All About Mulch with Davey's Mulch Expert

Nate Conn, district manager at Davey's North Central Wood Products office in Lombard, Ill., discusses all things mulch and biochar, including how Davey is producing both. 

In this episode we cover:  

• What is North Central Wood Products? (:44)
• Forms mulch comes in (1:25)
• How is mulch processed? (2:12) (3:04)
• Can you use any biomass to make mulch? (4:14)
• How do tress and other biomass end up looking like much? (4:49)
• Different types of mulch and their functions (6:16) (8:15) (9:46)
• Premium mulch and plant health benefits (10:55)
• Volcano mulch and its risks (12:16)
• Do landscapers take note of the risks of volcano mulch? (13:38) (14:29)
• Are colored mulches okay for trees? (16:32)
• Most popular mulch colors (18:46)
• How Nate got into his role (19:26)
• Benefits of using biochar (20:05)
• How Nate is creating biochar (23:23)
• What is a Pyrolysis rotational drum (PRD)? (24:27)
• What does biochar look like? (27:49)

To find your local Davey office, check out our find a local office page to search by zip code. 

To see Davey's North Central Wood Products office in action, watch our YouTube video, Davey Commercial Premium Mulch Production & Delivery Services.

To learn more about mulch and biochar, read our blogs, What Type of Mulch to Choose: Mulch Selection Guide and Davey SoilCare®: How to Improve Soil Health with Biochar.

To learn more about mulching around trees, watch our YouTube video, Tips on How to Mulch Around Trees & Common Mistakes.

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. 

Have topics you'd like us to cover on the podcast? Email us at podcasts@davey.com. We want to hear from you!  

Transcript

Doug: Welcome to the Davey Tree Expert Company's podcast, Talking Trees. I'm your host, Doug Oster. 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. This week it's all about mulch, and maybe a little bit of biochar, as Nate Kahn, who is a district manager in the Lombard, Illinois, office of the Davy Tree Expert Company, which is also called North Central Wood Products. Nate, welcome to the show. How are you?

Nate: Thanks, Doug. Happy to be here. I'm doing well. Happy Friday, sir.

Doug: Yes. Tell me a little bit about what North Central Wood Products is. What do you guys do there?

Nate: Awesome. About six years ago, we had an overwhelming amount of biomass, and wood waste recycling from our tree care divisions in this area, just outside of Chicago. We started a mulch facility from the ground up in our East Dundee location. We've since grown to multiple locations throughout the Chicagoland region. My job is to take all of the wood waste and biomass produced from our tree care operations, and recycle that into all natural mulch products. Distribute that to landscaping contractors throughout the Chicago region.

Doug: How does it come to you? In what form or what forms does it come to you as?

Nate: Great question. Most of our territories here in the Chicago region will recycle wood from tree care removals, which will go and be separated. We also take the chips, which are the branches and brush ground up through chippers, which are also stored in bulk at their facilities. We have a bunch of semis on the road when one of our territories has an abundance of biomass. We send our semis and wheel loaders to their operations. We load 80 to 90 cubic yards of biomass into our trailers. We transport that back to one of our processing facilities, whether it be East Dundee or Lombard.

Doug: When it goes to the processing facility, what does that look like? Are you taking big giant pieces of wood and making it into mulch or is it all wood chips? What does it look like if I bring something to you?

Nate: Yes. We also offer a disposal to local tree care companies at our main facility in Lombard. We take logs as big as 48-inch diameter, up to four feet. We take pretty much anything brush logs that I'll get separated into one pile for processing with a larger grinder. Then, wood chips recycled from tree care operations where crews have already chipped brush from trees goes into a separate pile. From there, we're able to make multiple products from the two processing of wood and, obviously, the raw chips that come in.

Doug: If I bring you a 48-inch wide, four-foot long stump or whatever it is, piece of a tree, what does it look like that you're dumping that into? It's got to be a huge machine, right?

