167: Use Biochar to Combat Climate Change

Wood burns twice. The first burn takes wood to charcoal. The second phase takes charcoal to ash. Unless you remove oxygen. Josiah Hunt, Founder and CEO of Pacific Biochar Befit Corporation explains that Biochar is made at a high temperature in an oxygen-limited environment. Organic waste is taken through the first burn phase and by limiting the oxygen, remains charcoal. The final product is buried in the soil where it improves water retention and fertility. And you can do this at your own ranch. Listen in to hear Josiah’s tips on how to make and incorporate Biochar into your vineyard.


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Craig Macmillan  0:00 

Today is Josiah Hunt, who is founder and CEO of Pacific Biochar Benefit Corporation. And we're going to talk about guess what biochar. Josiah thanks for being on the podcast.


Josiah Hunt  0:09 

Thank you.


Craig Macmillan  0:11 

Let's just get right into it. And let's start with some basics. What exactly is biochar?


Josiah Hunt  0:15 

Biochar is a funny word. First. biochar in its most basic terms is biomass charcoal, which is redundant because charcoal is from biomass and the generation like where the word came from is even funnier in my opinion, the word biochar was born out of the word Agra-char. But in the world first Agra-char conference in 2007, a company came forward and said, Sorry, we've already trademarked that back to the drawing board. And they came up with biochar. That's that's the origin story that I've heard. I think one of the really interesting questions is, why did we have to come up with a new word for charcoal, and the reason for that is climate change. So I think the key differentiator from where the word biochar came from is part of an idea, rather than a simple material. And that idea is wrapped up in waste organic material used to create biochar, a biomass charcoal, which is then buried in agricultural soils, where it serves two important purposes, carbon dioxide removal by sequestering that stable carbon into the ground and long term soil fertility. So this helping address climate change mitigation by removing carbon and climate change adaptation by facilitating food security. So it's a lot packed into that concept. So the word charcoal just couldn't hold it anymore.


Craig Macmillan  1:39 

Just couldn't hold it off. We're talking about charcoal, which people have been making for millennia, essentially. So how is biochar made and are there multiple ways of this different materials, etc.?


Josiah Hunt  1:51 

High temperature in an oxygen limited environment. So you're you're basically reaching these combustion temperatures, but you do so with an oxygen limited environment. So a woodchip brought up to 500 degrees Celsius would become a glowing ember. Its molecules so excited, they're shooting off photons. Now, if that woodchip came up to five degrees Celsius, and there's sufficient oxygen, you would have complete combustion first, that woodchip would volatilize off the gases become a chunk of charcoal, and then the oxygen would come in and destroy that charcoal, releasing all of its energy, and leaving only the ash mineral residue. If you have limited oxygen, that first part occurs pyrolysis part where you go from woodchip to charcoal, but that second phase of burning from charcoal to ash can only occur with the presence of oxygen, and thus, the limiting of oxygen is the key component to making the material.


Craig Macmillan  2:48 

And then second phase is where the carbon is leaving into the environment?


Josiah Hunt  2:52 

A better way to put this is that wood burns twice the first phase of combustion and the first phase of burning would be from woodchip to charcoal. And the second phase is from charcoal to ash. And that second phase can only occur in the presence of oxygen. Therefore, if you can limit the oxygen, you control, whether you're generating charcoal or ash.


Craig Macmillan  3:16 

So controlling the oxygen is important. If you have a way of stopping that process midway. That's obviously the key to this, you have to be able to stop at the end of the process step not going any further. Is that right?


Josiah Hunt  3:29 

That's correct.


Craig Macmillan  3:29 

How do people do that?


