Cover Crops for Weed Control in Corn and Soybeans Without Herbicides

0:00 You know, there's kind of a common misperception out there among farmers that a lot of the university soil health research maybe just lives in a greenhouse or is very disconnected from what we as production agriculture people are doing. And sometimes that criticism is fair, but there's a lot of good stuff going on out there. And so we wanted to put this webinar series together to highlight some of the great work that's being done.

0:30 And we know, personally know, a lot of people doing this great work. And so that's who we're having on for this webinar. And so our guest today, Dr. Erin Silva. Erin, welcome. It's great to have you here. We've had you at other events. I've heard you many times. Erin holds the Clif Bar, love some Clif Bars. I didn't know they had an endowed chair of organic agriculture. That's great, but she holds that chair and really is leading the charge with their center for integrated ag and their organic network, the O Grain Network. And there's a lot of cool research coming out of that.

1:02 And I want to just and Erin, you may tell this story, so I hope I'm not stealing too much of your thunder. But I love this story that, you know, back in 2013, there was this Indiana farmer named Rick Clark. Many of you know Rick. We know Rick very well. And he heard Erin talk about terminating cereal rye after the soybeans have already came up. And Rick just always points to that as such a pivotal moment for him being able to do not just no-till, but organic no-till soybeans. It was a real game-changer for Rick and it really allowed him to get into the system that he's now in and that he had always really wanted to get into. So that's just one little example of how some of Erin's research has had a hugely positive and practical effect on farmers, not just in Wisconsin, but across the Midwest. So Erin, thank you for bringing that practical precision, that practical research.

2:00 You know, no-till organic farming is really hard. It's a difficult classroom. And you've been teaching and learning there for a long time. So welcome to our webinar series and we'll let you kind of kick it off as you talk about how cover crops can be used to control weeds and corn and soybeans. And then when you're done, I'll come back on and I'll help proctor the questions.

2:22 All right. Thank you, Keith and Jonathan. It is just such an honor to be here. When Keith invited me, I just jumped on the chance. The work that Keith and Green Cover Seeds has done to build this amazing community of regenerative farmers is a very amazing group and very discerning farmers. So just very grateful to be here and thank you for the invitation.

2:49 As Keith mentioned, I do a lot of work in organic production systems here in Wisconsin. But I do also think that the work that we do is very applicable across regenerative systems. You know, with farmers looking to build soil health and to reduce inputs, organic might be more on the extreme end of reducing inputs, but I really hope that some of what I talk about today, and it's going to cover a lot of different things, so I'll go a bit quickly, but happy to dive in deeper at the Q&A or after the talk, it is going to help farmers that may not be certified organic, but again, looking to regenerate their soils, build soil health, and reduce inputs. So I will share my screen and I will jump into the slide deck.

3:48 All right. So I decided to focus the talk on cover crops for weed management. And how do we use cover crops as tools to manage weeds not only in organic systems, but regenerative systems more broadly. Again, looking at ways to reduce chemical disturbances that come with the application of herbicides. And looking for ways to utilize outside-the-box practices to continue to build soil health and very importantly soil biology.

4:20 So why cover crops? I don't think there's any need to emphasize a stress with this group, but cover crops bring so many benefits to regenerative ag systems. And I really think cover crops are the foundation of regenerative ag systems. I mean, certainly compost and compost teas and other amendments help drive that biology, but cover crops are really the foundation. Bringing those living roots in the soil, bringing that diversity, bringing those sugars and those compounds to feed our soil biology, that is all centered on the use of cover crops. And cover crops also allow us to reduce inputs.

5:02 And again, I certainly don't want to judge the use of herbicides. There's increasing research to show where there might be longer issues in terms of soil biology and other aspects of water quality. But they are a chemical disturbance and different chemicals are going to have different levels of impact.

5:19 Disturbances to soil biology. But not only are they potentially disturbing our soil biology, also there's a cost to buying those inputs. So if we can use these cover crops to fuel the biology, unlock nutrients in the soil, help drive the plant's immune systems while decreasing the need for chemical inputs, it's a win all the way around.

5:46 I just want to talk a little bit about organic management. Again, I'm not going to center on organic management, but just to stress the role that cover crops play in weed management. Anyone that's considered organic, I know one of the concerns that I hear from farmers is the need for tillage within particularly organic grain systems, also organic vegetable systems.

6:08 And though organic management typically offers a lot of benefits to soil health, including the historic utilization of compost, the openness to using compost teas and alternative amendments, and the use of diverse cover crops and diverse crop rotation, we do know that effective weed management is a necessary component. Tillage isn't essentially to the weed management, but we also know that that is not necessarily conducive to building soil health.

