Cover Crop Nutrient Cycling in South Dakota: What Five Years of Research Actually Shows

0:00 My name is Keith Burns, co-founder of Green Cover Seed. And before you watch this webinar, I want to give you a little context about this episode. We invited Dr. Anthony Bllye from South Dakota State to share five years of peer-reviewed research on cover crop nutrient cycling and soil health across South Dakota. Anthony is a fourth generation farmer and a 34-year extension soil specialist. And he gave us an honest presentation, which means he shared the good news and the hard news both about cover crops.

0:29 Some of what he presents might surprise you. His data shows that in dry years, corn following cover crops sometimes yielded less, not more. And he doesn't soften that finding. He also notes that several common soil health parameters showed little change over the short term of this study. We chose to share this research without editing out these parts, and we want to explain why.

0:50 At Green Cover, we believe farmers deserve the full picture. Presenting only the wins while hiding the complications would not serve you well and it would not reflect who we are. Our mission is to help people regenerate, steward, and share God's creation for future generations. And sometimes that requires honest education, not just cheerleading.

1:11 What Anthony's research actually reveals when you follow it all the way through is that water and management together are the two key components to making cover crops work consistently ahead of corn. In wetter climates and wetter years, cover crops supported or improved yields with relatively little intervention. In drier conditions or drier years, that same cover crop still has tremendous value, but it requires more intentional management around species selection, seeding rates, and termination timing to avoid competing for the moisture that your corn crop will need.

1:44 The research does not tell us that cover crops and corn don't mix. It tells us that moisture management is what separates a cover crop that helps your corn from one that hurts it. One of the most practical tools in drier environments is having a rotation where the cover crop can be planted the summer before your corn and planted to species at winterkill. A cover crop that dies with the first hard freeze has already done meaningful work feeding your biology through its root system, protecting the soil surface through fall and winter, and cycling nutrients into the profile, all without pulling a drop of moisture in the spring before your corn needs it.

2:23 That is not a compromise. That is a smart deployment of a proven tool in a water limited environment. We've worked with and learned from farmers all across the Great Plains who have spent years building soil health through no till diverse rotations and cover crops and the results over time tell a compelling story. Getting there requires understanding the trade-offs and managing around them.

2:45 Watch this webinar episode with an open mind. Take notes on what applies to your operation. And if you have questions about species selection, winterkill options for your area, or how to manage the moisture risk, our team is here. Reach out to us at greenco.com or call us directly. We are glad to help you think through what makes sense on your farm.

3:09 Thank you everyone for joining us. I think we're going to have a really good presentation and discussion here this morning or I guess this afternoon already. So my name is Nathan Schot. I'm a sales representative here with Green Cover, been with the company for quite a few years now. I live in Hastings and work here in our Bladen, Nebraska location. So I get the privilege of just working with farmers and ranchers all over Nebraska and up in the Dakotas and out east adopting cover crops and these regenerative principles on their operations. So it is my pleasure to introduce our speaker today, Anthony Bllye. He'll be talking on the subject of cover crop nutrient cycling and soil health benefits on South Dakota crop lands.

3:51 So Anthony is an SDSU extension soil field specialist. He's been in that role for 34 years supporting producers with soil fertility testing and health education. He brings research experience and industry leadership and he has with his agronomy degrees committed to stewardship and honoring mentors through his professional work and service. Anthony is also a fourth generation farmer on their farm there in northeast of Sioux Falls. So he has the research and academic experience, but also he was up at 2 a.m. this morning helping some lambs.

4:32 You know, in the trenches working on the farm, too. So definitely looking forward to hearing his presentation. So, with that, Anthony, I'll turn it over to you.

4:41 We'll bring it up here and get it going. Let me know if it looks good.

4:48 Yep. Looks good. Take it away.

4:50 Okay. Got to move this bar. And there. Okay. Yeah. Thank you very much, Nathan. Yeah, good to be here today and this is a review of a project we did, started in I think it was 2017 and did it for five years and so we were looking at cover crop nutrient cycling and other soil health benefits on South Dakota crop lands.

5:20 Yeah, this grant was funded through USGS and the USDA NRCS local South Dakota level. As I mentioned, we started in 2017 and wrapped it up in 2020.