Nate: It is a huge machine. Yes, sir. We have a more bark 1300 tub grinder that processes most of the really large material that's brought into our operations. It has a large grapple kit, capable of lifting about 5,000 pounds. The tub itself is about 12 feet, six inches diameter. As big a piece that you can bring us into our facility, we can process through our Morbark 1300. The first process from grinding wood down to a smaller product and manageable product for our regrind goes through screens on the backside of the mill.

The mill takes the material in through the tub as it spins, the material is then ground with 20 teeth. That brings it down into the mill and cuts those really big pieces of wood into long shreds of wood, so that it's a little bit easier to refine into mulch products of different particle size.

Doug: You call it biomass, is there any biomass from a tree operation that you can't take, or does any tree work?

Nate: Any tree works. We can take anything in. The only thing that we don't take is yard waste because yard waste requires an IEPA permit to hold that material on our site. Leaves, branches, stumps, wood, anything from recycled trees that have been removed from pruning operations or removals. We take it and we make that back into mulch, and we put that back into clients products.

Doug: I understand that you're making the big tree smaller through that grinding, but then, how does it end up looking like mulch?

Nate: Great question. Chips that come in, we make multiple products. When we first started, we made double ground products in East Dundee, which was raw wood chips, basically ground. Twice more through a small horizontal grinder and inch-and-a-quarter screens, which made it a very nice product. That's been one of our stable products that's gotten us into the marketplace. Now we're up to 10 different products that we sell, ranges from a premium, which is a more shredded product, which has a nicer matting characteristics for the bed. We have our double ground, we have a triple ground.

We also have a process for making hardwood fines through a trommel screener. For example, that material will come in in wood chip format. We'll grind that through a Morbark 1000, which is a smaller tub grinder. That goes through a Phoenix 2100 trommel screener, and that drops all the fines from the wood chips that holds all of the nutrients, the nitrogen, all of those things. That gets and sits and ages. It breaks down into a really nice dark, rich color, then we sell those hardwood fines. It's probably one of our more desirable products that we manufacture here. This year, we're introducing color products. We're making black, brown, chocolate, red, and then any other colors upon request.

Doug: I'm glad you're here because I need you to break down for me what the different types of mulches are and why people use them. Talk about the premium. What is it about the premium that people love?

Nate: Premium products for mulch have a lot of benefits. They're ground through screens. When I talk about particle size with mulching and what's best for your soil, we take different size screens, which affect the particle size for mulch. With premium, we try and narrow that down to an inch and a half. One of the things that's been done throughout our region and it's been explained to our clientele for years, is to put down two to four inches of mulch in your landscape and garden beds. Yes, we agree with that two to four inches being a good amount to apply to those landscape garden beds.

Unfortunately, year after year after year, if you continue to put down that two to four inches of mulch, you actually over apply that mulch to that garden bed, which can create too much moisture and not allow that carbon dioxide to be released from that. We really do want to maintain that two to four inches. When we talk about our premium products and I explain this to our clientele. We've done a really good job of lowering our particle size down so that it becomes more of the soil composition through its decomposition process. You don't have to remove that material every year or two years by being over-applied.

A lot of the mulch products that you'll see on the market and premiums have a lot of really large wood particles. We want to reduce those wood particles because that takes a lot of time to break down in your soil beds. What we're really after and the benefits of mulch are obviously moisture retention, that gas exchange from oxygen to carbon dioxide, oxygen coming into the soil, and carbon dioxide being released. Also, the maintenance of moisture within your garden bed so that your tree is insulated, protected, and has what it needs, the nutrients of water that it needs.

Doug: Do most people, when they're looking at the mulches, feel that the premium looks better too, even though it's going to work better? Is it an aesthetic thing too?