6:45 So a lot of what we've been doing with cover crops is this idea of how do we mitigate the impacts of tillage. And I just want to say I've opened many talks with this quote, but again, this is not necessarily to stress or dominate the conversation with organic, but instead just really stress the power of cover crops and the power of cover crops to heal our soils and the power of cover crops to drive soil biology. So this is a quote from a paper that came out of California. It essentially is summarizing a wealth of research related to the impacts of tillage and the impacts of cover crops. So it's taking studies over multiple environments, multiple years. And one of the things they note when they looked at all this data across multiple studies is that particularly when we look at the impacts of arbuscular mycorrhizal fungal populations. And a lot of regenerative farmers are very aware of the importance of microbial communities and especially fungal communities, they saw that even with tillage, cover crops increased arbuscular mycorrhizal formation similarly to when tillage was used or not, suggesting that the continuity of root associations with the cover crops is at least as important for arbuscular mycorrhizal formation as decreasing soil disturbance.

8:09 And this is significant. So when we look at the soil health principles, those living roots in the soil that cover crops provide are key to maintaining the functional soil biology that we want to see in our regenerative cropping systems.

8:26 And again, a quote from that paper, when a cover crop is used, especially legumes, arbuscular mycorrhizal formation in the cash crop can apparently withstand some tillage. So looking at ways to replace tillage, replace herbicides, and utilize cover crops, and build bring the power of cover crops to regenerate the soil is really a core of what we're doing with our research at UW-Madison.

8:53 Systems-based approaches, and again, just stressing that repairing of soil biology, but also the impact of soil carbon storage and nutrient cycling.

9:05 We, as people that are interested in regenerative farming, I'm sure you're all aware of these five soil health principles. I know that Rick Clark and Gabe Brown and some amazing farmer leaders in this space often build upon the five core soil health principles. And their examples are I think really impactful in terms of how we think about building health in our soil health in our systems. But when we look at the core five soil health principles, minimizing soil disturbance, maximizing roots, maximizing soil cover, maximizing crop diversity but I wouldn't just say crop diversity, but diversity more generally in our fields, and then integrating livestock, cover crops really feed into all of these soil health principles and support all of these soil health principles, including the possibility of integrating livestock into our cropland, into the land that we're typically growing corn and soybeans and other annual crops.

10:03 So, going into a bit more about the weed management aspect or the weed suppression aspect of cover crops, again, so many different ways that cover crops can impact and disturb and help manage different aspects of the life cycle of weeds. At the seedling stage, we can see cover crops playing a role in physical suppression with the creation of mulches or competing directly with weeds that are germinating. Allelopathy, the power of allelopathy of cover crops, particularly with cereal rye, but other cereal grains as well, preventing, especially small seeded weeds from germinating, incredibly powerful function of cover crops.

10:50 Competition of space, nutrients, and light, so instead of having bare ground, filling that with cover crops and creating that controlled managed competition is a very, very strong and powerful tool with respect to weeds. When the weeds are growing, again, that competition, always having cover crops higher than the weeds is a very powerful tool. I'm being able to use those cover crops to be able to create systems that are using mowing to manage weeds and prevent them from growing to going to seed.

11:29 Natural enemies, there's ways that we can utilize cover crops to bring in natural enemies. And we see this, for instance, with foxtail. And I know foxtail is one weed that we struggle with at our research plots. And having those residues on the soil in the fall and leaving those residues creates habitat for insects and small mammals to be able to predate on those foxtail seeds and bring down populations. I believe the same is true for giant ragweed. So, the ability to draw down problematic weed populations without the use of herbicides. So, lots of different mechanisms where cover crops can help manage weeds and manage weed population without having to go to chemical interventions.

12:17 So, the first study I'm going to talk about, and again, I'm just going to touch upon each of these in a pretty high-level way, is our work interceding cover crops on both 30-in rows. So, we've done this for a few years. I'll highlight some of the research that we did 2 years ago in 2023.

12:40 So, farmers in Wisconsin are interested in learning, how can we utilize the practice of 60-in rows to capture more light, potentially be able to build soil corridors, integrate more diversity into the field, more in-field diversity by bringing in diverse cover crop mixtures, and also having a tool for integrating livestock. Having the corn on wider rows allows for more cover crop growth and more opportunity to be able to graze those cover crops in the fall. So, many of the farmers that are interested in these wider row systems are interested in it for the ability to be able to integrate livestock.

13:20 So, we were interested in exploring to see, especially in organic systems, can we have adequate yields of corn on 60-in rows while still building in this function of intensifying cover crops, building soil health, suppressing weeds, and potentially even being able to integrate grazing? So, we compared four interceded cover crop mixtures on 60-in rows against a standard cultivated 30-in corn system.

13:48 So, these are different cover crop mixtures that we used. These were purchased from a company here in Wisconsin, based out of the north central area of Wisconsin. Different mixes with different compositions, different levels of diversity. One with oats and flax and ryegrass and Essex and rapeseed, buckwheat, radish, turnip. Others that were a little bit less diverse. Different combinations of legumes versus radishes. And then this mix one was one that a farmer had created that they were having some success and interest with. That had a bit more diversity as well with annual legumes and sunflowers. So, we tried several different mixes again, and you can see the proportions across the top here.

