 In 2013, the USDA Natural Resources Conservation Service entered into a cooperative agreement with the South Dakota No-Till Association and IGRO, SDSU Extension, for delivering the latest soil health and productivity technology to South Dakota farmers and ranchers. A series of four local events were held in South Dakota in Sioux Falls, Watertown, Belfouche, and Mitchell. I feel like Buck Rogers or something with all this equipment hanging on these belts and tactical wear. I'm guessing by now most of you have heard or are aware that there are a lot of soil microorganisms. A lot, a billion, and about a gram of soil, which is about the end of my thumb, a billion, a billion organisms in that big little chunk of soil. Okay, that's neat. There's actually thousands of different types of organisms in that same little thing. So I'm not going to go over all that with you. I'm thinking that most of you that are here probably are aware at some level that there's a lot of them down there and they're very diverse and they're very important to the soil. It's now been internationally recognized the role of soil microbes in food production. This is the 2013 report by the prestigious American Academy of Microbiology. Pretty, pretty startling title how microbes can help feed the world. So this isn't some guy from Broglie, South Dakota come to tell you about how microbes are going to save the world. There's actually a whole lot of other people that are thinking the same way and that we can take a much greater advantage of the soil microbes that live in the soil. Okay, what are these things doing there? Why do I care? I don't really want to know all about each individual microbe or how diverse they are. I want to know how they affect my farming system. This is just a range of benefits that soil microbes can provide in your farming system. And they provide these benefits simply by living their lives. They're just living just like you and I, they're taken in carbon or some other. They're also getting energy from carbon or some other energy source. They're breeding, they're multiplying, they're doing the same things. But along the way, they're actually doing all this stuff and it really amounts to something substantial because there are so many of them. And I want to just go around the ring here a little bit and talk about things you might not think of. Microbes have been found to suppress weeds, either by directly degrading the weed seeds or by some chemical interference with the weed group. Soil structure and aggregation, what do you think microbes are made of? They're made of carbon, okay? So they're part of the carbon that feeds the soil structure. They exude all kinds of mucus and things that are called polysaccharides and all kinds of stuff all over their bodies that help stick things together. I mentioned that they're soil carbon. They have a huge impact on nutrient retention and nutrient availability and most of what I'm going to present. We'll be talking about these things down here. Of course, many of you were nitrogen fixation, having inoculated your soybean seeds. There's a whole other thing, there's all kinds of chemical warfare and positive things that are happening out there with plant growth promoters. So benefits from soil microbes, you can't put them all in one bin. They're actually, you could probably think of a few more that aren't on this chart. So, okay, you convinced me in two slides, soil microbes are important. They provide a array of benefits. How can I get some in my farming system? And this C3-A is sort of the basis. These are the fundamental pillars. If you want to increase soil biology and get this array of benefits, think about how you can integrate some of these things into your current system. Acknowledging that there's constraints, largely economic in a lot of cases. But there are things you can do. But there's things you can do to reduce the amount of tillage, to increase the crop diversity, to have cover a larger percentage of the year. For instance, by using cover crops, you will in fact increase soil microbiology. Both diversity and numbers, you will start to see the benefits that I showed you in the previous slide. Now, we take a look at a couple fields here. One has cover crops and one doesn't. And these should be pretty fundamental things that most people are aware of. Which one handles the elements better? Okay, and the real, the key issue with cover crops or some other form of keeping cover on your fields all year round is this one right here. If you have something growing on your field, you are pumping free energy, carbon and nitrogen into your soil. Who doesn't want carbon, nitrogen and energy in their soil? Everybody wants it. If you don't have something growing there, you're not taking advantage of building your soil using the sunlight. If you have something growing there, I think it's intuitive to most people that you have better water infiltration, better water storage and less erosion by water for wind. Okay, how about the critters, all right? It's real easy to see if you're a farmer, if you're an outdoorsman, the difference between a field of black dirt and a field that has something growing in it. And the things that you can see, like deer and pheasants and insects, it's really easy to tell that they're going to be more numerous in this field. But I bet what you didn't know is how the microbes react to this. If you have black soil