Subscribe
Share
Share
Embed
Soil microbes play an essential role in releasing nutrients from the soil in a form that our fruit trees and other plants can access. So, if your soil doesn't have a healthy and diverse microbe population, your fruit trees will not thrive. The problem is that microbes are so tiny that we can't see them with the human eye.
How do we know if we have a good microbe population? According to the Soil Conservation Council of Canada all you have to do is bury a pair of 100% cotton underwear in the topsoil of your garden. Leave your undies in the ground for a couple of months. Then, when you dig them up see what they look like. If your soil microbes have been busy digesting and recycling organic matter, then all that will be left is the elastic waist band.
To learn more about this process, I've invited two experts from the University of Guelph to talk about the "Bury Your Briefs Campaign" and about the role soil microbes play in keeping our fruit trees and other plants healthy. They are Cameron Ogilvie, Knowledge Mobilization Coordinator and Kari Dunfield, Canada Research Chair in Environmental Microbiology of Agro-ecosystems.
The host of the Orchard People radio show and podcast is Susan Poizner of the fruit tree care education website www.orchardpeople.com.
How do we know if we have a good microbe population? According to the Soil Conservation Council of Canada all you have to do is bury a pair of 100% cotton underwear in the topsoil of your garden. Leave your undies in the ground for a couple of months. Then, when you dig them up see what they look like. If your soil microbes have been busy digesting and recycling organic matter, then all that will be left is the elastic waist band.
To learn more about this process, I've invited two experts from the University of Guelph to talk about the "Bury Your Briefs Campaign" and about the role soil microbes play in keeping our fruit trees and other plants healthy. They are Cameron Ogilvie, Knowledge Mobilization Coordinator and Kari Dunfield, Canada Research Chair in Environmental Microbiology of Agro-ecosystems.
The host of the Orchard People radio show and podcast is Susan Poizner of the fruit tree care education website www.orchardpeople.com.
Susan is the author of four books on fruit tree care. Learn more here: https://learn.orchardpeople.com/books
She is also the creator of five-star rated premium online fruit tree care education at: https://learn.orchardpeople.com
HOW TO TUNE IN TO OUR PODCAST
The show airs on the last Tuesday of every month on RealityRadio101 at 1:00 PM ET! While it’s no longer live, you can still watch or listen anytime—and catch the recorded podcast anytime afterward.
📺 Video Podcast: Watch the recorded episode anytime on our YouTube Podcast Playlist.
🎧 Audio Podcast: Download the podcast and listen on your favorite app after it airs.
🌐 Article: Read the article linked to the show "Bringing Life to Your Soil: How to Improve Soil Quality Naturally" and find the video and podcast links there too!
✍️ Do you want to learn to grow organic fruit trees successfully? Sign up for OrchardPeople.com's free monthly newsletter at https://orchardpeople.com/sign-up/
For premium fruit tree care education visit: https://learn.orchardpeople.com/.
FOR MORE INFORMATION ON GROWING FRUIT TREES THAT THRIVE:
✂️ How to Prune Fruit Trees:
🪲 Fruit Tree Pests and Diseases:
🌳 How to Feed Fruit Trees:
🍎 The Best Fruit Trees to Grow:
🌱 How to Graft Fruit Trees:
These show notes may contain affiliate links to products. We may receive a small commission for purchases made through these links at no cost to you. Thanks for your support!
- (00:00) - Introduction
- (00:58) - Meet the Experts
- (01:25) - Understanding Soil Microbes
- (04:03) - The Bury Your Briefs Campaign
- (07:13) - Microbial Activity and Soil Health
- (10:15) - Best Practices for Soil Health
- (15:13) - Bacteria in Soil
- (18:10) - Understanding the Importance of Consistent Testing
- (19:13) - The Role of Fungi in Soil Health
- (20:47) - Exploring Soil Organisms: Beyond Bacteria and Fungi
- (22:02) - The Fascinating World of Springtails
- (22:52) - Debating Soil Minerals and Rock Dust
- (25:21) - Actinomyces: The Source of Healthy Soil Smell
- (27:15) - Studying Soil Microbes in the Field
- (28:36) - Urban Agriculture and Soil Microbiology
- (31:02) - Bio Fertilizers: A Sustainable Alternative
- (34:34) - Nurturing Soil Microbial Populations
- (39:01) - The Importance of Soil Microbes
- (42:11) - Conclusion and Final Thoughts
Creators and Guests
What is Orchard People?
Learn how to grow and care for fruit trees with fruit tree care educator Susan Poizner of OrchardPeople.com. Discover how to create permaculture plantings, food forests, and forest gardens in both urban and rural settings. Meet experts on all aspects of comprehensive fruit tree care, including pruning, pest and disease prevention, fruit tree grafting and budding, and soil management.
