July corn update and dealing with drowned out areas of fields
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Anthony Hanson:So we're glad you could join us for today's session. We'll be covering basically our corn agronomy updates, especially in some pretty variable conditions we're dealing with when it comes to moisture. And that's for, kind of the other half too. We're gonna talk about what's going on with all of these drowned out areas of fields we're seeing across the state. So this is one where, you know, it's hopefully a pretty timely topic for folks, especially as we've been seeing more and more rain across at least most of the state, knowing that other areas, you know, have been a little bit drier, at least have missed, some of this extreme rain that we've been dealing with.
Anthony Hanson:So first, I want to welcome, Jeff Coulter. He's our extension corn agronomist. We also have Anna Cates coming up later. She is our soil health specialist, working as well on a lot of these different areas dealing with our soils. So with that, I'm going to turn it over to Jeff Coulter first and ask just, you know, what are you seeing across the state for our core?
Anthony Hanson:And I know I've been driving around a little bit in West Minnesota just saw one field that was tasseling so far. Nope. Especially with all this variable weather we've been having house looking across the state.
Jeff Coulter:Hi, Anthony. Well, overall, the crops looking pretty good. But as you've mentioned, you know, we got these pockets that received quite a bit of rainfall around Renville, Wilmer and Fargo. Some of those areas received lots of rainfall and we've got kind of a repeat of last year where we got like ponded areas where some of the corn has died due to flooding. We've also got in those same areas, variable conditions, uneven fields, nitrogen deficiency showing up.
Jeff Coulter:So those areas that got too much rain are looking really rough, but the other areas that have been able to handle it that didn't get quite as much rain, they're looking quite good. And I think overall, have a pretty good crop on our hands in Southern Minnesota. When we look at the crop progress, we're right on track with the five year average. The USDA crop report, the most recent one said that 6% of Minnesota's corn was silking, which is right on track with the five year average and just slightly ahead of where we were last year. So the crop is in a good place.
Jeff Coulter:The temperatures we have now are just perfect for corn. So, you know, we're starting to enter that critical period of crop development for corn. We're actually in the critical period. We just started that. So the other thing I should mention is as far as drought stress, there's basically no drought stress in the state except for in Far Northwest Minnesota and also a little bit in North Central Minnesota.
Jeff Coulter:So those are the two areas where we're seeing a little bit of drought. Otherwise, we don't have any drought stress pretty much in the state. So we're going into the critical period with pretty good moisture levels throughout the area, except for those areas that have too much moisture. So I think overall things are looking good. We're entering the critical period and that's going to last through three weeks after silking.
Jeff Coulter:So I think for a lot of this corn, know, two weeks from now, we're going to be in the hardest silking pollination that's going to be going on. For the next three weeks after that are also going to be important for ensuring that the kernels that are pollinated remain set and that they don't dry out and wither away.
Anthony Hanson:So Jeff, especially related to that, do you want to mention a little bit about what's going on with nutrient uptake in corn right now at these stages? Especially I know some folks weren't able to get out and get supplemental nitrogen out. Is it too late for that basically? Or what are we gonna be looking at for nutrient use overall with the plant?
Jeff Coulter:Yeah. So right now the corn crop is taking up nutrients at the highest rate that it will take them up at, and that's going to extend for another couple weeks for sure. And then it will slow down a little bit, but it'll it'll still be going on. So if there are fields that look very uneven and have clear nitrogen deficiency symptoms due to excess rainfall, those fields could still respond to a supplemental application N, and that can be put on using a high clearance sprayer equipped with the wide drop applicators. That's one way of doing it.
Jeff Coulter:And we should get a yield response that should pay for itself in those fields. The areas that the drowned out spots or the edges of the drowned out spots where the corn looks really rough, their yield potential is definitely gonna be lower and may not be worth extra N, but once we get out of those rim areas that are the perimeters of those potholes, that corn should respond to N. We did see last year that we did get a, I think it was right around a 15 to 20 bushel yield response due to supplemental N applied at the V14 stage. So that can be done. Typical rates are about 40 to 70 pounds of N per acre, with the higher rates being for like corn on corn situations and the 40 pound rate being closer to the corn following soybean rate.
Jeff Coulter:And we want to get that supplemental in on as soon as possible and probably around the tasseling time, slightly after tasseling time is the latest that we wanna be doing that. So the earlier the better on that.