for a long period of time, you know what happens there? It gets hotter at the surface and that actually kills some of the microorganism. It gets drier at the surface. That either kills or reduces their activity. The surface is exposed to more UV radiation from the sun. That also kills bacteria on the surface. The more tillage, the more physical disruption of filamentous bacteria, the more susceptible your land will be to water and wind erosion, which will also remove microbes from your field. So in general, these guys are reacting, you can't see them, but there's all kinds of literature out there in different areas that will support. If you have bare soil, you will have less microbes, at least in the top, the top little bit. I don't know how much data there is, deeper, obvious, but let's get to the next slide. What happens deeper, at least in a lot of the soil depth that most farmers are interested in, is affected by having something growing there. Did you know that 10 to 40% of the carbon that your plant's fixed don't go to produce biomass of the plant? They don't go produce grain. They actually leak out of the roots into the soil. Well, why would they do that? Well, I don't know why they do that, but there's a consequence of that. And the consequence of that is all that carbon that the plants are fixing are supporting microbes in the surrounding soil. So it's really important to recognize that if you take the plant out of the system, now you've taken the source of a large part of the energy for soil microbes out of the system. And this is huge. When you think about looking at a field and you see stuff growing, you see animals using it, you see insects and beneficial insects. It's very intuitive, but think about what's going on underground. It's simply not the presence of the roots. It's the carbon. It's the energy. It's all the other things that they're leaking out into the soil. Cells are sloughing off of their roots. That's food. That's food for the microbes. We have been working the last five or six years on using cover crops. Again, simply as a means to keep something growing longer during the season. And we've been looking at how growing cover crops can promote soil biology. That's been a focus of our lab's research. We also have researchers that are looking at how they affect insects, researchers that are how they're looking at weed populations. What I've been looking at is the soil biology of these systems. People talk about soil microbial communities and how they might change with my management and am I doing good or am I doing bad? Do I have good soil or do I have bad soil? Those are the kind of questions I hear. They're really difficult questions to answer. I've got to tell you that. The questions that many of you are asking me are right at the edge of our scientific knowledge. There are some things we can do now. They may not be the best things, but there's something we can do now. We have good reason to believe. More often than not, they're important. And one of these things is the ratio of fungi to bacteria. They're in the soil. And this diagram or this picture here is simply some fungal filaments and these little things here are bacteria sitting on them. The idea is you take a soil sample and measure the ratio of fungi to bacteria in that soil. It is not the be all end all. It's a way to get at this change in soil microbial community due to your management. However, in the literature, there's enough scientific findings that support that soils with a higher fungal to bacterial ratio tend to have higher carbon and nutrient retention. Those are, I don't know, what else do you want? Carbon and nitrogen and other nutrient retention. That's pretty good stuff. Again, it's not a one-to-one correspondence, but it's a pretty good trend. We have some plots at our research farm that were established in 2000. And they feature three levels of residue removal. There's a low, which is where we just take the grain, just like a lot of cashcroppers do. We have a medium residue where we bail the stover, take those bails off as if they're going to be used for cellulosic ethanol production. And we have a high residue removal, which is a silage cut. So three levels of corn residue removal. These are no-till corn soybean systems. They've been in over 10 years. We added splits to them where we had cover crops. They were initiated after both the soybean and the corn phase. I know the question's out there. How do you do that? Well, I have an agronomist, Shannon Osborn, who works on that very issue, and they've tried all kinds of different things. And let me tell you, it doesn't always work. Each year, the cover crops don't always get established. But over 10 years, you can see the differences. These two graphs, the top one is 2009. The lower one is 2010, where we took soil samples. We looked at fungal-bacterial ratios. The black bars are the residue removal without cover crop. And if you look at the black bars, in 2009, 2010, with increasing residue removal levels, you have lower fungal-bacterial ratios. Again, that's an indicator of what the soil is doing. And it's especially important if you look over time how it's progressing. And it tends to be linked to positive things like carbon and nitrogen retention in your system. But the other interesting thing, and it's mostly in 2010 that this shows up, is in the subplots with cover crops, we don't see the reduced