Show host Susan Poizner, creator of the fruit tree education website OrchardPeople.com, is an award-winning author of three fruit tree care books and an ISA Certified Arborist. This podcast is the winner of the 2021 GardenComm Silver Award of Achievement for Broadcast Media: Radio Program Overall. Learn more and access archived episodes at https://podcast.orchardpeople.com/.
Learn more about Susan's books and courses at https://learn.orchardpeople.com/books.
#068 Bury Your Briefs to Evaluate Soil Microbes with Cameron Ogilvie and Kari Dunfield
[00:00:00] Introduction
Susan: Hi everyone. Some people have pet goldfish. Others have dogs and cats that they nurture and care for, but me, I have to be different. In the last few months I've been learning a lot about soil science, and now my favorite little creatures are the beneficial microbes in our soils.
Now, I don't love soil microbes because they're cute. I don't really know what they look like because these organisms are so small that you can't see them without a microscope. You can't pot microbes and they don't bark and they don't chase a stick. But they are so worth taking good care of and nurturing.
And that's because soil microbes help us grow healthy plants and trees. Soil microbes include bacteria, fungi, and millions of other tiny organisms in the soil. And so that's what we're going to talk about in the show today.
[00:00:58] Meet the Experts
Susan: My guests are both from the University of Guelph in Ontario. They are Cameron Ogilvie, Knowledge Mobilization Coordinator, at the University of Guelph.
Hi Cameron.
Cameron: Hi there. Hi.
Susan: And we also have Kari Dunfield, Canada Research Chair in Environmental Microbiology of Agro Ecosystems. Hi Kari.
Kari: Hi. Thanks for having me.
Susan: It's great to have both of you on this show.
[00:01:25] Understanding Soil Microbes
Susan: So now let's talk about soil bacteria and other soil microbes. So let's start with you, Cameron. I want to talk about what these creatures are. What are these organisms? What are soil microbes?
Cameron: Yeah, so you've already mentioned a few of them. Bacteria, "fun-guy", "fun-jee", whatever you'd like to call them, but there's a bunch of other microorganisms and really we're just categorizing them based on size. So these are organisms that are in the soil that we need a microscope to, to really look at and observe. We call them mesofauna or macrofauna, which are larger than that. But these are microfauna or microorganisms.
They're the very small living things in the soil that really are responsible for a lot of the, the major processes that we think about in soil.
Susan: It's interesting that you call them fauna. To me, fauna means they're little animals. Are they considered animals?
Cameron: Absolutely. Absolutely. There's a livestock below the soil surface.
Susan: Amazing. So why is it that soil microbes are so important to gardeners and farmers?
Cameron: Yeah. Soil microbes are really at the heart of the, major cycles that take place in soil. So when you think, about, nutrient cycling, we can, apply nutrients to our soil, but there are a lot of nutrients that are, that are already in the soil, and microbes are a key part of, breaking those down from the other parts that they're connected to and releasing them so that they're available for plant.
microbes are a, key part of, diseases, but they're also, an important part of creating a resilient mic microbial population that prevents disease outbreaks from occurring. so really there's a lot of things going on.
Susan: essentially from what you're saying, I understand that microbes feed our plants for us.
Cameron: Absolutely. Yeah,
Susan: they feed our plants and we, if we're giving our plants synthetic fertilizers, so these are made in factories. yeah, sure, the plants can take those in. They're in liquid form, but there is so much, so many important nutrients in the soil. We can save money on fertilizer if we have a really beautiful, diverse microbe population.
Cameron: That's right, and we're beginning to understand a little bit more about the capacity, that microbes have to supply those nutrients. and, some of what Kari's working on right now.
Susan: So we'll talk to Kari in just a moment.
[00:04:03] The Bury Your Briefs Campaign
Susan: We're gonna get the nitty gritty on what we're gonna find in the soil, but first of all, Cameron, tell me about your Bury your Briefs work.
Okay. Why have you been, what is the connection between soil microbes and farmers burying their underpants in the soil?
Cameron: Yes, bear your briefs, soil, your undies, whatever you want to call the campaign. It, was actually started by a, few Ontario farmers, a couple years ago. and I believe you got some photos that you were planning to share of Blake Vince, who's a very innovative, progressive Ontario farmer who's, who's done this.
Project himself. The idea is that underwear, cotton underwear is really just made up of cotton fibers and, those fibers, that cellulose can be broken down by microbes, different types of microbes. And so the, goal of the, the campaign was to get farmers thinking about. The activity of the microbes in their soil, how much work are they doing to break down, different types of material because as we were talking about earlier, microbes break down plant material or dead material and release nutrients from it.
