Cover Crop Termination Methods: Tillage, Herbicide, Mowing, Roller Crimping, and Frost Kill

0:00 We are super excited to get started today. So this is the fourth part of a six-part webinar series that we're putting on to cover the basics of cover cropping. So we started out with what are some of the reasons why you might want to plant a cover crop. What are some of the goals that cover crops might help you to achieve. Then we moved on to talk about species selection. With so many different cover crop species options, it is a little intimidating to know where to start. So we held a webinar on that and then we went in to talk about planting your cover crop. So now this week, now that you know how to plant your cover crop, let's talk about termination. So today Nathan is going to cover some of the different options that you have available and some of the considerations that you might want to keep in mind when you are looking at terminating your cover crop. So I'll go ahead and pass it on over to you Nathan.

0:55 Awesome. All right. Thank you, Sophie. Thank you, Jonathan. Happy to be with you all today and kind of share on this termination topic as part of this series. So my name is Nathan Chot. I am a sales rep here with Green Cover. I've been with the company for three going on four years now in sales. So I work with farmers and ranchers day in and day out, advising on cover crops and implementing these practices on their operations. And then I also get to manage our test plots here at Green Cover. So I'm located I live in Hastings, Nebraska, South Central Nebraska. So this is where our test plots are at. And so I get to also kind of have the balance of in-off sales work and field management kind of field experience. So I'm excited to bring that together for you all today.

1:41 So today's topic, termination. How do I terminate my cover crops? I wanted to kind of frame this conversation up with this first question of why terminate, right? Like why, you know, if cover crops are such a great thing, why would you stop a good thing? And so in some instances, you know, it may not be necessary to terminate, but most of the time, we need a proper termination in order to keep the cover crop from becoming a weed, right? So we always have specific goals we're trying to accomplish with our cover crops. But if we allow them to go unmanaged and uncontrolled, that same cover crop that's providing benefits, at some point we'll start to compete with our cash crops. Maybe they'll end up seeding out and creating a volunteer issue down the road. And so it is really important to have a termination plan in mind. And really, that termination plan needs to start at the beginning of the process. So we always want to start or begin with the end in mind. And so from the beginning of your cover crop plan, how you plan on terminating that should inform your cover crop selection.

2:51 So you know if you call me or one of my peers here at Green Cover, you know, when we start discussing the cover crop that you are wanting to plant, we're like, okay, what are your goals? What are we trying to accomplish? Well, when aren't you planting? When are you terminating? and how are you going to terminate. Those are all going to be specific because how you can terminate often informs what species will work in that context. So there's a lot of different options when it comes to cover crop termination. Today we're going to be talking about these five. So we're going to discuss tillage, herbicide, mowing/grazing, roller crimping, and then like a frost or winter termination. Um, there's probably some more options out there that I didn't think of, but I thought these five are pretty much the basic ones. So we're going to go through the list. We're going to talk pros and cons of each one. I have some kind of helpful pointers or maybe a little tricks to help kind of get you thinking about different ways on some of these and then kind of wrap it up with some timing discussion. And hopefully we'll get that all done in the next 25 30 minutes and leave some time for Q&A at the end.

3:56 So before we jump into the first termination option though, I want to frame this up with the idea that all five of these termination methods that we're going to talk about today are just tools. And so sometimes I feel like in agriculture we can kind of get into camps of like, oh, I'm a no till farmer. I would never till my field or no, I'm organic. I couldn't possibly spray. And while maybe those are your contexts, so that does determine your termination method. Um, these are just tools. They're not morally, you—