Anthony Hanson:So Jeff, I've been driving around a bit lately in Western Minnesota, especially around the Wilmer area, but then also heading down from Morris to Lambert yesterday. I saw a lot of fields that it wasn't just the potholes. It was whole sections of fields that had been flooded out, and I'm seeing a lot of areas where the corn just died off entirely. And we'll talk a bit more about that later, especially with Anna. But how long does that corn actually survive when it got submerged like that?
Anthony Hanson:And, you know, what's kind of the prognosis for these areas that are sort of on the edges of those areas that were flooded where the corn still survived, but you can see where it doesn't look quite as well.
Jeff Coulter:Yeah, generally when the temperature is like in the 80s or higher, like we had last week and before, you know, about two days underwater is all it takes for the crop to die. But in some cases the crop could hang on maybe three to five days if the temperatures are cooler or if the flooding wasn't that extreme and it was more. More like soil saturation and plus a little bit on top. So it varies, but basically just a few days and the crop that survived around the margins of those potholes and stuff, I think that's not gonna produce much at best 100 bushels an acre. But then you start to get out beyond that a little bit where the corn looks, where the canopy's larger, it's probably showing nitrogen deficiency symptoms too, and they're looking a little rough, that corn can yield 175 bushels an acre or so depending on things.
Jeff Coulter:So you can kind of tell based on the canopy size, big canopy, strong looking canopy has good yield potential, even if it's a little nitrogen deficient. And then you start to get closer to those potholes and then the yield potential drops off pretty fast.
Anthony Hanson:All right, so we did have a couple of questions come in and one was earlier, I think we touched on it just a little bit. But do you want to comment on a little more about what's going on with basically our current overall temperatures we have across the season, kind of the climate models and kind of sounds like we're on track. But you know, a lot of folks been thinking it's been a pretty cool June so far in a lot of areas. Kind of how is that how's the corn kind of caught up in some of those areas temperature wise?
Jeff Coulter:Yeah, it's possible that we may be slightly behind, but I think on average, we're right on track where we should be. What's unique this year is that we had such a wide window for planting where some farmers were planting in mid April, and then we had some that were planting in, you know, the first two May. So we have a very wide planting window and that first planted stuff is the stuff that's starting to silk. That may be kind of making it look like we're more on track than what we really are. At this point, we have nothing to worry about in terms of temperatures, that type of thing.
Jeff Coulter:When we're in the vegetative stages, having it a little warmer tends to be a good thing. And then when we get to the reproductive stages after pollination than having cooler temperatures tends to be a nice thing for- helping to ensure that colonel fill goes well and that the crop isn't under any stress. So- you know, temperatures we have right now, if we could keep these for the next five weeks, we would have a really bumper crop, I think. So I don't think we have too much to be concerned about with the temperatures. We're about on track.
Jeff Coulter:Was a little cooler earlier on, but we did have a few warm days in there. A lot can change in the coming weeks as the temperature, depending on what the temperature does. But if we could keep highs in the around the mid 80s and have relatively cool nights, I think that is about ideal for corn from this point onward.
Anthony Hanson:All right, one question that also came in here. Basically, the question is just wondering in Minnesota, is there a point that you should give up replanting corn, whether it's these wet conditions or other issues, and start planting other things, cover crops, which we'll talk about with Anna in a little bit. But kinda what's the window for especially a lot of our corn? It seems like it'd be quite a bit late. You maybe could be looking at silage options, I suppose.
Anthony Hanson:But what are your thoughts on that question of at least on the corn side of things, what you might be looking at for planting windows or other options?
Jeff Coulter:Yeah, it's it's too late right now for even silage corn. I've seen a note from Seth Nave. I think it was from yesterday and someone asked him about what the yield potential was for replanting soybean. And I think he was like, well, it's not gonna yield much at this point. It may be providing ground cover.
Jeff Coulter:So, probably not gonna get much yield out of it. So at this point, it's probably like, you know, we're not going to get any grain from replanting in these areas, but, you know, we want to get them covered because things like soil mycorrhizae are important. That's a fungus that attaches to the roots of growing crops or plants. If we don't have that fungus around surviving, that can be a problem because that can lead to phosphorus deficiency in the following year's corn crop. I mean, if you've ever had a field where you've had, say, two years of corn growing in a row or something, and the first year you had a drowned out or you did that place didn't get planted for some reason, and then it gets planted again the next year, what you'll see, it's common to see purple phosphorus deficiency in that corn that's planted on top of that fallow area.
Jeff Coulter:So we want to try to avoid that get that soil covered, keep the weeds down, that type of thing.
