Dr. Jill Clapperton discusses measuring nutrient density, soil health and agronomic research
Dr. Jill Clapperton is the principal scientist and CEO of Rhizoterra Inc. and the founder of the Global Food & Farm online community.
Jill has decades of experience helping farmers and food companies solve problems. She has a Ph.D. in plant ecophysiology and is a leading researcher in measuring the nutrient density of food, helping farmers to improve soil health through regenerative farming principles.
Rhizoterra Inc. is an international food security consulting company guiding people, organizations and corporations as they endeavor to create healthy, productive soils that grow nutrient-dense food in a way that honors our farming culture, regenerates arable lands and sustains environmental integrity.
In this interview, Dr. Clapperton discusses her work with x-ray fluorescence — a handheld technology that could enable growers to receive real-time information about the nutritional characteristics of the plants they’re growing. She also goes in depth on the soil food web and its importance, and how agricultural policy can affect soil health. And she discusses the role of researchers in agricultural progress — how both farmers and scientists can listen to one another and support one another better.
Acres U.S.A.: You’ve done some work with an x-ray fluorescence device to test crops in the field — to help growers know whether their management strategies are working or not. Can you describe your work in this area?
Clapperton: We are going for what you, as a farmer, can measure in the field. It’s not that we want to take labs out of business or anything like that. Sometimes you see things in the field and think, “This is X,” or, “I think this is a calcium toxicity, or a calcium deficiency.”
Well, with a handheld XRF or a handheld instrument, you would be able to say yes or no. Then you would be able to adjust immediately. Whereas if you had to send leaves to a lab, you’d get them back in two days’ time. Then you’d adjust. You may have lost some things by then.
I think we’ve always thought that plants don’t require us to be on top of it — like with animal husbandry. But that’s not really the case. I think that we do need to have more instantaneous analytics for plants too.
Acres U.S.A.: How does the XRF work? How accurate is it compared to lab measurements?
Clapperton: I’m using a Bruker TRACER 5i, but they also make what’s called a 5g. The 5g has a graphing window. It makes it more accurate on magnesium. So, on the lower end, what we’ll call the lighter metals — magnesium being a lighter metal, sodium being a lighter metal — the TRACER XRF analyzes any minerals from sodium to uranium. It is fully calibratable. In other words, a lot of the other instruments out there have factory calibrations, but this one allows for custom calibration. It’s a research instrument. It’s every bit the research instrument of a desktop.
That means that you can point and shoot. We do that on twigs, on vines, on tree limbs and things like that. In one pass — set up correctly, with the right voltage and the right amount of current — you can run sodium to zinc in one pass. In anywhere between 30 seconds and 90 seconds, you will have a spectrum that shows you everything that’s there in amounts that are measurable.
You’ll be able to make a decision. For example, maybe you have no zinc — you’re flatlining on zinc. Or you have no copper. Well, then you know that you have some issues that you need to address.
Acres U.S.A.: Will it show it in all molecular forms? If you have zinc oxide versus zinc sulfide, will it show the total amount of zinc regardless?
Clapperton: It will not show molecular forms. It does total elemental analysis. You could think about it as an atomic analyzer. It analyzes atoms. Let’s say you were looking at a fertilizer that was zinc sulfate. You would see a sulfur peak and you would see a zinc peak. You could put two and two together quite easily because of the proportions — that you had zinc sulfate.
It doesn’t measure molecules; it measures atoms and elements.
Acres U.S.A.: But if there was zinc sulfate and there was also zinc oxide, you would get zinc and sulfur — you see the zinc from both molecules — but you don’t see oxygen, because the XRF doesn’t go down that far on the periodic table, correct?
Clapperton: Right. You’d get zinc and you’d get sulfur. Then, you’d look at that and you’d say, “Well, there is a little extra zinc in there.” That would be the zinc from the oxide.
There are calculations you can make. My calibrations give you concentrations. Without the calibrations, you can’t get concentrations; all you would see would be the elements that are there. For some people, that’s adequate.