Josiah Hunt  3:32 

There's two kind of main ways one would be we're working with continuous flow machinery. So the woodchips come enter a system in which they experience incredibly high temperatures and limited oxygen environment where pyrolysis occurs, the gases leaving gases go off and they have their own work to do. And then that carbon flows out of that hot chamber into areas where we maintain that oxygen control. And we allow the temperature to begin to drop down to temperatures that are ambient, essentially. And once you get that charcoal material to ambient temperature, it is safe, it's recalcitrant, and will will last for a very, very long time. So that's how we do it in a continuous flow. And then generally at the tail end of the process, we're adding water for dust control and safety. And if you had a batch process, you would initiate a paralysis to occur you initiate process to create basically start big fire, it would be one way to do that, and then allow it to go through that first phase where you'd have you know pyrolysis carrying wood becoming charcoal and then extinguish it, you got to stop it, you got to either completely cut off the airflow and snuff it out or introduce so much water that you would quench it that's also snuffing it out so that would be kind of a batch process approach to stopping it.


Craig Macmillan  4:46 

So that's the the key stopping and along the way there and having some way of doing that. And that's what makes this whole thing essentially work. Now I've got this stuff. What is this charcoal, it used to be wood now what is it chemically? How was it changed, what do I have here in my hands?


Josiah Hunt  5:02 

Biochar differs from the plant biomass that it was made from in that it has undergone a thermal thermal chemical conversion, an irreversible process where the associations of the carbon and other elements in there become completely reassociated, you have a wood chip that goes into a temperature range of 500 degrees Celsius plus and becomes a glowing ember shooting off photons. And those carbon atoms realign themselves into a different form that is highly aromatic versus aliphatic, meaning you're basically tightening these carbon rings here. And that helps the material become highly recalcitrant, meaning that it will have a persistence. In the environment, an order of magnitude are orders of magnitude greater than the plant biomass that was made from lasting hundreds to 1000s of years in the soil, and also with some very interesting changes to the surface characteristics.


Craig Macmillan  6:09 

So that leads into the next question there. So we're talking about something that will remain in the soil for a very, very long time, which is one of the reasons it's of interest to agriculture. What are some of the applications why are people using this in agriculture? And how are they using this in agriculture?


Josiah Hunt  6:25 

The charcoal material has some really interesting attributes some some really interesting characteristics. Other than just being highly recalcitrant, charcoal is the oldest known filter material, maybe most widely used over a long period of historical time, it works great, it can hold nutrients, it can hold plant nutrients, in this case, against a gradient, and it can hold plant nutrients in such a way that they will be resistant to environmental loss yet still plant available or biologically available, I should say, because sometimes it's the microbes or fungi who would access the material off the charcoal surface and make it available to the plant. And so that filtration characteristic is an incredibly important part of, of how biochar helps plants grow is it can help keep nutrients in the topsoil and resistant to environmental loss in a way that plants can still access them.


Craig Macmillan  7:24 

And the same is true for water, correct?


Josiah Hunt  7:26 

Yes, biochar material is incredibly porous. So a lot of the vascular tissue of the plant body remains intact. So it's really interesting, because you have this, you have this like, just completely dramatic molecular change, where the woody cellulosic material becomes a target material. And on a molecular level, it's so incredibly different. But on a structural level, most of the plant body remains. And so you can take a small piece of charcoal, and oftentimes a botanist, would be able to identify the plant species, it was made from


Craig Macmillan  8:02 



Josiah Hunt  8:02 

Yeah, the vascular. And in fact, this is an important piece of archaeology. So this is like in archaeology, they'll, they'll find little bits of charcoal, because it's highly recalcitrant. And they'll be able to identify what species of plant it was, because of the vascular tissue. And it can be pretty evident sometimes, I mean, it's really easy to tell the difference between oak and pine, you've got to be a connoisseur to be able to tell whether it's a Valley oak or red oak, yes, the vascular tissue of the plant body remains primarily, you know, largely intact. And so this is really interesting, you have a material that, you know, on a very, very micro level is very porous, but then even on a macro level, you have this vascular tissue of the plant body. So a lot of the a lot of the capillary action that the plants were taking advantage of transfers over to this biochar material, which is really interesting because now you have this highly recalcitrant material with incredibly high surface area, a functional surface of that and, you know, just incredibly intricate porous design determined by the DNA, that plant material, you know, it's just riddled with tubes and tunnels and nooks and crannies that help hold water and provide habitat for microorganisms.


