Do You Really Need Potassium Fertilizer? What Your Soil Test Isn't Telling You

0:03 All right. So, Dale, we had a webinar last year talking about potassium fertilizer, and we've had a lot of comments, a lot of feedback from that episode. One of the comments that was made during that webinar was this idea that you do not need to apply potassium fertilizer. So, we wanted to have Dale on here to kind of dive a little bit deeper into this topic. And Bill, can you give us a little bit of your perspective and what we as Green Cover are recommending for our customers?

0:31 Okay. Well, the phone calls I was receiving basically were all along the lines of are you guys really telling farmers you don't need potassium fertilizer because that's going to be a disaster in my area. And I said well no that was a statement by a guest on one of our webinars. That's not necessarily our opinion. That was the opinion of one of our guests. And so rather than repeat the same 30 minute phone call over and over and over again with different people, thought it might be prudent to kind of express some of the science on potassium and a little bit more about how potassium works in the soil and why kind of a bit more about what our position is or at least my personal position on potassium. I don't want to necessarily speak for Green Cover Seed. We are not in the business of making fertilizer recommendations. That's not what we do. We are a cover crop company. And so I want to explain the role of cover crops and potassium fertility.

1:51 Well I guess what I'd like to do is start with two questions. First of all do I really need potassium fertilizer? That's a question and the second one is how can I manage because potassium fertilizer is currently very expensive in relation to how it's been in the past. The second question would be how can I manage my soils so that my need for purchased potassium fertilizer becomes less.

2:27 So two questions: do I need potassium fertilizer and if I do how can I reduce my need for potassium fertilizer? So the first question, do you need potassium fertilizer? I guess I'll follow that up with another question. Have you been getting a response to potassium fertilizer? If you've had skips and your crop looks just sick and awful where you have a skip in application where you have not applied potassium, your crop seems to suffer, then I'm there's your answer. Simply that's your answer. If you have withheld potassium and had a yield decrease in your system on your soil, you need potassium fertilizer. That's simple. But how many if you don't know, if I ask you do your does your crop respond to potassium fertilizer and you say I don't know. Okay. Well, that leads to the rest of the discussion here.

3:37 Because usually we apply fertilizer in a mixture. You know, we'll have nitrogen and phosphorus and potassium and maybe sulfur and zinc and some various microbes out there. And it's hard to separate the effects if that's the way you're applying fertilizer. It's hard to separate the effects of the potassium from the other ones. And a lot of people have routinely applied potassium because we've been led to believe based on the advice of what we were taught in college or on the advice of extension agents or soil testing laboratories so soil fertility experts that we needed potassium fertilizer. So I think where we want to start is what exactly is a soil test and what does it do.

4:29 So a soil test, it doesn't work like a gas gauge. It is an extraction that's meant to mimic root uptake of nutrients. So historically we have taken an extraction from a soil using an acid or something meant to mimic root uptakes, we get a concentration, a numerical value that represents concentration of potassium in that soil and in that extract. Actually, it measures the potassium in the extract and it, that numerical value does not. Okay, it measures the potassium in the extract and that numerical value does not.

5:20 Listen very carefully here. This is critically important. The worst thing that they can ever put on a soil test is pounds of available potassium per acre because that is absolutely not what that number represents. In no way, shape, or form does it tell you how many pounds of available potassium you have per acre. It is an availability index. And that's it, an index. It's an indicator. That number on there is simply a relative gauge of availability.

6:04 If it says 320, that does not mean you have 320 pounds of nitrogen per acre or potassium per acre. Not at all. And that number will change throughout the year. And that's one of the things people don't understand about these soil tests. They are a snapshot. Potassium availability will change dramatically throughout the year. Wetting and drying, freezing and thawing will change that potassium availability index number.

6:42 And so depending on what time of year you soil test, that potassium availability index number can change dramatically. That doesn't necessarily mean that the availability of your ability to supply that throughout the year, if you take a test in March and then you take another test in April and they're dramatically different, that doesn't necessarily change the potassium supply and availability of that soil during the growing season. It's going to be the same. It's the same soil.