You need to calibrate for a matrix. What do I mean by matrix? Soil is a specific matrix. Flower is another matrix. Dried plant leaves are a different matrix. Does the material you’re testing look like cookie crumbs? Does it have a high amount of carbon in it? If it’s very high in carbon, then that’s one matrix. If it’s very water-like and it doesn’t have any carbon in it, then that’s another matrix. If it’s liquid, it’s another matrix. You end up having quite a lot of calibrations.
It’s a very good tool if you’re interested in heavy metals, because the TRACER has been used for a very long time in mining. It’s also used in art. Every one of the great masters had their own unique black, and their own unique white, and their own unique reds. They are a signature for that particular painter.
Acres U.S.A.: That’s fascinating.
Clapperton: That’s how this instrument came to be. All the major art museums in the world own TRACERs. They use them to create atomic signatures for their artworks to prevent forgeries, and also in case of theft. Any painting that shows up can be verified as original because it would have the same signature that you would expect for that particular master. The same is true for bronzes. All bronzes are forged unique to that particular bronze artist. So, it’s another way to verify bronzes sculptures.
It’s been used extensively in archaeology. We now know, for example, with obsidian, which is often used in spear points and arrowheads and knives — we know where all the obsidian mines are in the world, and we’ve analyzed samples from each of them. The calibration is such that now, if you find an arrowhead and you analyze it on a TRACER, you could actually know what mine it came from. So, you could start to understand the movement of peoples.
And now we’ve adapted it with the inventor of the Bruker TRACER, Dr. Bruce Kaiser, to agriculture.
Acres U.S.A.: Is this something that a grower could go out and purchase? Do you sell the calibrations?
Clapperton: I do sell the calibrations, but it’s an expensive device. The starting point is $45,000, without any calibration.
Acres U.S.A.: You can run a lot of plant sap tests and soil tests before you get up to $45,000.
Clapperton: Exactly. So, you’d have to be a co-op or something like that. But I’m working with others to make this more available, or to have other instruments that farmers can use to get after these things. There are a number of optical spectrometers that we think will do molecules — they don’t do elements very well, but they do molecules very well — that will probably be able to do this at a much lower price point. We’re working on building these instruments, as well as calibrating these instruments, right now.
We believe that growers really need this technology. Not only from the purpose of nutrient density, but also for anti-quality factors. The one thing that we’ve seen is that spots of rust, or bunts, or smuts, or any of these kinds of things — they have a very different signature than the rest of the leaf. Diagnostics will be available here in the next year or two years that will change the face of agriculture for sure.
Acres U.S.A.: Could you compare it to a standard soil test that you got from a different lab? Does it line up that way?
Clapperton: On some things, it does. But it’s a total gain. You know how hard it is to get a total phosphorus? There’s no such thing. You would use a Bray 1, and then you would use a Bray 2, and then you would hope that the Bray 2 extracted all your phosphorus from your soil. Even the Mehlich and the other ways of extracting phosphorus — they extract it. But XRF gives you a total.
The one objection is that people say, “How do I know it’s available?” Well, do a leaf test — your plant is the ultimate authority on what is available in your soil. Your soil test isn’t the ultimate authority; your tissue test is. Plants will get what they want. If it’s in there, they will get it.
Acres U.S.A.: Why don’t labs use XRF?
Clapperton: Some of them are going to. Even though it’s been used in art and archaeology for a very long time, I think what’s interesting is the simplicity of some things. Some people think it can’t be that good because it’s not an automated technology. You don’t have an auto sampler, where you can walk away — load the samples in and walk away. I think you could design one easy enough, and I don’t think that would be very hard.
But there are some labs that are using them now. They’re using them to understand heavy metals primarily. But they’re also using them for soil tests. It’s a hard thing. Everybody is used to seeing available nutrients, not total elemental analysis. What’s available is what the plant sees and what the plant uses. That’s what’s available in your soil.