fungal-bacterial ratios. So again, what we see is evidence of cover crops overcoming some of the negative changes that might be associated with harvesting cornstone. And what I want to add is we have data on soil carbon. We have data on aggregation. We have data on highly erodible fraction. And largely that data parallels the data on these two slides. If you remove the residue, you end up with less aggregates, less carbon, more highly erodible fraction, and a change in microbial communities to a more bacterial-dominated system. If you add cover crops, you can reduce those changes. So this is a role for cover crops. We also have done a fair amount of work with nitrogen, which is obviously the prime nutrient. Microbes don't just think of nitrogen as a nutrient. I mean, it's important to them. They're going to be roughly 10% dry weight nitrogen in their body, so they need a lot. But nitrogen's more than a nutrient to microbes. They have the ability to take atmospheric nitrogen and fix it into a form that can be used for plants. Why is that important? Well, they actually trade that nitrogen to the plants for some food from the plants. They also take ammonia and oxidize it to nitrate. And in doing so, they actually get energy. That's how they run their cells. That's how they run their metabolism. There's also organisms that you might be aware of that reduce nitrate to ammonia. And those organisms are using nitrate in the same way we use oxygen when we breathe. They also will take combined organic nitrogen and mineralize it to ammonium. And in this study, what we did was look at three cover crops, clover, rye, and vetch, and compare them to a fallow situation. This is no-till corn, no, corn, soybean, wheat. So after the wheat, we planted the cover crops, and then it was coming into corn again. And what I did was look at nitrogen mineralization once the cover crop was killed over the corn growing season. And these three different colors here are different periods of the corn growing system. And what we're measuring here is how much nitrogen was mineralized. So you can see with the two legumes, clover, and vetch, we had a lot of nitrogen mineralized over the corn growing season. And even rye was slightly above fallow, but don't necessarily discount rye out. Because what you've got to remember is what I measured here was nitrogen mineralized over the course of the corn growing season. That didn't mean that rye didn't have something else to give the next year or the year after. So rye took up some nitrogen. It didn't take up as much as the legume because it doesn't have any fixers. And it releases it more slowly because it doesn't decompose as fast. But still, that doesn't mean rye is no good. It just means rye's. The timing of the nitrogen release is different than the legumes. But this is an important role for soil microbes. The more you have, the more diversity you have, the more of these types of benefits that you're going to have. Lately, what we've been looking at is one group of microorganisms called our muscular mycorrhizal fungi. And many might have heard of them. They're a type of fungus that only lives with a plant. It has to have a plant to live. So that's why we're interested in them. They're partners with nearly all your crop species except for brassicas. The fungus, actually, this is a blow-up here of the root. Can't see it very well. But the root surface here, and what the fungus does is the plant sends out a chemical signal, a cum hither signal. And the fungus sits in the soil in a spore and it germinates a filament and attaches to the root and actually invades the root, goes inside the root, and inside the cortical cellular root forms a structure called an arbuscle. And that's a diagram of the arbuscle. And this is a blow-up of the arbuscle. And they call it an arbuscle because it kind of looks like a tree. But I like to think of it, I don't know. They'll get the idea, I think. But it kind of looks like a tree. To me, it looks like a lung or a kidney. And that's exactly what it is. It's got lots of little fingers. And what it does is maximize the surface area between the fungus and the plant. And why do we care about surface areas? Because that is where the exchange takes place. Just like in our lungs, we take air in, goes into our lungs, interacts with the blood that's in there, strips the oxygen out, and puts CO2 back in so we can exhale it. If you have a structure like that that's got all kinds of little fingers in surface areas and branches, it's built for exchange. And that's what this does. The mycorrhizae brings water, brings nutrients, particularly phosphorus and other mobile nutrients, into the plant. The plant says thank you by giving the fungus some sugars all through this exchange structure called an arbuscle. Well, we think these fungi are very key in terms of soil microbiology and benefits that you might get to your farming system. And this is one way of looking at it. On the left is a plant without any mycorrhizal fungi. On the right is a plant with mycorrhizal fungi. All those little threads are filaments of mycorrhizal fungi, they're different colors because they represent different types or species. And they attach to the root. Basically what they do is they expand the root system. They don't just expand it into more volume but because these filaments are smaller than the roots, they actually able them to access small pore spaces. And