 Dr. Meehan mentioned that I teach soils and land use and instrumentation and sampling. I currently teach introductory to soil science. So at any time, take out your phone and just look at that while I'm talking. You don't mind? That would make me feel better that I'm actually teaching. So just keep that in mind as you move forward. So one of the things that we spent quite a bit of time mentally thinking about is the effects of how the physical properties end up being a big driver in any success whether it's agricultural or whether it's reclamation, restoration. And so we kind of throw this in a basket with other soil parameters such that if we want to get back to the actual yield or productivity at the bottom, we have to understand what's happening with the soil properties on top. And so Wade did a nice job of talking about those limitations. Those are the types of things that we think about all the time, not in a weird way, but it's sort of in a, we have to keep these in mind if in fact we want to have successful reclamation. Because any one of them by themselves might actually decrease the potential for success. And so things like the soil physical properties, soil biological and so chemical properties, whether it's soil water, microbial and fungal populations or the sodium content in pH. And so today we're going to be talking more about the soil water and the cone penetrometer resistance and bulk density. So Chantel is up front. She's helping me tease the lab and she makes me put this in every time we teach to make sure that the students remember that soil is has many components to it. It has a mineral phase and organic phase and it has air and air and water. And so an ideal soil, an ideal soil would have 45% mineral, 5% organic and the rest of it would be make up by pores, pores meaning that can be filled with air or with water. And so this is ideal. Just your neighbors probably don't have it, but you do, right? You probably have Steve, right, Steve, what put Steve in there? And so keep this in mind as we move forward because as we start talking about compaction, this will shift quite a bit. And so, okay, so we're going to have a, there's no math involved. Unfortunately, the homework that's due at Friday at 10pm, it's all math, but I'll let Chantel grade those. And so the definitions for this talk, we need to think about this as bulk density. Bulk density is the dry mass per volume, total porosity. This is like all the pores that are in that soil. And so if you go out and you take a sample or pull up a pick up an aggregate or a pad or a clod, hopefully 50% of that clod or that is made up of pores. And so the other thing that we spend a lot of time thinking about is gravimetric water content. This is the mass of water per mass of soil. I don't care if it's pound per pound. Those of you that like the metric system, if it's grams for gram, so be it. The last thing is penetration resistance. Now those of you that remember our coat of arms for the state of North Dakota is strength from the soil. It's fitting, right? And this country was founded on agriculture and they depended on the soil for their livelihood. Penetration resistance on the other hand is strength of the soil. Strength of the soil. Meaning if you want to push something through soil, it's going to take some force. And that force is how much strength it takes to actually push through. So things like roots, things like earthworms, beetles, all the other macro and micro invertebrate that are in that soil. And so we'll spend a fair bit of time talking about those. Okay? Traditionally, if we wanted to go out and figure out what the bulk density of soil is, it's one of the most important parameters that we can measure. But it's also the biggest pain in the butt to measure. Okay? Because it's a lot of work and to get a good sample it takes a lot of effort. And so typically we would take something that looks like a three by three inch core and we have something that we can drive it into the soil. And then we would have to get it out of the soil without it all falling out. And in sands it's near impossible. Then we'd have to shave the top and shave the bottom to make sure that we have one volume of soil that we know of. And that's the volume part. Then we take that to the oven and we put it in there for 24 hours at 105 degrees Celsius, which is above the boiling point. And then we dry it for 24 hours and then we weigh it. And therefore we have a dry mass of soil per volume. And that's how we get at the bulk density. And it sounds like it's easy, but it's really not as much fun as I really accentuating my voice about it for. The other thing that I'm terribly interested in, and if those of you who have one of these nuclear devices that can get at density, I'm terribly interested in learning more. Not only from the reclamation standpoint, but those of you that are associated with farming or ranching, we've all heard about the carbon sequestration. We've heard about the carbon markets that will be coming or already here. One of the biggest challenges we have is actually getting the bulk density of the soil to correct the carbon content too. So therefore we can figure out what the mass of carbon is in a soil. And so please see me if in fact you've used one of these or have knowledge of these after the talk. OK, so just throwing out some numbers, right? You know, we like to talk about numbers and scale, but it's always good to put boundary conditions on what we're talking about. So if we went to Northern Minnesota up near Big Bog, north of Bemidji, you can go on a mile long boardwalk. It's a gorgeous walk through a bog. That density of that material is about 0.2, let's just say. So that means 0.2 grams of material in a volume. And that's grams per cubic cubic centimeter. And that's really like crunching a paper and that would be the density. OK, now if you go down the list a little bit, go down to those urban lawns. OK, sports medicine and sports injuries are real. Why are they real? Because the athletes are playing on things that are very dense, very hard. And why is it dense and hard? Because they've been running on it every year for how many years. And so that density is 1.5 to almost two. And most of the time, most biological organisms cannot function and grow in things that are above 