I’ll give you an example. On a soil test, let’s say you get 45 ppm iron, and there will be 60,000 ppm of iron in your soil. Is that really what’s available? What is the concentration in your plant? Same with manganese, same with magnesium. Some soils are very rich in magnesium. Is it all available? No. Is some of it available? Yes.
But the plant can leak out acids; it can leak out protons; it can leak out more basic compounds. It can leak out phytates and all sorts of really complicated molecules that will latch onto and chelate things that it needs, and it will keep them in and around the roots so that it can use them.
We’re missing out on that. We’re saying, “Well, plants aren’t very complicated — how would they know?” The truth of the matter is that if you’re stuck in one place and you can’t move, you’ve got to be really good at getting what you want. If you can’t run away, then you have to defend yourself. So, plants are very good at taking care of themselves. They are way more complicated than a lot of people will give them credit for.
There’s often, too, this argument about phosphorus. “How much phosphorus is there in my soil? I have to keep adding it.” Do you? How much really is there in your soil? I have seen soils where there’s hardly any — where you definitely need to add phosphorus. But I’ve also seen soils that are in the 6,000-ppm range, where I wouldn’t touch phosphorus again for a very long time.
Acres U.S.A.: So much more of it is the ability of the soil microbes to make that available to the plant.
Clapperton: The microbes are going to make it available to the plant, but the plant drives it all. The root exudates are what attract the microbial community to that root. Just as I talked about with art — that there are these unique chemical signatures — every different plant has a unique carbon signature that is leaked from its roots.
The signature changes a little bit, depending on how the plant’s feeling. But that signature is there to attract what the plant needs. The plant will say, “Oh man, something is grazing on my roots right now.” So it’s going to send different signals down. It’s going to move different molecules down. It’s going to move other molecules up. That’s going to change the whole microbial community, and they might just have to hold the course for a while because they’re not going to get fed very much until this whole situation goes away. The plant is also going to send down some really complicated molecules, like flavonoids, and maybe some terpenes, and maybe some isoflavonoids, to try to attract some insect-eating nematodes — to come and parasitize these insect larvae that are grazing on the roots.
The plant might realize, “I’ve got a disease. Okay, I’ll send out signals, because I need some other things. I need to build up my soil Bacillus thuringiensis population because I need some more bacteria in the area to kill root feeders.” Plants are sending out signals all the time that modify what they can take up — that modify the microbial and faunal communities around them. But it’s always for the same purpose: to exclude the competition and to make a beneficial rhizosphere.
Acres U.S.A.: That rhizosphere will be different if a plant is surrounded by different plants, correct?
Clapperton: Yes, it will be, because now, I (the plant) may not like the competition too much. Maybe I don’t like my neighbor very much. So maybe now I’m going to send out some signals that say, “Bug off.” And I’m going to interfere with your root system a little bit. I might even interfere with you a little bit and make you all stressed. Weeds are very good at doing that — especially weeds that are living in very hard climates — they’re very good at excluding the competition.
Acres U.S.A.: So, they’re allelopathic in their own sense.
Clapperton: Yes, but that also means that they need different minerals and nutrients. So, if I have to be super allelopathic, then I’m going to be taking up a whole bunch of trace elements. I’m going to be making out of my root exudates a whole bunch of compounds that will chelate metals and will put them into an organic form so they don’t leach away — and also so I can transport them into the roots.
Acres U.S.A.: So then, in terms of the spectrum of what a farmer should do — should he or she focus more on feeding the soil, feeding the microbes, or feeding the plant?
Clapperton: All of the above. I would say that the plant is going to also drive your microbial and soil biome. The most active microbial area in the soil is in the rooting zone — the rhizosphere. The plant doesn’t exist without a rhizosphere of some kind. The better the soil — the more organic the soil, the more organic matter it has, the more diverse the community is — it’s going to have more services, and that plant’s going to be able to tap into those services. The rhizosphere is a partner. The root, the soil, the soil organisms — they’re all connected.
It’s the plant that’s driving the changes in either one because plants can change soil structure, if they want. Some plants create really soft soil structure; some plants create really hard soil structure. Depending on the conditions, that same plant that you think creates bigger clods may create a very fine soil structure because it’s stressed and it needs access to more things. By the same token, when it changes that soil structure, that means that different microbes have access to organic carbon, to nutrients, and to the roots.