because they're small, they have a high surface area to volume ratio. And again, surface area is what you're after. Surface area is the key to exchanging things. And so this is like, I don't know, this is not what you would like. This is the enhance model. The enhance model, why do we care about this enhance model? Well, it's taking up nutrients. It's taking up water. And you know what else? Because this fungus can only grow with a plant, it needs its plant host. Therefore, it's resistant to pests and pathogens. It does not want its host to die because then it dies. So once you're colonized by mycorrhizal, you tend to be more pathogen and pest resistant. One question that comes up to me is, well, how do they get these nutrients? Well, they have special capabilities. And these mycorrhizae actually produce enzymes that go out into the soil that help mineralize and mobilize nutrients so they can be taken up by the mycorrhizae and transferred to the plant or just the plant themselves. They also produce things called chelators, which is a compound like EDTA that might go out there and complex, say, a copper molecule that's tightly bound to the soil. Break it off there, bring it into the mycorrhizae and transfer it to the plant. They also can change the pH locally. We're talking at the micron scale there, but the micron scale is what matters to whether a nutrient is gonna be available to the plant or not available to the plant. These guys, can you believe it, they reduce erosion and how they do this is two ways. This is a picture of a fungal hyphae on an aggregate and so simply because of the thread-like structure, they help hold aggregates together. But this is a microscopic picture of a fungal filament and these are spores right here. There's a bunch of mucus that hangs off here and it's basically this protonaceous glue that they produce and that protonaceous glue called glomalin or glomalin, pronunciation varies, is very effective at gluing together aggregates. So you never think about it, these invisible organisms that you don't see, you see erosion like that and you think, well, I gotta do this thing or I gotta put up a fence or something. I can't remember what they're called, debris barrier, erosion, landscape cloth, but it's actually these microscopic organisms that can make a big impact on erosion. They can also make a similar impact on water storage. If you have improved soil aggregation, you have improved soil structure and then your structured soil behaves like a sponge where water can infiltrate, more water can be held in that sponge, those are all good things. I believe the NRCS has developed some data this year that for cover crop, folks that cover crop three years, at least three years, they had 10% better yields in a 2012 drought year. And a lot of that has to go with soil structure. Well, I don't know if it had to do with AMF, but AMF, mycorrhizal plunge, I certainly play a big role in that. Why else do we care about AMF? Well, this kind of figure's been shown dozens of times. It's called the big plant, little plant. And on the left is some sorghum, we've added mycorrhizae. What's unique about this picture is this mycorrhizae, the mycorrhizae we added to the pots on the left, actually we collected from a producer's field down by ideal. We took his soil, we extracted the mycorrhizae and we added it to the soils in the sorghum on the left. We did not add them to the right. Those are the dry weights of the plants. You can see there's a big difference in the growth and vigor of these plants with and without mycorrhizae. Ag management, okay, I want more of these. You convinced me there's enough data out there to show that low numbers of these can stress the plants. In general, mycorrhizae are negatively affected by tillage, fallow, because they need a plant to grow, flooding, because they need oxygen. Rotation and host plants, that can go either way depending on what plants you're talking about. And lastly, they respond negatively to inorganic phosphorus inputs. You wonder about that. So if you put a lot of inorganic phosphorus inputs on there, the plant has enough phosphorus. It doesn't necessarily need the mycorrhizae to help bring phosphorus and other nutrients in there. So it doesn't send the come hither signal for the mycorrhizae to colonize the plant. The mycorrhizae sits in there, eventually decays because it cannot reproduce and make more. So phosphorus concentration has been shown to be a big negative inhibitor of AMF. We used a kind of rudimentary technique for looking at mycorrhizal numbers. We counted spores. Again, this is not necessarily the best measure, but what we found is if we look in a native prairie, there's a lot of them. If we look in almost any agricultural soil in this region, there's not very many. No big surprise. We then embarked on a multi-year study at several sites where we used another technique to look at the numbers of mycorrhizae. And this technique is based on propagules, which includes things like spores and infected roots and little bits of filament. Anything that can give rise to a mycorrhizal infection. It is hugely labor intensive, involves a multi-step thing for every single sample that you want to say, well, there's this much mycorrhizae in there. You have to grow 15 plants and analyze them to see whether they're effective or not by mycorrhizae. It's a heck of a lot of work. But we did this. And we did this at