5:36 Like to acknowledge the team. The team is paramount to successful getting it done. And it was a very large grant. And so there they are. Dr. Jason Clark played a big role in this. He was then our new soil fertility specialist and he came on board and we had this grant and he could take advantage of that. Dr. Chris Graham is in our west research area out by Rapid. Peter Stone is manager of the southeast farm. David Key is now a extension crop production specialist on campus, assistant professor. He was a field specialist like me. Dr. Samuel is now a University of Arizona assistant soil specialist there. Very proud of that. He was kind of the postdoc on the project if you will. And then we have Hunter Bloomberg. He was a graduate student. John Waltzen was a full-time employee of the project. He's now at Circle Seeds in Three Forks, Montana. Sarah Bower is our soils field specialist for forage, excuse me, forage field specialist. Bruce Beck now retired agronomy field specialist. There you have me. I was the primary investigator of the grant. So my job was to see that everybody was happy, had what they needed, kind of direct some of the work. In a sense my style is let the horses run. If my employees have good ideas and good suggestions, then we go with that and I try to support that as much as possible. And we had very, we had several undergrad students working on the project and really too numerous to mention.

7:30 Here are a list of our peer-reviewed research articles that the crew put out in nitrogen communications and soil science and plant analysis in the agronomy journal, in frontiers and in the soil science society of America journal. A couple three master's thesis were generated out of this. So we have some students that got good experience here and extension publications. This project contributed greatly to Dr. Clark's update of our corn fertilizer recommendations, nitrogen recommendations in South Dakota.

8:25 Okay, there we go. Better watch what I'm pointing at. A number of conference presentations as well. So the crew got to go to meetings and present the work that we did.

8:37 But let's get to the project. So the objectives are threefold. Cover crop influence on nutrient availability for the following cash crop, mainly going to focus on corn nitrogen response. So having a small grain out there and then planting that cover crop. That's the easiest way to do a cover crop. Got a lot of time there, a lot of flexibility, but then follow that with corn and see how it affects the nitrogen and spots of that corn. And then the cover crop influence on the yield of the cash crop and soil health measurements mainly in corn and soybeans. And then the cover crop influence on soil moisture status prior to that following cash crop. We only had three sites where we installed soil moisture probes and I'll show you that here as we progress forward.

9:31 So as a good scientist, both a scientist and a farmer if you will, the first objective we had 13 on-farm sites. The producers chose those cover crop blends. We just came in and established our plots. They were all established after a small grain crop. Usually wheat and oats. We established our check plots by spraying out or keeping those control plots brown. And so we visited those plots and just kept that way. We had five sites where soybean was the

10:09 Falling crop and eight sites where corn was the falling crop. There was four reps at each site. Plot size was most would say this is small but for small plots these are fairly large, 15 by 50 feet. Objective two we had 14 on-farm sites. Those were the corn nitrogen response responses for different cover crop blends. And they all followed a small grain as well. Those cover crop blends were a blend of 50/50 broadleaf grass, a broadleaf dominant so 90% broadleaf 10% grass, a grass dominant as you can see there 90% grass 10% broadleaf and then a control without the cover crop and those cover crops were the grasses were oats, barley, foxtail millet and sorghum sudangrass and the broadleaf cover crops radish, turnip, field pea and common lentil. Our nitrogen rates applied as SuperU. SuperU is a highly protected form of urea. It's got nitrification and mineralization inhibitors in there as well. So 0, 40, 80, 120, 160, 200 lbs per acre. Again four reps at each site and the plot size there was 15 by 50 feet.

11:31 Just a picture of one of the sites here. Showing that we did what we said. We kept those cover crop plots bare. You can see there were some dead carcasses there where we had to keep that brown. So anyway kind of an interesting shot there. A lot of growth there as well.

11:58 For the third objective, the soil moisture probes, we had three sites across South Dakota. One by Mitchell, one by Hayes, and one out there in the shadow of the Black Hills at Sturgis. And at those sites, we installed soil moisture probes. What you're mainly seeing here is the post that has the data station on it. But to the right there, you can see a little white tube or a little white thing sticking out of the soil. And there's a buried line there to that. And that's a 4 foot moisture probe that measures soil moisture every 4 inches. And they're very expensive. So we only got to install them on the zero cover crop 80 pound nitrogen rate and the grass cover crop 80 lb nitrogen rate. Now these probes have been automated. They're Bluetooth. You don't need that white post there with that box and all that wire and you can just walk up with your smartphone, access it, upload it to the cloud, which I wish we would have had, but that's how fast things change.