It all works together. There’s no separating them. They’re all feeding off each other. If the microbes have to change — let’s say something happens and you get too much water, and the pH changes, and you get inundation, and then the microbial community changes — that’s going to affect the plant roots. That’s going to change what leaks out of the plant roots. It’s going to change how the plant grows, which is going to affect the soil structure. We have to think of the system.
Acres U.S.A.: Can you speak a bit about oxidation and reduction — redox — in the soil? What does that mean, and why is a reduced environment better than an oxidized one?
Clapperton: Let me explain it more in terms of human health. Oxidation often means that we are having issues — inflammation. It often is associated with inflammation, and not the best metabolism — if we’re having too much oxidation. Reduction is a much better situation. We don’t have peroxidase.
Plants are the same. Plants that don’t have high inflammation are probably working better. When plants have diseases, just like in our own bodies, we tend to see a lot more oxidation.
If we look at the ratio between oxidation and reduction, we can look at the amount of inflammation in the plant, just as we can look at the amount of inflammation in ourselves and in our animals.
That’s the key point in all of this. What we’re always trying to do is to reduce the amount of inflammation, which means we’re trying to reduce the amount of oxidation. Think about rust. What is rust? Oxidation.
Acres U.S.A.: How do we do that?
Clapperton: Partly by creating diverse plant communities instead of always going to monocultures. We still need to grow food, and we need to have money to do the things that we do — so we need cash crops. But that doesn’t mean we can’t have companion plants with our cash crops. It doesn’t mean we can’t grow living mulches with our cash crops. If we can keep the soil covered more, we will have a more reduced environment.
We will also have more pollinators, and we have more beneficial things happening, which means that everything is going to be in a more reduced state and less inflamed.
Now, I’m sure — and this is not my expertise — that there are ways to feed plants that would assist with that. I have more expertise in human supplements than I do with plants. I’ve always found that with plants, as long as I am putting them into a soil that is on its way up — more organic matter, more diversity of roots — things grow well.
This is where fertilizer comes in — using fertilizers that are in a more organic state. That’s why people are using humic acids and finding that the roots respond to that better, as well as mixing a lot of trace elements in. You don’t want your iron oxidized; you want it chelated — attached to an organic compound that can be broken off. Then your iron goes into a chemical compound, which can be taken up by the plant.
So, it’s all about having things attached to an organic form so that we can recycle them. Think about your soil like a digester, because that’s what it’s doing — decomposing, digesting. You’re getting more organic compounds. Organic compounds are held; they don’t leach. Not to the same extent that our more inorganic compounds leach. We don’t want things to leach. We want to hold them in the soil so that the plant has access to them when it needs them, and so does the soil microbiome.
Acres U.S.A.: Changing gears, how do you think changes in our crop insurance program would affect soil health?
Clapperton: That’s a loaded question. I have to say that I think crop insurance has been very behind the times.
I understand they are insurance agents, so it’s actuarial. They like to have 20 years of data in order to make changes. Well, if we waited for 20 years every time to make a change, of course you’d always be behind the times, because things are changing so fast. We need changes. Well, we’ve seen that things have changed — like cover crops, for example.
There are a lot of rules with respect to crop insurance that have changed with cover crops. Now we have to change again for companion crops. But we have to understand that those insurance companies and the banks have a risk too. In my opinion, I would like to see them change a little bit and actually start understanding agriculture in a better way.
In other words, if I have an organic soil, my organic matter is higher and my water holding capacity is higher. My cation exchange capacity is higher. I’m a lower risk for failure from drought. I’m a lower risk for failure from flooding. Why don’t I get a better rate?
Acres U.S.A.: And what if there wasn’t this safety net, period — how would that affect our growing practices?
Clapperton: I think that, well, some people would fail more. There’s no question about it. But some people would thrive, because there’s a lot of farmers — especially younger farmers — that are paying off their land, that have bank loans, and the banks simply will not allow them to not have insurance.