14:39 Now, what we found in this study, looking at cover crop biomass, is that indeed that the mixes did differ depending on the different compositions. Grass added aggressive growth early, but contributed little to the overall biomass. Brassicas grew very aggressively and added early season shading from their leaf structure and contributed substantially to total biomass. And legumes established slowly and contributed very little to the overall biomass. So, depending on the goals of the system, depending on the level of weed suppression needed, certainly developing these functional mixtures with different proportions of grasses, brassicas, and legumes were a tool to be able to get the functionality desired from that interceding mixture.

15:29 Looking at the weed biomass, the 30-in control, which was cultivated, had the lowest level of weeds, but we did see differing weed biomass depending on the cover crop mixture. So, what we found was that the mix that had high legumes and low brassicas had the highest weed covers. And the mixes with high brassicas and low legumes tended to having the lowest weed coverage of the interceded treatments. So, again, whenever selecting cover crops, it's important to think about what sort of functionality do you want from those cover crops? And even designing the mixtures, thinking of what you want to dominate. In these systems where really we're looking at deriving weed suppression benefits because we weren't using any herbicides in these systems.

16:19 Having high amounts of brassicas that allowed for vigorous early growth as well as high amount of leaf coverage was an important thing to consider. If you were looking for a system where you're looking at deriving more nitrogen, your mix in the ideal mix might be different. But with this system where again that weed suppression aspect was critical, having that high brassica mix was really important.

16:46 Looking at grain yields from these systems, yields were lower within the 60-in rows. And I do want to stress that when we're using these 60-in row systems, we do increase the in-row population of corn. So, when we're looking at the overall corn population across the field, we have the same number of plants per acre, but our seeding density within a row is greater in the 60-in system.

17:15 However, even with this similar seeding rate of the corn, our 30-in corn did yield highest at about 200 bushel an acre. Our different mixes did yield lower, probably bumping around between 135 to 150. I do want to stress though, this was a drought year in Wisconsin, and the drought conditions likely exacerbated the yield losses between the tighter in-row spacing as well as that potential competition of the cover crop in the rows.

17:51 The cover crop mixtures all performed similarly, but we did see a decrease, a 27% yield reduction in these 60-in rows. So, that's one thing that we've seen in these intensive cover crop systems is that there is some sensitivity to precipitation that we do need to understand how to reduce that risk.

18:14 I'll move on to talk briefly about interceding cover crops now on the 30-in row system. So, our research questions here were similar. Can we use cover crops underneath a corn canopy to suppress weeds? Looking at reducing the need for soil disturbance in organic systems or in regenerative systems as well, looking at ways to reduce herbicide use as well as potentially having another tool for herbicide-resistant weeds. So, wanted to know more about these dynamics within our typical 30-in systems.

18:50 So, in this system, we had three different cover crops that we tried both alone and in combination. Annual ryegrass, red clover, and oilseed radish. And we also had two controls, a cultivation, so using mechanical weed management, as well as a weed control. We planted these at the V3 growth stage. And in Wisconsin, we've typically seen that this is the ideal stage for planting interceded cover crops. Our research on the East Coast as well as the central Mid-Atlantic region, some of that research seems to indicate that seeding closer to the V5 stage of corn might be ideal. But in the upper Midwest, our growing conditions seemed to indicate that if we wait to plant until V5, there's not enough sunlight that can come down through the corn canopy to support that initial cover crop growth that is going to lead to really meaningful biomass. So, we've been planting a little bit earlier, closer to the V3 stage.

19:57 To show the cover crop biomass by mixture, a lot of the similar trends that we saw within that 60-in row study with the different cover crop components. Annual ryegrass can come quickly and establish well, but oilseed radish puts on more biomass overall. Here's 2 years here that you can compare 2022 and again, that more challenging drought year in 2023. And here we had very lower, much lower red clover establishment in 2023.

20:28 And mixing functional groups, so having those cover crop mixtures, particularly in 2022, was a tool for having higher biomass. And I will say that these cover crop mixtures were corrected for seed density. So, it wasn't necessarily additive that we had three times as much seed within the three-way mix, but instead saw synergistic additive effects of having that mixture, and that more diverse cover crop seeding.

20:58 Looking at weed biomass in these various mixtures, one thing that was really exciting for us was that it did appear that those interseeded cover crops did offer some weed suppression. So, in this cultivated treatment, we had about five cultivation passes, which is typical in organic grain systems. We had some initial blind cultivation, and then we also had some row cultivation done. Versus in these interseeded mixtures, we had that blind cultivation passed on, but we didn't do any row cultivation. So, we were able to eliminate two cultivation passes, and plant those cover crops at a time at the V3 stage, which is about when we stop that blind cultivation. So, the presence of those cover crops, even at that relatively small growth stage, seemed to impart a degree of weed suppression that, again, I think could also be powerful when we're looking at herbicide systems, or systems that

22:08 Do use herbicides, where we're looking at potentially eliminating or changing our herbicide passes, as well as offering a different tool for herbicide-resistant weeds. So really exciting to see cover crops establish in these interseeded systems, and really exciting to see that they do have some weed suppression benefits, and allow us to do less soil disturbance in organic systems.