13:20 So the results for objective one first want to just show all the locations that we had predominantly there in the southeast. I'm only showing the locations that were successful. In 2019 we had excessive precipitation in South Dakota, kind of started the latter half of 18. And so we lost numerous sites and you can see these ones that were successful turned out to be in the southeast corner.

13:53 So these are the spring soil test values just right ahead of planting the cash crop. We looked at soil organic matter, the carbon nitrogen ratio to 6 inches. I apologize for this being in the metric scale but 15 centimeters is roughly six inches of soil depth. Nitrate nitrogen at the 0 to 6 and then the whole 24 inches. Olsen P, extractable K, sulfate sulfur and at two depths. The only thing that we saw that cover crop had an influence on was the nitrate nitrogen and that's what we wanted to have an effect on. The other soil test parameters, no influence, which is okay. And some would think, well, this is kind of negative to cover crops. We didn't influence that soil organic matter. But let's just think about the fact that the amount of dry matter that a cover crop produces in relationship to the amount of organic matter in the soil is really incomparable.

15:03 So we know that the prairie built itself over many many years, some say thousands, tens of thousands of years in some places and so that organic matter buildup was slow and steady. And so a very short-term look at with one cover crop year isn't it, we didn't expect to see a lot of change in that. But that cover crop did sequester the nitrate nitrogen, the nitrogen. It kept it, put it in the organic form, which we want to see. We want that to cycle well then in the organic form. And so we were encouraged by that. And several others have also found the same thing.

15:53 Here were those sites here. You can see the location and then the crop that was growing after the cover crop. And the associated yield.

16:06 So at these sites we just had with and without cover crop. Of course good scientists do statistics and so two of those sites were significantly different when we applied the statistics to them. But the trend is the trend and that's what farmers are most concerned with. So if we look at the summary of this data we see that the cover crop where the cover crop was had a higher soybean yield 64.3 versus 63.1. Again that's not statistically significant but it is a trend. And the corn also had a yield increase that was not significant. And so over the long haul we can see that it had a positive effect.

17:11 But I wanted to go back to these slides and look not to be negative or bring negativity in here, but the Plankington 2020 site had a significant decrease in yield. The plots without cover crops are at 192 bushels roughly and the plots with cover crop were 153. But look at the Plankington. We had two sites there and quite frankly they weren't very far apart, just a few miles, but one picked up a rain and one didn't. And I'm not kidding, that's what happened. And so there was an improvement in yield with the cover crop there where it didn't. So it's all about precipitation and as I go forward here throughout the discussion, hopefully get that across because we built a lot of our results on the relationship to precipitation and cover crop biomass.

18:10 So objective two, we had at these sites here. We were able to establish a few out there in those good silt loam soils on the east side of the Missouri River that cuts across South Dakota there down the middle. And you can look and see at the distribution across our precipitation zones here. Wet in the southeast and dry as you go to the northwest.

18:39 Some of the soil health parameters that we measured at these sites were POX C which is a readily decomposable form of carbon. There's many forms of carbon in the soil. This one here is the one that goes first. So we measured those, took those samples and measured that. And what we found is that there was hardly any effect on POX C. Now remember I commented the fact that the cover crop biomass while it looks like it's a lot out there and providing good ground cover which we know it does. It's one of the advantages of a cover crop keeping that soil surface protected, one of those soil health principles. But when we think about that biomass in comparison to the long-term carbon organic matter that's been built up in the soil, it's hardly an influence. And so we can see there that there's no influence there.

19:56 The next thing we measured because we wanted to know if some of that cover crop biomass was going to be readily available as far as the nitrogen pool. And so we measured potentially mineralizable nitrogen PMN. You can see here a rack of vials there with different colors. And it's a colorimetric type of procedure. And you can see the same thing that the effect of the cover crop is not strong. In fact, the control plots are higher or just as high as those cover crop plots. And we tried to do this in the fall and in the spring as well to see if there's any difference and there wasn't there.

20:48 The other thing we measured was soil respiration. It's really an estimate of microbial biomass or activity. We used the electrical conductivity method with the trap there in the mason jar. And as you can probably tell, the results were a little bit elevated with the cover crop. One of probably one of the brightest soil health parameters that we did measure. And so elevated over the control. So that cover crop is doing what we hypothesize that it's doing. It's providing a living root, again one of the soil health principles, and those microbes are taking advantage of that and using those exudates that those cover crop roots are putting out there. So we were encouraged by that.