Nate: Absolutely. Like I said, a lot of the mulch products are aesthetically pleasing to our clients. They want their garden beds to look nice. The premium is really an imitation using organic hardwood, or I shouldn't say hardwoods, but mixed species woods and biomass from our tree care operations to imitate bark. In our geographic location here, the majority of our clientele, think bark mulch is the best mulch. I've done a lot of soil compositions and sent a lot of bark products to labs, versus our material. Our material actually holds a lot more nutrient value for your soil than bark.

Now bark does have some great characteristics in terms of moisture retention. In terms of the actual composition and structure of the components in that product, the nutrients are much better with a hardwood mulch. A lot of it is aesthetically pleasing. I think a lot of people have really just become accustomed to that look of bark material. That's why we've made our fine shred products or our triple ground premium product to imitate the aesthetic looks of bark material. Some customers like finer cuts, some customers like bigger cuts. We do offer some variations, double ground, triple ground, premium. Those are slightly different variations of mulch and how they're cut particle-sized.

Doug: The top end is the premium?

Nate: Yes, sir.

Doug: As the particles or the pieces get bigger, we go to double ground. Is that how it goes?

Nate: Yes, sir. I'll give you an example, a lot of strip malls, a lot of your highway mulching, things of that nature, that would be more of your double ground, maybe your triple ground. When we're talking about fine shred or premium, and a lot of the colors, it really comes down to the homeowners, and what look they're looking to achieve. Mulch will always offer great characteristics and great protection, insulation for your landscape beds, regardless of whether it's color or not. Really, the benefits of the scale and particle size are really aesthetically pleasing, and of course, price point.

The larger particle wood like a double ground, is obviously cheaper because it's processed less. As it gets refined and as it gets colored, the price does go up because we're handling that material, we're processing that material into different structures.

Doug: As you said, and this is something I didn't understand, that premium product, the way that that's shredded is better all the way around for plant health, right?

Nate: Absolutely. With the two to four inches of mulch, I explain to customers all the time the importance of knowing how much mulch you have over the top of your garden bed. It is really important. One of the biggest mistakes that I see done in the Chicago area is what we call volcanic mulching. The landscapers will come in and they'll put six or eight inches, and they'll taper mulch down from the color or the stem of the tree down to the garden edging and the lawn. What that does is it actually smothers the color on the tree, which is not great for the tree.

Really, at the base of your root color on your tree, you want a half an inch of mulch. It's really almost next to nothing. You don't want to bury that stem in mulch. Where you want your two to four inches of mulch is actually outside of your color, over the root system, underneath the drip line to help retain that moisture. Obviously, mulch, adds a great benefit for weed control. We're adding, four inches of matted material, which helps weeds from coming in.

Doug: Nate, I wanted to see how long it would take until volcano mulch came up in our conversation, and I'm glad that you brought it up first before I brought it up. Because we talk about it on this podcast about every other week because it is such a problem. For you as your whole business is mulch. I ask this question all the time. What's it like when I'm driving in the car with and you see all the volcano mulch, or they're applying volcano mulch? What happens?

Nate: Most of the time, I just have to keep looking on the road, to be honest with you, because it's frustrating when you understand the damage that's actually being done to the trees by volcanic mulching. I actually have been known from time to time to stop and do some educating with landscapers in a Home Depot parking lot and explain, how mulching should be done. Sometimes the response that I get is, "Whatever, just leave us alone. We've been doing this for years."

I actually have some mulching one-on-one pamphlets and things that I've printed out for our clientele, and that the Institute has also provided here at Davey. I just do my best to try and educate around what's best and around mulching techniques. It's very difficult to drive around and watch landscapers put eight, ten inches of mulch right against the stem of a tree.

Doug: Do any of them listen?

Nate: No, they just keep doing it.

Doug: Hey, you're fighting the good fight, though. At least you're trying to educate them.