1.7. And so that becomes a challenge. But go down to the rights of ways. You have anyone up from 1.8 to 2.1, very hard. What is for a structural reason, right? That it's part of an engineering criteria. OK, so when we think about how that density is related, though, we can look at this as like, OK, how does the actual density impact the total pores that are in that sample? OK, this is one of the most important measurements that anybody in soil physics or looking at soil physical properties will want to determine. Because the pores will dictate how much water the soil can hold, how easily the roots can move through. And so it's a very linear relationship. That's exactly what it is. As the bulk density increases on the x-axis there, that the total porosity will also go down. Makes sense. If you start squishing a soil, you don't have as much room for pores. And that's where the air and the water reside. And so keep that in mind as we move forward. OK, so now let's look at those same soils and we'll look at what that total porosity is based on those relationships. And so if you look at the top on that sandy soil where the bulk density was 1.3 ideal, if you have a soil with a bulk density of 1.3, that means half of that soil is pores. And the other half is solid phase. Beautiful. That would be the most ideal condition you could probably find. However, as you start getting more and more dense, as in the bulk density increases, look how that total porosity goes down. In a silt loam that has a bulk density of 1.5, now it's only 43%. But if you go down to that bulk density where it's 1.8 or 2.1, it gets pretty small. And so there's ramifications for that. There's ecological ramifications, which then dictates how difficult it might be to get things to grow. And so these problems that compaction cause are reduction in porosity, and then how those pores are connected. If the pores are connected, water moves through fairly well. If the pores are not connected, they send water tends to move very, very slowly. Root restriction, a major problem with compacted soils, and we'll show some pictures. It just roots to have a functional ability to move through soil. But when it becomes too dense, that doesn't happen. And therefore, you would get reduced plant growth and increased runoff. And so this is an example of a reduction in porosity. So those of you that have had a kidney stone, this is what they did to scan you with to find where that stone is. So you're not laying on the floor in pain. But the one on your left is a soil that is not compacted. And so what you're seeing there is actually the pores in that soil. Look at the one next to it, though. Look how the pores are very restricted and they're not connected anymore. That's what compaction does. And so that has huge ramifications, again, on air and gas exchange, but also on water movement. And the roots to move through. So just kind of a pictorial diagram. The one on your left is showing problems here. But as you get more compact, you see that the roots get limited and how deep they can go. And this is a major problem with compaction, especially after pipelines have been installed in the right of way, is that that zone where the plants are actually living is fairly shallow. Whereas if you have a soil with good porosity, low bulk density, those roots can explore to much fuller depth. Here's just an example of stunted maize in Pennsylvania. This is one that a picture that Sam Crote took. So this was one of our research projects on the West in Research and Extension Center. This is an alfalfa. We consider alfalfa to be pretty hardy, pretty tough. But if you notice on that picture, it goes down about four inches and then what to do? It says it takes a right-hand turn, right? Because of the fact that it could not penetrate through that very, very dense soil. So there's no doubt that yields are going to be reduced or plant growth is going to be reduced because of the fact that the roots are only living in about four inches of soil. And so this is one of the problems that is a long-term challenge, not only in reclamation, but also in agriculture as well. So let's get back to that picture, that diagram. The one on the left is an undisturbed soil. That one is ideal. And then the one on the right is the one where you have compacted soil. And so the mineral actually takes up much more of the actual volume that you have than the actual pores do. And so that has more ramifications than how much water then, how much water that soil can hold. So if we think about, if you flooded a soil and it filled all the pores, that's the saturation. That's how much water the soil can hold. If, in fact, though you start increasing the bulk density, what happens to the amount of water that it can hold? It goes down quite a bit, right? It's a linear relationship. And so the more, if we're thinking about long-term improvement of the soil, having more pores can hold more water, but holds more water, it has more ability for plants to actually use that water. If, in fact, you have a very dense soil that can't hold much water, those plants will not have much water to actually use. And so this becomes an exceptionally important parameter when thinking about soil-water balance. OK, so the main physical limitations for root development and plant growth. Big shocker, right? Low water content. Extreme temperatures, which we don't normally associate here as much, but it certainly does happen. Poor aeration and high penetration resistance. Now, again, as we just showed, we were talking about the water content. So as water content decreases, the penetration resistance, that's the ability of the strength of the soil that increases. Water acts like a lubricant. Water acts like a lubricant for roots and for other biological organisms. If, in fact, you don't have much water, you don't have much lubrication. If you don't have much lubrication, you're not going to have much penetration. And so that's where the water comes in. So this is not the Titanic after it hit an iceberg, but the one on the left is a schematic of what a normal root would look like. And the one on the right is one that is trying to go through a very dense soil that has a high penetration resistance. It causes a lot of physiological issues with the plant. Plants will produce ethylene. When