So you bury these briefs in the ground and, and you come back a couple months later and see how much of that underwear is left.
Susan: So let's have a look. We'll briefly put on, for those of you who are watching on Facebook Live, we're gonna put up a picture of Blake's underwear. This is before he planted it in the ground, buried it in the ground to test it out.
So you've got a before picture. Blake is holding his undies and they are white and fresh, and he's in a field. Okay, so now after that, he buries the undies for a little while and digs them up in a couple of months. Let's have a look at what those underpants look like, let's say two months later. So that picture is going to come up on Facebook Live if you're watching it on Facebook Live.
Here it is, Blake, with his underpants and all you can see there is an elastic waistband. A little bit more, they look a little bit like a thong. It's all gone. Yep. So for those of you who have seen that, so Cameron, help me understand, these creatures in the soil, they don't have teeth. How is it that they are tearing apart underpants and eating the bits?
Cameron: Oh, that's a good question. I'd love Kari to chime in on that, that a little bit too. But part of what you might think about in the way that we di Digest food is, yeah, we've got our teeth, which crush, which crush our food and help break it down. But really there's a lot of, we call them enzymes.
In our saliva. So it's chemicals that we release, which those chemicals are actually what's part of allowing the food to break down in our mouths and in our digestive system and release those nutrients for us. And so microbes do that as well. They release. Chemicals, types of enzymes, which allow them to access the nutrients and the food that they're interested in.
[00:07:13] Microbial Activity and Soil Health
Susan: So Kari, I'm gonna get you to pop up and answer that question, and as well as a question from James in Toronto, is there a correlation between soil microbes and earthworms? For example, if you have no earthworms or very little, does it also mean less microbes? So it's a tricky
Kari: question. another way that people look at soil health.
So one of the ways is bury your underwear, but another thing that people suggest to do is to count earthworms with the idea that the number of earthworms in your soil indicates a healthy soil. The tricky part is some soils actually don't have a lot of earthworms in them natively. If you're in a forest, in Ontario, there's probably not very many earthworms.
So it just depends. But it definitely is an indicator of, higher soil biodiversity. So it is another test to look at the microbes in your, the earthworms in your soil.
Susan: Interesting. Also, we have a question here from George. I'm not sure where George is from. One of you guys can take this question. It's a good one.
What about colored underwear? Not white?
Cameron: That's from
Susan: George.
Cameron: Yeah. Good question. Yeah. Then I think, oh,
Kari: go ahead. Go ahead,
Cameron: Kari.
Kari: Oh, I think the original, experiment is with like cotton, no dyes. No. so you want it to be white underwear. I have seen people do experiments with pigments because there will be organisms that are breaking down those pigments and it's another test.
But if you're actually gonna do it in the soil to check out your activity, I would use white cotton briefs.
Susan: So I'm gonna go back to you, Cameron, 'cause I know that you've worked with farmers specifically on this. Does it ever happen that they bury the briefs? They bury their undies and dig them up a couple of months later and they are actually not eaten. They're whole.
Cameron: A hundred percent, and the reasons for that can be varied. So as we're saying in simple terms, this experiment should show how active the microbes are in the soil. And so, presumably, if you have a larger microbial population, you'll see more breakdown of that underwear. But microbes can be active or inactive for different reasons as well.
If there's a limited amount of water in the soil, that will reduce microbial activity. If the temperatures are too hot or too cold, that's going to change which microbes are active. And so I knew a grower, for example, who planted a pair of underwear in a field that he thought was really good, really healthy, and just because of the season that he had, where it was a little bit drier, a little bit less rainfall, he didn't see the same breakdown that he was expecting. So there's a lot of variables that play into how active microbes are in the soil.
Susan: So we have a question as well here from Chris from Toronto.
[00:10:15] Best Practices for Soil Health
Susan: What is the best way to make the soil habitable for the microbes? What should we be feeding the soil?
Cameron: Great question. Yeah, so we typically talk about five practices. I'll try to just run through them briefly. Number one is reduced disturbance. So minimize how much you're mixing up that soil. It's like a tornado coming through your house. It breaks apart all the structure, all those little homes that microbes have there.
So reduce disturbance, rotate your crops really well that provides different food sources for the microbes. Keep the soil covered. This is part of insulating that soil. Think about insulation on your house. It keeps your home temperature regulated. Microbes like to be regulated as well. Keep living roots in the ground as much as possible.