7:23 How we use soil test, if you understand what a soil test is, it's not like a gas gauge where you have to know you're half full and you need to add it. It's not like that at all because there are numerous interactions within that soil. And how do we get once we have this availability index, how do we develop a soil test recommendation from that availability index? Because we do this extraction, it says 320 parts per million. What does that mean?

8:05 Well, historically what they did is experiment state agricultural experiment stations would put out experimental plots. They took an extract and determine the availability index on all these different plots and then they put varied amounts of potassium fertilizer on these soils and then they made what was a response curve like this. And that response curve, there said okay if we put on this amount and we got this response and at this index we put on this amount, got this response and it took on an availability index of 320. It took this amount of potassium at an availability index of 80. It took this much potassium to give maximum economic yield. Now a lot, basically in other words a lot of trial and error went into developing these recommendations.

9:16 Now where your availability number lies on that curve determines the recommendation and the recommendation is just that, it's an opinion. It is different soil test labs at the same extraction value will give you wildly different recommendations because it is an opinion. It is a prediction and you don't know, the same soil test value may and the same recommendation that's profitable in a wet year will may not be the most profitable in a dry year. You know it is an educated guess and that's it. And people sometimes think of these soil test recommendations as being absolute and they're not. They are an opinion and should be treated as such.

10:16 And what exactly does that soil test actually measure? Well, primarily what that soil test is measuring is potassium in solution. And potassium in solution is basically the potassium ions floating around out in the soil water. And what that represents, the analogy that I was taught in the soils class is like a coffee dispenser. And you have this little glass tube along the side of the coffee dispenser which tells you the

10:50 Level inside the bigger part of the coffee dispenser. Well, this glass tube only holds a small, very small volume of coffee, but it's the same level as the coffee in this thing. So it tells you whether you're half full or quarter full or whatever. It does not tell you how much coffee is in there. I can look at that and say 'half full, that means I'm half full.' Well, I said 'What does half full mean? Does it mean one gallon? Does it mean two gallons? Does it mean 20 gallons? That depends entirely on the size of this. How big a round is it? How tall is it? How big is the big part of the coffee dispenser?'

11:42 And that's what soil test doesn't necessarily tell you, because in that soil there are more forms of potassium other than what's floating around in the water. There is exchangeable potassium and that is somewhat available, and that exchangeable potassium is basically the potassium that is held by magnetic electrical charge. Potassium has a positive charge. Clay particles have a negative charge. And this microscope view here is clay. This is what clay looks like under a microscope. You see all these little looks to me like decks of cards that are spread out, and in between all these little flat layers, these are the surface area where potassium is held.

12:45 Now potassium can be held on the outside held by electrical magnetic attraction to the outside of these clay particles, or it can be in between all these little crevices. Now obviously the potassium held on the outside of these clay particles is going to be much more available to roots than the potassium that's in between these particles. And that's what a soil test doesn't adequately measure. I mean it's an extraction, but it doesn't tell you how much of the stuff is in here. It honestly doesn't. It is an availability index.

13:34 So if you look at here's a study done in Kentucky way back in 1958, but I mean still very valid today, maybe even more valid than it was then because what they did is they for four years they grew a crop of millet and they took a soil test before they started, and then four years later after four crops were removed they took another soil test and they measured the amount of potassium removed in the crop versus the soil test. So take this first one, this Eden, you can see soil test level before cropping was 300 and after four crops it was 193. So the soil test went down 107. Put that number over here to the side. Potassium removed in the four millet crops however was 10 times that.

14:42 Now if it were like it worked like a gas gauge that soil test would have gone down 1100. So number one, two lessons here. Number one, this does not measure, and it says available potassium, pounds per acre. You can see why that's incorrect. There's a lot more pounds per acre of available potassium obviously than what that soil test indicates. It is an availability index, not pounds per acre available. So this up here is just not correct. And you can see on this one went down 99 pounds on the pin broke, but there was 275. So that's roughly three times as much. And you go down through here, several of these 50, yeah, it's about 50 lbs there, 40 lbs, 41 lbs. And so there's three times as much. This one went down 50. Yeah, what is that, 42, 42 pounds. Yeah, that went down about three times as much. So you can see that in all of these, the one down here at the bottom went down 9 lbs, but it took up, you know, five or six times that amount. So there's a lot of potassium coming from somewhere that's not being reflected on these soil tests.