they produce ethylene, it triggers them to sort of go into a response mode of, OK, this is not going well. And so one of the things that plants are really, they're exceptionally intelligent, although they're not in the same vein as the students in my 210 class. But you can see that how difficult it might be to get at that point, to get that root to move through the soil. So thinking about this long term, we have a couple of people in the room that were part of this project. This was 40 years at a coal mine in North Dakota. What I want you to see is the red dots are the roots and the black dots are the soil organic matter. So after 40 years, and the soil organic matter comes from the roots and the plants that have been established there. What happened after 40 years going left to right across that graph with the organic matter of that soil? Nothing, right? A lot of work, a B&I spent a lot of strong efforts and working through this, but look at the roots. Did the roots do any better, right? That's what compaction does. It limits the potential growth of plants. And so, which is tied very closely with water content and the penetration resistance. OK, so penetration resistance, blah, blah, blah. This is a measurement that was long. People have been doing it for a long time. These are what we're calling a static, meaning that it's just a constant force that goes down. These are, they have, so the one that I brought just for defense, there's a cone at the top. And that cone is like at a 30 degree angle. And that's a fairly common standard practice of what these look like. And then most of them have either electronic or a dial. And those that can't, you probably can't read this, but it says ludicrous penetration resistance. OK, those of you who remember, back to the future anyway. So anyway, the idea is you would take this, you would push it down into the soil, and you would take a reading and get a gauge of what the penetration resistance of the soil is. OK, fundamental measurement, operator to operator, it tends to vary a little bit. But if we move to the picture on the right, this is one that you can purchase. It's built in North Dakota. It uses software that is developed by Amity. It's a farm QA. I'm not promoting, but I'm telling you that locally made. This is example of what some of the data would look like. So we were at a coal mine. We were looking at the penetration resistance of our treatments. The software is wonderful. It's all GPS. So you can go back later and actually collect all your data without writing anything down in the field. But that red line that you see, that is what we would call kind of the limitations for root penetration. And that is 300 psi, the 300 pounds per square inch. And so if you look at that, it doesn't take very much depth in, let's say depth in inches or feet. No, it's inches. So at what depth was that root restriction? About five inches, five, six inches, OK? And so again, that's where the roots are living in that top five or six inches of soil. And therefore, we would expect and hope to have, after spring melt, we would fill our profile full of water to be at field capacity, meaning that's the water that the soil is going to hold. If you're only filling it five inches, that's not very long-term growth over the course of the season. That's pretty, that water is not very useful long-term. And so getting ourselves to think more about how do we get and what conditions cause us to have some issues with penetration resistance with this one. So this was at our research site at the Williston Research and Extension Center. The 300 psi is noted with the vertical bar. OK, look at the road, which is the brownish color, the one in the middle on the right. At what depth did you see penetration resistance exceed our 300 psi? Four inches? That's the exact same picture I showed with the alfalfa. That was the four inches that you saw. And so again, pointing out the nature of soil properties, the compaction, the dryness will lead to, unfortunately, increased penetration resistance. OK, so Jared Lardy, he gave a talk here last year, I think. He became a father of three here on Saturday. He had triplets, so he couldn't come. I'm like, OK, whatever. But what we were trying to do with his project was actually try to identify what is the relationship between bulk density, water content, and penetration resistance. So Wade gave a very nice talk about what kind of parameters might go into saying that this area might be unsuitable for reclamation or very challenging for reclamation. Well, we wanted to think about how we would add more value to that product. And so we wanted to develop and figure out what those relationships were. So if somebody is interested in like, OK, this is the bulk density, this is our water content, this is our penetration resistance, what is the success potential for that reclamation project? And so he did lots of stuff. He wasn't a card player, which was nice. So he worked hard. Zach, did you play a lot of cards? Oh, he left. Oh, no, there he is. Yeah, he's back there. So Aaron Green, do you want to watch him too? But anyway, he homogenized surerals. He looked at them. We had something where we can compress soils. And then he used a penetrometer to get that. So we had different water contents. He compacted them to different bulk densities. And then he did the penetration resistance. So let's look at what that might look like. So on my notes, I can see. Anyway, so one of the things on this graph on the left-hand side over there, it's the penetration resistance. And notice that it's in megapascals, because that's how we talk in those circles. But two megapascals is the 300 psi. So that was the limit we talked about, that soils, that roots cannot penetrate those soils. And then the other bar that you see is bulk density of 1.7. We would consider that to be pretty challenging for any roots or earthworms to move through. And so we put those as sort of our limits on what we were showing here today. And so what do you notice about, if we look at the penetration resistance in the two equals the 300 psi, what do you notice about that data that's there? How often is it below two? Some? A little bit, right? What about how often is, and sorry, the gravimetric water content, that's how much water we actually added to the