4:25 Know, higher or lower ground. And at the end of the day, we just need the right tool for the job. So if you got a certain cover crop and you have a certain ability to use a tool and that works, then that's great. Now, we always want to be careful not to overuse any one tool, right? Like if we're using tillage to terminate, but we're tilling 20 times a year, that's going to have really detrimental effects on our soils. So as long as we're not overusing them, then they don't necessarily have to be harmful. And we always want to consider the side effects. So as we go through this list, each termination method is going to have pros, but then the cons. And so you have to consider those cons and be like, okay, I really want to terminate. Can I put up with this, you know, this shortcoming or this side effect? Because we don't want to just whitewash over those and we want to basically really consider them and understand them. And so it all really comes back to context, but I just wanted to throw this out there as kind of that, you know, opening framework of these are just tools. We're just going to find the right tool that best does the job in the best way. So with that, we'll go ahead and start talking about tillage as our first option. So the pros of tillage, first and foremost, it's very effective, right? You're going in there with a piece of iron, you're cutting the plant off at the roots, it's dead, it's dying, it's done. The caveat there, it's very effective. It's not like 100% necessarily. I have seen fields of like cereal rye in the spring that was disced up and then some rain came for a couple days and then that rye was kind of able to re-run and grow again and then the farmer had to disc it again. So it's not like I tilled it once and I'm golden. But it's still a very effective tool. Plants can't resist, you know, a disc blade. Obviously tillage is organic friendly. That's a big plus, you know, for all of our organic customers if you're trying to avoid herbicide use. I've got the Omry listed logo there to point that out. And then this third bullet point is one that I'm probably not overly qualified to talk about, but this is something I've heard from Christine Jones that tillage may be more friendly to our soil biology than compared to herbicides with the caveat that you kind of do it shallow like so a shallow till and then immediately get something replanted. So if we're doing tillage and then having long fallow periods, I don't think the statement applies. But if we're tilling shallow and then replanting quickly, potentially tillage is more friendly to soil biology compared to some herbicides. So those are the pros, but what are the cons? Obviously there's side effects and drawbacks to using tillage. The first and foremost is erosion. So that top right picture you can see that's a field that's been tilled up and then a big rain event came and washed a gully out. So you know that's a pretty common site to see in hillier countrysides after rainfall events. But then you know sometimes as a sales rep I hear kind of the counterargument like well I'm in pretty flat ground. I, you know, erosion is not a problem for me. Well this top left picture wind erosion still applies no matter how flat your field is. So this is a picture from the spring. Bad dust storm came up. I think that was from Oklahoma or Texas. You know caused a dust storm and then the vehicles crashed. So tillage definitely opens you up for erosion. So that's a con or a drawback of this termination practice. There's moisture loss. So you know if we're in a drier situation or we're trying to conserve moisture, if you go out there and terminate a cover crop using iron, that's going to open up the soil, that's going to allow you know water loss, evaporation to happen. So that's a con most likely. Also carbon loss. You know we're trying to build our soil organic matters up. That's often a goal of the cover crop specifically is to increase soil organic matter levels. Well, if you go in there and you use tillage to open up that soil, what happens is you're allowing a flush of oxygen to suddenly get into that top layer of soil that gets the microbes going faster and they chew up the organic matter. You basically like oxidize it away. So carbon loss is a drawback of tillage. And then you know fourth bullet point here damaging soil structure where you know talk about soil aggregation and you got earthworm channels and all the root

8:55 Channels and that's how air flows in and out of our soil profiles and that's how we infiltrate water. Well, when you come in with a tillage implement most likely you're going to collapse that soil structure and seal that over. This bottom right picture of the blue disc there. This is a picture I took a few years ago. This was a freshly worked field started raining and right behind the disc you got ponding. So you can see that that soil structure was damaged from the tillage equipment and then water wasn't able to infiltrate. So definitely some side effects or cons of tillage, but I want to make the point that not all tillage is equal.

9:32 So this is a Sweet Plow. This is a customer of mine out in eastern Nebraska. Barry Young sent me these pictures a couple years ago now. But this is an implement he uses. So he's an organic farmer. And this sweet plow, he's in this picture, he's terminating an alfalfa stand. And so it's got 5ft blades. They ride just under the surface and basically cut the roots off of the plants. And so the idea is you're not necessarily turning the soil. You're not exposing the soil. Hopefully we're leaving some residue there, but we are still terminating those plants. And so this for Barry at least has been a very effective tool.

10:09 He's used it to terminate some alfalfa stands and also he'll use it on his cover crops. That picture on the right here, that's like some foxtail grass that he swung through and it, I mean that's a beautiful kill on that. So definitely still disturbance but if a moldboard plow is like the most disruptive tillage implement maybe a sweet plow is like a lesser one. So not all tillage is equal but some general points there.

10:38 All right herbicide. This is you know tillage and herbicide are probably the two most common termination methods. So the pros of herbicide, you know, using a sprayer and going out there and spraying some sort of herbicide, whether it's glyphosate or a cleft or whatever it is, is one, it works in no till operations. So if you are in that more fragile environment, you know, more steeper hill slopes type thing or you're really trying to conserve moisture and you're a no-till farmer, this is often the termination method you're using. So we're going to protect that soil armor, keep the residue on the soil.

11:13 One of the nice things about this is it allows for targeted termination of certain plants. So you could have a cereal rye cover crop, plant your soybeans into it, wait a little bit, go out there, soybeans could be up, you could terminate with herbicide and not harm the soybeans, but kill the rye. You know, you can't do that with iron. Iron's going to kill everything. So gives you that management option there.

11:38 The cons of course with herbicide, we're damaging soil biology. Kind of going back to that point I made on tillage of maybe tillage being more friendly to soil biology. Herbicide may be more damaging. We don't necessarily know the impacts of all the different chemistries and what they're doing to our soil biology. Some herbicides are like antibiotics essentially. So they're going out there and just killing everything. More and more research is being done here. Obviously if it's a biocide it's killing. So that's harmful.