22:31 We saw no difference in corn silage yields from the interseeded cover crops, which was good. So the interseeded cover crops did not appear to compete with the corn. So we didn't see a yield bump, but we didn't see a decrease in yield. We saw yields that were on par with cultivation, and in some cases, maybe even bumping a little bit higher, even though they weren't significant. So looks like cover crops in these interseeded systems can offer some weed management benefits, offer some soil health benefits, and not cause a yield drag.

23:09 However, there are other solutions for minimizing tillage in organic production systems that also have cover crops as a foundational tool. Not only generally conservation tillage, and decreasing the depth of tillage and cultivation, but not only intercropping, which we just talked about, but the use of living mulches, and the use of roller crimping. So I'll talk briefly about our work both in corn and soybeans with roller crimping and living mulches.

23:41 A lot of you may have heard of the roller crimping system. I'll just go through it very briefly that we have establishment of the cover crops in early fall. And this is something that's going to differ depending on your growing region. In Wisconsin, we want to be sure to get that rye established early if we're using rye as our roller crimp cover crop. We want to be able to get it in early because of the fact that earlier planting does impact tillering. And tillering is key to be able to get the degree of cover crop establishment that is going to be able to suppress weeds without the use of herbicides.

24:22 I would imagine that you could plant a little bit later if you were going to come in and use a herbicide within these systems, not something that we've done regularly. We've always gotten fabulous weed suppression with the rye alone, because of that ability to physically block sunlight from reaching the soil surface, as allelopathy. But then herbicide-based systems, you would have that additional tool.

24:48 Rye will grow. To terminate rye mechanically, we need to wait until rye reaches anthesis. So in this photo, you can see those yellow anthers. That's an indicator that rye is at the correct stage for termination. That typically happens around Memorial Day or early June. And this is a photo of one of our research fields. And again, you can just see the power of that cover crop. There is no herbicides in these systems. That rye was able to prevent weed seeds from germinating, and keep weed seeds from germinating throughout that time where we were growing the soybeans. And it allowed us for a just a really clean mat for the combine to be able to come over and be able to harvest those beans.

25:35 I will say other cover crops can certainly be roller crimped. The key is that they have to be winter annual, or they have to be an annual cover crop, and they have to be terminated at the right stage, which with a grass would be at anthesis, and with a legume would be at early pod set. So with perennial crops like alfalfa or multi-year legumes such as red clover, those you cannot terminate mechanically. But if you're using an annual crop and coming in at the right stage, they will terminate mechanically, but you will not have to come in with a herbicide pass.

26:15 These are some of our no-till soybean yields over the years. You can see that they bump up and down. These are organic soybean yields. So we're typically getting between 40 and 60 bushel an acre, which are very respectable yields, especially when you're talking about organic prices. Some years, with the blue bars, you can see the tilled yields yielding more. Some years, it's not significant, indicated by the NS. Some years, though, these green bars, especially the last couple years in Wisconsin, we actually see our no-till roller crimp beans outperforming our tilled beans. And some of that is due to the wetter conditions we've seen the last couple years, and the fact that we get such good weed suppression with that cereal rye cover crop.

27:03 But the dry years are years that are more challenging. So 2021, 2022, 2023, as indicated with the black bar, you can see again, particularly that drought year in 2023, got very little rainfall at the right time, and that's where we see more of that yield gap. So areas that have irrigation are going to have much more flexibility and reduced.

27:26 Risk when using roller crimping, but particularly when we have dry times at soybean planting, there can be a risk with respect to achieving yields that we'd ideally like to see.

27:41 We collected data from farms that were using this system. I know that there is often criticism of university research not getting off our research station land, and how reflective of that is it of the real world. So we went around and collected some data on farms. We did find that soybeans yield vary for anywhere from 20 bushel an acre, which is not ideal, up to 65 bushel an acre on farm, which again, very excellent soybean yields. We found that the weed suppression varied anywhere from two—I'm not sure what the units are on that, but two to over 2,000. I think that's probably grams per meter squared. So lots of differences in weed suppression. But both of these are essentially tied to the rye biomass. And this is really the critical part of the system to not only set fields up for, but to evaluate in the spring. And again, this is particularly in the case if we're not using herbicides. And we want to be able to get that rye biomass up closer to 10,000 lb per acre to create that thick mat that's going to suppress weeds.

28:54 And this is really dependent on getting that planting date earlier, getting a higher seeding rate. So seeding a bit heavier than you would than a typical cover crop, closer to two, even three bushel an acre. And being able to sure that there's adequate fertility in the field to support that cover crop growth. And the cover crop in these cases really your weed management plan. So putting the deliberate effort and the strategy is important when you're setting yourself up for weed management success.