Nate: Yes, we also do send a lot of communications out to our landscapers. We actually just had something new for North Central Wood Products. We did a luncheon in [unintelligible 00:13:58]. A lot of our landscape contractors came in and we were able to run a Taco Truck in, we fed everyone lunch, and we showed them some of our new products. We talked about mulching techniques, and it was wonderful that the response was great. Some of the old timers will say, that they have been doing this for a long time and volcanic mulching. We're interested in the idea of trying some new things. All we can do is our best to educate and explain to people the benefits of mulching. How to properly install.

Doug: Besides the obvious benefits for the plant and proper mulching, wouldn't a landscaper save a little money if they put it on the right way?

Nate: I think, unfortunately, to be completely honest with you, landscapers want to put as much mulch down as they possibly can, so they can charge more money. One of the things that I've talked to landscapers about is if you go with a hardwood fine product, which is really a smaller particle size, it breaks down in two to three years. I recommend putting down an inch to two inches. I have had landscapers say, "Well, then I can't come back every year, and put down more and more mulch. They won't pay me to have to dispose of all the old mulch, to take that out of their mulching bed."

I think a lot, and not everyone, there's some really great landscapers out there that really do care about the benefits. I think it's just been driven into their heads that this is a routine thing. We're going to put down two to four inches of mulch every year, we're going to volcanic mulch it. Once we get too much material built up, then the customer is going to pay us to remove that material from our landscape beds. Whereas if we put down our two to four inches originally when the tree is planted, and then we come back next year, maybe in the fall. Or maybe two years down the line, we put one to two inches in there, we were really able to maintain that two to four-inch, mulch over the top of that landscape.

One of the things that my clients always say is, "Well, it doesn't look great if I skip a year." I say, "Absolutely." Really, all it takes is a garden rake and a little bit of time. You can ask your landscaper to do this, to go in with a hard rake and rake over your mulch and freshen it up. The color of that material that's underneath is exactly what we're doing in our mulch operations. It's natural decomposition by the material turning aerobic and anaerobic and with moisture. By raking over your garden beds, you still get a really aesthetically pleasing look. I think that you're just so used to applying more mulch and more mulch, and more mulch. Really, what I try and tell people is, "You don't necessarily need that."

Doug: That's interesting insight, an inside look at the business. Talk to me a little bit about colored mulches. That is becoming a big deal. Is that okay for the trees?

Nate: Yes, it is. We've teamed with a color company that's really spent and taken a lot of time to formulate a really great color product that's made from all-natural materials that are not toxic to plant material. When we first started our operations here, we were like, "No color, no color. We're not doing this." There were a lot of reasons for that. One is obviously we're adding chemicals to wood products and then we're putting that back into the ground, which isn't what's best. The other argument that was always brought up is the amount of water that it takes to color mulch. We do add a lot of water in our coloring operations.

Teaming up with a really good company that makes a superior product, because of the heavy pigmentations and color, we're able to use a little bit more water, but there's less chemicals actually being put on the mulch product. We're able to use a lot less color and a lot less chemicals. The chemicals that we are using are very, very natural. It's really all about aesthetically pleasing. I have this conversation with clients all the time. They're like, "I like all-natural products. I understand the benefits of, but the color just holds this color much longer." I can't argue that.

When you're making mulch, we hold mulch and we age mulch for sometimes six months, depending on what that product is to get that really dark, rich color. In all honesty, the sun is always going to fade the color. It doesn't matter if it's colored mulch or all-natural mulch, it's always going to fade. All-natural mulch will absolutely gray out in UV light faster than that coloring. Because you have the color pigmentation that's absorbed into the wood that will hold that color a little bit longer. Again, I always explain to my customers, you can always take a hard break and roll your mulch over.

I always get the comment back, "Well, that's a lot of work to do. I have a lot of garden beds." I say, "Well, that's totally up to you. We've done the best that we can to create a color product that is the least invasive to your plant beds.

Doug: What is the most popular color?

Nate: We sell a lot of brown and chocolate. That's really the most popular. In terms of commercial, black has actually been a really big seller this year. There's been a lot of homeowners associations going with black mulch and also red, it breaks my heart to make red mulch, but there is some profit margin in it for our mulch company. I'm not going to lie. We do sell quite a bit of red, but brown and chocolate are by far, the most popular.