12:08 There's the human health concern. You know, in my mind, mainly this is just like the operators working with the chemicals and some of the dangers that come with that. And then also some weeds are herbicide resistant. That's not necessarily in regards to cover crop termination, I realize, but it's just something to think about is like we keep relying more and more on some of these herbicides that are becoming less and less effective. So far, pretty much every cover crop is just fine, and I don't think there's going to be any issues there. But some of these herbicide tools are becoming less effective. So definitely a con on that front.

12:39 Quick little disclaimer. I want to zone in on a couple species of cover crops, but I do want to say that I'm not a herbicide expert. Green cover doesn't sell herbicides. So check with your dealer and distributor as far as some of this goes. In fact, check me and always read the label. But there's two cover crops that I feel like people probably have the most difficult time terminating with herbicide. And one is annual ryegrass. So this is a meme that I think the USDA put out on some post a while back. And I think it's hilarious that annual ryegrass after a herbicide termination, I'm back. Because it can be hard to kill, right? And why is it hard to kill? Well.

13:19 Annual ryegrass is a super impressive cover crop with a really deep root structure and it has way more roots than above ground biomass. So if you're trying to terminate with a herbicide, you're trying to push that herbicide all the way down into the roots. Obviously it translocates through the grass leaves, but it can be pretty difficult. So here's some notes on some advice on how to better kill annual ryegrass with herbicide.

13:42 Some rules of thumb: it must be 50° out on a sunny and dry day. Spray in the daylight between 9 and 6. Always use a full rate of herbicide if you're trying to kill annual ryegrass. And then throw in that ammonium sulfate and the additional surfactant. Roundup comes with surfactant in it, but I don't think that's sufficient. You need some additional surfactant. So again, not a herbicide expert, but this is some notes I have from some agronomists. If you go to that ryegrass cover crop.com, that's going to have some more information and you kind of get into the weeds more about how to better kill annual ryegrass. But if you just go out there and spray it thinking it's cereal rye, it most likely won't be effective. So wanted to call that one out.

14:24 And then I also want to call out hairy vetch. Mainly because glyphosate or Roundup doesn't really work very well on hairy vetch. It'll burn it back, but it won't really kill it. And so if you're terminating hairy vetch with a herbicide, you need a broadleaf herbicide like a 2,4-D. And that'll pretty well take care of it.

14:46 Okay, so mowing and grazing. We've talked tillage and herbicide. Those are pretty common. Most likely those are the two options you're using on your farm. But can mowing and grazing be a termination method? The answer is it depends. Why does it depend? Well, this is why. So on the left picture, this is a cover crop field that was just grazed. And you might look at that and go, 'Oh, it's mostly straw. It doesn't really need to be sprayed. Like I should just go plant the next thing.' Well, two weeks later, it looks like this field. Now of course, if your plan was to regraze this, that's great. But if you were going to go try to drill in the next crop or you know, whether that's a cash crop or a forage crop, this is all of a sudden competition.

15:31 So the caveat for mowing or grazing to work is basically if the growing point of the plant is below the ground, it can't be grazed out. If that growing point gets above the ground, so like a lot of your broadleaves, they lead with the growing point and then you graze it below the growing point, then that plant's going to die. So a lot of your broadleaf plants can be terminated. Most of your grasses cannot be terminated with mowing or grazing. So it does work in some instances. Obviously the pros of using a graze out option is that it's very friendly to soil health. Obviously grazing in general can be, as long as it's well-managed, grazing can be a plus for soil health. But we're kind of saving that pass, right? We're not having to go out there and disturb the soil structure with tillage. We're not putting out herbicides or anything. We're just using the animals or maybe a mower to terminate. So that's ideally great.

16:30 But the challenges or the cons of mowing and grazing is that it won't work for most grasses or really any plant that has that regrowing ability. So if a plant regrows really well, this just isn't an option. And then the risk is we often risk hurting the next crop if we don't do a proper termination. So like every spring, it's late April when we're recording this, I always get the question multiple times like, 'Hey, I got cereal rye out here. I'm looking to graze it. Can I just like plant into it and be done?' And as much as I'd love to say yes, the issue is even if you graze it really hard and it gets warm out and the heat comes like summertime, some of that rye is still going to regrow. And that part of the rye that regrows is going to hinder the next crop. And so it's just always better, unless you know, it's pretty much just always better to go ahead and do the termination, start with a clean slate, get that next crop going without any of that undue, unneeded competition. So as much as I'd like it to work, it probably won't.

17:32 Now again, if we're planning a cover crop and you know, hey, I want to be able to graze this out, you just have to put that into the plan. Pick the species that will allow it to be grazed out. But in general that's not always an option. But when it works, it works.

17:46 So all right, roller crimping. This is definitely a newer termination option. It's really becoming more and more popular. There's getting to be a lot of crimpers out in the countryside. The pros to roller crimping is very friendly to soil health, right? Like, we're not spraying, we're not tilling, we're not disturbing, all of that. Also, it's a lot cheaper. I didn't put that on this list here, but it takes a lot less diesel to go pull a roller through a field than it does to pull a disc. And we're not having to buy inputs of herbicide for every single acre. So there's cost savings there, too.

