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Talking Trees with Davey Tree
Biochar: The Secret to Better Soil and Plant Health
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Nate Conn from Davey's North Central Wood Products office and Brian Borkowicz, senior advisor for the Davey Institute, answer questions about biochar, including how it’s made, the benefits it provides for soil and plants, how to choose the right product and why consumers should consider giving it a try.
To find your local Davey office, check out our find a local office page to search by zip code.
To learn more about biochar and its benefits, you can:
- Visit the Davey SoilCare® webpage
- Watch our YouTube video, How to Improve Soil Health with Biochar
- Read our blog, Biochar Soil Amendment: Everything You Need to Know
Connect with Davey Tree on social media:
Twitter: @DaveyTree
Facebook: @DaveyTree
Instagram: @daveytree
YouTube: The Davey Tree Expert Company
LinkedIn: The Davey Tree Expert Company
Connect with Doug Oster at www.dougoster.com.
Connect with us: podcasts@davey.com.
Welcome to the Deby Tree Expert Company's podcast, Talking Trees. I'm your host, Doug Oester. Each week, our expert arborists share advice on seasonal tree care, how to make your trees thrive, arborists' favorite trees, and much, much more. Tune in every Thursday to learn more because here at the Talking Trees Podcast, we know trees are the answer. Well, today we have a very interesting episode. I am going to learn all about biochar and we're going to teach you all about biochar. I have two guests: Nate Kahn, who is district manager for the North Central Wood Products. That's Davey's Chicago mulch office. And Brian Borkowitz, who is the senior advisor for the Davey Institute. Welcome to the show, guys.
SPEAKER_01Thanks for having us, Doug.
SPEAKER_02Thank you.
What is biochar?
SPEAKER_02What in the heck is biochar? Who's going to answer that question to start with? Because I keep hearing lots of stuff about biochar and what a positive it is and how many people are using it. I just don't know much about it. What exactly is it?
SPEAKER_01Well, biochar is an exoskeleton structure. It's essentially carbon that's made from pyrolysis, the process through pyrolysis. Our biochar, each biochar, I think, is distinctly unique in terms of how it's produced and what process it's produced by. The technology is incredibly old. It's been used by the Mayans thousands of years ago, but essentially it's taking a wood-based product. And in our case, it's recycled tree debris from our tree care operations. So we're not going out and cutting down trees for land clearing and trying to dispose of that product or try to dispose of a waste stream from a wood mill of something like that. It's really our recycled tree care operations and all the chips that come from removing and pruning trees on our customers and clients' properties. So that material is then pyrolicized uh through a gasification process in a limited oxygen environment. Pyrolysis by decomp uh by definition is decomposition through high heat. Uh, and we cook that material at about a thousand degrees to 1200 degrees Fahrenheit for a certain amount of time in a rotary drum. Uh, and then we get a carbon exoskeleton structure that's really great for soil amendments.
How does Davey use biochar?
SPEAKER_02Brian, when does biochar come into your world as a professional? Uh, from the very beginning, or is it something recent?
SPEAKER_00Um, well, what's interesting is as Nate said, you know, biochar has been used by a lot of the indigenous folks all across the globe. They've been it's been used in various forms for agriculture and soil improvement and water cleaning, really for thousands of years. But uh really over the last you know, 20 years, probably more like 10, has it really come into our world or the Davy world of tree and landscape care? So it's it's a relatively you know new product in in that space because it really does um you know five key things for us as arborists and landscape you know professionals for for soil care. Um one of the first benefits of it is it attracts and holds water, uh actually up to about four times its weight in water. So it's a sponge for water. It it attracts it and holds it. It also is a sponge, if you will, for microbial activity, where in most urban soils we don't have a lot of uh microbial activity. This is a way a media uh can hold some of those biologicals, those good bugs, if you will, in the soil structure for for better root and plant growth. Um, the other key part of using biochar in the urban space is it also reduces compaction. That's probably one of the biggest benefits that biochar does, is it reduces compaction in the soil profile. So that allows a lot of root development. When we get good root development, obviously we get good plant care. Um there are is also a lot of data that when we mix it with some of our amendments like compost and manures, it increases the the canide change capacity, so the ability and the productivity of the soil. Um so that's a key part. And then the big thing, as Nate mentioned, it interrupts the greenhouse gas emissions process because we're sequestering that carbon into that wood structure, and then we're embedding it back into the soil so that it doesn't decompose over a long period of time again. So we're it's really a good carbon um negative or removal strategy um in in the soil and for our services.
