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Welcome to University of Minnesota Extension's Nutrient Management Podcast. Each month we bring you the latest research in nutrient management for crops and how you can incorporate the latest tips and best management practices to your farm.
University of Minnesota Nutrient Management Podcast Episode: “Cover crops in Minnesota: Recent challenges and future solutions”
February 2024
Written transcripts are generated using a combination of speech recognition software and human transcribers, and may contain errors. Please check the corresponding audio before referencing content in print.
(Music)
Jack Wilcox:
back to the University of Minnesota Extension's Nutrient Management podcast. I'm your host, Jack Wilcox Communications Generalist here at U of M Extension. Today we're going to talk about cover crop challenges and solutions. We have four panelists here with us today. Can you each give us a quick introduction?
Anna Cates:
Sure. Hi, I am Anna Cates. I'm the state soil health specialist. I work out of St. Paul for a University of Minnesota Extension.
Jeff Vetsch:
Hi, I am Jeff Vetsch. I'm a researcher, soil fertility work, out of the Southern Research and Outreach Center in Waseca.
Jared House:
I'm Jared House. I'm the administrative manager for the Grant Soil and Water Conservation District offices out of Elbow Lake, Minnesota.
Ryan Buetow:
And I'm Ryan Buetow, the Minnesota NRCS State Agronomist based in St. Paul.
Jack Wilcox:
What were the cover crop issues for 2022 and 2023?
Jeff Vetsch:
Well, my territory is primarily south central, southeast Minnesota and the challenges that we saw in South Central was primarily in the fall of 2022, where we had really dry conditions most of September and October, which reduced germination and really hindered growth even though we had a nice long mild fall. So we had some research studies that just did not have great establishment and where it did germinate, it got patchy or fall growth and that carried over into the springtime. In southeast Minnesota, they had good conditions in the fall of 2022 for establishment, but the second half of May through all of June was extraordinarily dry in those areas, which didn't hinder cover crop or crops that were planted into cover crops, I don't think very much for ones that were terminated in April. But anything that was terminated in May or planted maybe like soybeans, planted green, those were ones that struggled as they had used a fair amount of topsoil moisture, and then they just did not get that rainfall to get things established.
The only other thing I observed, and that was from the fall of 2023, was what looked like some herbicide carryover and some stunted plants growing in September and early October, and that might've been due to the drought of the summer of 2023 and the slow breakdown of some pre-emerge herbicides, and we could see that in most of our grass species and our cover crops, which is interesting because the grasses are typically pretty tolerant of some of those typical pre-emerge herbicide products.
Anna Cates:
Tolerant to a point, right? Anybody else see that?
Ryan Buetow:
Well, to tie that a little bit, I saw a situation where cover crops took the blame for some soybean damage in the spring. So that dry period going from 22 into 2023, maybe there was some clopyralid sprayed out there, something didn't break down as quickly as it normally would, and all of a sudden they're starting to see some damage in their soybeans. So maybe that's that extra moisture use from maybe a rye cover crop, but maybe also just the drought itself.
Jared House:
I know in west central Minnesota, I've gotten a few producers who's contacted our office that we have cover crop contracts with and they mentioned that they actually just delayed planting in anticipation of the herbicides not breaking down or with more herbicide resistance, they would make some more applications later in the year that they were worried would affect the cover crop. So we didn't get them in as early as we could have and we actually missed some rains because of that, but they have been actively managing for the herbicide.
Jack Wilcox:
Based on the conditions right now and what we saw last spring, what do we think are some good management practices going forward?
Anna Cates:
I guess that last year, like Jeff said, we still had some difficulty getting cover crops established in the fall, but we've had some nice growth conditions. So driving around, I drove up to Northwest, Minnesota in the last week. I definitely have seen some cover crops on the landscape, I've seen some pictures of nice green cover crops out there. I know that some people maybe were more hesitant to plant this fall if they were worried about lack of moisture or just the waste of the seed like Jeff described. You don't want to put seed out that isn't going to have good germination conditions. So I think that for those people who are watching their fields green up with pleasure at this point, it's just going to be a matter of walking that line and making sure you don't let it get out of control. Might be in a situation where we have a lot of growth and we want to terminate before we have really good weather conditions for herbicide action. That could be a concern this spring.