29:27 And again, that really is the key driver here when we're looking at why some fields get really good yields and low weed pressure, and why some fields fall short.

29:40 In terms of system profitability, looking overall at the different costs of production, that especially in organic, even with that extra cost of rye seed, we are having some savings with not having to do cultivation passes over the field. You could do a similar exercise in conventional, comparing the cost of cover crop seed with your herbicide program, and the savings there.

30:07 Here we have prices of the cost of the soybean prices are anywhere from 20 to 30 dollars per bushel, which is pretty standard that we've been seeing over the past few years. And what we found in this system that you can take a little bit of a yield loss in the no-till system, but because of these other savings of less inputs, less passes over the field, that you can still come up ahead. So break-even loss at $20 per bushel is about five bushels an acre, and $30 is about three bushels an acre. But there is some cost savings in these systems because of the reduction of passes over the field, or again, the reduction of herbicide passes.

31:04 Pushing planting dates earlier, this is one of the things that Keith had mentioned earlier in terms of some of our research, and we wanted to revisit this. So one of the limitation of mechanically terminating rye is again, you have to wait till that anthesis date, which isn't until usually about Memorial Day or even early June. But we also know that delaying planting can have a situation where we're not reaching our yield potential. So farmers were wondering more about the recommendation of planting earlier into standing rye, and what would be the best date, how early could we push it, and then what would be the impacts on soybean stands.

31:46 So again, we know that, and this is some data from Iowa State University, that the more we delay our planting date, our relative yields will decrease. So if we're starting to plant into June, we are going to be losing some yield potential.

32:03 So we tried three different planting dates, May 19th, which is rye at full heading, May 27th, which is early anthesis, and then June 2nd, which is mid-anthesis. So early anthesis is when you can start to see the anthers, but you may not be able to see the pollen, and that yellow pollen will easily be disrupted from the anthers once it reaches full anthesis. And then we terminated rye on June 11th, which was at full anthesis.

32:38 So looking at soybean damage across these different planting dates, May 19th, May 27th, and June 2nd, you can see that the June 2nd planting date is the planting date that had the least amount of damage.

32:57 Earlier planting dates had a bit of damage. That May 27th planting date had significantly more damage than that later planting date. And some of the issues that we see, I know some of you that may have tried this, you may recognize these bent soybeans. That tends to occur more at those earlier planting dates. The later we come and plant closer to crimping, the less that we'll see that. We'll see some crimped soybeans, and again, that happens more at those earlier planting dates. Each of these again were crimped over the beans. We see some cut soybeans, and that tended to be more exacerbated with this May 27th planting date, and also some dead soybeans.

33:42 So, it looks like from the damage standpoint, that either planting earlier around the boot stage or waiting until pretty close to when you'd be crimping provide the least amount of damage to the beans.

33:59 So just as a picture of what those beans look like at each of those dates. The May 19th is more of the VC stage. The VE stage at May 27th, this is a stage that tends to be more susceptible to damage. And then the June 22nd, I mean they are putting down a root, but they're not coming out of the soil, which explains the smaller amount of damage that we're seeing then.

34:23 So, this earlier stage, we did see some bending, but they weren't necessarily killed by the crimper. And if we plant even earlier than that, I think that also exacerbates some of these issues with bending beans. This roller crimping stage, this is where it's more fragile. They the stems are easily crushed or they're easily snapped, and any of you that have planted soybeans, you can relate to that. And again, this stage, because the majority of plants hadn't come out of the soil, there just was limited damage.

34:58 So, looking at the weeds of each of these planting dates, the weed biomass tended to be greater when we planted first and crimped later. That action of the planter tends to open up some space that allows weeds to come through. And there is a trend towards a greater amount of unterminated rye at earlier planting dates. So, you will see some more volunteer rye, which doesn't necessarily impact yield, nor does it impact harvest, but it would cause potentially some rye that would continue within the system in subsequent phases of the crop rotation, which can be a concern depending on what crops you're growing. Soybean lodging was a bit more at that earlier planting date, in part perhaps because of those bent beans.

35:46 But yield response, interestingly, even though that May 27th date we did see more damage, we actually saw the highest yields. And last year was probably, out of my 20 years at UW-Madison, one of the most ideal seasons that we've had to use these systems. And indeed, we did seem to reach yields that were approaching 100 bushel an acre of organic beans in roller crimp systems. So, they really can be phenomenal systems to work with if, particularly the precipitation is coming at the right time.