This is part of good food sources for microbes. So the more time of the year you've got roots in the ground, the more those roots are releasing food material, feeding those microbes. And then the fifth is incorporating livestock, manure, compost, and other organic amendments. These are just other food sources for microbes.
Susan: We have an email from John. So John says, hi I wear boxers, love the topic. Ha. Hello to all. Thank you, John, for writing us. Thanks John. And I wonder if John is gonna be running out to the garden to bury his briefs. I.
So
Susan: we'll see. So how do you feel that this campaign has given people a little more sensitivity to the importance of the role that microbes play?
Do you think that they were, they've been overlooked for a long time?
Cameron: Yeah, so you could maybe drum soil science down into three areas. So we talk about the physical aspects of soil, the chemical aspects of soil, and the biological aspects of soil. And I'd say it hasn't been until the past 10, 20 years when we've really started talking about the biology. We were big on soil structure, physical properties, big on the chemical properties, nutrients, and understanding things like this. And now we're getting into the living aspect of the soil, which, really, the living aspect is the reason why we've got the physical and the chemical things working properly.
Susan: I put this on Facebook and there was so much chatter about it. A lot of people, gardeners, fruit tree growers who wanted to try it, and there was a really interesting message from Dee, from Wisconsin. So let's see what she wrote on Facebook. It's very common in farming both dairy and crops to do this.
We haven't on our new farm yet, but we did on our last, and it was a great test. It's best to do it at regular intervals to track soil health and impact new or different methods on the soil. She says check out the studies on no-till versus conventional tillage and cover cropping or no cover cropping.
And she says, it's fascinating how much healthier one soil is over another. Yeah, and she says that you should dig them up in exactly 30 days. She says do one to three pairs per field to get a better understanding of our soil health across the farm. So this is no joke. Dee is from Wisconsin. This isn't just in Ontario.
Cameron: That's right. it really has spread and it's elevated the conversation for sure.
Susan: Yeah, I think it's important. We have a question, live question from Facebook Live right now, and it's from Brent from Michigan. Hi Brent. In my garden, I like to feed fungal and bacterial side of the soil in the fall so I can keep an even balance between the two.
I know veggies like more of the bacterial side. This is how I feed my bacterial side. It's with dried molasses and fungal with leaf mold. Tell me what you think. And Brent says, I have never buried my underwear.
Cameron: Maybe Brent will be burying his underwear this summer. I'd be interested to follow up on that.
But what he's talking about there, is molasses as a sugar source. And so yeah, I think the general idea that he's going off of is that bacteria, maybe, feed off of some of those more readily available sugars. So molasses would be an example. And then, leaf mold, I think he was saying, for fungi, which tend to be a little bit longer.
Feel free to help me out, Kari, with the word that I'm looking for. But
Kari: residence time, like it survives in the soil for a little bit longer.
Cameron: Yeah. Or the more difficult or the
Kari: longer. Oh
Cameron: yeah. They're getting better. Yep. So Sounds good.
Susan: Yeah.
[00:15:13] Bacteria in Soil
Susan: So Kari, let's go over to you right now.
We've been talking about fungi. We've been talking about bacteria. Let's start off with bacteria. What are they? How are they different from fungi and how are they helping us in the
Kari: soil? Bacteria are probably my favorites, because even they're really hard to study, but there's like billions of them in every teaspoon of soil.
So they're not just really abundant in your soil, but they're really diverse. So we think of bacteria as using sugars, and we think of them one way, but they actually have a lot of different capabilities so they actually can live without oxygen. They can live with oxygen and they play a lot of different roles in the soil so they do a lot of things like transformation of nitrogen and sulfur and phosphorus. And because of their incredible diversity, they have a lot of really key roles in the soil. So that's why they're really important.
Susan: So I just wanna flag what you said. You said there are literally billions of bacteria in one teaspoon of soil.
That's
Kari: right. Billions. And we don't, they're tricky too because we don't, we can't name them and we can't see them. So we have to use kind of different techniques to be able to study them. So they're
Susan: great. And, what do these bacteria, when, if I were to say, what do they look like? What would you say?
Kari: I would say, I could tell you what 1% of them look like 'cause that's the amount that we can actually grow in the lab, and then, and you can picture them. So you'll see little plates of bacteria and they look circular when you grow them on agar. And you can visualize them. But those ones are a very small fraction of actual bacteria. So there's actually 90% of bacteria that we have a gene sequence for, but we have no idea what they look like and we've never grown them. So we're not sure what a lot of them look like.
Susan: Wow. Okay.
We have an email from Laura. So Laura writes, hi, do panties work? Hilarious.
Kari: If they're cotton and white. Sure. If they're cotton and
Susan: white, it'll
Kari: work well.