21:55 So if we look at the yields of those second objective sites, there's a number of ways you can analyze this data and because it's a pile of data that we created and got to move this window so I can see my data. You see the locations there on the left hand side of the screen and then the next column is the statistical analysis and where you see the bold letters, the very small letters, the confidence is high that those cover crop treatments were significantly different. Okay. And that gives the least significant difference between any two of those yields what it would need to be. And then the coefficient of variation is just the accuracy of the test. And when we see 10 and 20% and even higher than that, it's not as accurate. But if those reps align then the statistics can pick that up. So the no cover there is in the blue, the blue letters of those significant sites. And then the red numbers are the blend, the broadleaf, and the grass, the yields of corn behind those cover crop treatments.

23:15 And right away, one thing you're going to notice is a decrease in yield. And it's pretty significant. And don't give up on me. Please don't leave. I want to put a glimmer of hope out there. We didn't do this project to predict an outcome. Scientists, at least I was trained by my mentors, the unbiased nature of being a scientist and you report what you find and then you look for the meaning because the meaning is really the important thing. The numbers are it takes the results to get you to an idea to think about or to find or to discover and so the meaning is the most important part. So, just looking at these yields, you can tell that we've got some good yield environments there. We had one site at Mitchell that the control plot topped out at 234 bushels. Salem down here at 212, but then you see some poorer yields, Blunt in the 80s and then down to 50 and let's see another one I want to highlight Beersford, you know, kind of intermediate there. You know, so we have a good. The first Beersford one at the top is a very wet year. In fact, if you look at that one, it's not insignificant, but that grass plot at 88.3 bushels versus the no cover at 79, we attributed that to just using more water. You know, maybe trying to keep that soil profile out of the anoxic conditions because that corn looked really tough. And we went back and forth whether we should include that data in our data set. And you're seeing the successful sites like I said we lost a lot of sites in 2019 and this one was in 2018 there at Beersford but like I said from June on in 2018 it was very very very wet.

25:37 So if we look at the nitrogen responses then we looked at the cover crop response of the corn to the cover crops here, cover crop treatment and now this is the response to nitrogen rate and so at a number of those sites we had significant responses to nitrogen and mostly it was all positive response and we've got our nitrogen response curves here in a little bit to kind of show you, but there they're those were the significant responders. Now, a number of those sites didn't respond. And quite frankly, to make this project successful, we had to work with our leading soil health producers in South Dakota because essentially those were the only producers that mostly, you know, were having small grains in their rotation and were planting a cover crop. So, we were already on producers' soils that were in really good shape. In hindsight, we probably should have went after producers that needed the cover crops more. But just the logistics of getting the project done, we went with a set of producers that were good at what they were doing and understood why we're doing it.

27:04 So here are the nitrogen response curves, and I'm going to put them out there just really quick. The ones listed in the red, they're not all of them, but all of the significant ones are there in the red. And then I put three others that were nonsignificant. You can see those response curves across those nitrogen end rates. Beersford 2018 was one of those. You can see that grass grass plot there.

27:39 Based upon the colors of those symbols there, brought that yield up and that was that really wet year. But we still had a response to nitrogen there. And then the other sites don't mean to pick on any one of these but just wanted to show you the work that we did. The summary is probably the most important thing, but the Salem site here in 2018 just no response, but yet a very very high yield. Very very high yield. A testament to what the producer is doing in regenerifying their soil. Bring that word in now. We see our long-term soil producers in South Dakota really really turning the corner on reducing their fertility needs. We need to continue to work on that and find out what we can do to help them. So why the variability in this corn yield response cover crops and nitrogen? The likely answer is rain and cover crop biomass. So we have high cover crop biomass and it's wet, we get higher yield differences and larger nitrogen rate responses. Where we have high cover crop biomass and it's dry, we have lower yields and smaller nitrogen rate response. And then conversely, with low cover crop biomass and wet, we get higher yields and smaller nitrogen rate responses. And with low cover crop biomass and dry, it's low and small. So the take-home message, the effect of cover crops on corn is influenced by precip and crop biomass. So how can we help farmers navigate through this, just a couple sites here on the wet just to kind of review that what I just talked about. These wetter years, big responses, lots of cover crop biomass and here that 2018 site's kind of blowing up. You can see that it reduced the optimum nitrogen rate down there as well. And then the dry year here at Blunt where we had is actually was wetter early and we produced a lot of biomass but then it got dry and that cover crop biomass sucked down those soil water levels and decreased the corn yield.