Doug: You need a t-shirt that says it breaks my heart to sell red mulch.

Nate: It does. It really does.

Doug: Nate, tell me a little bit about why this job is right for you and how you got into this.

Nate: I started off as a crane operator here at Davey, because of my heavy equipment background, I transitioned into mulch. I'm really passionate about it. I'm really passionate about being able to recycle wood waste and not put all of that material into landfills, be able to recycle that in-house here. I'm here for the long run. Now that I'm engaged in biochar, it's really exciting to be a little bit outside the box with Davey and offer a lot of different benefits. I guess, you will, to a company that knows a lot about trees. I want to do the same thing with mulch here.

Doug: I am glad you mentioned biochar because we've talked about it a couple times on the podcast. I never realized what a positive it was. Before we learn about how you're making biochar, tell me a little bit about the benefits of using biochar in the landscape.

Nate: Absolutely. Biochar has been around for thousands and thousands and thousands of years. It was used by the Mayans. It's a very old technique and product that we used for soil amendments to help neutralize our soil. I believe the Mayans were the first ones that used biochar. It's an exoskeleton that's created through pyrolysis. Pyrolysis by definition is decomposition by high heat. When most people see biochar, they're like, "It's charcoal." I always say, "Yes, it looks like charcoal, but it's not charcoal. What it is is carbon." What we're doing is removing all of the gases from the wood or the biomass that we're processing through this PRD, and we're removing all those.

We have something that's locked up as carbon for thousands of years. The benefits of biochar are extraordinary. Biochar holds five times its weight in moisture. It becomes a host within the soil to attract good fungi, good mycorrhizae. It also helps store and hold all those nutrients. It also helps neutralize the pH in that soil from heavy alkalines and things of that nature, but also add some great water filtration characteristics. Biochar is used in many applications. There's a lot of talk around using it in concrete where it actually increases tensile strength and PSI in concrete, asphalt, and steel.

Where it has my heart is being put back into the agricultural application, back into our gardens, and back into our soil. It's really a great fertilizer. We don't have to put chemicals. It's probably the best organic natural fertilizer that we have because we're attracting all of the good nutrients, fungi, and mycorrhizae into that soil. Where we're holding a lot of moisture, which is really great. We're creating air voids within the soil for oxygen. The benefits are just absolutely fascinating and outstanding. I've been reading a lot of studies put up by the Biochar Initiative and the increase in crop yields for agriculture are incredible.

One of the things that I know in our region here in Chicago is we've really been over-applying biosolids from wastewater treatment plants and leaf litter that's been picked up from your local municipalities. The NRCS has done a great job of putting some of this into the ag fields to help with the disposal of that. What we're doing is over-applying and we're throwing off the balance of that soil composition. Biochar is really what I believe is the answer. Some of the studies and things that I've read is in a couple of years with 5% biochar added to agricultural applications, we can see 20% plus increase in crop yields. Black gold is what I like to call it.

Doug: You're just about ready to start making biochar, right?

Nate: Yes, sir. February of 2023, I was approached by the Davey Institute and some local people here within our organization and talks of starting a biochar kiln and getting into biochar. By September 23rd, we were breaking ground on a building and putting in concrete and infrastructure to house this PRD that we had purchased to manufacture biochar. We are just finishing up our construction phase. We've gotten temporary occupancy to start our kiln, which is wonderful news. It's been a lot of really hard work.

We've been very fortunate to have a wonderful team at the Institute, support and back all the way up to the top of Davey with Pat Covey's support and helping us get this off the ground. Construction phase is almost finished up and we are probably going to be starting the kiln this coming Monday. We're going to be officially in production of biochar.

Doug: What is PRD? What does that mean?

