Developing Disease Suppressive Soil with Jill Clapperton

Hi, friends, this is John and this is the Regenerative Agriculture podcast. Today I'm delighted to have with me Jill Clapperton, who I'm certain many of you have heard of. And if you have not, then you're really missing out. You're going to enjoy this conversation. Jill has done a lot of fascinating work over the years in the plains in Canada on developing disease suppressive soils and microbial populations in a broad range of fascinating topics. Gill, I don't want to diminish the broad array of work that you have done. I think it would be best for you to share a little bit about your pathway and the scope of the work that you've done in agriculture and agronomy over the last few decades.

Okay, yeah, we can do that. I started actually. I have a PhD in Plant Eco physiology, so I'm actually more of a plant physiologist than anything else with a fascination with the rise of sphere. So although it was plant ecophysiology, I studied the effects of air pollution, sulfur dioxide, air pollution, on plant photosynthesis, and then how that affected mycorrhizal fungi and then how that affected the biochemistry of the rhizosphere. And I was very lucky early on to be mentored by Dr. Dennis Parkinson, who was a renowned soil ecologist, and then later on by Glenn Bowen and Albert Rivera from Australia. Well, Albert Rivera in the 50s published the first papers on rhizosphere ecology. So I've been very fortunate in my career to be mentored by really brilliant scientists in their field. And then I sort of went on from that. After I graduated with my PhD, I went on to work for Agriculture and Agri Food Canada as the rhizosphericologist. So rhizosphere ecologist means that I was studying the interactions between plants, soil organisms and soils, and not just microorganisms. And there I was very fortunate to meet Dr. Valerie Bien Peltier, who is a renowned acrologist. So she studies mites, soil mites, but started to become very aware that the soil fauna were just as important as all the microbes that we were studying. Eventually I started to work on earthworms and I founded the WormWatch program and also had the methodology developed through the Worm Watch program accepted by the FAO for ecological monitoring. So what it really came down to is we started to really understand that the plant, well, I guess we've always understood that the plant really dries everything that happens in the rhizosphere. So the rhizosphere being the Root, the soil attached to the root, and then the soil that's influenced by the roots. When we do that, you can really see that your most biologically active area in your soil is in and around the roots. So if we think about a crop, then it's in the crop row. It's not in the bulk soil, it will be in the crop row. And then once we're in the crop row, we also start to understand that every different plant species that you grow within your community or crop row, whether you're growing companions or covers or doing multi cropping, multi species cropping, then each one of those plant species that are there exude their own signature of carbon compounds. And when I say that, I'm not just talking about sugars, I'm talking about amino acids and lipids and nucleic acids and anything that the plant makes. And when the plant makes things, they always have carbon backbones or carbon skeletons, let's call them carbon skeletons. And then when we start putting meat on the bones and we start adding, you know, mineral nutrients and oxygens and hydroxyl groups like. Oh, groups and things like that, that make these very long or very short carbon chains, skeletons functional so that they have this ability to do things within the rhinosphere. And some of them will actually call to action phenomena like, so examples for nematodes that can parasitize insect larvae that are feeding on the roots of a plant. Or they'll call to action the rhizobium, because we have a legume and it wants to fix nitrogen. It's not just about sugars. And a lot of people focus on sugars, but it's not just about sugars. There's this whole interaction that happens in the rhizosphere, which is all about predator prey reactions. So soil fauna acting pretty as the predators, and not just them, but also the nematodes and the protozoa, which be also predators feeding on the bacteria and the fungi. Now this is really, really important because if we just had microbes in and around the roots of plants, the microbes would out compete the plant for the nutrients that we put down with our crops, because they're very good at growing new generations and less than 24 hours, and so they use it all up. A lot of people say, okay, well microbes just need sugar. Well, actually they don't. They need a carbon source, which would be like the exodus from the plants. But actually they need amino acids and they need lipids and they need all the things that the plant produces, but they also need iron and Manganese and boron and calcium and all these other mineral elements, the same as the plant does in order for them to grow their skeleton. Grow a skeleton and then grow the meat onto the bones. For example, if we are looking at things that are beneficial rhizosphere organisms, so things that promote plant growth, like a lot of the pseudomonad bacteria, they need a lot of iron. They produce a fluorescent compound that requires them to have iron. So they will actually use the iron in and around the roots, which means that the plant actually has to compete with the microbes for that iron. So if you think about it now, if we go to the next step, then if we have these predators coming in and eating them and then pooping out the minerals and the other form of carbon, then the plant can have access to it. The predators are really important in the nutrient cycling. In fact, they're more important than anything else because. Because somebody needs to recycle all the bacteria and the fungi that are hoarding a lot of the nutrients from the plant. I started working on that, and then I started to understand this whole idea of signatures and how all these different plants, like plants that I would grow between the rows or the COVID crop that I would grow as a fallow replacement, would affect the nutrient density in the subsequent crop. And then it was like, that's really interesting. If I put separate, like keep the plants as monocultures, as a cover, then I have a different nutrient density in the wheat. But if I mix these plants, they have another different nutrient density. So how does that work? It became really obvious that plants exude root exudates that allow them to have access to mineral nutrients that they wouldn't get if they didn't exude, like, acids or bases or calcium or things like that, so that they could bind up the things they need and then bring them in through the plant root and then shuttle them up to the chute. Microbes are very much involved in that process as well. So the rhizosphere is really this factory, if you want to call it this very big city around the roots that has all these multiple functions that is driving your plant health, but it's also driving soil health. Because the mycorrhiza, when plants are colonized by mycorrhiza, they. The mycorrhizae actually change the whole physiology of the root, including photosynthesis. So they will actually stimulate photosynthesis, and then they stimulate the movement of amino acids and organic acids over sugars to the root in order to bathe the. The whole rhizosphere. In a substrate that attracts plant growth promoting rhizobacteria and excludes a lot of your pathogens. Because yes, the roots can actually do that too. They can actually make the root environment or the rhizosphere, so it excludes plant pathogens. Or they can make it because we haven't given them enough nutrition, they can't produce those compounds or they can't defend themselves. And so then we offer openings to some of these pathogens. I started to really, as I was a scientist with Egg Kenna, I started to really understand how earthworms were affected by agricultural practices, how crop rotation were so important for disease. And then we started to play with COVID crops and companion crops and multi species cropping and really understand how the, when things grow together, sometimes they actually grow better than they do by themselves. Eventually that led me to working on my own and moving to the United States with my family and starting my own company, Rise of Terra, so that I could explore more of the things that I was really interested in. And also to work less in academia, but more with farmers. Because I also realized that in a lot of cases I was actually hampered as a research scientist. I was always pushing back against boundaries and pushing back against ideas that people thought were, a lot of my colleagues thought were kind of crazy, but farmers were already implementing very successfully. So it was about being able to work on concepts that were at least 20 years in the future. So for me, that was always, my goal was to always look forward 15 or 20 years and think about where farmers should be or where farmers thought they should be, and then actually work towards an understanding so that by the time all the growers got to that place, we would know a lot more about it and they'd be able to implement things immediately or perhaps even before that. And certainly some of the innovative growers in the world have already sort of surpassed that 15 year window and started doing things within 10 years of us knowing some of these things. I was doing a lot of work with Dr. Ross Welch from Ars at Cornell. He was very helpful in steering me well into nutrient density and the understanding of what nutrient dense food was and how to look at the minerals in food and what that meant. And I'd already seen changes when we had different crop rotations and different cover crops and different companions, but wasn't really fully understanding of it and was thinking strongly about staying in academia to work on.