18:22 I'm definitely a big fan of the mat you can make on the soil surface with a crimper. So basically, you have all this standing up biomass and you crimp it over and you get this nice thick mat of biomass that's going to lock in moisture. It's going to be a weed barrier. It puts all that organic matter right on the soil surface where microbes and earthworms can start pulling it into the ground. And so that's definitely a nice feature of roller crimping.

18:48 Potentially the ability to plant green and roll later is definitely a pro and something that can work really well. I know Aaron Silva up there in Wisconsin has done a lot of work with this, the idea of like you have cereal rye, you plant soybeans into it, come back later, crimp the rye, and you know that keeps living roots in the soil all the time and you still didn't have to disturb anything. So definitely a potential pro there.

19:16 Now the cons of roller crimping is it's not guaranteed to work. Of probably everything I've listed thus far, this is easily like the most hit or miss. As long as you have the right species for the mowing and grazing, but you know, roller crimping, it's pretty often, you know, guys will go out there and they'll try to do a crimp kill and like you get 80% of it. Well, 80% is not really enough. So there is definitely a lot of art to roller crimping and having it done successfully.

19:44 Another con is that it requires a very specific growth stage on plants. So essentially where like tillage and herbicide, you can terminate based on the calendar. Say, hey, I want to plant corn May 1st, so I'm going to go terminate, you know, April 25th or whatever the plan is. With roller crimping, it's not the calendar, it's the growth stage of the plant. So you kind of have to allow nature to dictate your schedule, and when the plant gets into the right growth stage now you can go terminate it. So obviously that could potentially cause some delay in spring planting. And so that's a con. And then also the third con I have listed here is it does require another piece of equipment. If you don't currently have a roller crimper you can't go and try it. Like you have to source that piece of equipment to make it work.

20:38 So going to get into this just a little bit here. How to make roller crimping work. These are just some things I picked up from my customers and the crimper that we have here on the farm at Green Cover. Some steps into making this termination method work best. So first off is pick the right species. So just at the beginning of the presentation when I said your termination method dictates the species you should be planting, this is a perfect example and one of the most important examples of that being true.

21:08 So for the most part, our cereal grains will roller crimp fairly well. As long as they're in the right growth stage, you can't do it too early, but the cereal grains are good options if you're wanting to roller crimp. Most of our legumes are also good choices for roller crimping other than a lot of the clovers. So I have most non-C clover legumes. Probably could have ordered that a little better. But you know, your hairy vetch, your winter peas, fava beans, those are legumes that terminate really well with a crimper. Some of the clovers will regrow. So like your crimson clover and Persian clover, those are going to be a little trickier probably to crimp terminate. And then any brassica or broadleaf that grows a stock and won't regrow probably will crimp fairly well. So some nuances there. But so yeah, you got to make sure you pick the right species. Like I'm terminating with a roller. Do I have the right species to do that?

22:03 The next step then is to get the timing right. I mentioned this a little bit ago, but we are going to target the reproductive stage.

22:10 Called anthesis, that is the point when plants will most likely terminate with a roller crimper. So if you think about a cereal rye plant, when it's growing vegetatively, it's just going to keep regrowing, right? If you're grazing animals out there, it just keeps regrowing. Cows take a bite, it regrows just fine. So if you go and try to terminate a vegetative cereal rye plant with a crimper, you're just going to knock it over. It's going to stand right back up or it's just going to send new leaves. It's just going to laugh it off.

22:36 But at the reproductive stage, when the cereal rye head has come out and it's shedding pollen, that anthesis stage, that's the point when you can successfully crimp it. So we're shedding pollen on cereals like hairy vetch. That's when it's like in really good bloom. We have if there's a lot of purple flowers out there, it's in the reproductive stage, it can be crimp killed. Basically, we need these plants to move past the vegetative stage that way, they're not as likely to regrow. And then lastly, we want to crimp, not cut. If you cut the plant off with like if your crimper is too sharp or too much down pressure, if you cut it off, it's more likely to regrow because basically you cut it off and the plant goes, 'Oh, I don't have a seed head anymore. Got to try again.'

23:20 So we don't want to cut it off, but we do want to crimp it as hard and as many times as possible on the stock. So basically how the roller crimping, how crimping kills the plant is you break like the cell walls up multiple times throughout the stock and then it can't flow nutrients and like moisture up and down the stock and so you basically you ruin the plant's ability to like cycle within the plant. But since it's not cut off, you're not triggering the regrowth. So the plant goes, 'Well, I don't need to regrow. I have a seed head, but then it can't do anything with it, so it dies.' That's at least how I understand it. That might not be perfectly scientifically correct, but so we want to crimp it. And if we can crimp it hard and multiple times, that tends to be more effective than just like one crimp like at the base of the plant. So just some tips and tricks on how to make your roller crimping more successful. There's a lot of YouTube videos on roller crimping specifically you could deep dive into and learn more there.