30:10 So let's look at the water data first before I go to my last kind of area of discussion. Had three sites here, Mitchell, Hayes, and Sturgis. You can see these 4-inch increment measurements here. This is after the cover crop was established in the fall until late as possible that we could keep that probe in and then we pulled those probes out. So one thing you'll see here on this opening graph is that Sturgis site there is showing the orange is the cover crop and you'll see higher moisture contents where we have that cover crop and you can see that in the latter half of the Mitchell site here too and the 0 to 4 centimeter depth. So that cover crop is doing its job. It's pulling that water up from below. Those roots are obviously growing and using water and consuming water and so that water has to come from somewhere. Then if we look at the next incremental depths here, 4 to 8 and 8 to 12 inches, see a little bit of a flip-flop. And so the cover crop soil moisture is especially at Sturgis and Hayes is lower than the control. And so this is these are the depths where that water is coming from. It's bringing it up to the surface and it's drying out this depth. For Mitchell, that quite hasn't happened yet. It's still having a higher content to the 8 to 12, 12 to 16. Here's 16 to 20 to 24. Mitchell still hanging on where the cover crop moisture content is slightly higher than the control. And definitely at the other sites now that the well Sturgis is kind of even, that's a high clay content soil. Not a lot of water movement at the depth but Hayes here we can see that the cover crop soil moisture has been depleted there at those deeper depths. And then as we go deeper, these effects get less and then even deeper. So it's waves of water capillary rise due to removal of higher evapotranspiration, this is the transpiration effect on that soil moisture and then the deepest depths here.

32:52 Okay. So how do we explain this? So we pulled all of our sites together as to the difference between with and without a cover crop. And we could do that on our sites with our nitrogen rates as well. I won't go into depth how we pulled all that data, but we pulled that data. And so here we have all the site years, objectives one and two.

33:19 Categorized them into responses that were non-significant there on the left hand side, and yields that were significant. You'll see the biggest differences are in those on the significant side and you're going to see negatives by them. On the non-significant side, numerically the plots with corn and soybeans with cover crops are generally a little bit higher yielding or to kind of the same. And so it's those big differences that are negative that are really picked up by statistics.

34:03 So use precip is the only thing that we could really use. And so if we plot this data by inches of precip during the crop yield year, we can see our non-significant sites are up in that right upper right hand quadrant when we have higher precipitation, and they're non-significant. The significant sites are the ones tending to be in the lower left hand quadrant where it's drier.

34:45 A couple different ways to look at that is, you know, you kind of look and say 'Okay, the green is good. The green is good to go.' So if we could somehow predict or know that it was going to be in the green, we'd plant our cover crop. If it was in the red or the pink, maybe we shouldn't. And then the yellow zone is kind of that question period. But we can't predict precept. We can't really predict that.

35:18 The other way to look at that would be to look at the precip during the year from August to August. Not a calendar year, but August to August. So that includes when the cover crop was growing, when it got seeded after the small grain and then almost through the corn production year. July and August are the biggest water users for the corn crop and September it's maturing and coming to an end. So it kind of moves everything to the right. Now this is showing we even need more water to be successful with a cover crop.

35:55 I'm so glad I had a really good team, a lot of smart people on my team. Dr. Samuel invited Dr. Mukerji from Utah State University who worked with a lot of climate data to help us out with this. It's good to have young scientists that are hungry for a paper and publication. When you tell them use this data, do it, they're just like wow, they're really excited to do that.

36:28 One thing that Dr. Samuel Mukerji wanted to look at was the standardized precipitation evaporation index. There are a lot of data pools out there that can show precipitation and estimated evaporation on a really small scale. They were able to choose some of our sites and do that for those sites. That's what the last part of what I have to talk about here is going to cover. They chose Beersford and Blunt. You can see the yield differences there, no cover crop in the green bars and the cover crop in the orange bar, or excuse me, I'm backwards. The cover crop in the green bar and the no cover crop in the orange bar.