36:25 Reduced-tillage corn, talk about that briefly. We've tried both roller crimping as well as utilizing living mulches, so cover crops that are continuing to grow that were established in the fall. Historically, looking at the yields of reduced-tillage corn, we've struggled much more with reduced-tillage corn roller crimping corn than we have with soybeans. So, whereas soybeans, again, reaching phenomenal yields, we see much more of a yield hit when we're talking about roller crimping corn. Typically, our yields of corn, organic corn, can reach up to 180, even 200 bushel an acre. Looking at our yields of roller crimped corn from 2019, some of these have two different years because it's two different fields, but we see, you know, typically we're lucky to be getting up to about 150 bushel an acre. We've tried two different ways of crimping. One was to mix hairy vetch and winter rye, thinking that winter rye would offer some more allelopathy, potentially some more weed suppression, protect the hairy vetch so that it wouldn't winter kill, but it does appear that that winter rye seems to have a negative effect on corn yield, and some of that we're thinking is because of the potential nitrogen tie-up. In more recent years, instead of mixing hairy vetch with rye, we've mixed it with oats. Oats will winter kill in Wisconsin, but it does offer some protection of the hairy vetch from winter kill, as well as some early residue, which I think also helps with weed suppression. So, increasingly in these systems, we're moving away from mixing rye with roller crimping in corn, and utilizing these

43:32 Without herbicides and be able to increase diversity and build soil health in regenerative systems. So a couple different cover crops that we've tried, sweet clover and red clover. Again, not reaching the yields that we're wanting to see, but we are seeing some promise with the sweet clover that we do want to keep pursuing. And using interrow mowing as a tool, this is something that I think is particularly a strong tool for these systems to limit competition.

44:01 So we are seeing yield bumps when we are mowing those cover crops that are present in the row until canopy closure, and that is helping to limit the competition both with respect to fertility, sunlight, and water that's going to potentially, if there is competition, limit corn growth. So I wanted to leave plenty of time for questions. I know I ran through that, but I'm happy to take questions from the audience.

44:33 Yeah, thank you, Aaron. So much good information there. I've got a ton of questions myself here, but I'll try not to hog up all the time, but I'll start with the first one, then we'll go to the Q&A panel here. Fascinating stuff that you're doing with the in-row mowers, the rollers. Have you looked at any of the robotic options that are out there right now with the single row robots going up and down and essentially doing some of these same techniques, but doing it with more autonomous equipment?

45:07 That's a great question. You must be peeking in on our research plans. We do. No, we have some autonomous robots coming to us and our partners at Cornell University. So I'm very, very excited to try to use that technology to be able to expand our windows of being able to mow, potentially expanding our frequency with that with limiting competition or compaction. So really exciting to see that technology might fit into these systems.

45:46 Yeah, I think there's huge potential for that down the road, so it's exciting to see what can be developed here. So let's go to some of the questions here. Corey is asking, and this is a great question on the alfalfa, when you're planting that corn into the alfalfa or even the red clover, sweet clover, what growth stage are those things and do you try to mow them down before you plant or how do you handle the growth stage of that permanent living cover crop? Yeah, corn. I mean, you're obviously doing a strip till pass here to make a place to yeah.

46:21 Yeah, great questions. There's so much about these systems that I think that we can all learn from together, and it's always great to hear farmers that are experimenting with this as well. So and I think tools and technology are so important as well. I mean, even though they were at a university, I wish we had every tool possible at our disposal, and we don't. So I think that there is a lot that we could also optimize with the right strip tillage tools that are adapted to these high biomass cover crops. Again, I can't stress how much I think that cover crops are going to offer us so many opportunities to do alternative management, lower inputs, and build soil health, and they really are the foundation, the cornerstone of regenerative systems. But we haven't necessarily built some of the mechanical tools that I think will allow us to be able to maximize our management of those cover crops. And we have issues with cover crop breeding as well, but I think there needs to be so much more investment in terms of cover crop based systems. So we are strip tilling. I think ideally to do multiple strip till passes would be great. Potentially even coming in the fall, do an initial strip, but definitely in the spring doing a couple passes, one at green up and then another before planting, but I don't think all strip till units are created equal. So I think there's a lot more we can do there. We are planting trying to plant around the third week of May, which is pretty typical for organic management. I know you could probably go in earlier if you have a seed treatment in conventional management, but a lot of that is really based that planting date is driven by the lack of seed treatments. We've done it a couple different ways. We've done it trying to mow and even remove some of that alfalfa or clover, even potentially as a harvested forage. We haven't necessarily gotten a firm answer in terms of what is best. There are some farmers in Nebraska that are trying this with alfalfa that are having incredible success with it, and they're recommending not doing an alfalfa harvest. And instead of using a

48:37 Strip till machine, they're using a stalk puller, which I hadn't heard of. I need to get one. And essentially, they're ripping those alfalfa crowns out versus trying to strip till, and they're finding that is key to limit the competition and getting that in-row seed or planting zone for the corn. So not harvesting, and that stalk puller is really a key tool there. And they're finding good success definitely on irrigated acres, but even on non-irrigated acres as well. And the mowing frequency, we're going in a couple two or three times before canopy closure. So that would be we'll mow probably every other week or so until mid-July.