Jared House:
I did a little homework before this podcast and I called some soil and water districts from Kittson County all the way down to Rock County in the western portion of the state. And what I've been hearing from staff is they're encouraging the producers to get their sprayers ready early and to watch that rye or whatever may have covered there and look at the soil moisture as well and be prepared and don't wait for the co-op to go out and spray because if they can't make it for a week or so, you might be a little too late and chances are you may have some impact, especially if we don't get the moisture.
Jeff Vetsch:
Yeah, and what we did in our research study last fall was we adapted to what we saw in the fall of 2022 by just holding off our seeding for a week or 10 days after silage harvest. In our research study, we were fortunate enough we got about two tenths of an inch of rain. It was just enough to moisten that top two three inches that we drilled. And then we were really fortunate we got another two tenths just a couple days later, and that was just the perfect amount. Even though subsoil moisture was extraordinarily dry, it was just the perfect amount of surface soil moisture to get that covered crop to germinate and establish really nicely. So I think that if you've come across those really dry falls, maybe you just hold off on seeding a little bit until you get some moisture so that you don't just leave those seeds lay out there and they just won't germinate.
Anna Cates:
Yeah, I've heard of some people creating mixes that are less heavy on the grasses, so using some species that have less biomass in them are going to take up less water or going to winter kill, that kind of thing. Just looking for a little less cover crop is a little less cover crop to manage. That being said, some of our research data, we have a study on planting green, and last year looking at our 2023 soybeans planted after cover crops, the places where we grew the most cover crop in the Granite Falls area, we didn't see a soybean yield hit regardless of termination. We grew up to 2000 pounds an acre of rye biomass, whereas in some other locations where we're at less than a hundred pounds an acre of rye biomass, we saw a big yield hit with late termination. So the biomass alone isn't explaining the difficulty of growing soybeans after rye in a drought situation. There could be some issues with seedling establishment and that kind of thing that are irrespective of the total rye biomass it seems like.
Jack Wilcox:
Ryan, you adjusted rye seeding rate requirements in the fall of 2024 when drilled. Talk us through your decision making process on that.
Ryan Buetow:
As has been mentioned here, cover crops are multifunctional Swiss army knife. There's a lot of different ways that we can go about doing things and we want to make sure that we're being responsive not only to producer feedback, but also some of the work coming out of the university showing that you can still see some benefits at some lower rates. And we're starting to think through there's ways to have these positive impacts on our resource concerns at these lower rates, especially when you have maybe a little bit earlier planting date and some more time to get that winter cover growing. So what we ended up doing is adjusting our cereal rye seeding rates for a single species cover crop. And the government, we don't always change things quickly, but we're able to change small things here and there. And so we've focused in on cereal rye as it's typically one of the easier cover crops to do. Cereal rye can handle a lot of different conditions, and so you might be seeing that on more acres as well.
But before the change, our recommended rate, our minimum rate was 55 pounds drilled or 83 pounds per acre broadcast. Obviously it's going to be really difficult to fly on 83 pounds, but basically an unincorporated rate was 83 pounds per acre, and that's very high. And so we were able to adjust that down. So if planting was before October 1st, whether it was broadcast, drilled, however it was put out there 40 pounds. And so the goal there was to get that seed out there early, get established and have some good growth in the fall. After the October 1st date, we went from 55 pounds to, we lowered it to 50 and that 83 pounds down to 75. And so the goal there is we definitely know that there's benefits from these rates. Some might even say that they're still high, but we're looking at things, we're trying to be responsive.
So really the goal is to make adjustments. We still need to make more adjustments down the road. Obviously these rates, they made sense. But as we started to do more research on cover crops and more information comes out, I think we need to make sure that we're making adjustments. So nothing against the rates as they were, but I think that we're starting to look at, we have enough data where we can make some adjustments to a few of these things.
Our multi-species mix, we didn't feel comfortable changing that because sometimes when you're talking 50% of the mix and then you have things in there that winter kill, we need to figure out what is that percentage that is enough to have some good growth, especially when it comes to things like nitrates. But when we're really focusing in on our resource concerns like erosion, those much lower rates, you can see a huge benefit from a very low rate. And with the drought that really expedited things for trying to reduce this. We want to make sure that people weren't throwing out a whole bunch of seed out there and then nothing germinates.
40 pounds per acre. The amount of growth you get if nothing germinates is the same as if you put out 83 pounds. At the end of the day, you want to make sure that we have something out there but also really try to make it more approachable so the more producers are trying this and we can get some more conservation out there on the landscape.