37:25 The precipitation there in blue in the bottom bars you can see the precipitation and then the SPI index. We have a very positive SPI index there at Beersford, and then a somewhat negative SPI index there at Blunt. These SPI indexes are real time and so you can get a good look at the past. Of course we don't know the future, but you can get a good look at the past because it's taking into account evaporation and transpiration, which is where our water goes. It's not just how much water falls, it's how it's used and how it's lost.

38:17 Here you can see the Beersford graph that has both SPI and precipitation along with the average evapotranspiration curve there in the orange. You can see a lot of positive SPI units there. It's a unitless number. When it's positive it's wet and when it's negative it's dry. And then compare that to Blunt where we started out wet there and in October, November, December, we grew that great big cover crop and then it turned dry.

44:12 First though, when you guys were comparing the sites, did you mention the one site had more clay soil so it held moisture better and so you didn't see the soil moisture difference? I mean, was that part of this discussion like really looking at those soil types or maybe even the organic matter in the different soils and kind of comparing that?

44:33 Yeah, I mean when I referred to the clay soil there at Sturgis, I was talking about the deeper depths. We looked at soil parameters on the surface of soils. I didn't — there's only so much I can show and I'm not like making a crutch. Don't get that way. But we did not find trends or linkages or correlations by soil type with cover crop influence on corn or soybeans. So that really wasn't brought out here today. But when it came down to the precip and farmers all know this takes rain. It takes rain to make a crop and they know when they get it the right time at the right amount they get a big corn crop or a big soybean or wheat crop and so this study is saying no different. And in some ways I'm sorry it took a lot of effort and time and money to determine something that maybe was just logical but there's the data and now we know and we go down those roads a lot, you know, in science, but that's why we have good people doing science.

45:55 Yeah. No, absolutely. So one question in the Q&A here from Dustin. When you talk about long-term regenerative producers starting to turn the corner, what is your definition of long-term?

46:09 This is just going to be my opinion. A lot of these producers we work for are 15 to 30 years in no till, crop rotation, cover crops. We're following the soil principles before they even existed. A lot of them are students of Dwayne Beck. I got to give Dr. Beck a lot of credit for his influence on South Dakota. He had influence on me and our farm and a lot of folks. And then the progression of soil quality was first and then it was soil health. And now we're dabbling into regen ag and it's a progression. And so the longer you can do these practices, the better and better and better it gets. And just a testimony in my farm, I've lowered nitrogen rates and I'm almost thinking like why do I apply any phosphorus anymore? Old habits are hard to break even with me and so it's a progression. So that's what I mean.

47:19 How do you think if you would have — because you mentioned that like most of the producers obviously you were when you were looking for people to participate they were doing cover crops long-term, you know, no tillers. How would some of those like soil metrics have changed had you included, you know, a complete new like new ground, long-term tillage, never seen a cover crop in its life? Like, do you think some of those results would have come in different compared to AB?

47:44 Absolutely. I think we would have saw a greater effect, a greater positive effect on soil health and those parameters in those soils that were — do I dare say beat up a bit, you know, and needed some help. And I think we, it dawned on me about halfway through that, you know, we should be working with producers that have poor soil health or need improvement in soil health than those that are leading the way. But you know, the producers that were leading the way had the drills and the capability to plant the cover crops and the interest probably. Yeah. And all of that. So that kind of came in perfect storm and took us that direction. But in retrospect, I, you know, it's those fields and farmers that weren't doing those practices that probably could have seen the best benefits.

48:42 Nope. That makes sense. Luke asked here, do you have cover crop biomass in nutrient contents to compare to the soil samples? So you showed that the cover crops didn't really impact anything other than nitrates. It'd be interesting to see what did you capture in the plant material, but maybe that was the scope of this.

48:59 We were focusing on NDF and ADF of the cover crop biomass. And that's in another area. There's a lot of folks working on this data and I showed you the most complete part of this project and you were right. But then we started separating broadleaf from grass and all of that and we got bogged down with the labor because we had so many samples from all the plots. So I'll just admit to you it didn't get done and it should have but it's a big part of it. We thought we'd pick it up.

49:51 Farmers at that time were most concerned: well, I plant this cover crop, how do I change my fertility rates for my corn the following year? And so the tool we chose to use was soil test at that time prior to planting that corn. What did it influence soil test? And except for the nitrate nitrogen, it had no effect on the soil fertility levels in the soil.