Susan: Okay,
Cameron: and the interesting part about it is different types of underwear material is going to have different types of fibers in it. Some of them are gonna be thicker than others. Some will be more easy to break down than others.
And so it's going to change the experiment a little bit. But
Kari: yeah, if you're gonna put it in different fields, just make sure you use the same type of underwear. If you're gonna compare.
Susan: Yeah. that's a really good point. So don't use your panties in one field and then your briefs, your husband's briefs in another.
They don't have to be like, brand new, do they? On Facebook, somebody else has said they have to be Fruit of the Loom and they have to be new.
Cameron: Correct. Yeah.
[00:18:10] Understanding the Importance of Consistent Testing
Cameron: So this is all just part of trying to make a consistent test that you can compare between different people. If you have, if you have old underwear, it's already going to be partially broken down.
Maybe this freaks you out, but it's all also partially inoculated. You've got your own microbiome, which you're sloughing off onto your briefs that you're adding to the ground too. So yeah, get a nice clean pair. White, Fruit of the Loom is great, Hanes, whatever, any of those basic name brands.
Susan: Oh, thanks for finessing. I've got somebody else on Facebook Live. Let's see if I could find it on an earlier Facebook conversation. She writes here, Renata from Kentucky, says I've never heard of that, but it's fascinating. I'm going to have a rummage through my husband's underwear drawer as soon as he sets off for work.
Kari: It's a good way to get rid of some of them too. Exactly.
Susan: Oh, there's the ones with the holes in them that I wish he would finally get rid of.
[00:19:13] The Role of Fungi in Soil Health
Susan: We talked about bacteria. How are fungi different?
Kari: Fungi are really important in the soil. They're different.
There's not as many of them in the soil as bacteria, but actually, because they have hyphae, mushrooms are fungi, so they grow with this hyphal network, they actually cover a huge amount of soil. So there's actually more biomass of fungi than there are bacteria just because they're bigger.
And one of the key differences is that they are aerobic, so they need oxygen all the time. So that's when you say you're aerating the soil, fungi needs to have oxygen to grow, whereas some bacteria don't. And that's a big difference. And they're often growing on organic material.
So they're growing, they're feeding off of that organic matter. So those are some of the
Susan: big
Kari: differences.
Susan: And yet they still do a similar type of good work. They're helping to process nutrients, and again, living symbiotically. So helping our plants and trees while the trees and plants help them.
It's kinda partnership.
Kari: Yeah, they have some really cool relationships with plants that we sometimes hear about. So are arbuscular micorrhizal fungi, which are AMF. They have a really unique relationship with many plants where they a symbiotic relationship.
So they get carbon from the plants and they supply the plants with nutrients and access to water, phosphorus usually, and so it's a really neat symbiosis that exists.
Susan: Amazing.
[00:20:47] Exploring Soil Organisms: Beyond Bacteria and Fungi
Susan: Kari, we were talking earlier, we talked a little bit about bacteria in the soil, and we talked about fungi and the difference, but I understand that there's a lot more creatures in the soil or organisms in the soil than that.
Can you tell me about another, for instance, organism that we might find in the soil?
Kari: There's, like Cam said, there's a whole world down there. So there's tons of different types of organisms there. And so mostly the bacteria and the fungi are the smallest organisms, but there are many organisms that feed off of bacteria and feed off of fungi that play a really critical role in what we call the soil food web, so they are feeding off of each other. So for example, one would be springtails or Collembola, and they are little microfauna that eat mostly plant material. And so they're also really important in this carbon sequestration or converting organic matter into nutrients that are available for plants.
Susan: Another, oh, sorry. Go.
[00:22:02] The Fascinating World of Springtails
Susan: I just wanna ask about the springtails, because I know, because you mentioned to me springtails are one of your favorites.
Cute. You mentioned cute. Why do you like them? They're cute.
Kari: They're cute, but they also play a really important role. And they actually, they're also really sensitive to things like pollution they can be an early indicator of soil pollution and soil health. So if there's springtails there, they're very sensitive, so it's a really good indicator that you have a healthy soil system. And we actually use springtails as a toxicity test 'cause you know that they can't survive pollution very well. So they're indicators of that. So that's one of the reasons they're really useful and really a neat organism.
Susan: Oh, I wanna learn more about springtails.
They sound cute. And I've got a picture of them. I'm going to share later.
[00:22:52] Debating Soil Minerals and Rock Dust
Susan: We have a message here from Brent on Facebook, and Brent says there has been a long debate between mycologists if there is enough minerals in the soil from sand, silt, and gravel, or do you think it needs rock dust to replenish the minerals? The mycelium break it down and feeds it to the plant. I wanna hear what your opinion is on that.