Anthony Hanson:Yeah, thanks, Jeff. Kind of with that, that's a good segue over to Anna here. So, Jeff, we'll keep you on in case any questions come on on the agronomy side of things. But Okay. Anna, welcome to the show here.
Anthony Hanson:It's been a little while since we've had you on, I think. But yeah, this is where we really want to talk about the soil health angle with all of these drowned out areas of the fields and kinda what options do we have looking forward where a couple weeks ago, we were talking about, like, yeah, there will be areas that will flood out. But now we've definitely seen how widespread that has gotten. So I think this is gonna be a pretty timely topic for a lot of folks trying to find out what to do. So I think I'll kinda hand it off to you first is what are you thinking about for options for folks that have their fields that they can at least access it hopefully now or soon and maybe be able to do something out there this time of year?
Anna Cates:Yeah. Well, Jeff hit on one of the big reasons to get some coverage out there, which is to make sure that you're kind of feeding your microbes. Mycorrhizal are plant dependent microbes. And so, there's a symbiosis where they're given a lot to your crop plants, especially like you said, in terms of phosphorus uptake, but you have to have plants there to kind of cultivate them. So, that's one big reason.
Anna Cates:Another reason is just to hold the soil in place. I mean, these are mostly depressional areas, so we're not necessarily losing soil from there out of the field, unless you're talking about, you know, as part of a gully or a grass waterway that's moving soil off the field from those ground out areas. But we like to see the soil covered to protect it. When you have a flooding situation, you often are gonna get a crust on the soil, right? And a crust just means that that hard surface where you have fine particles kind of cemented together, and then it's harder for water to enter in the future.
Anna Cates:So, if you let a crust form now, then you might in rains in July and August have slower infiltration into that part of the field. Whereas if you get something planted now, then you'll be able to capture rains later in the season instead of continuing to have water in the field that just makes it hard to go about operations later in the season. So that's one big logistical reason alongside that biological reason.
Anthony Hanson:Yeah, I guess continuing that a little bit. I'm also just wondering, like what else essentially freezes up in the soil whether it's microbes or other things just related to nutrients, other areas when you have all that moisture just saturating everything and how long does it take to kind of restart any of those processes?
Anna Cates:Yeah, well, you think about what it's actually like to be inside the soil. I mean, I think about it as being in like a haunted house maze or something like where you don't know exactly where you are. You can only see the area. This is, I think, what a microbe experiences. They only see the area kind of right around them.
Anna Cates:So there's small pores and big pores in the soil and a microbe in a big pore in a situation like this might only be under saturated conditions for a few hours or something like that. Whereas a microbe in a small pore might be under no oxygen conditions for several days, right? As we've gotten lots of water on the landscape and most microbes are like us, they use oxygen to complete their respiration, their life processes, but when oxygen isn't there, then the microbes who use nitrate as a energy source take over. And so, you're to have a lot more processing of any soluble nitrogen in the soil that can lead to a pulse of nitrous oxide emissions biophysically, but it also just means that you kind of have a shift in kind of who's active in your soil, right? So your usual microbes aren't going to be active.
Anna Cates:Microbes have a lot of strategies to survive these kinds of situations in terms of becoming essentially inert for a period of time when conditions aren't favorable. So, you're not going to lose your major oxygen using microbes in the soil, but they're going to be more dormant for something like that. So, when you think about kind of the processes happening in your soil, you've got to think about those small pores and large pores. If you have good soil structure, you're going to have some of both. And so there's going be kind of some refugia where there's oxygen areas, oxygenated areas in those large pores where your main microbes are gonna survive.
Anna Cates:Way, way more of the microbes use oxygen than use nitrates. So you do need to make sure you have some habitat for those otherwise you're gonna end up with a whole wetland plant community, which maybe you need to think about just taking that area out of production. But hopefully it doesn't come to that.
Anthony Hanson:Let's see, got a couple questions coming in, but we'll start off. What options are there for planting at this point? We can talk about cover crops, but but there's a few other things in the mix too. I don't know if you wanna comment on. We're talking about maybe like grain sorghum, milo.
Anthony Hanson:Yeah. Kind of what's in the toolbox for us right now at this point for either potential forage options or just overall cover?
Anna Cates:I don't know the planting date for grain sorghum off the top of my head. You know, it's a warm season grass, so this might be an appropriate time, but I just don't know that off the top of my head. This is a time where the mix or the cross between cover crops and forage crops is going to be really critical because you're at a time where you can plant something like sorghum Sudan grass or millet or one of these warmer season, grasses that can produce a ton of biomass, which can be really good forage. So this is a really good time if you have a decent sized area to think about, you know, is there an area that I could actually harvest around and then maybe let some cattle out or let somebody come through and cut it for hay? You know, this doesn't work.