Nate: PRD stands for pyrolysis rotational drum. Again, pyrolysis by definition is decomposition through high heat. The way that biochar is made, the way that we are making biochar, there are all kinds of ways to make biochar. Essentially, what we have is a very long unit that looks almost like a locomotive. We have a primary burner and we have an oxidation box or oxidation side. What we do is we take our recycled biomass. The majority of what will be fed into this PRD unit will be recycled wood chips from our tree care operations. We will then take that material and grind that through an inch-and-a-half screen to make it a very consistent particle size.

One of the keys to making great biochar is a neutral atmospheric pressure, a very consistent moisture content, and also particle size. If you've got all different-sized particles, that material coming through, you're going to have all different variations of carbon content. What we're really looking to achieve is a very high level of carbon. We start our primary burner on our primary side by adding fuel, and by fuel is our ground wood chips through an inch-and-a-half particle size that goes into our primary. Our primary, we raise those temperatures up slowly because the entire unit is filled with brick. We need to make sure that we're raising that temperature very slowly.

We bring our primary side up to about 1000 degrees and then we light our oxidation side. Now, our oxidation side in this process is really what allows us to burn in this unit really clean glass. We're not emitting any pollution into the air whatsoever, which is what's fascinating about the unit that we went with is, usually if you light a fire in your backyard, you have plumes of smoke and all this black smoke and white smoke. There is absolutely none of that because we're able to raise the temperature in our oxidation side higher than our primary. That process has started with natural gas.

Once we get our oxidation house up to 1500, 1600 degrees Fahrenheit, we actually introduce a secondary fuel source, same fuel source, but at a secondary point within the unit. The oxygen and moisture that's being broken into that high heat in this combustion chamber, essentially, actually creates even more heat on the oxidation side. Once we get that reaction and that balance between our primary and our oxidation, I always use this reference, the oxidation is much like a carburetor. If you're familiar with cars, it's a fuel-to-oxygen ratio. Once we get that balance right, this unit runs solely off of wood waste.

We take our natural gas away and we keep our oxidation temperature higher. We bring our material in from our stoker and that runs down a very large barrel that turns at a very slow revolution. That material is being cooked in this kiln at high temperatures, removing all of the gases. What comes out the other end, and hopes to be 90% plus in carbon, and creating a great biochar product that can be used in all sorts of applications. My hope is that we can start within our own Davey organizations, and really start to educate our clientele about the benefits of biochar.

Doug: What does it look like when it's a finished product coming out of that PRD?

Nate: Currently, it looks like charcoal. It almost has some luminescence like a graphite look to it. It's very brittle. You can take a piece of biochar and break it. You can see that it's been thoroughly cooked through all the way. It has this just beautiful, shiny color into it. It's actually a very small particle size. In the industry, we would call what we're producing right now, a medium or a little bit larger than rice. One of the really exciting things that's coming up is the R&D in terms of the refinement of biochar, the benefits of multiple particle sizes, and how those can be introduced in different applications.

We're going to be working really closely with the Davey Institute and some really talented people there to help us really formulate the perfect product. Set some really great education around the applications that can be put out into the marketplace. Right now, it's about, I would call a half inch minus particle size.

Doug: Nate, that was absolutely fascinating. You schooled me on mulch. You schooled me on biochar. That is great. I appreciate your time. I know we will talk again. Thank you so much for being on the show.

Nate: Doug, thank you so much for having me. Look forward to coming back and talking more soon.

Doug: I always learn something during these podcasts and I hope you do too. Now, tune in every Thursday to the Talking Trees Podcast from the Davey Tree Expert Company. I am your host, Doug Oster. Do me a big favor. Subscribe to this podcast so that you'll never miss a show. If you've got an idea for an episode, maybe a comment, send us an email to podcasts@davey.com. That's P-O-D-C-A-S-T-S at D-A-V-E-Y.com. As always, we'd like to remind you on the Talking Trees Podcast, trees are the answer.

[music]

[00:30:01] [END OF AUDIO]