16:19 There have been some new developments that have led to a need to say, okay, so our soil testing for potassium is not really very accurate. And I would argue that maybe it's not the soil test problem, it's our interpretation and understanding of soil test which is the problem. But because of that, we've been looking for better ways to understand potassium fertilization and how do we know what we're supposed to apply out there?

16:55 The reason that this is becoming more important over time is that we simply farm differently than we used to. Those soil test recommendations for potassium were developed almost exclusively in tilled soil with no cover crops, no grazing or manure applications, no surface residue cover, completely different conditions than the way most people listening to this webinar are farming. So are they still valid if you don't farm that way? And I don't think they are.

17:39 Another thing that is different now than when it was, is that we have a very long history of potassium applications. And when you apply, let's say 100 pounds of potassium to a crop, of that applied amount only about 50% of it actually ends up in the plant according to radioactive isotope studies. Where's the rest of it go? Well, it ends up on the outside of those clay particles. It's electronically attached to that and it can be pretty easily pulled off of there in future years. So it may not show up on the soil test, but it's there. And if you've been essentially overapplying potassium beyond crop removal, then you will have a buildup of available potassium even though it may or may not show up on a soil test.

18:46 Because of this changing of cropping practices and changing of nutrient availability in the soil from past fertilization, we found a need to further refine our soil testing processes. One such new test is a Haney test which is a much better prediction of nutrient availability if you are in a more regenerative system. If you're tilling, fallowing, no manure, no grazing, old traditional soil test might be just fine for you. They might work plenty good for your situation.

19:47 We want to definitely explore using the Haney test. The other test I would consider, and this is a very new one, is what's called a total nutrient digestion test. And this is something I'm really pretty excited about because it does offer one more layer of information. Now, just like the old soil test, it's all in the interpretation. This is simply a number, but what this number tells you is now available from Ford Laboratories. This is more to determine all the exchangeable potassium in that soil. That's where the total nutrient digestion comes from. This is an attempt to measure how much reserve do we have in there that we may or may not be seeing on a traditional soil test. So it's just kind of new this year.

20:55 I have no idea how to use these numbers. I do find them rather interesting and that's what Willie Ptorius at Word Laboratories is researching, trying to find out how can we use these numbers to make good potassium recommendations.

21:16 They sampled 68 farms. The lowest potassium total in the top 8 inches of soil where most of the roots are was 660 pounds. The highest was 9,354. That's quite a range. And just to show you how much variability there is out there in the potassium supplying power of different soils, the average was 3,735. Now, what does that mean? I don't know. And I don't think anybody really does yet.

21:57 Of a measure of if you could theoretically extract all the available potassium out of that soil, this is about what it would amount to. And that's not really feasible, practical or good advice to give anybody. But it does show that we are trying to, there are people out there who are trying to gain a greater understanding of what that reserve pool of potassium amounts to. But wait, there's more.

22:30 So I showed you the coffee dispenser. There's the amount in the tube. There's the amount in the rest of the thing. But there is another, just like in the coffee dispenser, there's when it becomes empty, you can go make some more coffee. Potassium in the soil, there is yet another source of potassium other than what's in the solution, other than the potassium ions on the surface of that clay. There is yet another source of potassium. And that is basically that all your rock particles, your sand, your silt, your clay consist of minerals that contain potassium.

23:25 So not only is there potassium attached on the outside, there is potassium inside those particles. They're part of the structure. Now, this is kind of like having a shed holding fertilizer. There's fertilizer in the shed, but the shed itself is made, I guess maybe I'd call it a lumber yard. You know, not only is there lumber in the lumber yard, but in a pinch, you could peel the boards off the lumber yard itself, you could take the rafters down. The whole thing is made of lumber.