Jared House:
Ryan, I would 100% agree with your last statement there. We've had a few producers that weren't comfortable with putting out that high of a rate, especially with not incorporating. And I think that'll help us reach some producers that are trying some innovative things and would like some assistance. Take for example, broadcasting cereal rye, pre-lift on sugar beets. When I mentioned that you should be using 80 pounds, a lot of them get scared away and they will end up doing, some of them will do it on their own, which is great, and I always encourage that. But they've been seeing some success with those lower seeding rates.
Ryan Buetow:
And I want to make sure that the producer can use their discretion to go higher. These are our minimum rates, these are the minimum amounts that we need to see some benefit. But let's say you're trying to graze it, you're probably going to want to put 90 pounds out there. So we need to make sure that this makes sense and we have a minimum that makes sense for what our resource concern is.
Anna Cates:
That leads into some of the research we wanted to talk about Jack, which is something that the Minnesota NRCS is funding me to work on is looking specifically at the outcomes of different cover crop applications. So we'll probably be designing a set of treatments with different cover crop seeding rates that we expect to provide different amounts of biomass, and then we can look at how much erosion we're seeing in those plots, both from water and from wind, and we can look at how much nitrogen is taken up by those cover crops. We touched on this a little bit, but there's really different concerns in different parts of the state. Obviously in southeast Minnesota, taking nitrate out of the soil is of primary importance. In Western Minnesota, slowing down wind erosion tends to be people's first concern when they're planting cover crops.
And you probably need a pretty different cover crop to address those two different concerns. So we hope to put some numbers on the amount of biomass that might be a target to achieve meaningful reductions in both of those important outcomes. And we'll be putting field plots in the fall of 2024 to get at some of that.
Ryan Buetow:
And obviously change can sometimes be slow, but we are trying to use expertise from people with experience in this type of thing to make some other adjustments to our guidance by next fall so that we can possibly see some differences, but we got to make sure everything is backed by that great university research.
Anna Cates:
Thanks Ryan. Jeff, do you want to tell us a little bit about your university research?
Jeff Vetsch:
Yeah. Sure, Anna. And so the project that I'm currently working on is in its third year and it's looking at different species following corn silage. And we're planning a winter terminated mix of oat, forage peas and radish. And then the other cover crop species of course is cereal rye, which we terminated in the spring prior to planting the next year's corn crop. The first year of this site was 2022. We saw pretty decent cover crop growth and a nice reduction in nitrate concentration in our tile drainage water from that cereal rye, marginal effects to the winter annuals or winter terminated annuals, which we expected for the 2023 growing season. We just did not get very good establishment of our cover crops in the dry 2022 fall. Didn't really see much for effects, which was understandable.
And then last fall we got a very good establishment of both our cereal rye and our oat blend and the cereal rye looks great right now and it'll be interesting to see with this very mild winter how much growth we put on here in March and possibly early April compared to our more traditional winters that we've experienced the last two years. And of course the winter or spring of 2023 was really cold and was not ideal for growth in April, so it'll be a good contrast to what we've seen in the past.
Anna Cates:
Are your tile lines running yet?
Jeff Vetsch:
No. Tile lines are not running, but we are near, I think very near field moist capacity. We saw significant rainfall in late October, and then soils were not frozen around Christmas time and we had 1.2 inches of rain during that period, which is totally unheard of that that would come as rain and infiltrate into the soil. Since then, we've just had little dabs of moisture here and there, not a lot, so it's still relatively dry, but field conditions are pretty good and another inch or two rain here in late February, March would probably get our tiles running and that'll be some interesting time to start looking at that early data.
Anna Cates:
Yeah, I've heard of tiles starting to run in a few different spots. Not everywhere, not a ton, but the profile is getting filled up with these winter rains that we've been seeing. Let's see. I feel like the other research project we should talk about is our planting green study, which is in its third year. Is that right, Jared?
Jared House:
Yeah, I believe so. I think the first application, at least in Barrett or seeding of the cereal rye was in fall of 2021, if I remember right.
Anna Cates:
Yeah, that sounds right. So this is looking at different termination timings of cereal rye, and I talked a little bit about that data, but we're really just trying to hone in on whether you can do green planted soybeans without seeing an agronomic hit and looking a little bit at some soil health responses too. And it's been working with a lot of great farmer cooperators. Jared has helped us recruit one in his area, and we've got all the way up in Northwest Minnesota too.