This means that they can no longer be creative and innovative. They might be able to experiment on maybe ten acres, which I would recommend they do — to prove out those practices so that they feel comfortable in going ahead without insurance. Or going ahead when they can.
I’d like to see the insurance companies evaluate practices more and have insurance for other practices. What about polyculture or intercropping? You intercrop and you walk away from insurance — but why? Your crop is at less risk. The cash crop is at less risk, and you’re intercropping, so if one crop happened to have a real problem, the other one probably will survive, and you’re more than likely to be profitable.
We should support success instead of supporting failure. It’s a mindset.
Acres U.S.A.: Are you optimistic that a lot of these practices are going to be taken up more and more?
Clapperton: I see them being taken up more and more. I remember even ten years ago — you talk about cover crops and people go, “What? What is that? Oh, it’ll never work.” And now it’s like, “So how do I do this cover cropping thing?”
You see the success of some of the cover crop seed companies. And now we’re talking about intercropping, and more and more farmers are trying intercropping. Who would have thought that in the last five years?
Acres U.S.A.: Or 60-inch rows for corn, with something in between.
Clapperton: Exactly! Sunflowers with fava beans and crimson clover in-between them, and the whole ground being completely covered.
Acres U.S.A.: Right — which is going to do wonders for your soil microbiome.
Clapperton: Think about the farmers that are still using chemical fertilizers. Think about the price of nitrogen right now. You need to grow fava beans. You need to grow legumes in-between your rows, because next year you may not be able to afford nitrogen. Maybe the prices will be high enough that you’ll be able to, but then — at how much profit? You’re glad that the prices are up, but you’re still not going to see that margin because you’re going to spend all of it on fertilizer.
This is the time to be really starting to understand intercropping and companion cropping and getting legumes into your system.
Acres U.S.A.: A farmer who is beginning to transition toward a more regenerative approach — what would be a first step that you would recommend?
Clapperton: Cover crop. Make sure you get a cover crop in. And make sure that you have at least three species. If you really feel that three species is too much, then do two. But never, ever, just grow one.
Acres U.S.A.: Even in these no-till systems — where you’re trying to roll down a rye or a vetch, and you really want to be able to do it without the herbicides?
Clapperton: Even in no-till systems — and everybody knows that I’m a no-till advocate — there’s no excuse. We need diversity. I would much rather that, if you’re going to roll down, you roll down ryegrass and vetch. Why are you just rolling down ryegrass? Why are you just rolling down vetch? They should be together, and you should be rolling them down together.
And why do you only have ryegrass and vetch? Why don’t you have a brassica? Why don’t you have an oilseed? Why don’t you have something else? Why are you limiting yourself to two? There’s no reason; you just roll down those others.
Acres U.S.A.: The timing of it would make it challenging, right — to make sure that they’re able to die at the same time?
Clapperton: Yes, but do we need them to die? There’s some beautiful new technology from Dawn Equipment — they have a between-row mower and a between-row roller. Some of that corn growing with alfalfa? It’s fabulous. You roll down or you mow your alfalfa, the corn comes up, and then it shades out the alfalfa and you have this complete cover of alfalfa.
You harvest your corn, then you have the alfalfa crop. And you’re getting free nitrogen the whole time. Corn and alfalfa love each other. We have the technology now. People have done the innovation. There’s no reason for us to stand down. We need to keep going.
Maybe I’m overly optimistic, but I believe that there’s a lot of really creative and innovative people in the world that are trying really hard to make a difference.
Acres U.S.A.: What research are you working on, and where’s the gap? What needs to be done in the future?
Clapperton: I think farmers need to be supported, and they need to be recognized for their creativity and innovation. Too often, I think, as a researcher and a scientist, we dismiss the results on farms.