24:05 And obviously it's a slow process. Once the lumber's all out, it's a slow process to tear that thing down and convert it into lumber. And this granite rock here, 4% potash according to a geology analysis. Now what does that amount to? Well, here's another study. This was done in Kentucky. Lloyd Murdoch did this study a long time ago. How much is the total potassium content in just 7 inches of soil in these experiment fields? You can see it's all a very high amount, much higher even than that 9,000. It's several times that because there is a lot of potassium locked in those rock particles.

25:00 And so what's the problem with this is that this stuff is virtually 100% unavailable. Maybe not 100%, the 99.99 percent repeating unavailable. But that's not to say it can never be made available and we'll talk about that. So, you know, the three pools of potassium in the soil that we talked about here, we got solution potassium, we got exchangeable potassium, and then you've got the potassium in the minerals themselves locked up inside particles of sand, silt, clay, and rocks in the soil.

25:43 So the process of exchangeable potassium going into solution, that's fairly slow, I mean can take days to months. And as solution K is taken up, you upset the equilibrium. All this potassium is trying to find, you know, it's just like water. If you have two buckets connected by a hose and you're bailing out one bucket, water's going to move from the bucket you're not bailing out over to the one you are. And that's the way this solution to exchangeable potassium pool works as well. As you take up solution potassium through root uptake, potassium will move off of that clay and into the water to try to reestablish that equilibrium.

26:39 Same is also true of exchangeable potassium and potassium in the mineral matrix, except it is painfully slow under most conditions. And under typical crop land conditions, till tillage, etc., it is pretty much non-existent. But this is really, this process is really where I'd like to focus because I think this is where we want to learn how to mine all that 30,000 pounds of potassium. How do we learn to extract that from our soil?

27:25 The potassium that's locked up inside the sand, silt, and clay. How does that become available? And we don't need to make 100%. Well, that'll never happen. No, it won't. Not in our lifetime, but we don't need it to. We only need about a hundredth of 1% available in a year to meet our potassium needs. How do we mine it out? Well, you know, geologists will do this with chemistry, but we're not going to go out in the field and apply harsh chemicals that will actually extract, break down rocks and release that potassium in there.

28:18 What we can do is essentially mimic the process by which potassium has always been made available from rocks. What I have here, this is a picture of granite boulders and there are lichens growing on these granite boulders. Right on that rock surface there are lichens growing. And a lichen is actually multiple organisms. It's not one organism. There is a plant. A lichen is composed of a plant and a fungus and a whole host of microbes.

29:01 And what those—the plant of course gives energy to the fungus. The fungus supplies enzymes and the bacteria supply enzymes that break those rock particles apart, chemically degrade them and change them into soil that the plant can use for sustenance.

29:24 What goes on in a natural ecosystem, essentially you have this flow of minerals starting from the rock. You have these lithotrophic microbes. Lithotrophic is a Latin term. Litho means rock and trophic means eat. So these are rock-eating microbes. There are microbes that basically derive their existence by eating rock particles and then those microbes are in turn eaten by rhizosphere microbes that live on the surface of mycorrhizal fungi and those mycorrhizal fungi funnel the nutrients into plants.

30:13 This is what happens in a natural soil ecosystem. This is the way it's supposed to work. And energy flow goes the opposite direction. You have plants photosynthesizing and they provide energy to mycorrhizal fungi. Mycorrhizal fungi supply that energy to rhizosphere. They supply energy to those lithotrophic microbes. And then of course the rocks don't need energy. But you get the picture. The lithotrophic microbes use that energy to break down the rock particles.

30:48 And in a natural ecosystem, this works incredibly well. Now, here is the redwoods out in California. 300 foot tall trees. How much NPK does this receive every year? Answer is obviously zero. And if you think this is rich soil, go out there and try and dig in that with a shovel. It is nothing but granite boulders. Some of the most miserable soil you'll ever see. How does this happen? 300 foot tall vegetation layer.