Kari: I believe it depends. I think what we're talking about is probably access to nutrients. So the way that we get nutrients in the soil is by breaking down rocks, and converting to forms that are available to plants.
So they need to be in a soluble form so plants can take them up. And so especially around phosphorus, phosphorus is bound up a lot of times into what we think of as rocks. And so micorrhizal fungi or other types of fungi can really have an important role in releasing that phosphorus from, bound up as rocks, and make it available in soil solutions so then the plants can take it up.
I think that's what we're talking about here. And they do have a really important role in some soils in releasing phosphorus from mineral form.
Susan: I think also what Brent is mentioning is you can buy a product called rock dust. Okay. And it promises to be bringing like X amount of minerals into your soil.
So the question is, are you wasting your money? Does your soil have enough minerals? And we just need the soil organisms to break it down, or do we need to buy a product called rock dust? Rock dust?
Kari: I think that, it's gonna depend on your soils, because some soils, if they're very sandy, especially if you're growing plants that need a lot of nutrients, you might need to add some type of fertilizer.
And in those soils, then one method is to add like a rock phosphate or a rock dust into your soils, and then you're counting on the microbes to be able to break it down and be able to make it available to the plant. So it's a combination. You need the microbes there, too.
Susan: We talked about fungi and we talked about bacteria. Is there lots more that we will find in the soil? Maybe give me another family of fauna that we would find in our soils.
[00:25:21] Actinomyces: The Source of Healthy Soil Smell
Kari: I was thinking one thing that you might be interested in is actinomyces, which are a thing that's a hybrid between a bacteria and a fungi.
So they actually are what causes, when you smell soil, when you think of what healthy soil smells like, that's actually actinomyces population in your soil. So that's what causes that smell. And so they look like little organisms and they make hyphae like fungi, but they're actually a type of bacteria.
So they're a really cool organism and they are responsible for that soil smell that you smell when you're smelling a handful of soil.
Susan: So now, we've been talking about these very tiny creatures. Now, how on earth do you actually see them? Can you take some soil and put it under a microscope and then you can see what they look like? Or how does that work?
Kari: You can do that. But actually what we do is use their DNA, so we use a molecular fingerprint like you would if you were gonna fingerprint, a DNA fingerprint for someone. And so that's how we study the organisms. And that's really necessary. And that's one of the reasons why soil biology has become so much more understood in the last 20 years 'cause these methods have been available that we can now study them and be able to track them in the soil and understand the organisms that are there.
Susan: So you're saying that you get them, not necessarily, from the microscope, image. I saw an image of taking, maybe you can describe to me how they take the sample in a...
Yeah, you can explain better, you know what I'm talking about.
[00:27:15] Studying Soil Microbes in the Field
Kari: What my group is really interested in what the organisms are doing in the field, not necessarily what they're doing in the lab, but what they actually are doing when they're out in the field and they're interacting with the plants.
And so in order to do that, what we do is go out to the field and grab just a small amount of soil. You actually don't need hardly any, you need 0.2 grams of soil because there are so many organisms in there. And we put it into a little tube, and then we take that tube and we freeze it in liquid nitrogen, in the field.
And so that captures the organisms exactly how they were when they were in the soil, and so then we can study them and understand what they were doing in the field.
Susan: And what were they doing?
Kari: We're really interested in things like, how much nitrogen they're exchanging. So we look at things like nitrogen cycling and organisms can produce greenhouse gases.
So we're interested in that kind of stuff. We're really interested in phosphorus solubilization, so that's the transfer of organic phosphorus to plant available phosphorus and those types of things, that's what we're mostly looking at. So lots of nutrient transformation.
Susan: So we have an email from Dan from Toronto.
[00:28:36] Urban Agriculture and Soil Microbiology
Susan: I know this study has been applied to large scale farming, but can this also be applied to a more urban type of raised bed? Have any studies been done on this? I ask because there are more people growing food in a controlled type bed.
Kari: Yeah, I believe that it would work in a raised bed, and I think that it would be a neat experiment to do, and I think it would be really cool to transfer it to an urban agricultural setting. And the Agricultural College at Guelph, we are realizing how important urban farming is for feeding people, and so I think that's one of the things that we're really interested in is moving into learning more about urban agriculture, and yeah, for sure if people are gardeners at home and they wanna try to study their microbiology, I think would be a really good way to start that and just see what's going on in those beds.
Susan: And I would just want to chime in and say, please do it everybody, and send me before and after pictures. I would love to do a blog or an article about what people's findings are, especially if you're an urban grower. Let's see what's happening in our urban soils. So I would love to see your pictures. You can send them to info@orchardpeople.com and that would be fantastic.
