the fact that experimental evidence for the benefits of biochar for soils has only become available in the past 15 years and these books were written at a time when this evidence was less available. All that has changed and Dr. Montgomery’s most recent book (Amazon link given below) covers this topic more fully.

These books and a growing number of people who are now lecturing and promoting the “Soil Life” proposition are nothing short of an ongoing revolution in North America and a number of other countries. Advances in microbiology, DNA mapping, and an understanding of the vast diversity of life responsible for how healthy soils function are moving this revolution along swiftly.   Find Dr. Montgomery’s book here:

So that is it for this month. There will be a lot more to share as the garden progresses through the summer. Thank you for joining me on the journey of this growing revolution as David Montgomery phrases it.

Copyright ©_2017 AirTerra, All rights reserved.

The complexity and simplicity of soil life…

Welcome to our April 2017 SoilMatrix Newsletter –

I am writing this on April 24, 2017 and watching a heavy snow falling in the park across the street from our home. It’s less than a month from the traditional seeding time in Calgary – May Long Weekend.   The question going through my soil-geek mind is: “How can I help the soil life get started with this cold spring weather we’re having?” But that’s enough complaining…

This month’s newsletter is shorter to give you more time to view an informative one-hour webinar on “Getting to Know Trillions of Friends Underfoot – Focus on Soil Life”. The more we know about these little helpers, the more we will be able to help them work for us and our plants this summer.

Only “living” things can be spoken of as having “health”, so we should view soil as a living, breathing ecosystem. Soil isn’t inert; it is teaming with billions of bacteria, fungi, and other microbes that are the foundation of an elegant and interdependent “Soil Food Web”. Soil is an ecosystem which, when managed well, provides nutrients, root protection, and structural support for plant growth. It also absorbs and holds rainwater for use during dryer periods; it filters and buffers potential pollutants from entering our waterways; and provides beneficial habitats for soil microbes to flourish and diversify and keep the whole ecosystem running smoothly.

This webinar was sponsored by a Calgary company “Black Earth Humates” and the No-Till Farming magazine ( and was produced by the United States Department of Agriculture (USDA) and its Natural Resource Conservation Services (NRCS) group.   This excellent video is highly recommended by yours truly – the soil geek:

Getting to know the trillions of friends underfoot: Focus on Soil Life:

Another great resource that goes into great detail on “Soil Health” is the USDA’s Soil Health website: – These excellent resources and webinars go into greater depth on the topics introduced in the YouTube video I just shared.

Also, see the introduction to the USDA’s online Soil Biology Primer here:

Each sub-link provides very helpful descriptions of the soil food web, bacteria, fungi, protozoa, nematodes, arthropods, and earthworms.

The more I learn about soil biology, the more curious I become.   It is interesting to learn how soil organic carbon is a necessary component for soils to support all of the various actors in the Soil Food Web; and how, vice-versa, a healthy Soil Food Web maintains a high level of soil organic carbon.   Sometimes soils need a little help to replenish the soil carbon when soils have become degraded. Nature does this through occasional forest fires that leave behind large amounts of charcoal (nature’s biochar) – the reason a forest floor turns into a lush green carpet of new life after a forest fire. We can mimic this natural process by amending biochar to our problem soils to give them a soil carbon boost and stimulate the Soil Food Web back into action.  Once biochar is present in the soil it is stable for a long time and continues providing support for the microbiology of our soils for a long time. Biochar can even help healthy soils remain healthy with the harsh weather we are currently experiencing..

Last but not least, AirTerra is one of 15 companies selected to pitch for funding at the Calgary Fundica RoadShow event taking place on May 4th, 2017 at The Commons, 1206 20 Ave SE, Calgary. The winner of this cross-Canada pitch contest wins $1,000,000 in funding. Wouldn’t that be glorious! You are welcome to join us by clicking on the link below to register for this event (use the Fundica promotion code: FRIENDSFAMILY25 to receive a 25% discount).  Come cheer us on and share in the excitement as we do our best to tell the story and raise the funds needed to set up a SoilMatrix Biochar packaging facility in Calgary!

Click here to register to attend AirTerra’s pitch for $1,000,000 to fund expanding biochar sales in Canada!

Hope to see you at the Calgary Fundica RoadShow pitch on May 4th, but see you all for sure at the end of May… the garden planting month!


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