31:30 And at the same time, here's our experience in crops. If we don't apply fertilizer, our crops just don't amount to anything. And why is that? Why can that natural ecosystem function exceptionally well without any added fertilizer in our crop land? We get this kind of miserable result when we don't add fertilizer.

31:58 Well, we're dealing with a whole different thing. Remember this energy flow? We need this energy flow in order to make that mineral flow go the opposite direction. Okay. So, what's in our agriculture ecosystems? What's wrong with this? What's not happening here?

32:21 Well, number one, how many days out of the year do we have plants photosynthesizing? Let's take a corn soybean rotation. Most common rotation in the United States. How many days out of the year do we have fully functional photosynthesis going on in a crop field? It's about, if you do the actual measurements, it's

32:45 About 90 days out of 365. 85 to 90 days. So if you only have 90 days of photosynthesis, how much mycorrhizal fungi do you have out there?

33:02 Mycorrhizal fungi starve to death during fallow periods and a typical crop rotation in the United States has about eight months of fallow every single year. That's why we don't have mycorrhizal fungi. If we don't have that, we don't have these rhizosphere microbes. If we don't have that, we don't have these lithotrophic microbes. So this whole ecosystem in the soil has been starved to death because of monoculture and fallow and I might add tillage.

33:34 And so if you want things to work we have to make our soil alive. We need to bring life back to our soil. And are we, can we? If we bring life to our soil, can we create conditions in which potassium fertilizer is less necessary? And I think the answer is yes, we can, because we can see examples in nature where that process works very well, and if we mimic nature in our crop land, I think it's entirely feasible to reduce our needs for purchased potassium fertilizer.

34:18 But that does not necessarily mean you just quit and go cold turkey and say, 'Well, Strickler says that I don't need potassium fertilizer. I'll just quit.' No, that's depending on your situation, that could invite economic disaster. Like I said, if you've been applying potassium fertilizer and you've had skips and that crop looks miserable where you've had a skip, then you need potassium fertilizer. But let's just say you are in the position of you have a soil that responds to potassium fertilizer and you want to create the conditions in which you don't need as much potassium fertilizer.

35:09 What can you do? Okay, so let's just start. Step one, remember in that energy flow diagram, your steps to reduce your need for purchased potassium fertilizer is to maintain living roots for as many days of the year as possible. And what that does is it provides root exudates. All these little droplets coming out of this root tip here, that's liquid sugar. That is microbial candy. When you, the only way you get those microbes fed, the only way you keep those mycorrhizal fungi fed is with root exudates. And those root exudates take plants. So you need living roots, living plants as many days out of the year as possible. Do not allow periods. Every time you have a fallow period, you will have microbial die-off. You will lose the microbes that are helping to make your fertilizer or your soil release more fertility.

36:14 Let me just show you, this is some information I got from Buzz Clue, South Carolina. Check this out. So what they did is they had cover crop plots and adjacent to no cover crop plots. First thing they did, they measured the amount of N, P, and K in the cover crop biomass. Let's just focus on potassium. We'll ignore the other ones for now. That's a topic for another webinar. But 260 lbs of potassium in the cover crop biomass.

36:50 The next thing they did was they took a soil test of what was. Now remember this is not, there's a reason the pounds per acre here is in quotation marks because that's not really what it is. It's an availability index. But let's for argument sake let's just look down here. The Mehlich one is one type of extract extraction. The H3A is another type of extraction. So two different types of extracts measuring the amount. You can see under the cover crop it was lower as you might expect because the cover crop would take that up. And that's a concern some people have with cover crops. 'Oh, this is going to suck up all my fertilizer and then my crop won't have any.' Okay, well, it does appear that there are lower soil test values in that field under the cover crop.

37:53 Okay, remember this while the cover crop is still green and growing. And so the difference here is 37 pounds or 20 pounds depending on the extract. Take a look at this. If you add the two together, add the two together, soil with no cover crop, depending on which extract,

43:59 It's just a fraction of that perennial root system. And the moral of the story is that when you put a perennial crop within your rotation, you have access to this huge huge root volume, and particularly if this is inoculated with mycorrhizal fungi. Look at all the potassium extraction ability that this plant has compared to an annual.

