“Don’t just try it once and think, ‘It didn’t do well. I’m never trying it again.’ It's worth trying out different cover crops and going to field days that may have some of these alternative cover crops growing.”
— Rob Myers, Director of Center for Regenerative Agriculture, University of Missouri
In this episode of the Cover Crop Strategies podcast, brought to you by SOURCE® from Sound Agriculture, listen to Rob Myers, director of the Center for Regenerative Agriculture at the University of Missouri, as he discusses 4 alternative cover crops and how to manage each one.
Myers talks about buckwheat, millet, canola and sunflowers.
- [Podcast] Why Cover Crop Acreage is Growing, and Important Rule Changes that May Reduce the Risk
- Examining the Properties of Buckwheat as an Alternative Cover Crop
- Cover Crops as Alternative Weed Control
- Sunflowers Blooming as a Cover Crop
The Cover Crop Strategies podcast series is brought to you by SOURCE®️ by Sound Agriculture.
SOURCE®️ from Sound Agriculture is a soil activator that gives crops access to a more efficient source of nitrogen and phosphorus. A foliar application of SOURCE provides 25 pounds of nitrogen & phosphorus per acre and enhances micronutrient uptake by stimulating beneficial microbes, and its performance is supported by a cash-back guarantee. Learn more at www.sound.ag.
Full TranscriptMackane Vogel:
Welcome to the Cover Crop Strategies Podcast, brought to you by Source from Sound Agriculture. I'm Mackane Vogel, assistant editor at Cover Crop Strategies. In this episode, listen to Rob Myers, director of the Center for Regenerative Agriculture at the University of Missouri, as he discusses four alternative cover crops and how to manage each one. Myers talks about buckwheat, millet, canola, and sunflowers.
I'm here with Rob Myers. Rob, if you want to start out and just kind of introduce yourself and give us a little bit about your background and then we'll get into a discussion about some alternative cover crops.Rob Myers:
You bet. I'm Rob Myers. I'm an agronomist at the University of Missouri where I direct the Center for Regenerative Agriculture. I also work with the North Central Region Sustainable Ag Research and Education or SARE program, and grew up on a farm in Illinois, but have been in Missouri for most of the last 30 years.Mackane Vogel:
And as I mentioned, today we're going to be talking about some alternative cover crops, some less common ones. I think the main ones we're going to be discussing today are buckwheat, millet, canola, and sunflowers if we can get to all of them. You've done some research on these for the University of Missouri, is that right?Rob Myers:
Yes. Going back to the early '90s, I've done a variety of field trials with these crops as well as others. My responsibilities over the years have often involved diversified cropping systems, so I've looked at some of these lesser known agronomic species for both grain and oil seed markets as well as cover crop opportunities.Mackane Vogel:
All right. So I guess why don't we start out with buckwheat? We've done some conversations and some articles on buckwheat and cowpeas and some other alternative cover crops, but I guess we can start with buckwheat, but also I want to start out by asking you what makes a cover crop something you'd call an alternative cover crop rather than just a cover crop?Rob Myers:
Well, it's interesting. In the cover crop marketplace today, there's over 40 different species of cover crops being grown, let alone varieties. I think if you added the name varieties in, you'd probably be closer to 80 or 100 options out there. But the various species that are available, when you look at what is mostly sold, it's a few of the cereal grains like cereal rye, wheat, triticale, oats, are the big ones on that side. If we look at the legumes, it's crimson clover, hairy vetch, Austrian winter peas are the big three.
And then in Nebraska it's primarily radishes, turnips, and to some extent rapeseed canola, which we'll talk about today. But then there's a whole bunch of other things. And sometimes these things show up in mixes, sometimes they show up in particular niche uses, and I think they're all valuable in their own rights. And so I think it's just good for people to be more aware of some of these less common ones.Mackane Vogel:
And so something we talk about all the time in the world of agriculture is there's never a one size fits all, but I guess starting with buckwheat, is there a particular region or a type of grower that you think buckwheat works particularly well for from what you've researched?Rob Myers:
Well, the first thing I always say about buckwheat is its unique niche is that it grows fast. And I've grown over 70 species of agronomic crops, both as cover crops and things we'd harvest for seed and buckwheat is the fastest in terms of getting to the standpoint of flowering and producing seed. And that's been why it's been used over the years. It's something that is sometimes looked at as an emergency crop. Let's say we have a very wet spring like we had in 2019 and people just can't get the regular crops in the field. Well, maybe it's July and you're finally getting a dry field. Well, you may not be able to plant corn then, but you could come in with something like buckwheat and plant it. Or you've got early season vegetables or you've got a wheat harvest and it's now July and you're wanting to plant something here again, buckwheat fits in.