Craig Macmillan  9:16 

Is there research that's been done other findings about what quantity or type or whatever of biochar and how that relates to increases in water holding capacity or increases in soil microbiome populations or things like that? It seems like that'd be a pretty straightforward idea.


Josiah Hunt  9:33 

I think I was looking at a graph this morning and I don't remember where it came from, but I think since 2007, there's been 28,000 research articles about that, that are related to biochar not specifically focused on biochar, but have biochar as a key word or an aspect. So biochar is is a you know, part of about 28,000 research articles. And a lot of that is focused on water because it's such an important part of the puzzle the dynamics between application rate and expected response get really nuanced. It comes down to what are the characteristics of the biochar material? And in many cases, what is really important, what are the characteristics of the soil, so you can expect to see a quite quite a range of different response, depending on the characteristics of the biochar material and the native soil that it's being applied to, you know, without any research articles, we're now at the stage where we're they're doing systematic reviews of the meta analyses, which begins to give you a lot of really powerful data. Overall, the water use efficiency, or there's so many different ways to measure it. And again, I'm a little bit undergunned the difference between plant available water and, and water holding capacity, you know, become existentially important to tell us that I probably don't have the same level of experience with.


Craig Macmillan  11:01 

You may not need to be the expert, but you probably are the expert on where to find this information that helps. So if you can, if you can connect us with some things, even just general stuff, we'll pass that along to our listeners. And it'd be greatly appreciated. Because again, this is an ID the reason I bring this up is that, you know, we were talking earlier about, you know, 2007 and whatnot. I remember the first time this was introduced to me, and it was probably around the year 2000. And it's from a college student. There was one of my students, and I was and they were like, Hey, that's a great idea. We should really try it. And I said, I don't know I don't get it. They're like that. And I said, Well, how much material do we need? And I'm thinking like tons per acre. They're like, Oh, no, no, we just use a little bit. We do this and I was like, Okay, that sounds like witchcraft to me. Show me the science. Well, now here we are 20 years later. And we do have a lot of science. This is not a story anymore.


Josiah Hunt  11:50 

There's a lot of science and, you know, the water conservation part. I think that's just such a key component of of the value that biochar can provide, particularly when we're talking about vineyards in California. And so I think it's it's useful to spend some time on that. So a couple key points of, of biochar and, and water use efficiency or water conservation. One is just that the material itself holds immense amounts of water. I mean biochar alone, the biochar that we're working with, we usually hold about six, six times its weight in water. But then the real important thing is how does it affect the water holding capacity or plant available water in the soil, and in most all aspects, the results are positive pretty much across the board. And here's a few key metrics, I think that would be useful to mention and that I find valuable. A couple of key points of biochar and water use efficiency or water conservation. One is that one of the easiest ways to think about biochar is that it is pyrogenic organic matter. Perhaps that's a better word than biochar. It's a much more scientifically accurate word. And when we think about this material, it's not unique. Humans didn't invent charcoal, or biochar for that matter. In fact, it's been part of soil development, as long as plant life and fire have coexisted. And according to geologic records, about 350 or more years ago, biochar became a significant component of topsoil development. And that generally, soil organic matter is measured by loss on Ignition, which does not differentiate between charcoal organic matter pyrogenic organic matter and non charcoal organic and studies that have used some very expensive and kind of painstaking processes to identify the charcoal organic matter as separate from the non toxic organic matter have shown us that charcoal organic matter is prevalent in most all agriculturally important soils, and oftentimes greater than 10% of the total organic matter, and not uncommon to find it as much as 30 to 50% of the total organic matter. And in some of our most valuable soils such as the Midwest plains like in Iowa, some of those those those highly fertile molecules up there can be 30 to 50% of organic matter in the form of charcoal. So I probably went too long into that definition or that that that distinction. But one of the easy ways to to think about biochar is that biochar is part of organic matter is not separate from and so when we're thinking about how does biochar impact my soil? Usually, we can kind of just consider what are the impacts of organic matter and what are the impacts of increasing my organic matter, and then think of biochar as a stable portion of your organic matter. That will have a lot of water conservation and tilth benefits, but it will not be a significant source of nutrients. And that's one of the significant differences of charcoal organic matter versus non charcoal organic matter, but in so many other situations, that's an easy way to think about the effects of biochar. So With biochar, and water conservation, one of the really important elements would be the soil type in determining what the projected outcomes might be. And there's been some really interesting findings in this area. At first, the primary focus was in sandy soils, which have a very low water holding capacity. And it's an easy win small amounts of biochar can have large impact on coarse soils, large positive impact, improving the water holding capacity in coarse soils