50:21 There are quite a few questions in here. Have you compared corn planted with and without companion crops? Steve here is in western Nebraska and he's seen no yield drag for the last three years though he is irrigated. Yeah, if you can supply that water, this was not a companion crop.

50:43 What were the cover crops? You had all grass, a blend and broadleaf. Was it cereal rye on the grass? No, it was oats and barley, forage barley. I can't remember the actual variety. Did it winterkill? Yeah, it winterkilled everything. It all winterkilled in our project. We had to make that decision too and yeah, we couldn't cover all those bases.

51:16 So if you know irrigation's available or higher rainfall environments, you're in control of the water. Grow cover crops. And could you touch a little bit more on what you saw on the soybean yield side of things? I know we didn't really see as many slides about that, but just maybe summarize what were the soybean impacts following the cover crop?

51:45 Yes, and the farmers at all those sites made the decision on what cover crop to plant and they were mostly all grasses. And if you remember that chart there, the soybean yield following the cover plots with cover crop was a few bushels higher than where there wasn't a cover crop. And so we saw no negative effects on soybeans. That little bit of positive effect is good and because soybeans are carbon hogs, they need a lot of carbon. Corn does too but they particularly need that and they don't leave a lot behind either. So they're hard on the soil. You think that became more of the driving factor than the moisture did?

52:42 Yeah, I think so. The ground cover, keeping the ground covered there throughout the season. Soybeans love ground cover, they just do. And so we've seen that positive effect. I'm confident in that.

53:05 Allan asked here: this study shows potentially little reason to plant cover crops. How are you counseling farmers about cover crops? Allan, it might be helpful if you would mention where you're located, if you're out in South Dakota. But in general, Anthony, when people come to you, obviously you're a big proponent of soil health and this is literally what you spend your career doing. And obviously a lot of guys use cover crops in South Dakota, that's a big area for us and other seed companies. What's your general advice since we can't predict the rain?

53:41 The first cut is whether they have livestock or not. And if they have livestock, it has added value for forage for that livestock and they can always see another use. So then we go to just the crop.

54:00 Farmer, and you know if you're in the arid semi-arid area, no one can predict the future. Cover crops are a good thing but I think we use them a little less frequently than we do where it's wetter. And you know we don't need to plant a thick stand. As I mentioned, what is good enough? And so if you think about a square foot, in my mind, two or three plants in a square foot is good enough in an arid and semi-arid area. And so I think, you know, we didn't look at planting density of cover crops here. And that's another total factor that I think should be considered.

54:51 We want to just focus on that biology, that kickstart of that biology there with that living root. You know, two or three plants a square foot is enough without livestock. Now, if you're putting livestock out there to graze, you need more obviously, but what's enough? And in that really dry area, dry conditions, you know, that one rye plant or that one cereal rye plant, you pull that up, them roots are going out and there's the advantage right there. So hopefully that answers that question.

55:31 Yeah, no, I think that makes a lot of sense and that's the challenge, right? When you're doing research like this where it has to be very controlled, it has to be a box and we have to fit everything in the box and compare this location or this farm to this farm but those are different contexts and they have different soils and different cropping history and one may have livestock and one doesn't. And you pointed out the one trial, just one rain made the one experiment go from a yield positive to a yield drag, right? Like there's just all these little moving pieces.

56:03 And so it really comes down to management. You know, this time of the year, if you have over-winter green cover crops out there and you're dry, probably should have terminated already. If you're in an arid environment with low moisture, if this moisture cycle continues and it stays dry, that should impact decisions this fall. You know, low seeding rates, maybe no seeding rates, crop rotations, what are we doing? I mean, I think the principles, the soil health principles, the principles of what we're trying to do here, keeping the ground covered, keep the microbes fed. Long term, those all make for more resilient soils and more resilient systems. You can hold more moisture, you can take in all the rain, right? Like if you allow your soil to be bare and to heat up, you're going to evaporate more water and you'll have runoff, you won't capture what you get, right? So it's this long-term play and a lot of your producers were long-term regenerative producers. So their grounds already improved some but it comes down to management and it's complicated. It's harder than conventional agriculture when you come to managing living systems and working with biology and plants. It's tougher but the rewards are there as your system improves.