Now, the thing that is important to know about it, I always look at cover crops as either they're warm season plants or they're cool season. So many of the things we think about from a cover crop standpoint do best in cool weather. A lot of the ones I just rattled off among the cereal grains, brassicas, legumes, those are all ones that do best in cool weather. Buckwheat is really more of a warm season crop with something that we'd want to plant in the summer muss. And I say that's important because of my own family farm in Illinois, we've had a grain elevator recommend to our tenant, "Oh, you can plant buckwheat in October." And that's not when you want to be planting it.Mackane Vogel:
How do you go about determining the seeding rates for some of these cover crops and what might that look like for buckwheat?Rob Myers:
Well, they certainly vary depending on the crop we're talking about based on the size of the seed and the growth habit of that plant. Typically, buckwheat's going to be planted around 50 pounds an acre if it's drilled. If we're just broadcasting the seed on the surface with no incorporation, I'd go a little bit higher rate, maybe 60 to 70 pounds an acre. So it is a little larger seeding rate. It's a bigger seed, it's very roughly the size of a soybean seed, maybe a little bit smaller than the soybean seed, but it's an irregularly shaped seed. It's really a four-sided seed kind of just look at it on the table. It looks more triangular in shape.Mackane Vogel:
And I think two questions we get a lot regarding cover crops are obviously how effective is it with weeded management? And then one that we hit a lot this past growing season was obviously how will it perform in a drought? So can you speak at all on those questions related to buckwheat?Rob Myers:
Yeah. So buckwheat is sometimes portrayed as being a really good smother crop, and when we say smother crop, we think of something that will smother weeds. And it can be. I've grown it a lot over the years. I've probably grown it in, I don't know, 25 field seasons. And the thing that helps it smother weeds is its fast growth, but like any plant, whether it's corn, soybeans, cotton, you name it, for it to be able to be competitive with weeds, it has to get started ahead of them. So if you have a relatively clean seedbed you're planting into and some moisture to get it going, then yes, it'll get a jump on the weeds and kind of suppress them.
What I have found, let's say you're planting buckwheat in June for whatever reason, that as you get into late summer, the buckwheat will start to drop some leaves and so on, and then you may get a flush of weeds coming through it. If you do get weeds that are starting to grow at the same time as the buckwheat, it's not quite as aggressive as some other things that are out there. Some of our bigger summer cover crops like a Sorghum-Sudangrass or a sunn hemp or even cowpeas, which are about the same height as buckwheat, but are just leafier. So to me, buckwheat isn't quite as good of a weed protector as it's sometimes portrayed, but it can be effective if you get a good dense stand of it and get it off to a good start.
Now, drought is a different story. So there's some misperceptions about buckwheat from a drought standpoint. I've seen literature references that say, "Oh, buckwheat's great in a drought." And I am confident that is not the case from my experiences. There are other plants in the summer that are much more tolerant to dry conditions. Many of the millets, cowpeas, mung beans, they all do better in dry conditions than buckwheat.
What often happens with buckwheat is we're planting it later in the summer, so it tends to not be growing during the dry as part of the summer depending on how people are using it, and then it's fine. But if you're planning it at the beginning of the summer, like beginning of June, and it turns hot and dry, it's going to suffer. So it actually tends to wilt very readily, more than most summer plants that I've seen. And then the next morning you'll go out, you'll think it's dead in the afternoon almost. You go out the next morning, it looks great because it's rehydrated overnight. So it's kind of a funny plant in that way.Mackane Vogel:
Very interesting. All right. Well, you mentioned millets, so why don't we move on to that. I was at a fuel day maybe a couple months ago and learned a little bit about millet. What I remember is there's lots of different types. Is that right?Rob Myers:
Very much so. Millets is a very confusing term. It's sort of like people in agriculture are familiar with the term small grains or cereal grains. There's a lot of things that fit in there. Wheat, oats, rye. While they're somewhat similar, I'd almost say really to me, what a millet is it's a grass crop that has a small rounded seed. That's about all it means. And so you have things like pearl millet that almost look like a cattail plant that come from Africa. You've got foxtail millet that comes from Southeast Asia, like China, that looks like a foxtail weed, very different from pearl millet. You've got things like finger millet that come from India that have very different... So all these millets come from different regions of the world.