44:34 It's also critically important that you have a wide range of diversity in that perennial pasture. You'll notice here this is not just grass. This also you can see this plant right here, that is plantain. This big dandelion looking plant here is chicory. This is alfalfa. We have some clovers out here. We've got a bunch of brooms out here, orchard grass. We've got a big wide range of diversity.

45:08 And the reason that is important is that many of those forbs—this is an illustration from Dr. Weaver who was at University of Nebraska basically a hundred years ago—but he documented the root structures of all these different prairie plants. And the grasses, as you can see here, had very dense root systems near the surface. But the forbs had very deep tap roots that could access nutrients, including potassium from way down deep in the soil, bring it up to the surface where it could be more biologically available.

45:51 Now, you say, 'Well, how do you make money with perennials?' Well, that's actually pretty easy. You graze them. Why? Now, I guess you've got a couple options. One is you could bail it up for hay or you could graze them. Now, what do you think? Take a wild guess what my preference is. If your goal is to improve your pool of available potassium fertilizer or fertility in your soil, which is going to be better, haying or grazing?

46:29 That brings us up to our next step to reduce your need for purchased potassium fertilizer, and that is move to a farming system in which your nutrients are recycled rather than exported. So take a look at this potassium removal in terms of potash K2O. Okay, so 20 tons of corn harvested for silage removes 520 pounds per acre of potash. 200 bushel corn—I'd say these are probably pretty equivalent yields. Twenty ton corn silage and 200 bushel corn probably very close as far as total yield. So you can, for practical purposes, assume this is the same crop of corn harvested two different ways.

47:28 Look at that—more than 10 to one difference in potassium removal when you harvest silage because most of the potassium in a plant is not in grain. It's in the leaves, it's in the vegetative parts, the leaves and the stems. So when you remove leaves and stems, you remove so much more potassium than you do when you only remove grain. And so this is why a silage program is such a nutrient drain. Same is true for hay. Take a look at this: six tons of alfalfa hay, 480 pounds of potassium removed. Hay is a huge nutrient drain.

48:16 Say, well, how do you make money then? Take a look at this. You take that six ton of alfalfa hay, graze it, turn it into beef, and beef is the only thing that leaves that field. You only have 600 lb of beef, only contains one pound of potassium. One pound. That's quite a difference in nutrient drain between haying alfalfa and grazing alfalfa.

48:50 When you move to a grazing agricultural system, your nutrient drain is very very minimal, negligible really. And so let's contrast that. Let's look at the fertility in a truckload of soybeans: 3600 lb of nitrogen, 705 lbs of phosphate, and 1,020 lb of potash. So you say, yeah, beans are, you know, $16 a bushel. So, you know, that truckload might be $15,000. That's a lot of money. But the fertilizer value of those soybeans is about a third of that value.

49:36 And how you feed that method, I'll just show you. Look at this—was a study done in Canada at Alberta and the hay.

49:48 Feeding method and this is pounds per acre of forage from the pasture. So they, the control was no fertility applied, no manure, no fertilizer. This is what the pasture produced, 1423 pounds. If that hay was fed in a dry lot, then they scooped up the manure and hauled it, whether it was spread raw or composted near around this 2,000 pounds. So about 50% greater than the control. But look at this where the bales were fed out on the pasture and the manure dropped directly from the animal. Look at this much, much bigger response. That's insanely huge.

50:38 This makes a difference in your overall productivity. Obviously, if you pay attention to the nutrients in feed, your cropping system, are you removing nutrients from the field or are you importing nutrients from the field or if you're just paying off and feeding it or if you're grazing it. So another step is, you know, obviously we showed the impact of feeding hay on there. Where's the hay coming from? And if you can import waste materials and I would include not only waste materials, but also feed materials. If you are importing feed to your farm and turning that into manure or if you are bringing manure in from an outside source, you can pretty rapidly build up fertility and that can perform many of the same functions as potassium fertilizer. And depending on hauling cost and your materials cost, that can either be very expensive or ridiculously cheap and you just need to put a pencil to it. But these plant and animal derived materials are worth more than just the nutrient content.