Jared House:
It's been a great study to be a part of and it's helped us locally promote more cereal rye and come up with some precautions for producers who are a little bit nervous about letting the rye grow in the spring. But I think, like you mentioned earlier, one of the biggest concerns we have here is wind blowing in the spring and ending up with a lot of snirt. I think we've been joking around in our office that we got to get shirts made up that say, don't flirt with snirt because-
Anna Cates:
That'd be a good one.
Jared House:
Yeah, I have quite a few examples of driving from Morris, Minnesota up to Elbow Lake every day and seeing and comparing different fields and stirred in the ditches, and so there are more and more producers coming in wanting to prevent that, but also having a concern whether there's grain corn or soybeans following that rye. And so this is definitely going to be information that's going to be useful for our producers.
Anna Cates:
Right now we're just looking at the soybeans after cereal rye and that planting green process, so we're not able to get into any of the questions that I've seen really cool data on from Iowa and other states about seedling disease in corn after rye. So we're not looking at that yet, but we're getting a start, at least on the agronomics.
Jared House:
Yeah, good clarification. Yes.
Ryan Buetow:
Well, and this year it hasn't even been snirt, it's just been dirt this very, very open winter, whether it's a cover crop, a winter annual like winter camelina, winter wheat, or even a perennial like alfalfa or Kernza. I feel like it's pretty intuitive that there's a benefit from that winter cover. It's just really unfortunate to see the amount of blowing going on this year.
Jared House:
Anna or anyone else, are you familiar with any research going on in sugar beets and cover crops? Because like I mentioned, we get a lot of wind blowing in the spring, and that's one of our biggest concerns. And whether that research is on success rates or just herbicide applications, especially with higher waterhemp and resistance and concerns with getting cover crops established after sugar beet lift.
Anna Cates:
Yeah, I am in the middle of working on some stuff with that funded by the LCCMR, and we're running a few events around the state with farmers talking about our results and just talking about the nuts and bolts of the agronomic systems. As you say, sugar beets are just such a challenge because of the long growing season and the destructive harvest. I've heard mixed results. Some growers are trying to seed a cover crop around the defoliation phase of cover crops. We did some experiments with aerial seeding cover crops in Polk County at that time. So that means you're flying the cover crop on the defoliator and the lifter go through and that action of harvest incorporates the seeds. Like any broadcast pass, this is totally dependent on moisture. So just a few days apart, we've got two growers just 10 miles apart who had really different outcomes based on their soil moisture, and we'll have more data on that coming out.
The other thing we're doing in sugar beets is that we have some pre-pile acres, so those early harvested sugar beet acres that got to cover crop, and we're looking at wind erosion over the course of the winter, and we haven't crunched all the numbers yet, but my student who's been out there actually collecting the sediment in the boxes all winter, he's seen some visual differences. So I think we might be able to detect what we all see in the ditches in our data from these sediment collectors.
Jeff Vetsch:
Anna, I think you might be familiar with Lindsay Pease's work out of Crookston too. She's looking at seeding cover crops during the sugar beet year, and she reported on some of that at the Nutrient Management Conference, which just occurred last week. So I think it's in its very early stages, like this was 2023, might've been the first year.
Anna Cates:
So that's part of the same LCCMR project that Lindsay and I are both on. And she added a component of trying to estimate the nutrient mineralization from the cover crops that are interceded with growing beets. So from the nutrient supply to beets perspective, it looked like there was probably some interesting stuff going on with nitrogen dynamics again in the first year.
But in terms of the soil benefits, we haven't been able to see anything that survives the harvest action after that. If we intercede something in beets, we haven't seen anything survive the harvest, but I have heard growers say that they have occasionally seen it. And then as you see, growers fine-tune their strip till system, especially in where they're working after wheat stubble. I saw one grower talk about a system where he was able to essentially use his wheat stubble for wind erosion protection for two years afterward, first by strip tilling in his sugar beets and then planting edible beans in those same rows. And so he had a cover crop in the system, but he was also getting that wind erosion protection from just keeping his stubble intact via a strip till system.
Ryan Buetow:
I like how often he used the word system there, so you can't just plug cover crops in and hope that it's going to change things. It's got to be part of that system and be making sense, right?
Anna Cates:
That's right. And the tillage changes, the fertility changes that come with using cover crops are a topic for probably a whole other podcast, Jack.
Jack Wilcox:
For someone who's brand new to cover crops and maybe has some concerns that were exacerbated by this last cycle, what should they be aware of? Are there any pieces of advice you would want to tell them?