soil is the different colored dots, okay? So a soil with 0.06 means that it's pretty much just air dry. A soil that is at 0.17 in this case was pretty wet, fairly wet. And so which of those gave you overall the least penetration resistance? Which of those water contents gave you overall the least penetration resistance? The highest, right? The green, meaning that a wet soil is fairly hard to compact in itself. And there, but it's easier for roots to move through. Why? There's lubricant, there's lube there. The actual particles themselves aren't so bound tight to each other. And therefore the roots can move through fairly easy. So what about the, what happens at the lower water contents? What happens at the lower water contents? It goes pretty fast, right? It's like, ooh, all of a sudden the penetration resistance is exceeding, exceeding what we would consider to be the root limitation, okay? So what about, what would happen if you did work on that soil when it was wet versus when it was dry? What would happen if you did work on that soil when it was wet versus dry? When compact as much at the dry, right? You don't see the bulk density starting at the bottom. It started at 1.2, the 1.3 meant that it's 50% pores. But when the soil is dry, it really doesn't get above 1.5. That's an important point to make is because if in fact, construction practices were happening when the soil was dry, the likelihood of exceeding 1.7 is a lot less, okay? The best times to do it when the soil is froze when actually you don't have any compaction at all. So we use this data then to sort of like think about how this might fit into a larger picture of the relationship between water content, bulk density, and penetration resistance. So, okay, then we threw all of us. We basically we measured everything we could. We threw it in a bucket, mixed it around and determined basically that you don't need to know the texture. You don't need to know the organic matter content. You don't need to know the electrical conductivity. Basically, if you know the organic, the water content and the bulk density with 84% confidence, you can predict the penetration resistance. That's the strength of the actual soil. And so that was one of the things that Jared had worked on for his masters. And if anybody wants more information on that, we can certainly provide that to you. Okay, so at the end of the day, is it practical for everyone to do that? Maybe, maybe not. I think in moving forward, I think some of the nuclear devices might allow us to get better idea of the bulk density to then get back and predict what the penetration resistance would be. Again, the penetration resistance is really gonna what matters with the plant growth. And so some of the things that we need to do a better job of though is thinking about keeping that soil covered. Because what we noticed was, if in fact, the longer and the wetter the soil was, the longer it was, the penetration resistance was the least, okay? The longer we keep water in the soil, the penetration stays the least. And that's an important point to note with respect to how you treat after a reclamation has been done, keeping water in that soil. And so the other thing is, can we do a better job of identifying plants that have a stronger root cap to penetrate soils that are more dense, that have a higher penetration resistance? These are things we can do. We need to do it. Because if we identify in these problem areas where Wade is talking about, if we can identify the plants that are gonna survive the most because of that root cap being able to penetrate, we're gonna do a lot better job with our reclamation. So I think that's one of the things that we should be working on. Okay, so I'm gonna leave you with this and you're not gonna stop your construction practices because the soil water content is off, right? There's a certain time of period you can work. Farmers are the same thing, farmers are doers. Farmers want to do things. And so they can't always wait until the water content is perfect to do their work. So we think about how we're gonna remediate it afterwards. So with that, I'll take any questions if you have any. So thank you. So the question is, right? So the question is before respread back, top soil respread back onto a pipeline corridor, is there an advantage to mixing or tilling up that soil? And I would say on the front end to assess first whether that it's even needed. If in fact the water content was low enough when the construction practices were done, there might not be much compaction. But if in fact there was lots of smearing and you had some issues with traffic ability, there might be some advantages to that. Now we did some deep ripping at the Williston project and we actually didn't see a lot of benefit from it. There's never a North Dakota for water and so that's always the problem but we didn't see a direct benefit from that. So it was a lot of work. There's a lot of shearing of bolts just to get the, just to lift it. Now fracturing it a little bit, I don't think turning it over is a good idea but maybe fracturing it up a little bit to create some cracks might not be the worst, but. Yes, sir. When you said that you'd get some. It didn't create it. So the question is, or the comment was asking if it changed our bulk density, right? But basically, we were looking at penetration resistance as a pseudo for bulk density. But I will tell you that the yields were not better when we did the deep ripping versus if we didn't do anything. So I do think there's more work to be done in that. It's not something that we can just say, oh, it's never gonna work. But I do think that over time we start implementing more of these treatments into our practices, we'll get a better handle because certainly some soil textures it might actually work really well whereas in sands it might not work that well or be needed, so. Oh, General. So the question is when we think about and report bulk density, do we also report what the water content was at the time we took the sample? And the answer to that is we have not. And we don't take as much bulk density just because of the difficulties of actually doing it as well. But we're trying to think about penetration resistance as a good pseudo for that. But that's not necessarily always the easiest either. So.