SPEAKER_02Nate, can you break down
How is it made?
SPEAKER_02the nuts and bolts on how it's made? I know you you we you talked about it there, but like like how is how how much wood are we talking about and and what is the space that is used to make this?
SPEAKER_01Yeah, the uh the footprint of our unit is actually relatively small uh and condensed. Um but we take our material comes in on chip trucks from our tree care operations. Uh we refine that product uh through a grinder to remove foreign objects and to create a consistent particle size that takes its journey through our PRD system. Uh it takes a series of conveyors uh that are now running fully automated. Uh, they run through uh a primary burner that generates the majority of our heat source that feeds our unit. Um, that consistently runs between 1550 degrees Fahrenheit and 1750 degrees Fahrenheit. Uh, because it's a limited oxygen environment, the draft of airflow through the two-foot diameter exhaust pulls a vacuum, sucking all of that air out. So as we introduce material uh on the opposite side of the unit, so we're adding material on both sides, one is a primary heat source, and the second uh for producing high-quality biochar, it comes through a tube where it allows that material to dry and allows those oxygen molecules to be released and we add air into that process. That's our combustion. Um, that's a hydrogen reaction that happens in a very controlled environment that allows us to burn clean emissions. That material then drops into a rotary drum. That's really where the magic of making biochar happens, where we control uh the temperatures of the pyrolysis and the retention time of the product. There are a lot of things that contribute into uh, you know, how fast that drum rotates, what speed that drum that wrote that retention time, uh, whether it be a high moisture content or maybe a lower moisture content, uh, or maybe the product is uh doesn't have a lot of leaf litter or fines in it. Uh, so that material is a little bit more volatile. So, you know, our our feedstock uh really is the big driving point uh that leads us to make the adjustments on our machine in real time uh to produce a high quality biochar. Um, so for example, as we have our drum set up in segments for temperatures, you know, we like to see that slow temperature progression to get us to that uh 1100 degrees Fahrenheit is kind of our target goal. And then we like to hold that product there uh, you know, for about 15 to 20 minutes so that we really maximize the pyrolysis and we get that exoskeleton structure and that real cook all the way through. Um, most of our material coming off of our PRD unit currently is at about 75% carbon content. Um, we do have a little bit higher pH value um than most biochars uh currently. Most people are a little bit nervous about that, that it's going to change the pH of their soil. But because um, you know, it is the coating of the potting ash, which is a byproduct of pyrolysis, is on the outside. That's how labs test that. And we also have to think about the cation exchange capacity. Biochar is a negative, its job is to absorb, its job is to hold airspace, its job is to hold water. So it holds a lot of that potting ash. But when you charge biochar, which is something we should talk about with nutrient compost or manure or chicken litter, it's gonna absorb all of that into its structure and hold all of those microbes, hold that moisture, hold that air, which really helps build that soil profile. And because it's a negative and it's attracting all of the positives, that pH value becomes very neutralized.
SPEAKER_02Brian,
How does it look when an arborist gets it?
SPEAKER_02what does it look like when when an arborist gets it? How is it chunks or powder or what what exactly are we talking about? And does it depend on how you're gonna use it?
SPEAKER_00Yeah, well, our our material, um, as Nate was saying, is a little bit different because our whole goal is um cost reduction. We're trying to reduce cost on the reduction of our biomass. So our material is about a half inch chip at the largest side, all the way down to some fines, which is kind of like a powder. Um, so our material is not um uh screened um unless a client has a specific need for that. But ours is um heterogeneous with all those different types of particle sizes. So it is a powder all the way to kind of a dust, and but we're mixing it with compost um at a at certain percentages so that it's uh it's readily available for the operations to help combat some of those big urban issues that we just talked about, the the water and the compaction and the CEC and the the microbial uh increase. So we're getting a ready-made product for our you know operations and external customers to use right out of the gate. Um, because what happens a lot of times in our biochar space is folks are using raw or what we say unblended biochars and they're applying them at much higher percentages that they don't really need to, and they can actually cause some issues um in their soil. If it's applied more than you know 20 or 30 percent by total volume of their soil profile, they can they can have some issues. So we're kind of guiding most of our folks um to an overall you know five to ten percent inclusion rate by volume um to help the over, like I said, to correct some of those benefits or increase those benefits that they have for when they're planting you know plants andor turf.
SPEAKER_02So Nate,
Charging biochar
SPEAKER_02talk about that charging, talk about the science of that. Uh what is that when the biochar is combined with compost or a manure or something? Is that what is that what that is?