Anna Cates:It's not going be practical for maybe a two acre or five acre drowned out spot, but if you have a large one, then you can actually think about forage production. Otherwise, it kind of depends on how much biomass you want to manage both this year, you know, do you need to be able to drive a combine over this area because it's in the middle of a bunch of passes for you, or can you go around it? If you plant something like sorghum sudan grass, some of the research they did at Lamberton show they could get, you know, like 6,800 pounds of biomass per acre by the August. So that's probably not something you're going to want to drive your combine over come fall. That species will winter kill, so you don't have to worry about it the next year, but it will be an uneven patch of your field.
Anna Cates:So if you're thinking about residue management, it's gonna look pretty different next spring, someplace where you had three tons of biomass versus just your soybean stubble or something like that. So I would think about those warm season grasses, but make sure you're aware of how much residue you could produce. If you don't want that much biomass around, then you could look at something that's usually a cool season grass, like oats or cereal rye. Those are readily available and usually pretty cheap and they're not gonna grow that much at this time of year. All of the cereal rye should overwinter.
Anna Cates:So you would probably have a lot of that to look at in the fall.
Anthony Hanson:Yeah. And that was gonna be one of my questions too. We hear about cereal rye a lot and yeah, I I'm betting that one we might be having questions on in the future here just because people are having to look at this cover option quite a bit more. Yeah. Yeah.
Anthony Hanson:Are there any others that kinda pop up for what would you say are, like, the most common ones people probably are gonna be looking at here? I think when you're looking
Anna Cates:at a drowned out spot, it's really about cheap and available seed. Using any bin run or VNS seed is gonna be a little bit risky in terms of carrying weed seeds or anything like that. But those certainly are going be the economic options. You can, like I said, usually get some of those small grains like oats and rye fairly cheaply, I would guess, and it shouldn't be a problem logistically ordering them at this time of year. Sometimes in the fall, the dealers get busy and applicators get busy, but shouldn't be able to broadcast those on if we keep getting good rains and you can't run a drill through the standing crop.
Anthony Hanson:Yeah, are there any kind of new and up and coming cover crops that seem like they might be interesting for this situation? I know we've been talking about other scenarios but yeah it's kind of what are you seeing for prognosis on some of these future varieties coming out a little bit?
Anna Cates:Yeah, I don't have brand new ones that I think it's important for people to be looking at. You're excited to try something new, there's always something new out there if you talk to a seed dealer. But I don't know that a drown out spot is necessarily the place to try something like that. I think in some ways you'd want to do it where you could see it and plant it at the right time and not do it this year where it's like, oh, you want to be opportunistic about when you can get into the field and just get that area covered to prevent erosion, prevent that crusting, keep your microbes happy, all that kind of thing.
Anthony Hanson:All right, we did have one question come in about fertility, think about these drowned out areas, probably having less nutrients available to some degree. So is there anything we need to think about that related to any cover we're planting whether it's for the cover crop angle or forages?
Anna Cates:That's a good question. I mean, generally your nutrients are going to become more soluble, in this flooded situation. They're literally going to be in the flooded solution, especially nitrogen. If you are able to plant something out there, you might be able to capture some of that, but mostly once it's soluble like that, it's either going be converted to a gas emission or leach out the profile whenever the soil does finally drain out. One of the reasons we use cover crops is because they take those soluble soil nutrients and transform them into organic forms where they are more likely to be around until the next year.
Anna Cates:So over the course of the whole next month, you're probably capitalizing on that to some extent where any nutrients that are in your soil are not gonna be lost during the fall drainage season, because they'll be taken up into the biomass. Did you wanna comment on that too, Jeff, though? I saw you unmuted.
Jeff Coulter:No, I think that sounds reasonable. I'm just really hesitant about putting any additional nutrients into a spot that's not gonna produce, you know, your cash crop. So, you know, it's not like if we don't have a great amount of nitrogen out there that's available for the in the drowned out area for the cover crop or whatever, I'm not too concerned about it. I think it's mainly about just getting some biomass growing out there and getting the ground covered.
Anna Cates:Yeah, applying nutrients to your cover crops generally only pays off if you are using them for forage where you would need those nutrients to produce the biomass for fee.
Anthony Hanson:Yeah, that kind of makes sense just to test out that ground next season, or at least in the fall to see what the situation is. But yeah, I could definitely see this being a case where if you worry too much right now and think, oh, I'm going to do something proactive, that might come back to burn you too a little bit.