Proso millet comes from Northern Asia, like Russia, very different growth habits. They're not only different species of plant, different genuses of plant. So the only thing they really have in common are they are annual grasses harvested for their seed, but they're very different plants. And as a result, they do different niches. We have, for example, among the millets, there's Japanese millet from Southeast Asia that does very well in wet conditions. It can even tolerate some standing water for a while. It's not quite like rice where you're going to grow out the whole season in standing water, but whereas none of the other millets will tolerate standing water.
Other millets like proso millet, pearl millet, even foxtail millet to some extent, are very tolerant dry conditions. So it really pays to know what your needs are in terms of picking a millet.Mackane Vogel:
Is there one or two particular types that you've worked with at all that you have experience with research on?Rob Myers:
I've actually worked with all the common millets and some of the less common ones. In the US, the two main ones that we see used for grain harvest, it's primarily proso millet, but that's been traditionally restricted to the high plains area, Colorado, Nebraska, Western Kansas. It's the one we normally see in the US grocery stores. If you see a product that has millet in it or just whole huffed millet, that's almost always proso millet. But there were many other millets domesticated as human food crops around the world, including the ones I just rattled off.
And pearl millet is the second biggest one in use in the US. Primarily, not so much for seed harvest, but for forage use. And we may think of, "Well, what do we need for a cover crop?" Well, forage ones certainly fit for grazing, but keep in mind all of our crops, like soybeans, as many people know, were introduced to us as a forage crop. So I don't get too hung up into whether something's primarily a forage. It's more what its growth characteristics are. Pearl millet of all the millets is the most vigorous growing one. So if we want to summer cover crop with a lot of biomass to it, we'd look at the forage types of pearl millet.
But the nice thing with millets is a lot of them play well together. In other words, if you put them in a mix, they don't really hurt each other's growth. So when we talk about summer cover crop cocktails that may be planted after wheats or after an early vegetable, we can put several of these millets together and that can be effective because they fill slightly different niches when they're growing. If it's a wet summer, some will do a little better. If it's dry summer, others will do better. So if I were doing a summer mix, I would certainly include some pearl millet, some foxtail millet, maybe some Japanese millet. It's a little harder to find Japanese millet, but because of its wet tolerance. And then you're getting a little more biodiversity in that mix.Mackane Vogel:
And I guess let's focus on pearl millet for now. What's a good way to terminate a cover crop like that? Is there a specific way that it should be done, or what would you suggest?Rob Myers:
Well, yeah. So all of these millets are going to be controlled pretty easily by a glyphosate or even to some extent if they're small enough, you could control them with grass herbicides like select or post. But if they're bigger size, you're probably going to go with glyphosate or you could go with a burndown herbicide. So some people are controlling them by mowing or grazing. Once they've produced a seed head, any of the cover crops we might talk about, whether it's millets or otherwise, the key to managing them mechanically is often letting them start producing seed or at least get to the flowering stage and then it's easier to kill them by mowing or a light disking or something.
There are people trying to terminate these with grazing, and you can do that again if they're reproductive already. If you have a hard intense grazing, you could terminate them. If they were still vegetative and not yet flowered and you were not grazing real heavily, you'd probably find they would come back just like mowing your lawn. So it's really all about the timing.Mackane Vogel:
And in terms of seeding rate or weed management, any comments there for millet?Rob Myers:
Well, I go back to the vigor and aggressiveness of the plant. So the pearl millet is the tallest and most actively growing one. It's going to be able to outgrow a lot of our summer weeds. Something on the other end of the spectrum would be proso millet is a very good plant for the high plains area. We can grow it in much of the Eastern US, but it's just not as vigorous as some of the other millets, especially in that climate, the warmer, wetter parts of the US. And so it's not going to be as effective in competing with weeds. That is proso millet.