SPEAKER_01Yeah, absolutely, Doug. So biochar in its raw form is an attractant. It's a it's a negative. It wants all of that positive nutrients. So, for example, if you take biochar and you put it out over the top of your garden bed or your turf, it will absorb all the nutrients right out of your soil, right up to it. It really wants to attract all of that good stuff. That soil needs, that profile. Um, so what we refer to in the industry is charging biochar uh with an amendment. It can be inoculated with a compost tea, uh, it can be inoculated uh in fish hatcheries where it's absorbing that nutrients from you know the water. Um, it can be charged with compost, uh mushroom compost, landscape compost, uh, worm castings, you know, any any real soil structure that holds um, you know, high nutrient value is what we like to blend our products with. Um, you know, we have three products that we're distributing uh pretty regularly to our Davy territories here and starting to sell externally, um, but we make a 90-10 uh blend, compost, biochar, 70-30, and a 50-50 compost first. Um, they really all can be used in any application on any homeowner's property. Um I like to say that any carbon in the ground is better than no carbon in the ground. Um, sometimes I think people think carbon is uh or biochar is too good to be true. Um, how many organic products um have you or your listeners tried and probably not seen a ton of success with? Um, what's been really cool for me in this experience is, you know, I didn't know anything about biochar two years ago when we started this endeavor. And I've I've had the opportunity to watch um, you know, real trials uh with universities and on farms, agriculture, and on homeowners' properties and to see the difference that it truly makes is is impactful. Um and it also is great for our business in terms of our long-term sustainability goals. But um our 70-30 and 50-50 blends are our most popular. Um, like I said, any carbon in the ground is better than no carbon in the ground. Um, some of that can be driven by you know, by how much you want to spend. Um, carbon can be relatively expensive. So a 70-30 blend might be better for someone that wants to just add some into their soil. Um, tree planting, you know, we recommend really getting that biochar compost blend and 12 to 24 inches of that root zone when planting a tree. Um, we don't want any more than 10% volume. So if you dig a hole and you put the root ball in there, um, you know, you think about adding no more than 10% of what you're putting back in there. So maybe a one-inch caliper tree is a one one 1.5 cubic foot bag. Um, you know, turf application, establishment, and maintenance, uh quarter inch. Um, you know, overseed top dress after aeration can be a really great way to see some green up. Um our biochar holds some nitrogen, some phosphorus. Um, so it adds a lot of just immediate um, you know, benefits to that top dressing of your soil, garden beds, gardens for vegetables. Um, you know, great story is we have a community garden in our East Undy location where our biochar facility is at. And one of our CECs came up and said, Hey, what do you think about putting some biochar in the garden up there? And I was like, Absolutely, what would you like? And she said, Well, what do you recommend? And I said, Let's do a one-inch uh, you know, overlay of your of your garden before planting and we'll till that in there and we'll see how it does. Um, and she did. And uh she came to me and she said, No more biochar in the garden. And I said, What do you mean? And she said, My tomato plants have grown so big they've broken all the cages. Uh, and I was like, you know, that's it's a great story about how we, you know, we just use that in our own community garden. And uh it just it really offers so much benefit to the soil. Again, if if you know nothing about biochar, and the only thing that you take away from this podcast today is is know that we all need air and we all need water, oxygen and water. And that's really what uh biochar brings a lot of benefit to a soil profile. Um, and oftentimes we don't think a lot about our soil and and what's in our soil. Um, but giving air and oxygen, um, sorry, oxygen and water to the soil is just a massive benefit for the microbes.
SPEAKER_02All right, Nate, I'm coming back to you because you
50/50 biochar
SPEAKER_02have all the secrets for this. If money's no object, which one of those things am I buying for my garden?
SPEAKER_0150-50? 50-50. Yeah, 50-50 would be a really great product. Um, you know, I would go no more than 5% on the 50-50 product. Um, you know, a one-inch uh top dress on top of your garden in the early springtime or fall. Um, I always recommend fall applications for biochar. It really gives, you know, if there's some season left uh at the end of the year, it really gives those microbes the chance to kind of uh start absorbing into that biochar. And then in spring, when you do a till before you plant your garden, you really get um, you know, a lot of that nutrients kind of uh blended together. Um if it's a garden bed with traditional planting, you know, a little bit over the top, half inch, one inch of the 50-50. Uh, and then obviously we recommend covering that with an inch to inch and a half of mulch. Um that really gives that that profile some room to grow, allows the roots um, you know, to kind of penetrate if you're doing new plantings and and kind of holds all that in there.