49:36 So many different variables in there and that's where the creativity of the farmer really comes in. So obviously, I love how you talk about cover crops being such a big part of the system. We definitely believe in that, too.

49:50 Mark is asking the question here. He says he's heard that cover crops mixes should include lots of species, but specifically lots of plant families. How do you look at building diversity into these mixes? Because, especially when you're going to do mechanical termination, the rules change a little bit when it comes to just trying to load up on diversity. So talk just a little bit about how you build these mixes and what are some of the things that you think about as you put them together.

50:21 Yeah, that's again where I think there's, it's just such an exciting field to be working in cover crops. There's so much that we can think about in terms of how to recreate what we're seeing in nature and look to nature and think about how do we want to try to emulate that?

50:42 And I think that it really again depends on what your goals are. How much do you want that biomass to be maximized? What is the function that you want to derive? How long do you want that cover crop to stick around? And I know, Keith, I've gone to you for advice, too. So I certainly don't have all the answers. I know that from an ecological standpoint, certainly I think having high diversity can be incredibly powerful from a soil biological standpoint. When we look at resilience and the function of soil biology, that having those diverse root systems, which are going to be feeding different compounds into the soil and helping to feed and support that soil biology.

51:38 If you're looking for a more immediate function, then sometimes a single species mix can be quite powerful as well. For instance, if you're looking at trying to clean up a problematic field and you're just looking at high biomass and allelopathy, cereal rye or sorghum sudangrass can be incredibly powerful. So I think that there's differences to look at in terms of long-term soil building, building soil biology versus trying to derive a more immediate function. And with weeds suppression, often it's biomass and getting that more immediate biomass. Although certainly the long term, a healthy soil is going to create a more balanced system that's going to lower weed populations and weed pressure more long term. But with some of these, and again, that's where I think, and I'm always seeing in the chat that people are giving suggestions, and I love suggestions, that for some of these living mulch systems, that something that is going to be less persistent might actually be better. Like that yellow blossom sweet clover. Another one that I'm excited to try, I think we have it in the field this year, which I got the advice from Sandy Seaberg, who's an amazing farmer here in Wisconsin, is mammoth red clover, which might be less persistent and be able to suppress weeds early, but not compete with corn. So yeah, I'm kind of thinking of that balance of you know, do we have an immediate need that we're trying to meet within a certain phase of the crop rotation, or are we looking at longer term soil building and building those biological communities that are going to lead to resilience?

53:18 Yeah, and you know, kind of a rule of thumb that I like to tell people is diversity is great and we want to encourage it wherever possible, but when your planting window is tight or your growing window is tight, you're just going to have less diversity because not as many things work. And when your goals are very, very specific, you're going to have less diversity because not everything is going to help you meet that very specific goal, whether it's weed suppression or.

53:43 Nitrogen fixation or depending on what it is. So it really boils down to what are your goals and what are you trying to accomplish?

53:51 Well said. Yeah, so let's talk about cereal rye a lot because that was kind of the star of the show when it comes to cover crops use. Talk a little bit about there's a lot of talk about it being allelopathic and talk about is that true when it comes to weeds? How about when it comes to the cash crops you're trying to plant, whether it be corn or beans? And then maybe also talk just a little bit about do you see differences in different rye varieties when it comes to how well they're being able to be crimped?

54:28 Yeah, no, all great questions. I mean, certainly in terms of weed suppression, yes, undoubtedly the power of allelopathy of cereal rye is incredible. And I know from some research done here at UW-Madison and looking at additional tools for herbicide resistant weeds, including waterhemp, giant ragweed, Palmer amaranth, it can be an incredible tool. The chemicals that are preventing those weed seeds from germinating, you certainly can visually see a difference in the field, and there are efforts to look at breeding for different levels of allelopathy.

55:13 From my observations, the data showed from roller crimping both soybeans and corn, I have not observed a difference in soybean systems. I think where we see soybean systems lag is more of those cooler planting conditions under the mulch, and that's delaying some of the early growth, but I don't believe it's allelopathy. With corn, I've heard so many different things from farmers, and I always take what farmers tell me really seriously because they're out in the field looking at things, and they really are incredible observers. And I know that rye and corn has certainly been a challenge.

55:51 Yeah, how much of that is also nitrogen tie-up? Again, and you know, some of the variability in terms of planting green as well and terminating with herbicides. Yeah, I've really want to move away from rye in corn. Rye is an amazing cover crop, but I think that there's some alternative cover crops that we can use that are probably better suited for whether it's planting green high biomass systems or roller crimping. But corn is just a bit of a primadonna when it comes to needing the right conditions and reacting to when it doesn't like things.

56:33 Well, yeah, we definitely see that a lot. You know, people will send pictures of their yellow corn or stunted corn. And I don't think that's allelopathy because my understanding is allelopathy will physically, chemically prevent that seed from even germinating. And so it's not really allelopathy, it's much more like what you talked about. It's probably a nutrient tie-up, something more related to that, which is a very real thing. And planting corn into heavy cereal rye requires very high levels of management. It's not where you start.