We know the results are not replicated. Yes, they are kind of anecdotal. But why wouldn’t you investigate that and see if there’s any merit to it? And then, try and take it further. Farmers don’t have time to look into the crystal ball 20 years down the road and say, “I’ve done this, this is really great. I know I need to take the next steps, but now I need to make more money, so I can be innovative for tomorrow.” It should be the researcher’s job to take the innovations that the farmers are talking about and take them to the next level. This allows more people who don’t want to be innovative and who don’t want to take the risk to adopt those practices without the risk.
Acres U.S.A.: So, the scientific system — the university system — is hampering this.
Clapperton: A lot of times, they’re saying, “We don’t see that in our research, so it can’t be right.”
Well, if you have ten farmers showing up and they’re all doing the same thing, and they’re all doing a whole lot better than everybody else, why are you telling them that the results they have are rubbish? Instead, the answer should be, “Wow, that’s amazing! Can we come see? Show us how you’re doing that. Come and look at our trials. We must be doing something wrong, because we don’t see those things.”
A lot of times, researchers are using plot tools, because they have to — they don’t have the land to do some of these things farmers are doing. And they’re doing replicated trials. And they’re doing things in singles, because they have to — because the scientific community dictates that, in a certain way.
I come from a different background. I come more from ecology. And in ecology, there’s no such thing as a true rep. I mean, I go into the prairie and where is the true rep? There are no true reps in the prairie. If I set out a transactor, if I set out plots in the prairie, they are all going to be different.
I have to use a different set of statistics. I am probably less worried about that than somebody who comes from a pure agricultural background in plant breeding and other specialties. They’re gonna be like, “What? You didn’t do 12 reps? You don’t have the power in that task. How can that be right?”
But for me, that’s the wrong way to look at it. I don’t believe that I’m the authority. I’m learning from farmers every day. And I hope that we are sharing in our learning.
And just as I’m trying not to be close-minded, and they’re trying not to be close-minded, we need everybody to try and not be close-minded. To be open to new things. Maybe it does challenge our understanding. I could say, “You know, that’s not what I see. This is what I see. But hey, you see this. Let me come and look at that.” Just because I don’t see the same thing that somebody else does, doesn’t mean it’s not real. It just means that I haven’t seen the same thing.
I will give you a perfect example of that. I worked on earthworms for a very long time in Canada. We had a national project, where everybody on the same day went out and was using a mustard extraction to get earthworms out. We all followed the same recipe. We even used distilled water so that we didn’t have any differences in water. We used the same watering can. Everybody used the same thing.
So, everybody in eastern Canada mustard-extracted all the earthworms. We sat there. There was nothing. Here’s the film crew, taking pictures of all the people in Lethbridge, Alberta, standing around going, “Wow — did all the earthworms go away today? What is going on? How is this not working?” We were all scratching our heads and going, “Hmm. This is not working very well.”
My students thought it was a big failure, and they wanted to change the experiment. I said, “Wait. Stop and think for a minute. How do we figure out what’s going on here? Oh, we should dig. Yeah, we should see if they’re there.”
They were all there. The mustard just didn’t bother them. Nothing felt the need to crawl out. They were all fine. And they were all there. There were lots of earthworms. They were just totally unaffected by the mustard. Probably something in our soils was de-activating the compound that caused them to be irritated and come out. Soap worked fine. We had no problem with dish soap or hand soap. But when it came to mustard, it didn’t work at all. Maybe it’s because we’ve put all our mustards on all those soils and the earthworms have adapted to it. I don’t know.
But when we reported the paper, there were a lot of scientific reviewers who said that that was not possible. It had to have worked. It works everywhere else in the world. You didn’t do enough reps. You didn’t do it right. You did something wrong.
Actually, no — we all did it exactly the same, and in these soils, it doesn’t work. Why should one size fit everyone? It doesn’t.
So, that’s what I’m saying — researchers can oftentimes, like everybody else, be really close-minded. They should be saying, “That’s not my experience, but it’s yours. How about I come and have a look at that and just see what it looks like? Maybe you can come and look at my experiments and talk to me about what we’re doing?”
In the end, everybody now starts collaborating and getting a lot further along. This is about sharing. We need to share and collaborate.