52:05 Now, of course, here's a table of nutrient content of manure. Here's your potassium content, somewhere around roughly 2% potassium on the average on a well, this is pounds per ton, this on a dry weight basis. This is as is. So about you know roughly 24, 25 pounds per ton of wet manure as potassium. So you say, well, you can calculate the nitrogen, the phosphorus, and potassium. That's the value of manure. Wait a minute. It's actually a little more valuable.

52:52 Here is manure. Here is nitrogen. 120 pounds of nitrogen applied in the form of fertilizer here at the yellow area. This is Hayes, Kansas on wheat. 120 pounds of nitrogen applied as fertilizer gave 25 bushel yield. 120 pounds of nitrogen applied as manure gave 60 pound bushel or 60 bushels of wheat. 60 versus 25 at the same applied level of nutrients. There's obviously a lot more going on to that manure than just the NPK value.

53:44 One of the best ways to harvest any crop if you want to build fertility is to graze that crop in place. Let that animal cycle that fertility back and deposit it as manure. This is a grazed cover crop. I want to show you some information that I received. Now, this was from when I went to Africa couple years ago, and this is a soil sample taken. This was their version of a Haney test. And this was taken October 11th and 2018. And if you look at the potassium, nitrogen phosphorus potassium 1410, 332. Here is a sample taken one year and a week later, one year and six days later after a grazed cover crop. Nitrogen goes up dramatically. Phosphorus goes up dramatically. Potassium also jumps. And there was zero fertilizer applied to this field. Zero. This is simply from planting cover crop and grazing. And obviously a lot of that is because of the mining action of that cover crop and the recycling of that potassium and nitrogen phosphorus in the plant material back to the soil through manure and urine. Now, the final step I'm going to talk about is encouraging earthworms. This is a picture I took over in Hungary. And this was about the heaviest clay soil I've ever seen in my life. It was I guess 60, 70% clay fraction. Heaviest clay I've ever seen. This is land that's been moldboard.

55:47 Plowed for probably three or four thousand years. Back in the times when they did it with oxen and a wooden plow, there was no organic matter, no soil structure in the soil, just beginning. They're just starting a cover crop program. And already they were seeing big dividends. And here's a cover crop route. And you'll notice this cover crop route is going right down a little bit farther down the way here we found the earthworm. That route was going right down that earthworm tunnel. Now, why would that route do that? Well, number one, it's mechanically easier to follow this path. Number two is because those earthworm casts, the earthworm feces, when that soil passes through that earthworm, if you understand how an earthworm's digestive system works.

56:51 Earthworms have a gizzard. They eat soil particles and then the soil particles grind against each other. Now, earthworms don't actually eat. They ingest soil, but they don't digest soil. What they're eating is the microbes that are in that soil. They eat the organic matter in that soil, the microbes that are in that soil. And then when they excrete that because all those rock particles are ground together inside that gizzard, all the rocks rub against each other from that grinding action. They're broken apart. Fresh faces are exposed. Microbes work on that and then the earthworm digests the microbes, deposits this cast, and then a whole new set of microbes arises in there. And all those microbes are lithotrophic organisms or there are a number of lithotrophic organisms within that population.

57:55 So just look at the bottom line here. The potassium content in an earthworm cast is three times that of the soil from which it came. After it comes out the back end of that earthworm, it's three times as rich in potassium as it was before it went in the earthworm. And same thing with phosphorus, same thing with nitrogen. This is like alchemy. This is like turning lead into gold. This is creation of fertility that would not show up on a soil test prior to the arrival of the earthworm. So earthworms are extremely important in converting that mineral matrix. And so how do you get more earthworm? You say, 'Wow, this is fantastic. I have enough earthworms. I don't need that fertilizer. How do you get earthworms?' Well, same way you get stray cats or teenagers, you feed them.