I think in
Kari: a raised bed setting, you actually have a really cool ability to do an experiment 'cause you could add compost to one and not compost to the other, and you can just test out like what's working better.
Do you see differences? And so you have really cool opportunity to do some neat experiments in your garden.
Susan: And by adding compost, are you adding food for the biology and the soil, but are you actually adding biology as well? Are you adding, tell me about that.
Kari: Yeah, you definitely are adding both.
You're adding the nutrients, you're adding carbon, and then you're also adding an inoculant, probably, of some microorganisms that come from that compost and are being added to your soil. So you don't necessarily need it 'cause you have, you don't need that inoculant necessarily 'cause you have organisms already in your soil.
But it's a good way to get a stimulation of the microbial community there.
[00:31:02] Bio Fertilizers: A Sustainable Alternative
Susan: I know there's also a lot of excitement around new products that are actually bio fertilizers. Can you explain to us what a bio fertilizer is and, how, or whether, it can help our gardens?
Kari: Yeah, bio fertilizers are actually just, it's short for microbial based fertilizer.
It's just replacing chemical fertilizers with a biological, like a microorganism. And we think of them as being new, but actually I think the first one was released in like 1895, which was a rhizobium. So we've known about microorganisms that can provide nutrients for a long time.
But, there's just been a lot of products recently that people have been using and gaining a lot of popularity. If you think about environmental impacts of chemicals, one of the things is replacing those impacts with a microbial fertilizer might be better for the environment.
So I think that's why they're gaining popularity.
Susan: And do they work? And what is it? Is it frozen, or I guess dehydrated, organisms that somehow come back to life when you pour them in your soil?
Kari: It depends on the organism. Some of them have worked for a long time. So Rhizobium is an example where it can take nitrogen from the air and convert it to a form that's available for plants.
It only works with certain types of plants. It has to be a legume. So that's one limitation for that. But there's other nitrogen fixing organisms that don't need that association with plants. It depends on the product. So one of the things is, do the manufacturers of the product guarantee that the organisms are alive and are they in a form that they're gonna grow and survive the commercialization process.
And so those are the things that the manufacturers have to consider, and you need to know that the organisms are still alive when you're putting them in the soil or else they're not gonna do anything for you.
Susan: And so that's a really good question. So I wonder if here in Canada or in the United States, if you, if they have to prove.
Can I just put together some white powder and say, this is microorganisms for your soil, or do I have to prove that white powder is actually living microorganisms, that it will help your soil? Are there rules about that? So in
Kari: Canada, there's different rules in Canada and the US, but in Canada, they do regulate microbial innoculants under the Fertilizers Act.
And so for Rhizobium, for example, they have to prove X number of viable particles per gram of inoculants. So if you're buying something like that, I think I would be looking on the bag for something that says that this guarantee of viability, because you want those organisms to be able to live.
Susan: So people who are listening to this like me. It's just like bottom line, I really wanna have happy microorganisms in my soil. I really do. I'm thinking that I need to be nurturing the soil rather than the plants and that these microorganisms will do everything for me. But help me to get there.
[00:34:34] Nurturing Soil Microbial Populations
Susan: So if I can't pour it out of a bottle, summarize a few different ways, and I know that Cameron did that earlier, but what is the most important way that we can help support these microbial populations in the soil?
Kari: So that's exactly it. I think the microbes are there and you just have to nurture them.
And so that's why unless you have a problem soil that doesn't have a lot of microbes for some reason, you can probably just use techniques to nurture your own microbes, and those microbes are already adapted to your system. And so that's probably the best way to get a healthy microbial population.
And what we're looking for, and what we mean by healthy is usually biodiverse. So you want a bunch of different kinds of organisms. And so the ways to do that is, a lot of times adding diversity above ground. So in agricultural systems, we say crop rotation or adding cover crops or a different type of plant.
So it's not just one monoculture. So if there's a way that you can add a cover crop or add some type of different plants into your system, each of those plants is gonna feed a different microbe. And so you'll have different types of microbes there and that's what you want, and also anything that puts organic matter back into the soil. So keep your plant residues on the soil for as long as you can and get those nutrients mixing into the soil. Minimizing tillage. Tillage is tricky for microorganisms because it, like Cam said, you're usually turning over the soil, especially inversion of soil. If you need to till, if you can minimize soil just being completely inverted, that's gonna make a big difference in your microbial population.
Susan: Cameron, I wanna ask you, having worked with farmers, what do you think makes the biggest difference in terms of improving the microbe population in the soil?