SPEAKER_02Well, to properly vet this, as host of this podcast, I think I need a palette of that stuff shipped to Pittsburgh so uh so I can test it and be sure that everything you're saying is correct.
SPEAKER_01Absolutely. I think we definitely get you some values coming. Yeah, absolutely. Love to.
SPEAKER_02Brian, let's talk a little bit
Advantages of adding it into planting
SPEAKER_02more about how the arborists are using it and what kind of conditions or all planting conditions. You know, we've been taught uh over the years, you know, we dig our planting hole and in most cases not adding compost, uh trying to use the native soil, but talk about the advantages of adding the biochar and how it's used in tree planting.
SPEAKER_00Well, yeah, tree planting obviously is the easiest induction, you know, of these materials. So obviously it's the you've got the hole open, you're kind of starting fresh. So as Nate said, if you're going with a 50-50 or 70-30 blend and mixing with the parent soil, that's really what you want to do is get incorporation with the parent so that you're getting a heterogeneous mix. But I would also say that in the arborist space and in the in the turf space, a lot of times we don't have the luxury of of just changing out the soil. So we've got um over the last you know 15 years, we've got these air tools at our disposal now that arborists and Davy arborists particularly use a lot of to help when they go into existing trees. They can't go out and and remove all that soil and replace it. So we can do these vertical aeration techniques and and soil invigoration with compost and biochar to help sweeten that soil. And you know, Raz Remsen, which is in our Minnesota market, uh one of our tech advisors, um, she kind of has uh an interesting perspective and she's done a lot of this work. So she comments that utilizing these char and compost within some of these parent soils and existing trees, the the soil seems like it comes back to life. It just seems like it as you're mixing it in with the air tools, um, it just kind of comes back to the way that you would think you'd want a a nice soil to perform. And you know, that's that's unusual. We didn't have that. I'm I'm I'm an old guy, you know. I mean, back in the day, we you know, the best thing we had was a drill that we could drill in the ground and you know, maybe throw some perlite. But the use of these air tools, and our our people are really getting good at doing that and utilizing these products to to help um trees before they become really stressed. I'm talking like native oaks, um, you know, really historic trees or or trees in the landscape that you know the soil is really compacted or or poor. We now have this tool and this product to help us with, you know, really, you know, focusing, as Nate said, on the soil again, not so much just the outwardly, you know, what we see signs on the on the tree, really focusing on the soil. So it it's a great tool. It really, really is. The only question
Consumers should know more about it
SPEAKER_00I have for you, Doug, would be what do you hear in the uh you're in the garden garden marketplace. What are you hearing about you know the use of of biochar compost in in the garden garden world?
SPEAKER_02From the consumer, uh it's a mystery to most of them. About once in every few months, somebody will come up to me and and talk about biochar, uh, about the positive things with it. Uh the most I've encountered it is is dealing with the arborists, and they're always talking about biochar and what a positive it is. So I think it's still a little bit under the radar, but every time I I discuss it with somebody who knows about it, I get excited about it. I'm like, I'm like, I gotta get biochar into my garden. That's why I want that palette coming from Nate's place.
SPEAKER_01Well, we can we can work on that. We want you to be a believer in biochar.
SPEAKER_00We're glad that you're you know exposing it because this is how it kind of it is kind of a groundswell of of knowledge. It's um, you know, I don't think just big you know e-blasts and things like that are gonna get it. As you said, I think people have to get it and use it and and and try it and then kind of witness it on their own. So we appreciate it.
SPEAKER_02Well, I'm I'm a I'm a believer after talking to you guys, that's for sure. Uh Brian and Nate, uh, thanks so much for spending some time with me and schooling us on biochar. I appreciate it. I'm sure we will talk to both of you in the future. Thanks so much for being on the show.
SPEAKER_01Thank you, Doug.
SPEAKER_02Thank you, Doug. I am going to have to get a hold of some of that biochar and use it in my tree planting and my garden. Now tune in every Thursday to the Talking Trees Podcast from the Davy Tree Expert Company. I'm your host, Doug Oster. And as always, I'd love for you to subscribe to the podcast so you won't miss a show. Let us know what we should be talking about, a couple different ways to do that. Send us an email to podcasts at Deby.com. That's P-O-D-C-A-S-T-S at D-A-V-E-Y.com. You can also click the link at the end of our show notes to text us a fan mail message. Your ideas could be on an upcoming show, and we'd love to hear from you. As always, we'd like to remind you on the Talking Trees podcast. Trees are the answer.