24:20 So, all right, the last methodology we're going to talk about today is frost kill and winterkill. So obviously the pros of frost kill is it's very friendly to soil health. There's no disturbance here. There's nothing unnatural about a frost termination. And it's free. Farmers love free stuff. So just letting nature take care of it and you don't got to worry about it. That's a pretty good plan.

24:49 Obviously the cons to frost killing, some of these don't really need to be even mentioned probably, but it only works on certain species. So if you have a lot of your cool season either annuals or overwintering annuals, they're not going to frost kill. It only works in the fall. You can't control when it happens. It's not going to work if you go too far south. So allowing something to frost kill is definitely a strategy that works. You know, if you have a warm season cover crop out there and you just want it to terminate, you self-terminate, let nature take care of it. But there's going to be some limits to your control, of course.

25:23 All right, so those are the five most common termination methods. So now we're going to talk just a little bit about timing and crop maturity and how to kind of weave these together. So the question of when should I terminate? Well, as the sales rep at Green Cover, the first question I have back to you is what's the next crop? You know, when does the cover crop need to be done? What when are you planting the next crop? Because that's going to dictate when your termination is. So a lot of times you're terminating either a couple weeks prior to planting. It could be you're planting green and going to terminate it a week or two after right at planting. So you got to think about that order of operations. What's the next thing going on in the field?

26:06 Second of what's the goal for the cover crop? So you know, if your goal is just some extra grazing forage on the side and when you're done grazing, you're done with the cover crop so it can be terminated and you can go ahead and terminate. But if your goal is like, no, I need 125 pounds of nitrogen. Well, then you need to wait until the cover crop can accumulate that much nitrogen. So you're going to have

26:30 to give it more time or allow that goal to dictate your timeline. So consider what's the next crop, but what's the goal for this cover crop and how long does it need to accomplish that goal. Thirdly, when should I terminate might depend on the termination method. If you're talking about roller crimping, the when is when it's in reproductive stage, when it hits anthesis, that's when you terminate. If you're using a herbicide, it might actually be easier to terminate in more of a vegetative state. If you're worried about that or you know, herbicide or tillage is probably going to be less time sensitive, but so might depend on the termination method. And then fourth, and this is probably the most important one to pay attention and monitor, is depends on the moisture situation.

27:21 So in the last couple of years, we've had a couple different springs. We've had a couple years ago, we had a really dry spring and some guys had their overwintering cover crops out there and they got caught because they let the cover crop grow too long. The spring rains didn't come and their crop, their cash crop suffered because of lack of moisture because the cover crop did use up some of that moisture. That's a problem. So if it's dry, we need to move that termination up. So you know, say you have a rye cover crop. It's well, I mean, today's end of April. If we're kind of sitting a little dry, we've missed some rains, you should probably terminate early. If it's a dry year and you're worried about moisture, again, of course, if you're irrigated, it's not really a problem. On the flip side, if it's a wet spring, then you want to be careful that you don't get yourself caught in kind of a moisture trap where what can happen here is if you've got a cover crop out there growing, you terminate it with herbicide in this example and then it rains. So now you have all this dead biomass covering the ground, it's going to trap that moisture in there, which side note is kind of the idea because when July comes, you'll have moisture because you have residue and you're keeping that moisture protected. But when you're trying to plant, that's annoying. And so there's a good to fair chance if it's wet, actually doing like a planting green, leaving that cover crop out there longer, letting it grow, letting it use some of that moisture, go ahead and planting, and then terminating might work better. So just got to keep that in mind. The when, when should I terminate? What's the moisture situation? Monitor it. Have a plan. You know, for my guys, I really prefer there's like we just have a dynamic plan. If it's dry, if you've missed a few rains, we're going early. If it's wet, we're going late. It just depends on that context.

29:09 Okay. So we're going to kind of bring this all together and wrap it up and then we'll get into maybe some time for some questions. So terminating, keys to success. So this is kind of the four bullet point review of everything. These are my four things you should be thinking about to successfully terminate the cover crop. So number one, select your cover crop species with the termination plan in mind. How are you going to terminate it? Let that inform your species selection. Number two, have a termination method with the correct equipment in place. So if you're like, hey, I'm going to terminate with herbicide, but you're relying on the co-op to come custom spray it, we probably need to make sure we have a plan in place that has some flexibility in terms of timeliness because they might be early and they might be late. On the flip side, you know, I've had guys tell me like, I'm going to roller crimp this cover crop. That's the plan. Well, spring comes and they haven't quite picked up their roller crimper from the manufacturer yet, and it's time to roller crimp. They don't even have it in hand. Like, that's a problem. So we need to have the termination method with the correct equipment in place. Third, have that targeted timing. So in mind, know, hey, I want to plant my cash crop on this date, you know, I want to terminate then on this date, that's my plan. Now we have a dynamic plan, we allow that to flex for moisture, right? We were just talking about if it's dry or if it's wet, but we need to have an idea in mind. We don't want to be waiting around twiddling our thumbs and all of a sudden just on a whimsical, you know, April afternoon decide to go terminate. Like we need to have a plan. And then number four, we should have a backup plan. So what happens if my plan, termination plan doesn't work? If I planned on roller crimping?