57:08 No, absolutely not. And I agree. I think what we're seeing is more related to nitrogen dynamics and potential, maybe there's some other nutrient dynamics as well. But I do think that there's promise in some of these legume-based systems of high biomass systems with corn. I still think that the nitrogen issue is something that we need to understand more to reduce risk to farmers.

57:33 Yeah, for sure. Well, I know we're running out of time here. I'm going to ask maybe one or two more questions. There's tons of questions in here, which just shows we had great participation and engagement. We appreciate everybody, and we're sorry that we didn't get to everybody's questions. But I do want to address there were two or three of them that had to do with using cover crops in very dry, very arid areas. You know, typically Wisconsin is not, you do go through some drought periods, but by and large, you're not an arid area. But how do you talk to people about if they want to try to incorporate cover crops into a dry arid area?

58:16 Yeah, and I think that there are cover crops that actually can be strategically beneficial in arid areas. And since there are some legumes, I wouldn't count alfalfa necessarily among them, but I again, I'm not in an arid area, so I don't want to speak as an expert by any means. But other legumes actually have more of a hydraulic lift.

58:41 Effect, which can actually draw up soil moisture. So, in some of the early research we did using different legumes and corn and monitoring soil moisture, one of the reasons why rye is very sensitive to dry planting conditions, at least when roller crimping or planting green, is it essentially acts like a straw and draws water up from deeper within the soil profile. There's legumes, however, seem to draw soil moisture up, but keep it in the soil profile. So, some of the research we did actually saw increased soil moisture at planting even in dry conditions with legumes.

59:19 And again, I think there's so much that we need to understand about not only what we're seeing above the ground with cover crops, but the power of the root system below the ground, not only with soil biology, but also with water dynamics. So, I certainly think there's options and options that could be beneficial. Managing those cover crops at the right time, and even with cereal rye, the issue is early in the season. They actually can be beneficial for droughts later in the season because they cool the soil surface, which is also very beneficial to soil biology. They keep that moisture held in the soil. So, it all depends on timing as well.

1:00:00 So, potentially in arid conditions, particularly those with lower snow cover, there could be ways and we were experimenting with this when I was down in New Mexico using winter killed cover crops that could help retain soil moisture. So, this is what I think one of those extra soil health principles that Gabe and Rick are often talking about. It's all about context. So, we take what we know and we adapt them to our particular context and our goals, but I certainly don't want to imply that there's not a role and that there's not a value and benefit to cover crops in arid systems, but you certainly have to understand where there's risk points and what cover crops to use.

1:00:38 Yeah, I think that's well stated. And again, we have that conversation with people a lot and yes, it's all about the timing and this is where diversity I think is such a big thing because we've seen time and time again where the diverse cover crop mixes use water moisture much more efficiently than a monoculture. It's just a far less competitive environment. And so, you have to figure out how to do the more diverse mixes and then you have to have some recovery time in arid areas. You can't be planting your next cash crop immediately.

1:01:12 And so, those are all things. And then lastly, what I always tell people, especially if you have livestock, consider it as your cash crop. Just grow covers, don't think of it as a cover crop, think of it as an annual forage crop and graze your cattle out there. There's never been a better time to do that because if you're growing commodity corn, there's not a lot of profit in that right now, but if you have cattle, you can graze out there, that can be highly profitable. So, be thinking about that for some of these arid area acres as well.

1:01:44 Well Aaron, I say we could be here another hour, but I know people have to get back to work and I don't want to take too much of your time, but thank you so much for joining us. It was very exciting. If people want to learn more about your work, what's the website they can go to? I know I've watched many of your YouTube videos, so people can go to YouTube and find a lot of your stuff, but what's the website?

1:02:08 If you Google O'Grain, O G R A I N, you'll find our website. We have a YouTube channel. Not all of my roller crimping videos are on the O'Grain YouTube channel, but there's a lot of presentations on the YouTube channel and we have a lot of resources on our website as well. And if there's any follow-ups, please make I'm easily accessible on the web and my email address and please reach out. I'm happy to follow up, but again, thank you. It's just such an honor to be here and invited to this webinar series.

1:02:43 Yeah. Well, thank you. And Jonathan just put the O'Grain link in the chat here. We did have someone ask, is it possible can we get your slides into a PDF to send out to. So, if you can get that to us, we'll send it out to folks.

1:02:57 Happy to. They can refer to some of that research and cross-reference it with the video. So, thank you everybody for joining us. Come back next week. This is the first of a series of six that we're doing. Next week we'll have Jenny Burhill, a great extension educator here in Nebraska, and she has done some fantastic work with on-farm research helping farmers do the research right on their farms and then helping to distribute that information across the state and the region. So, join us again next Wednesday at noon for another session. So, thanks everybody. Have a great day.