Some of the others I mentioned are more intermediate in their competitiveness with weeds, not bad, but not necessarily the best. I mean, the most vigorous summer grass crop is among the sorghums. You'd go to Sorghum-Sudangrass or a forage sorghum if you wanted a really tremendous growth. Pearl millets, a little bit behind those. But it has some advantages for grazing in that it doesn't have the prussic acid poisoning potential. So they each again have their niche. And pearl millet is one I like a lot for dry weather and just provide diversity.Mackane Vogel:
We'll come back to the episode in a moment, but first I'd like to take a moment to thank our sponsor, Source from Sound Agriculture, for supporting today's podcast. If you want to make your fertilizer plan more efficient, source it. Source from Sound Agriculture optimizes the amount of crop nutrition supplied by the microbes in your soil, providing 25 pounds of nitrogen and phosphorus per acre. It's cost-effective and easy to use. Just throw it in the tank and spray and season. If you want to unlock your crop's potential and increase ROI, there's only one answer, source it. Learn more at sound.ag. And now, let's get back to the episode.
Let's move on to our next alternative cover crop. I think it's time to talk a little bit about canola, which I think it's kind of an interesting one. Can be used for oil seed or as a cover crop, and it's also usable for livestock feed, right?Rob Myers:
It is. Not a lot of people realize that you can graze canola just like you might graze turnips. They're very similar plants. They're members of the Brassica family. And what I've heard from people that have grazed canola or rapeseed is it can take the cattle a day or two to get used to the taste of it. It's sort of like us going to the salad bar. If we'd been used to eating romaine lettuce and you suddenly threw arugula in, you might say, "Hmm, that's kind of spicy. That's a little different." But I think that's what happens when they go out and eat the canola rapeseed. It's got a little hotter taste to them, but they get used to it.Mackane Vogel:
Yeah. The arugula cover crops. I love that.Rob Myers:
Yeah. So canola and rapeseed, the reason we would look at them as a cover crop is the fact that at least in the Southern half of the Corn Belt, we can look at these as overwintering. And so if we were compare them with radishes, now sometimes people like radishes or turfs because they won't overwinter. They don't have to deal with them in the spring. But if we want something, they'll provide a little more erosion protection, provide some living roots through the spring, then that would be the reason to go with rapeseed or canola.
The other reason, it's kind of a minor thing, but I have had people tell me, "Well, I grew some radishes and they really smelled in the spring." That's usually a pretty short-lived phenomenon, two or three days where the tubers are breaking down and they release a sulfur compound, and it can vary by year. But I always tell people not to plant radishes right next to your house, especially on the upwind side, because you might not enjoy it for a day or two in the spring.
Well, canola, you can detect a little bit of that scent in the spring, but it doesn't have nearly the smell of the decaying radishes do. And unlike turnips, which that big bulb can be a little bit of an issue when you're trying to plant your corner soybeans, depending on how much it's decayed, you don't really have that problem of planting into having a radish tuber or a turnip tuber that you're trying to deal with. So there's some advantages to the canola rapeseed, so it could provide more weeded control in the spring because it's going to continue to grow during the winter. So it's just an option for the Southern half of the Corn Belt for something over winter.Mackane Vogel:
And is this another one for termination, probably a glyphosate situation in the spring or-Rob Myers:
Yes. Now, the only thing we do want to be careful of when we pick canola for use as a cover crop is there are spring canolas that are glyphosate-resistant. There are starting to be some winter canolas, but for the most part, the winter canolas are not glyphosate-resistant. So you would want to be sure of that, that you were getting something that was not glyphosate-resistant. But otherwise, yes, you could kill them readily with glyphosates, but also could be controlled with some of our broad leaf herbicides as well.Mackane Vogel:
And for seeding rate, what would you say for canolas?Rob Myers:
It's interesting. When we look at a lot of our cover crops, whether it's cereal rye or buckwheat or whatever, sometimes we say, "Well, if you want a little better performance, go to a little higher seeding rate." That's actually not the case with canola. We want to keep that seeding rate down because to get it to survive the winter, we need what we call the crown tissue, which is the interface between the stem and the root to be as big as possible. So normally, if it's a good-sized canola plant going into the winter, we'd like that to be bigger than the size of a pencil in diameter. And if it's smaller, that plant's going to be less likely to survive the winter.