Cameron: Yeah. So I don't think that there's going to be one solution that fits all cases. I think it really starts with a commitment from the grower, and then they will find solutions that work for their system because I think we really do need to acknowledge that one farming system is not the same as another. But to think about general practices, let's just compare crop rotation to cover cropping, let's say. So with crop rotation, this is really dictating the main crops that are being grown for the majority of that growing season.
And cover crops are really just being fit into the shoulder seasons. If you're planting them after corn, you've got from, let's say, late October into the time that you plant some crop next season. So there's less growth that happens with those cover crops. Tremendously important, but there's less growth, and so I'd say prioritize getting a good crop rotation in place, and a good crop rotation will have a greater impact on your microbial population than or your microbial community than cover cropping, though cover cropping remains incredibly important.
Susan: So it's amazing. So it's biodiversity, it's organic matter. One thing that I've started to think about is watering, which I can get really lazy about, and I think, oh, it'll rain in a few days. But something that I learned, I don't know if it's true, but the fact that many of these organisms need water in order to move around and slosh around in the soil.
So if I'm not watering, I'm not nurturing those populations. Is that correct?
Kari: That's true. They can get by with very little water probably too. Because they can live, like they live right in the middle of those soil aggregates so they can access water so they don't dry out as quickly.
But if you want a population to grow, then they definitely need water. So that's something that you can think about. The one cool thing about microorganisms is some of what they do for plants is actually help make them drought resistant. Because they're so small, they can access that water that's trapped in soil aggregates that the plant roots can't access, so they can actually help plants acquire water when in drought situations.
[00:39:01] The Importance of Soil Microbes
Susan: Until now, we've been talking about the good guys, the good bacteria, the good fungi. So are all microbes in the soil good guys? Or are there some bad guys as Well,
Kari: I like to focus on the good guys, but there's definitely plant pathogens. There's definitely bacteria and fungi that can grow on plants and that's what they do.
And if you think of there's billions of microbes in a gram of soil or billions of types of bacteria and fungi. You can name probably a dozen or so pathogens that are really key to orchards or have key economic impacts. And so they're very important to study and important to control because obviously they have a huge economic impact, but there's a few bad guys, I think, in the whole world of good guys out there.
So you
Susan: like the good guys? Why do you, okay. But we're gonna wrap up. But why do you love soil mi microbes? Why do you spend so much time studying them?
Kari: Oh, I think they're just involved in so many things like you don't even really think about.
It's a microbe that's driving these things. They're honestly regulating, like climate change by the greenhouse gases, and they're feeding, they're driving plant yields and they're holding your soil together. They just have so many really important roles and we just don't really think of them as playing those roles. And so that's why I think they're so important to study.
Susan: And what about you, Cameron, with the work that you've been doing, why do you feel that this is such an important thing to put a stress on?
Cameron: Yeah, I think for me it comes down to the fact that, that soil is not dead. It's alive, it's very much alive.
And so we can think about soil as another living organism, maybe even of itself. And that living organisms, there's a lot of things that they share in common. Yeah, so I think that really elevates the way that we think about soil and soil management. That it's not just a dead substrate that you're working with, but it's a living being, and we need to feed it, in the same way that we are leaning on it to feed us.
Susan: Exactly, which goes back to my introduction. So I'm not getting a dog. I don't know if you guys have dogs and cats. My pets are my soil microbes. What about you guys? You also have dogs and cats, or is it just soil microbes that have your heart?
Kari: We have a lot of dogs and cats in this house too, but we definitely think about soil microbes and my kids think about them. They draw me little bacteria once in a while. So I think that we know about them and talk about them a lot.
Susan: Cameron?
Cameron: Yeah, dogs are, are pets for us.
Susan: what about pet microbes?
Cameron: Oh, definitely Pet microbes.
Susan: Definitely pet microbes. Okay, that's perfect. Just like me.
Okay. Okay. So the moral of the story is most soil bacteria and most microbes are good, but you sometimes get the meanies out there.
[00:42:11] Conclusion and Final Thoughts
Susan: Well guys, thank you so much for coming on the show today. I really appreciate you spending time and bringing some clarity to what's going on under our feet and the importance. And I really wanna thank all the people who sent in questions today, to ask you questions. Any last words before we wrap up? Why we should love our microbes?
Cameron: It's been a pleasure. Thanks for having us.
Kari: Yes, exactly. Thanks for paying attention to them. We're always trying to tell everybody that soil is alive, so it's great too that people are listening to that. Yep.
Susan: Oh, wonderful. thank you so much for coming on the show. So that's it for today's episode of the Urban Forestry Radio Show.