35:23 Probably not because any herbicide is going to take it out. Frost is going to kill it. And frankly, it's kind of a beneficial plant in general. So yeah, I guess my long answer is it depends or my short answer is it depends. And that's a really good mindset shift there too because I think a lot of people might immediately think that any reseeded plant is going to be an issue, but buckwheat is a great example of a species that I mean you really don't have to worry about it being extremely persistent and it's going to cold kill pretty easy.

35:52 So it's just is what is reseeding going to like that volunteer is that going to compete with the cash crop or will it complement the cash crop? Because if it's a complement then it's not too big of a concern. But if it's a competitor then we need to be even more aggressive in our termination.

36:09 Okay. So we have someone who says that their number one goal for cover crops is to build soil organic matter for next year. So they're asking what termination method would work better towards this goal, either terminating the warm season mix by frost or using another method like crimping, and then following it with a winterkill cover crop or even an overwintering cover crop. So I guess the question is, do you let the warm season grow long enough to be cold killed or do you terminate that warm season cover crop and then plant a cool season cover crop after that?

36:44 That will I mean I think the best case scenario would be overwinter. It might depend a little bit about where they're located. So I definitely if it's all about organic matter I you know either roller crimping or just kind of grazing it and setting it back. The challenge is most of your warm season species if it's a warm season grazing mix likely there's things in there that are going to regrow and so you can't really just completely graze it out. If it's all about like soil organic matter though, probably what I would do is you put a diverse mix out there, you graze it, that's going to take a lot of the species out. So, you know, if it's a mix of legumes, grasses, brassicas, and broad leaves, we could probably graze out maybe 40 to 50% of that mix. The remaining 50% of like the grasses or maybe some of the brassicas because they'll regrow, but that probably opens up enough space that we can go in and like plant the overwintering cover crop anyway and just let frost take it out.

37:43 So maybe the answer there would be kind of like a multifaceted approach. Graze out some of it, frost out the rest, and then just go in there with the cool season stuff. Like I said, it depends a little bit about where they're located. If we need to be a if we're trying to get that overwintering cover crop in earlier because we have a short fall and a harsh winter, we might need to be more aggressive with an actual termination. But if it's a long fall and they're likely to catch like an early frost, but then have some good growing season left yet in the fall, it's probably more relaxed.

38:15 So you brought up roller crimping as a termination method which is certainly gaining in popularity and lots of folks are innovating with technology when it comes to making cover or making roller crimping working for them. So let's talk a little bit more about so what do you think about roller crimpers that attach to a planter? Is that a good idea, a bad idea? What are some of your thoughts there?

38:40 Well I love saving passes in a field. That's kind of what you're trying to do there. I would say I wouldn't rely on a planter attach crimper for full termination. So likely that's just going to do a partial termination. It's going to help us lay down like the residue in the field, create that mat that I was talking about, you know, that weed barrier and that sort of thing, but it's probably only going to kill like half to 80% of the cover crop. And that's, you know, it might work better for some folks, but likely it's you're still going to have to either crimp it again across the whole field or using some herbicide. I will say at Green Cover, the planter here used to have a crimper attached to it. Now it doesn't. Like we did that, now we don't. But yeah, part of the issue is like getting enough down pressure. Like if you have a really big cover crop you're trying to crimp, like the planter's already got a lot going on on it. So trying to like pack too much into one implement may be a challenge.

39:31 But if it's a more reasonable cover crop that you're trying to terminate, like if it's easier to do, then probably combining those passes is more viable.

39:46 What about postplanting termination? Like if you were planting soybeans and you're planting them green and then you're roller crimping your rye once the beans are already emerged. Can you give some thoughts on that?

40:01 Yeah, tons of resources on this. Like I said, I'd YouTube Aaron Silva and kind of see the work she's done on it. It's all about timing. You know, you don't want the soybeans to get too big and then cause an issue with the roller crimper damaging the beans, but for the most part, they're pretty resilient and flexible. So it's a super cool idea. It scratches a lot of soil health itches as far as the living roots and very environmental like soil health friendly termination. But I like I said I'd always want to have a plan B. I'd be kind of scared to do that if I was an organic farmer and then, you know, didn't have the herbicide to fall back on because that's the one thing even with the planter, you know, your the previous question with hooking the crimpers up to the planter, like if the crimper can kill 50 to 80% of the cover crop, like you'll probably get away with less herbicide, right? Like you'll have less herbicide so even that has some value. Maybe we can reduce some of these rates on things.