So the things that affect the size of that crown tissue is the time of planting, the fertility in the soil, nitrogen and phosphorus in particular, and how closely they're planted. And of course, we can affect all of those things, but if we plant it a little lower seed rate, I would typically recommend around three pounds an acre if we're just planting straight canola, it'll survive better than if we planted like five or six pounds, which sometimes you'll see references that say five or six pounds. That's kind of an older recommendation, but I would keep the seeding rate down and certainly if you're putting it in a mix, cut it even further, maybe just a pound an acre.Mackane Vogel:
All right. Good notes. Well, let's move on to the last one that we'll talk about for today. It's sunflowers, and this is kind of an interesting one, sort of a versatile crop. I feel like it's used for a lot of different things, but seeing it more and more as a cover crop, what are some of the beneficial reasons somebody might want to use sunflowers as a cover crop?Rob Myers:
Well, we don't see a whole lot of use of sunflowers as the sole cover crop planted in the field. It's almost always in a summer cover crop cocktail, and I go back to that warm season versus cool season. Sunflowers are what we would call a warm season plant. I also stress that they're native, which many of our cover crops are not native, so that's a plus in a lot of people's minds. The one thing I'll add while I'm talking warm season, cool season, sunflowers are more tolerant of cold temperatures than some other things. I mentioned the millets a moment ago, they're going to pretty much all die as soon as we get like a 31 degree night. Sunflowers will keep growing until it gets down to about 28 degrees, depends a little bit on the characteristics of that night, but that may give it another couple of weeks to grow in the fall.
So it can, even though we're planning it ideally in the summer, let's say you for some reason work putting a mix of cover crops out till late August. It's still okay to put sunflowers in there because it'll grow pretty long in the fall in many regions. So why would we put it into a mix? Well, deep taproot is one thing. It's going to help create some deeper rooting channels than many of the other cover crops. Certainly from a wildlife standpoint and pollinators, it has some benefits both for the long flowering period and seed produced for songbirds and other animals that might be out there.
It's vigorous in terms of weed suppression. Sunflower is very competitive with weeds. I'd kind of put it up there with Sorghum-Sudangrass almost. If you did have a solid stand of sunflowers, they're pretty competitive with weeds. So I think it's just if you're going to do a mix of several different summer cover crops, it's a really good one to put in the mix. The only slight disadvantage of sunflowers, if we're broadcasting that mix, it doesn't do real well broadcast on the surface. It's really better to seed it into the soil in some fashion if we can.
The other thing I'll add, a lot of the sunflower that's sold for cover crop mixes is what's called Peredovik, which is an old Russian variety. It's a taller variety. It's a fine variety used, smaller seed, which can help it with broadcast establishment, but it actually is a little less vigorous in terms of its leakiness than a lot of the modern hybrid sunflowers. So I always tell people just if you're going to have a mix by whatever's available to you, the modern hybrids are equally good and maybe better in some ways than the Peredovik, but just if you can get the Peredovik at a low cost with good seed germination, it's fine to use. I have found it interesting that a lot of the mixes only use Peredovik and don't use the widely available commercial hybrids.Mackane Vogel:
Interesting to note. Also, plus that they look very nice in the field, right? I mean, not the most important thing, but also a plus.Rob Myers:
I've heard farmers say with summer cover crop mixes, they get a lot of good vibes from their neighbors if they put even if just a few sunflowers in that mix.Mackane Vogel:
Nice. All right. Well, now that we've kind of gone through these four different alternative cover crops, just got a couple more sort of general questions about all of them for you. So I guess if you're listening to this and you're someone who's never tried planting any of these, what would be your advice on how to get started and maybe how to just do a little bit of a test initially? What's a good way to ease into planting a cover crop that you've never tried before?Rob Myers:
Yeah. Well, so again, first of all, think of the season that we want the cover crops. So since the majority of cover crops are fall planted of the group that we've talked about, the one that is the easiest to adopt in that group is the canola rapeseed. And by the way, canola and rapeseed really only differ in their oil characteristics. They're the same species of plants, they're going to look the same, perform the same. There are some varietal differences in terms of winter hardiness. So canola is a good one to start with. You can use it just as a sole cover crop if you're going to be wanting something alternative to maybe you're going into corn and you don't want a grass cover crop that's going to tie up as much nitrogen, that could be a reason to just use canola, especially if you're going to graze it.