57:17 Yep, that's the context. You know and I don't put context in one of the soil principles. There's five soil principles. Context is how we talk about it, how we think about it, how we apply it.

57:29 And it's different. You're exactly right, it's different. So nice, very good. Okay, in Minnesota, yep, higher, lot higher rainfall there. Rainfall. It'd be pretty rare there not to plant a cover crop because of dryness. I mean, you know, one out of 15, maybe one out of 20.

58:01 Yeah, you don't want to farm for the drought. You want to be prepared for, want to make decisions like we're always in a drought. Correct, yep. Not the definition of drought. Um let's see. Eric, quick question. Will cover crop spring mix of oats, clover, peas, and turnips keep growing if grazed? Yeah, Eric's the peas, not the peas, sorry. The clover and the turnips will likely regrow. The oats will depend on the growth stage that they're grazed at. Yeah, early enough, they'll just keep.

58:32 Growing. Yep. Keep it vegetative. None of these cover crops were grazed in the. No, none of these are grazed. No. So that's another factor there, right?

58:49 Yeah. Lots to do. I think that is most of it. Nathan, you've got a few questions in the chat on the left hand side.

58:58 Oh, tricky. Okay. All right. Okay. Yep. I see these here. Dustin is asking, 'How do you define excessively wet, Anthony?'

59:12 Oh, might be different in South Dakota depending, you know, it depends on where you're at and then your landscape as well because excessively wet is different in the Red River Valley than it is in the hills of southeast South Dakota. I mean, yeah, I think that's a context question that's like you're the expert on your farm. I got to empower producers to be the experts. They know that. And so it's kind of a gut feeling. It's got to be a gut feeling. And that SBI tool can help you there, I think. To kind of see if you're positive or negative. And I mean, we got to use these tools that we invested in because they work. I really do. I do think they work. And so any of that type of information. I mean, if you're a drought monitor person, you look at the drought monitor. We're in drought now, so we're obviously we can answer that question, but you know, you look, it's a number of different pieces of information to get to that.

1:00:21 Yeah. So Dustin just chimed back in. He says he's in northwest Iowa, average rainfall 28 in. So I would say excessive and then the issue is like average rainfall 28. So if like say you hit 30 or 35 but like it depends also when that falls, right? Like I don't know if you walk out in the fields and you can tell if it's excessively wet, right? Yeah.

1:00:45 But here's a good question from Chris. So the moisture sensors that you were showing Anthony would deeper rooted cover crops like a daikon radish help in the drier areas. You were saying you could see in those moisture sensors the plant wicking up water, the water fronts. Yeah. Yeah. So, is the logic there potential that like a deeper rooted plant can help pull up that subsoil moisture that then would be available to something else or is it just using it?

1:01:17 You know, fibrous root systems like rye, cereal rye and wheat and all that, they do a good job and Sudan sorghum Sudan grass is kind of like corn. You can even put corn in your cover crop, but it takes all the above. I really do. I mean, all those different root architectures have a different purpose and that's why we see our multispecies cover crops to give us to give us what a solid static corn or a solid static soybeans can't give us. The cover crop is we're putting all those different root architectures together and they're all important. They're all really important. And so anytime we pull the waterfront up, we're pulling up below just the effect like on a normal day, go out and lay a piece of metal on the ground and then come out in the morning, flip it over. It'll be wetter under that, right? So that water you've stopped that water from coming up. But that's the effect I'm talking about is that we have this constant movement of water from the soil into the atmosphere. And it's called evaporation. And we put a plant there and it's transpiration. So yeah, I mean it's all about the biology.

1:02:35 Deeper and the diversity. Yep. I like it. All righty. Well, looking at the clock, we have quickly exceeded our time. So it's already 1:00, so we'll wrap it up there. Anthony, thank you so much for the presentation and taking the time out of your busy schedule to share this research with us. I think there's value there and kind of understanding the pros and the cons of any management practice, right? Like there's both sides and then figuring out how to manage, you know, maybe in spite of things or things to be aware of. So, thank you everyone for joining us. Be sure to tune in next week for, I believe, the fifth webinar in our series here. We'll be having Megan from Colorado State presenting on diversifying systems to build soil health in water limited high plains. So, we talked about kind of lower rainfall areas up into South Dakota, but now we're going to be heading out to Colorado. So, be sure to tune in next week. And with that, have a great day. Bye.