a producers field where he had put out replicated strip trials. Again, no-till. Again, following wheat before corn. And he had no cover crop. He also had a conventional-till check. And then there's five different cover crops, clover, oats, pea, pea Timothy, canola, radish, pea. And we looked at the number of mycorrhizae in those soils. The numbers we found in his field were pretty low, you know, they're pretty low here. But one thing that was clear was the oats, pea mixture had significantly higher mycorrhizae. We would love to do dozens of these studies. And hopefully you got the idea from the previous study, we simply can't with these methods. But we have done replicated trials at our research farm and we've got two years of data there. We use the same technique looking at mycorrhizae. We had no cover crop, again, no-till, wheat cover crop, going into corn, same kind of rotation. Canola, which is non-mycorrhizal, oats, vetch, and then various combinations that you see there. And again, we saw in both years 2009 and 2010 that oats was able to promote the highest numbers of mycorrhizae. So, in terms of cover crops, we think including oats in your cover crops is a good bet for increasing mycorrhizal numbers. We also went down to a farm, an ideal, and that producer has much longer rotation that includes wheat. And after the wheat, he planted a five-way cover crop mix. And he did that in about half his fields before they went to corn, the following year. So we took paired samples, fields with wheat, and the five-way mix, fields with wheat, and no cover crop. And we took samples back to lab, we did that technique, and we saw much higher numbers in this producer's fields. And we think it's because he does no-till, does a lot of crop, and he doesn't put much in organic pee on his soils. He puts a little bit of manure every four or five years. We found really pretty good overall numbers there, and we saw about a doubling in mycorrhizae with the cover crops. So those are numbers, but the other thing you can measure, and that's important, is diversity, mycorrhizal diversity. Again, using this kind of basic spore technique, we've looked at crop fields in our area, and prairie. And again, what you see is not so much diversity in the agricultural fields quite a bit of prairie, probably not a surprise. But why should we care about diversity? And this is data from another researcher. It's been 15 years ago, it was published. But if you look at the number of our muscular mycorrhizal species, that's the X-axis for all these graphs. It is positively correlated with chute biomass, root biomass, plant tissue pee, and negatively correlated with soil, Olsen pee. So you see a lot of benefits, and it sort of looks like you don't have to use as much input to get all these benefits if you increase the diversity of mycorrhizal. So that's what we care about diversity. That's what we're working on now, is trying to develop and adapt techniques to examine the diversity of mycorrhizal species as it's reflected by ag management. We think that's a very important potential indicator. The problem is the techniques are very difficult, complex. We're using some DNA-based techniques that we took us over a year to kind of get them where they could tell us about the diversity of mycorrhizae in these crops. And the first thing we did was to perform a laboratory or greenhouse study, really. And we looked at the diversity of mycorrhizal fungi in a prairie, again, right here. And you don't have to know all those names, but the point is there's a lot of different colors in that pie. And they represent a different mycorrhizal species. So as you would expect, the prairie's very diverse. Then what we did was we took this soil and inoculated four different candidate cover crops to see which one actually retained the most amount of diversity. And we, old clover and veg, this is a type of diagram that shows how many species were in each one. And the bottom line here is, again, old retained the most diversity in the system. Wheat retained the least diversity. And clover and veg were about intermediate. So that's where we are. We probably got another, I'm hoping, year till we get an approach where we can actually go out in the field and run these same tests on a more routine basis. But that's where we're going with this. In terms of building soil boating on your farm, there's only a couple of things you really need to think about. What do they need? They need food, more diverse crops, more diverse plants, equals more diverse types of foods. Each plant exudes different kind of compounds into the soil. If you have more continuous cover, you have a more continuous source of food. Habitat, they like a little spot. To live in, some of them don't like to be disturbed too much. If they've got filamentous growth structures, like migraecal fungi, so they need habitat. They need stable aggregates. And they also would like to have diversity of plants, equals more niches, equals more diversity. And the vision, and I've kind of put this thing together to think of a vision. If you think of a farm system and you think about it as a sandbox where you've got to put everything in every year and then take it out, and I call it a pass-through system because a lot of that stuff just passes through, or is actually, you add some nutrients and they get fixed to surfaces and never to be seen again. It's a pass-through system or a