More often, I would suggest using it as part of a mix. Use it with a winter cereal, whether you're using it with cereal rye, wheat, triticale, even oats, and then add a legume into that if you can. So a Brassica, a grass, and a legume is a really nice fall combination. Now, if you're a brand-new cover crop user, maybe just two species is enough to start with, so then maybe try cereal rye and canola in front of soybeans. Or you could do in front of corn, you could do something like hairy vetch and canola in front of the corn. But yeah, that's the way I would look at that one.
And then the summer cover crops, again, just use them as part of a mix. This idea of a diverse cocktail that may have anywhere from six to 12 species can be a nice way to go in the summer. We found some really good soil improving benefits from using summer cover crop mixes after early harvested crops, whether it's a spring cereal or winter cereal or early vegetables. And those are really excellent for grazing. We can get a lot of extra economic value from grazing those mixes. So putting some millets in with some legumes, with some broadleaf plants like sunflower and buckwheat can be really effective.
The summer legumes, we didn't talk about today, but things like cowpeas, sunn hemp, mung beans, there's a variety of summer legumes that can be used. So lots of options. That's what makes it fun. I find a lot of farmers that have been doing cover crops a while say, "One reason I like cover crops is it's fun. It gives me something different to grow, experiment with." And that's the bottom line is experiment a little. You don't have to plant huge fields of these right away. Try a strip of them and see what works well for you.Mackane Vogel:
Absolutely. Yeah, that's a great way to look at it. You mentioned cereal rye. I think a lot of our listeners are familiar with planting cereal rye. Are there any other key similarities or differences in terms of how you might manage the cover crop that you want to point out between cereal rye?Rob Myers:
Yeah, I'm glad you asked that because there is a big difference of canola versus cereal rye, cereal rye is well known for being able to be planted later than pretty much any other winter annual cover crop. And that's a big difference from canola. Really, to get canola to perform well in most of the Southern Corn Belt, we need to plan it relatively early in the fall. So what time is that? If you went by frost date, I would say you need to plan it probably about a month before your frost date, wherever you're at in the fall.
Now, will it grow if it's planted closer to the frost date? Yes, but it's just not going to get big enough to survive the winter. So you're really not any farther ahead using canola if you're planting it late in the fall than you would be planting radishes or something. In fact, I probably wouldn't waste my money planning them at the same time. I'd plant cereal rye. Like if you were waiting to plant rye in early November, that's really too late to get any benefit from any of the Brassicas unless you're really far South and then they could work for you.Mackane Vogel:
All right. Well, I hope all you growers out there are taking notes. This is some good info. Rob, before I let you go, anything else you want to add about any of these crops?Rob Myers:
Well, like I said, I just encourage people to experiment. If you think, "Well, I don't want to hook up the planter and figure out all these seeding rates," some of the seed companies are pretty good about selling a pound or two of some of these. You can take them out, broadcast them by hand in a corner of your field or part of your vegetable garden and just watch them and see how they grow for you. And try a couple different planning dates. Don't just try them at one date and think, "Well, it didn't do well then. I'm never going to use it again." You may find something that does really well planted earlier or later than you think.
So it's worth trying them out in different ways and also going to field days that may have some of these growing, seeing what's available in your area. We have, for example, in Missouri a variety trials where we grow a lot of these species farmers can come look at, so it's worth checking them out. Seed companies are good to talk to get info, and we do have some guides on these available on our University of Missouri website on all these different crops for both cover crop use and seed harvest as well.Mackane Vogel:
Yeah, I absolutely echo what you said about the field days. I've gotten a chance to go to a couple here in Wisconsin, Iowa, around here, and actually one of them, I saw some alternative cover crops that had some millet growing and even got to try a little snack that was made out of some millet, so that's always fun. And like you said, always cool to see it in the field and kind of see a firsthand account of it.Rob Myers:
You bet. Well, thanks for having me today.Mackane Vogel:
Thanks for joining us. Big thank you to Rob Myers for today's presentation. The full transcript of the episode will be available at covercropstrategies.com/podcasts. Many thanks to our sponsor, Source from Sound Agriculture, for helping to make this Cover Crop podcast series possible. And from all of us here at Cover Crop Strategies, I'm Mackane Vogel. Thanks for listening and have a great day.