Anna Cates:Yeah, I don't think we're telling farmers anything that they wouldn't already, you know, naturally want to do in terms of cutting costs and making this kind of the lowest input part of the field possible because it's not going to have a big return outside of maybe a crop insurance payment.
Anthony Hanson:And kind of thinking about other areas you've worked in too and just wondering like whether it's soil carbon, some of these other angles, it's not nutrient specifically, but what be going on in these situations where you do have these saturated fields?
Anna Cates:Yeah. Well, you know, depressional areas are going to be your lowest your lowest part of the field are going to have higher organic matter already because of these repeated flooding events where you're bringing fine particles downhill and having them settle in the bottom and carbon sticks more readily to fine particles than it does to sand. So that's why the bottom, those depressional areas are going have both the fine particles and the high organic matter. One interesting thing I read though, is that in sort of former prairie pothole lands, the highest carbon was actually found at the edge, that area that is getting a little bit of residue every year, essentially from a little lake edge effect, and so the bottom of the depression might not be exactly your highest carbon, but instead the extra, the sides are. And these depressions are areas that are often problem areas in these wet years, and then occasionally we have a couple of the drier years we've had recently, and then they end up being our star areas, right?
Anna Cates:Because they're holding that moisture longer because they have that higher percentage of fine particles and they're able to retain water in small pores between fine particles. So you're always gonna be managing one part of landscape or another, one part of the landscape or another is likely to be the winner, right? Unless you have a flat irrigated field. In terms of soil carbon buildup processing, I think the main thing to think about there is just how the structure, the texture and structure of soil at the depression level is going to be different and going to hold carbon more effectively. When we cite research plots, of the things we try to be really careful about is where they are on that slope in the landscape, because it makes such a big difference in terms of the nutrient delivery, the ability of the soil to hold water and crop performance as anyone looking across the landscape from the highway can see.
Anthony Hanson:I think one last question I have just thinking about this is, you know, some of these areas they've dried out alright, but there are definitely others where you can see standing water. So some of these folks, you might end up mucking in that seed instead of really trying to have a good bed to plant into. So kinda what's what are your thoughts on waiting a bit more for things to dry out, hopefully, for planting versus, you know, maybe trying to get something in to take advantage more of the summer just to have something green out there for more of the season balancing those two ideas.
Anna Cates:Yeah I think that it's more of a logistical question than a biophysical one here. Two weeks more or less of growth for your cover crop is probably not the deal breaker here, but instead it's when can you get weed sprayed and either get a high clearance piece of equipment or a drone or something to get some cover crop seed spread, and timing that around the rain is always good, but moisture is probably not going to be the limiting factor in these situations, but you never know, the rain has been turning off in the middle of the summer, so I don't want to say, you always want to hope for a rain if you're broadcasting seed on the ground, but I would say it's okay to wait a little bit if that allows you to effectively spray out the weeds that are there and get the right equipment to effectively broadcast or drill the cover crop in.
Anthony Hanson:Yeah, that is a good point. I am not one to bet on excess rain in July. Normally it can happen, but yeah, especially this latter half of July. We'll see what happens with the forecast. But yeah, it's one where hopefully it dries out at least for these folks here.
Anna Cates:And I should note too that the big rains for sure.
Anthony Hanson:Yeah, I should note too that, you know, the other parts of the state that Northwest Minnesota, they were abnormally dry for a while. So not everyone is this wet, but there's a good chunk of the state that seeing a lot of these potholes in other areas. So for other folks and Jeff, I don't know if you wanna chime in quick. It sounds like it's looking pretty good or consistent for corn and other crops. At least when we get further south, I think Southwest Minnesota and some of Northwest Minnesota too.
Anthony Hanson:Alright, I think with that, unless there's any other thoughts, Anna or Jeff on things, think we might close out here. So thank you for you too for joining us here. I do wanna again thank all of you for attending the University of Minnesota Extension field notes program today. Again, we wanna thank our sponsors, the Minnesota Soybean Research and Promotion Council, as well as the Minnesota Corn Research and Promotion Council for providing some of the funding for the basic behind the scenes logistics of doing this work here. Again, when you log off today, there'll be that quick survey so that helps us out.
Anthony Hanson:And we'll be working on next week's topic to figure out what would be kind of the timely thing for us to cover for next Wednesday. So, again, thank you, everyone. Have a great rest of the day, and we'll see you all next week, hopefully.