41:01 Yeah, it's definitely a cool idea. I know some people do it in corn. Obviously, corn tends to be a little more sensitive to the cover crop and in some of the competitions and things, but yeah, there's a lot of people pushing the envelopes in a lot of directions.

41:20 We talked mostly about large-scale commercial termination of cover crops. Let's talk just a little bit about terminating a cover crop in a small-scale or garden setting. This would be a situation where someone's likely using hand tools or a lawn mower or flail mower of some sort. In my experience, I've seen that if it's not a super persistent cover crop that has a really strong vigor and regrowth pattern, a lot of times you can just tarp that cover crop with a black silage tarp. And again, it's going to depend on what time of year you're doing this, but ideally, you have a good amount of days where it's pretty warm out and that plant is essentially killed by the lack of sun and the heat. And there are some thoughts about this being perhaps detrimental to soil biology because you are essentially superheating the surface of the soil to kill the plant. But in my personal experience, I have seen that earthworms actually thrive in that type of environment. Especially if you're in a place where it's cooling down in the evening. So you're going to still have that biomass from the plant there that's creating a really great environment for soil for earthworms to come up and lots of garden snakes and things like that.

42:42 Yeah. If there's a lot of worms, I wouldn't be too worried about the soil biology. Like, if the worms like it, then it's probably okay. Yeah, tarping is definitely something that folks do. I mean, I've seen handmade crimpers. I think Jonathan, who was on here to start off with, he in his garden, he'll just kind of he's like a 2x4 with a piece of angle iron bolted to it and some ropes and he crimps it. I think there's a YouTube video if you search Green Covers YouTube page, you'll see how he does that. I mean, I've crimped oats in my garden beds with just a square shovel, just kind of chopping them down. It doesn't have to be pretty or fast if it's not too many acres.

43:18 Yeah. A lot of the principles work too. And the same thing, you know, think through the pros and cons. Like maybe in a small garden setting, tillage isn't that big of a deal if you're going to replant right away and like if there's not going to be a lot of erosion type of thing, you know, you're not too worried about soil structure because you can water it and stuff. So yeah, because you probably don't want to use a lot of herbicide in a garden setting, but yeah. And also that's normally a situation too where people might be amending their garden beds pretty heavily with maybe compost or fish or whatever it is. So yeah, there's definitely a lot of differences in that in that sort of context, but we do have a YouTube video and I can link that in the show notes once we get this posted.

44:02 This is a really good question. Alexandra asked this. She said, 'Is there a significant difference in moisture loss between tillage done as early as possible in the spring when temperatures are lower versus tillage done right before planting so you have roots in the soil for as long as possible?'

44:24 Village done early in the spring versus right before. I do not have a scientific answer for that. I think that's something maybe you'd have to look into or see if someone who's done any research. Logically, I'm going to say I would want to till right before because if you till early, then your soil is going to be exposed until you get it replanted. And you know that residue is a lot of our water holding, keeping the soil cooler. And so obviously like the plants are growing and so they're using up some moisture. So if it's dry and we're trying to terminate early, but I don't have a super great answer. My hunch is the later termination is still better for moisture conservation.

45:14 Just in terms of the soil loss from the tillage event because you can hopefully bank more moisture before you end up tilling. Because if you're tilling and then planting right away, we're minimizing the amount of time when we have exposed soil and a lack of living plants. Kevin commented that back to this concept of what Christine Jones was talking about. Ideally, if you're doing a tillage pass, you do it right before you're planting. Because tillage is breaking up mycorrhizal fungi populations, but they do have the capacity to reinoculate plant roots once they're reintroduced into the ground. So theoretically, if you can get something planted right after a tillage pass, then that mycorrhizal fungi will continue to live in the soil and then colonize those roots once they're back.

46:10 I mean there's some research from the Rodale Institute that talks about that same timing of tillage followed by an immediate planting and can be really awesome for actually building more organic matter because you're essentially incorporating that plant material into the ground and then reintroducing roots which kind of super boosts soil microbiology and just really gets the system going. So lots of different thoughts on that. We could have a super long conversation on that alone. And if you just think about it, that's where I think part of the key is more of that shallow till because that mycorrhizal fungi is running throughout the soil profile and so you kind of just scalp it almost, like you just almost like a haircut maybe, and so then it can just regrow and get back up to those new plants coming on.