59:00 You look at this rotate research from Kansas. This in a wheat sorghum rotation and they put a cover crop in the wheat stubble on part of these plots. And without the cover crop only 2.8 worms per square foot. Look at what you got with sunhemp. That's roughly seven times the number of earthworms out there. And this was just at the end of a six-year period. So you increased your earthworm population sevenfold with by the inclusion of a legume cover crop every other year in this. So every other year, so three cover crops.

59:51 Now what do worms need for food? They need something that's high in protein because their bodies are made of protein and they need material that's high in calcium. And the two classes of cover crops that fit that bill are legumes and brassicas. Legumes and brassicas are both very very good at building earthworm populations. So you need, you know, in the wheat sorghum rotation wheat straw miserably low in protein miserably low in calcium. Sorghum residue low in protein low in calcium. So by inserting a legume cover crop in there you can dramatically alter the value of that for worms. What are other ways of building earthworms? Well, how would you increase the population of any other form of wildlife? Provide food, provide shelter, and stop killing them. So food we already talked, you know, growing plants high in calcium high in protein.

1:01:06 Legumes, brassicas, and try to keep green growing material out there as much as possible. And it's the decaying material that feeds the earthworms, the stuff that falls on the ground that the earthworms can start ingesting and digesting, then providing shelter and cover.

1:01:29 Earthworms are killed by high temperature soils. They're killed by low temperature soils. If you want to keep them active, you want a stable soil temperature. You want stable soil moisture. You gain both of those from leaving a mulch on the ground, leaving crop residue, leaving cover crop residue on that soil surface is absolutely critical to building earthworm populations.

1:01:56 And then stop killing them. What kills earthworms? Tillage, infuro insecticides, of course, any sort of soil fumigants, just absolute death to earthworms. So we really need to stop those practices. Fallow is not good for earthworms. We need to stop practices that kill earthworms. And if you get really good, you provide the cover, provide a roof over their head, three square meals a day, leave their food on the top of the table, which is the soil surface, and stop killing them. And you can grow some really nice earthworms.

1:02:48 Now once you have gone through all these steps, the next question you say okay, I'll do this and this and this and this. You'll do those six steps. Let's just say hypothetically you take all six of those steps. You say, 'Okay, can I reduce my, can I stop buying potassium fertilizer now?' And my answer will be, 'I don't know.' That'll be an honest answer. I don't know. There's only really one way to know. Well, you can soil test and you still won't truly know.

1:03:28 It'll give you a much better idea in my opinion, but you still won't truly know. The only way that you will truly know whether or not you can get by without potassium fertilizer input, and you'll want to keep doing this more than one year. You'll want to keep doing this. This should be a part of your normal routine is to put out no fertilizer, reduced fertilizer rate strips.

1:04:00 Do this for a few fields. Don't do a lot. Don't do a big acreage. When your no fertilizer strip is the same yield or close to the same yield as your fully fertilized strip, then you'll know you've arrived. And you can stop buying fertilizer when the yield, the value of the yield that you lose is less than the cost of the fertilizer you've been buying. When you reach that stage, it's time to stop applying fertilizer.

1:04:44 And you need to do this every year. You can't just do this once. You need to be doing this in an ongoing manner because you don't know how the potassium supply and availability of your soil is dropping year after year. Maybe it's staying steady, maybe it's going down dramatically. You will not know that until you have gone through this process over and over again. And so you need to be doing this on an ongoing basis. And yes, it's a pain. Yes, it takes time. Yeah, you got to stop and slow down harvest and weigh this strip and weigh the adjacent strip.

1:05:30 But if you could save the money you're currently spending on potassium, won't this be worth it? I think if you're watching this webinar, you're probably watching it because you are concerned with potassium fertilizer cost. And so if you're looking forward to potentially saving that cost, the only person who can answer the question of can I get by without buying potassium fertilizer ultimately is you.

1:06:09 I can't give you that answer. Only you can answer that for yourself. So, Noah, I think I am, and just as a shameless plug, I have written a book, Restoring Your Soil, and a lot of the information that I have in this, there's about half a chapter in that book on this very topic on how can you create soils that provide enough fertility for your crops in a sustainable basis without having to buy fertilizer.