self-sustaining system where you can put nutrients and pest protection in at smaller amounts and get some of those services here. And the real key thing here is how much you lose. You don't want to lose these inputs that you've purchased. You put it into your system. You can add less and lose less and maintain your yields. Those are all, I think, the goal. And obviously as a producer, this is the most important thing is balancing your bottom line in these systems. And this is a way I've been thinking about this whole issue about nutrients. And I want to use phosphorus as an example. You put phosphorus on, lots of inorganic phosphorus, or you put a little bit and hope the soil biology takes care of the rest. And this analogy is, let's say you needed one liter of water a day. You're out there in the field somewhere and need one liter of water a day, right? There's two approaches. One approach is you can take a big cattle trough. It may have a few holes in it. Who knows? Fill it up with 1,000 liters of water, right? You only need 100. You need one liter a day for 100 days. So it turns out you're going to get your 100 out of that 1,000, but you're going to lose 900. 900 of those liters is going to work out of the holes, go into the soil, whatever, evaporate. The other way to do it is to lock your phosphorus up in microbes, in plants, in some kind of organic matter in the soil and have just a little bit come out at a time. So you've got a little dish here that only holds one liter, but it's always full. You can always get your one liter of water you need that day because you've got a one liter dish. But because it's a small dish, you don't have very much evaporation. You don't have very much loss as long as you keep everything tied up in here. And that's one way of looking at a system that could provide the same amount to a plant and yet be conservative in terms of imports and exports in the system. And this is my last slide. And I think it became more apparent when I gave a talk a couple of months ago, and people are still struggling with this. And the bottom line is it can be done. I mean, you have people here in this state, producers here, that have demonstrated these concepts that I just showed you. And then the last year or two, there was a big publication out of the Iowa State Lab. And I just want to read this one quote. So as results of our study indicate that more diverse cropping systems can use small amounts of synthetic agrochemical inputs as powerful tools with which to tune rather than drive agroecosystem performance while meeting or exceeding the performance of less diverse systems. So it can be done. And I think that's important to show people because you're going to have some struggles trying to do these things. But folks need to know that there's work out there that shows it can be done. And with that, I'd like to thank you for your attention, acknowledge some collaborators and sponsors. And if there's time, I'll entertain questions. Yeah, we have some time for some questions. We have a question for Mike. Is the reader happy? All right. Have you needed research? We do not generally engage in any sort of commercial product evaluation that historically that's been a role of the land grant universities. And I do know one quick route, specifically that Ron Gelderman at SDSU has done some work. Oh, the part where they put on Starter Foss, if you say putting on too much Foss, they make the plant not called to be a thing. How much is too much? Well, that's a really good question. It's really hard to nail down the exact amount, mainly because of differences in soil type and soil test. And so whatever if you use Bray, Olson, May Lake, whatever, you're getting a different fraction of that phosphorus. And then what that relates to in terms of the plant and its ability or propensity to give off the signal is also unclear. I mean, there's curves. Like the one I showed you with a reducing curve. And I think for any given set of circumstances, a soil and a test, a particular test, you could develop these curves. If you took a soil type, a plant type, and a particular phosphorus test, you could develop and get that information. But there's not a real comprehensive database of that information. Is there a difference in different types of plants? Well, generally the organic sources don't seem to show that repression. Mostly what the repression is is related to inorganic. In terms of different inorganic sources, I'm not clear on that. But there is a difference between organic and inorganic. I've been reading a lot about spring foster. Fungal size, which you see, what you think. What I just heard today is you're actually going to try to kill these fungus by putting the fungus size on. Is that true or false? I've heard that question before. And actually, I have a small project going with South Dakota State University looking at that very thing. I did a little literature review of that last, I don't know, six months. And what it shows is the fungus size that are systemic, right, are particularly inhibitory. The fungus size that are applied as a soil drench seem to have the most inhibition. Those are the only rules in terms of gathering all the data in that I see. If the fungus size is not systemic, there's generally less of a chance that it will negatively affect micro-IC. In terms of more specific data, we are working on that right now. Pete Sexton and I are doing that.