Craig Macmillan  15:30 

What's a small quantity, a small quantity?


Josiah Hunt  15:33 

That's a great question. You opened up a big box there. Biochar is a three dimensional application not a two dimensional so like if you add nitrogen, your soil, it's going to disperse throughout your soil. So nitrogen is simply you know, pounds per acre, whereas biochar, it's not going to distribute itself through the soil on its own, it's wise to also consider the area cultivated. So for instance, two tons per acre cultivated only in the planting row is very different than two tons per acre, cultivated 100% of the acreage or two tons per acre and the top six inches versus two tons per acre, two feet down.


Craig Macmillan  16:11 

Is the real metric, then like volume to volume may think in cubic yards to cubic yards,.I just use percent organic matter equivalent, what I've found the most useful and looking at Biochar application rates, and again, kind of going back to how I find it really valuable to just kind of consider biochar applications within the frame of I'm going to change my soil organic matter, I'm going to be adding some stable soil organic matter. How much do I want to add and why? And framing biochar applications in that I find very useful. And then also, when I'm looking at when we've seen successful applications, either through work that we've done, or in research articles, how do we translate that into another successful application that might have different cultivation practices. And what we found is the percent organic matter equivalent is the most transferable number. And so what that would mean is that the biochar is primarily organic matter, but some of it can have a lot of ash content. So that would reduce the organic matter content of the biochar. You know, most of biochar that we're working with 95% organic matter. So then you're looking at the effect of that biochar in the area cultivated, right, so let's say if we have 10 tons wet weight of biochar might be six ton dry weight of biochar, which might be you know, 5.5 or 7%, dry tons organic matter. And then if we're cultivating that in to an area of our soil, we measure the general area that we're cultivating into, and we can come up with an organic matter equivalent. So just as a rule of thumb, a number that I find useful is that if you were to cultivate nine tonnes per acre down to six inches, it would be equivalent to 1% organic matter.


Okay, yeah. So that gives us an idea that gives us that gives us a sense.


Josiah Hunt  17:55 

If you're doing a quarter of your land, like say you're doing two, two foot wide planting rows, and they're eight foot on center. Now you're a quarter of your acreage and you're going down 24 inches, that's 1%. Nine dried tons per acre plowed to six inches depth would be equivalent to 1% organic matter.


Craig Macmillan  18:13 

Now let's let's bring this back to the vineyards because I know that there have been some folks that have been doing trials and whatnot with this that I think you're familiar with, how would somebody apply this method? In a vineyard setting? We would want to get it close to the vine row. Can we do it in the middles? What what's kind of the strategy? Do you know?


Josiah Hunt  18:31 

with vineyard applications, we've learned a lot over the past several years, and I want to, you know, provide a big shout out to Doug Beck with Monterey Pacific who has been instrumental in helping pilot you know, and pioneer, some some really successful applications of biochar and vineyards. In some of the early trials that we did. We found that with a pre plant, you know, with fresh plants going in the best utilization of biochar is in the planting row only Delve are plowed you know, right down the planting row only don't waste any the biochar on the surface broadcast. Keep it in the planting row only and take it to depth. That's one thing we learned. And so using biochar in pre plant has really shone as you're shown shown, shawn as past of shown I guess, is as a really successful way to utilize biochar, it helps get the plants up. And we've been seeing significant yield benefits, where the biochar has been plowed down the planting row. And the application rate in that we found to be quite successful is in the range of about a half percent organic matter equivalent in those field trials. Now, that doesn't mean that's the only successful application. That's just one that we identified early on as being quite successful.