Anna Cates:
Well, this part is, it's a mental issue as much as it is an agronomic issue, right? There's a real tension to starting something new and watching it evolve, especially as you're approaching that first cash crop planting after cover crops and just being confident that you haven't sunk the whole ship. So what I really hear growers say is that they want someone to talk to during that period, and you could call Jared or whoever your local soil and water is and he'll listen and he'll tell you to talk to somebody else who's been successful. You could call any of us and we'll try to hook you up with someone in your area who's had a success. I would say that's a big part. Maybe the rest of you have some more practical pieces that you would bring up.
Jared House:
I just reiterate the producer to producer, farmer to farmer networking. I know that the farm maps application that SynRAM has put together has been a very nice tool for sharing case studies of specific examples and contact information for producers, but more practical items are start small. I feel like I always say, start with your cereal rye and incorporate drill in if you can. We try to use broadcasting as a last resort because that is very hit or miss depending on when you get it down, when you get your rain afterwards. But we at least get some spotty results within a field if it's drilled in. But start small, ask questions, and if you see something curious in a field nearby, talk to that producer. I'm more than confident saying that they're more likely going to share with you what their experiences are.
Ryan Buetow:
When you're learning something new, there is the potential for failures, but that potential goes down a lot faster if you are listening to someone that's already had those failures. So you could try to find ways to avoid things. You're not going to become an Olympic swimmer by not knowing how to swim and jumping into the deep end. So maybe starting with the doggy-paddle before you move up to the breaststroke, try to find ways to try out the simpler concepts before diving into planting green, multi-species mixes, that stuff.
Jeff Vetsch:
Yeah, I don't know that I have a whole lot to add. I would agree that start where the most sense and the easiest things and the most likely to be successful. Cover crops after canning crops, after corn silage, things like that where you got more time to get a good establishment. I agree with the broadcasting in standing crops, it can work, but there's times when it doesn't and that's frustrating. I've heard a lot of growers tell me that they had just as much success blending their cereal rye in with their P&K fertilizer and just having a very light dose of tillage or vertical till to give just a little bit of incorporation and doing that after harvest. They get just as good establishment as putting it out there a month earlier as the crops are nursing. So I think those are good places to start.
Anna Cates:
Yeah. You mentioned a couple of good easy buttons, Jeff, like the post silage, post canning crop, post wheat is another one. And then maybe also you could think about areas that really need the help. We talked about those pre-pile acres and sugar beets areas that are going to see a lot of traffic headlands. That applies to your canning crop fields too, where you're seeing a lot of traffic and heavy trucks. It's great to be able to get something growing out there. So think about where it's easy and where you might see the most meaningful benefit for your farm. Maybe it's sloping land, maybe it's just the land next to the road that somebody's hassling you about. Maybe it's the land in the back where nobody's going to see it. It just depends on your goals for the cover crop system.
Ryan Buetow:
And that's right, you need to have a goal because if you don't have a goal with that cover crop, what is it going to do? So what's the saying? Failing to plan is planning to fail. If you don't have a goal for that cover crop, how are you putting together your mix? What are those actual species supposed to do? We have a lot of different cover crops that have these really cool superpowers, so rye can help us battle some weeds. Maybe radish or turnip can help break up some compaction. So try to think through what do I want to do in these areas and how can this cover crop help me do that?
Jared House:
I would also just add that, you can't always anticipate success or you can't anticipate success. So just because it doesn't work one year doesn't mean it won't work the next year. So have a multi-year plan of how you want to address it. You can make changes whenever you need to. Active management is key, but don't just plan on trying it for one year and then saying it doesn't work because we do know it works. We have people up, like I said, in Kittson County almost in the Canada that can make cover crops work down to Rock Homestead County. It can work, but we just have to be flexible and want to make it work.
Anna Cates:
I'll just advertise one other resource that we're putting together from Extension, which is a Cover Crop Academy that'll run over the next year. And this is particularly for soil and water, NRCS and CCA types who advise farmers on cover crops. This will be a year-long chance to do a little hands-on research at our research and outreach centers in Waseca and Lamberton and Crookston, and we'll have a lot of access to some experts from Minnesota and beyond who will talk about some of the elements of the system that can be a little more tricky to master. So we'll put information about registration for that with this podcast.
Jack Wilcox:
Are there any last words from the group?
Anna Cates:
Send us pictures. We love seeing how the cover crops are growing.
Jack Wilcox:
That about does it for this episode of the Nutrient Management Podcast. We'd like to thank the Agricultural Fertilizer Research and Education Council or AFREC for supporting the podcast. Thanks for listening.
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