47:01 We had somebody ask about allelopathy when planting green. So do you have any thoughts about that? Yes, this comes up a fair bit. So the allelopathic effect of rye, to my understanding and most of the academic articles I've read, this is when rye is able to keep other plants from germinating. Whether that's through the different signals it can send in the soil or just good old-fashioned competition, rye has the ability to keep other plants from germinating. So a lot of times what happens then is someone will plant, like normally it's corn, right after rye, whether it's green or recently terminated rye, and the corn comes up really yellow looking and kind of sad and spindly, and then immediately, without necessarily doing too much research, the rye will be blamed for its allelopathic effect and the impact it had on the corn. But it's my understanding and the opinion of green cover that since that corn came up, we didn't have a germination issue because we have a corn plant, right? The seed germinated, so it's not an allelopathic effect at that point. Now it's nutrient tie-up, and that's a whole another can of worms.

48:14 Because rye is a really good nutrient scavenger. And so if it's growing out there and if it has two or three months of growing season, it will have sucked up pretty much all of the available nitrogen specifically, but the other nutrients too in the soil. And so that corn is germinating just fine. But as it starts to grow, it has nothing to feed itself. So that's where we thought about trying to go into that during the presentation, but I didn't decide not to because of time. But we need to be very aware of whether we're doing some starter fertilizer or seed inoculants or whatever we're doing for that early season nutrient management following cover crops because that cover crop likely is tying up a lot of that fertility. Or on the flip side, say you're planting a heavy legume cover crop thinking that's going to feed.

49:02 Feed our cash crop. The nitrogen that the legumes fix isn't immediately available upon termination. That plant has to break down. Your soil has to break that plant down and convert it into nitrogen that's available for the cash crop. So we just need to be aware of both of those two things when dealing with these spring cover crops. You know, likely it's not the allelopathic effect, it's nutrient management. And then how do we overcome that? You know, that might be an earlier termination. Sometimes the disc tillage does help expedite our plant breakdown. That's going to depend on where the soil biology is at. If you have a really humming system of really active soil and really good microbes and a lot of worms, they're going to cycle that plant residue a lot faster and make that available.

49:52 The other thing that I think guys always need to think about is what's your corn's nutrient demand curve. They don't need 100 pounds of nitrogen in the first two weeks of them growing, right? A lot of our nutrient demands are in season. We need a lot of that nitrogen when we're filling the ear and those sorts of things. So it doesn't necessarily need to be right away, but there needs to be something. And if we have a really good cover crop out there of grasses mainly, there's probably not much for nutrients for him. So yeah, that could be its whole own webinar.

50:21 Definitely. So I'm going to do one last question and just if anybody else has any questions that they want to ask, and maybe if it's not even on the topic of termination, go ahead and send those in the chat right now because we will save those and we'll be referencing those in the final episode of this webinar series when we do an ask me anything. So if you have any thoughts, any things that you're wondering right now, go ahead and send them in the chat. So then I'll go to this question from Sue. She asks, 'Is it possible to have a cover crop mix that doesn't need to be terminated as the cash crop will outcompete it?' Essentially something that would not you wouldn't have to worry about actually having to terminate that crop because it's not going to be growing persistently at the time that you plant your cover crop or your cash crop.

51:23 Like the cover crop would have to be pretty minimal in terms of biomass and vigor in order to plant into it. Potentially, you know, some guys and gals are experimenting with perennial cover crops, having a perennial living system, especially like with corn interseeding and having strips of perennials and they're planting the cash crop between the strips of perennials. That might be kind of what Sue is referring to there or something that could be looked at. I think if you don't want to terminate, you know, maybe that could look like just timing your establishment different. So thinking along like the corn interseed topic, maybe we plant our cash crop, then we wait a couple weeks, plant a cover crop, companion crop more so beside it, let those go through the season, let the companion crop die with frost and harvest our cash crop. It could be more of that mindset of companions with the cash. But yeah, off the top of my head, I don't necessarily have a specific mix where you could just plant the corn into it. It would depend on the cash crop and when they're wanting to plant and have to be more of a discussion there, I think.

52:38 Yeah, definitely. Look into companion cropping more at that point if it's less of a sequence and more of just a compliment.

52:44 Well, thanks so much for a great conversation today, Nathan. I know we probably could have gone much longer on some of these things. So just for people on the YouTube video, if there's any of these topics that you'd like us to elaborate a bit more on, make sure to comment that below because we're always looking to produce the most helpful content for you guys. So next week we will be talking all about the basics of biologicals when it comes to biologicals on your cover crop seed. Definitely tune in for that episode and then our final episode will be on an ask me anything. So we'll be taking any of the questions that we didn't get to hear and be chatting about those. So yeah, thank you all so much for coming on today and thanks Nathan for some great information.

53:29 Absolutely. Hopefully it was valuable and yeah, if there's anything we didn't get to, come back in two weeks and you can throw them at Keith and see what he says. So I enjoyed it and yeah, if you ever have any questions, don't hesitate to reach out. Thanks everyone.