Craig Macmillan  19:45 

Are you familiar with or do you think there are ways to do things post planning?


Josiah Hunt  19:50 

For post planting there's been a number of different approaches, and I can't say if I've seen any single approach rise to the top as being In the winner, and I think this might be due to how many different management practices there are after the vine's planted, which I think have a wider spectrum of variety than than the planting process itself. And so something that Monterey Pacific has been working on is applying it to existing. And I guess I'm not sure how much of this they've published and how much needs to keep quiet. So I better hold my tongue I'm getting describing exactly what they're doing.


Craig Macmillan  20:30 

So here's an example. So one of the things that I've heard from other people but I haven't seen anything on is that they make biochar which when asked you about they make biochar and then they, they grind it essentially, or they break it up and then they mix it with compost, and then they they band that on in the vine or like they would have compost. Anyway, all they've done those, they've added some biochar to it, but it sounds like the incorporation is really crucial.


Josiah Hunt  20:53 

Yes, you nailed it. That's it. That's how they're doing it. So basically, what what a lot of the folks are doing with compost applications in existing, they're simply just incorporating biochar as part of that. So rather than looking at doing compost, only, they're doing a biochar amended compost and applying the same method, and this works out really well.


Craig Macmillan  21:15 

It does work out well. Okay, so I was gonna say it sounds like there may be some limitations there. But there are some benefits.


Josiah Hunt  21:20 

Yeah, no, this works out really well, the biochar you blend it up with the compost, it flows through the equipment, no problem. And there's a lot of synergy to biochar and compost working take they work really well together. That that basically captures it however, using compost, you can consider including biochar as a portion of that. And then what portion becomes a really interesting question. A lot of people have been kind of in the range of between 10% to 30%. By weight when they're doing maintenance. That's the range that I most commonly see.


Craig Macmillan  21:52 

So let's say I'm interested in this either as a pre plant or maybe as abandoned, I need to go with compost, can I make my own? And if so, what materials do I need? And what can I do? How hard is it to make biochar myself from a vineyard or winery? What do I what do I need to do this?


Josiah Hunt  22:06 

Making biochar yourself by hand in the vineyard is it's hard work. But it's totally it's it's not rocket science, it can be done with some fairly rudimentary approaches. Commonly, what's done now is when a when a vineyard is gonna get ripped out, they'll go and they'll push all the piles up metal vines, the whole thing that push all the piles up right after harvest, and then they're gonna be aiming to replant by March, you know, replant several months later. Now, this is really tricky here, this is the biggest problem, because yes, you can make biochar to that material. But with that much moisture content in the biomass, it's gonna be really hard to do that. To do it in a rudimentary fashion, one of the easy ways to do this would just be push up those big piles, let them dry, which kind of requires that you fallow for a year, and then you come back the following year. And you can do what's called a conservation burn, essentially, it's the same thing. But instead of lighting the pile from the bottom on the inside, you just do a top lit pile. So you light it from the top, and then the flame starts at the top and the heat causes the wood underneath it to volatilize releasing its gases and the flame consumes all the gas is as it as it comes down. And it also kind of then works as a protector of the charcoal that's created. This conservation burn approach is cleaner burning. And if you quench it at the right time, you can get a significant amount of charcoal, but it does require that your vines have to be dry, which is in most cases that we've seen. It's going to take a year of fallow to get there.


Craig Macmillan  23:40 

So I could do it with vine material.


Josiah Hunt  23:42 

You can do it vine material, you can do it in the field without any fancy equipment other than just doing a top down burn, which just takes a little bit of a slightly different approach to it. And there's been some some farms that have really been doing a good job with this Kendall Jackson hosted a little workshop or something on this down in in the King City area a couple years ago, a lot of different vineyards that whose names are escaping me right now have been tinkering around with this method of biochar production, it's fairly easy, but it does require a fallow period and let that material dry. The other would be to potentially grind up that material and take it to another location where you could have a centralized biochar production facility. But the difficulty particularly in vineyards is is the metal content you just got you got a lot of of wires and steaks in there. And that makes that makes it tough.


Craig Macmillan  24:32 

How would he do things need to be? Can I do this with landscaping waste? Can I do it with grasses? How much lignin do I need? How well would he do this step up to be?


Josiah Hunt  24:45 

That's a great question. You know, you can make biochar with omega with biosolids, you know, which is not very woody. It'll just have very different characteristics. So woody biomass will have different characteristics than say grass biomass, the grassy based biochar can actually be really interesting materials, particularly because you have those monocots you have those really long, you know, the different type of vascular tissue. And so monocots makes some really interesting biochar, in my opinion. And you know, part of the question gets to what's the best use so if you have grass clippings, generally you have quite a bit of nitrogen content and grass clippings might be more beneficial in a composting pathway to because when you burn something to make biochar, it's hard to keep the nitrogen around a good chunk of that nitrogen is going to leave during the burning process. So sometimes you take your grassy materials and you manures and those can make good materials for anaerobic digestion and or composting, and then the materials that are kind of more woody content, harder to compost, and therefore, often prime candidates for biochar production, but you can use most any of it.


Craig Macmillan  25:48 

That is fascinating and encouraging. I think there's a lot to be done here. It sounds like not only are we getting some science, we're getting some experience. And now we're also getting some application. I think that's really, really great. And that's a big part of any aspect of farming is people have to have some science to base it on, but then they have to try it. And it sounds like that trying is happening. And that's really, really exciting. Really, really encouraging. Is there one piece of advice or one thing that you would tell a grower related to biochar one thing say, Hey, that's a great idea. Here's either why or here's what you might want to do.


Josiah Hunt  26:17 

No pressure, no pressure, no.


Craig Macmillan  26:21 

I like putting you on the spot.


Josiah Hunt  26:24 

The one thing Oh, my gosh.


Craig Macmillan  26:25 

Career, take your entire career, boil it down to like two sentences.


Josiah Hunt  26:31 

Biochar has shown to be an investment in your soil infrastructure, in that adding nitrogen is like fuel. You know, it's like putting fuel in the tank, whereas adding biochar is more akin to an infrastructure investment that is not necessarily putting fuel in the tank, but it's going to improve your fuel efficiency so that you can increase your ratio of output versus input with rising cost of fertilizer questions on the availability of water that becomes increasingly valuable. And I think those are the primary reasons why an investment in biochar would want to be considered.


Craig Macmillan  27:12 

And I think that's great advice. And I think that's a really good way to look, we're not talking about a, an input the same way that we might think about something that, you know, goes away, this is an investment in infrastructure. And I think it's a really good way to think about it. Um, where can people find out more about you and what you do?


Josiah Hunt  27:27 

The website for the company is We've got a lot of information, I think we definitely have some room to improve how how well organized the information is, but there's quite a bit there. We've been working with vineyards for quite a number of years. And throughout the website, there are sprinkled different bits of information and case studies about some of the vendors that we've worked with.


Craig Macmillan  27:48 

Yeah, and I want to underline that definitely, there's a lot of great information, including webinars and articles, the meta analysis that you've mentioned, it's a really great resource, and I encourage people to check it out.


Josiah Hunt  28:01 

Yeah, we have a whole section on white papers and stuff that we've produced, you know, benefits of biochar and agriculture and, and other white papers that we've produced specifically to try and help provide these resources.


Craig Macmillan  28:11 

Well, that's about all the time we've got. I want to thank Josiah Hunt, Founder and CEO of Pacific Biochar Benefit Corporation for being our guest today. Please check out their website, check out our website. They'll be more links and information, all kinds of resources there. As always, thank you for listening to Sustainable Winegrowing with Vineyard Team thanks Josiah.


Josiah Hunt  28:31 

You bet Thank you Craig.


Can you hear my dog drinking water from the water bowl? He's a super he's like a water buffalo drinks a lot and loud.


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