SPEAKER_03 0:08

All right, welcome back to the Field Notes podcast, brought to you by Greenpoint, Ag and Accufield, where we discuss real-time agriculture problem problems and their solutions, the trial results, and infield tips and share agronomic insights from leading industry experts. Each episode is catered specifically to you in your region. So my name is Abigail Waller, and I will be your host of the Field Notes Podcast. I'm the Ag Technology Specialist for South Alabama. And I am joined today by Curtis Fox. Carrie Webb and also our guest speaker is Mr. Trent Roberts. So Curtis or Carrie, if you wanted to all start by introducing yourselves, that'd be great.

SPEAKER_00 0:48

Yeah, I'm Carrie Webb, Soul Fertility Agronomist for Green Point Ag. I cover Mississippi, Louisiana, and Arkansas.

SPEAKER_02 0:58

I'm Curtis Fox. I'm a area agronomist for Southeast Arkansas. Covering, I guess, right around I-40 south to uh the Louisiana line.

SPEAKER_01 1:11

So my name's Trent Roberts. I'm a soil fertility extension specialist with the University of Arkansas. My office is in Fayetteville, but we do all of our work with the real crops in eastern Arkansas.

SPEAKER_03 1:24

Awesome. So today we're going to talk about some micronutrients. And Mr. Trent, I've heard you're the guru and the expert for this. So I'm excited to hear what you have to say. So kind of what we really want to focus on today is beyond the nitrogen, potassium, and phosphorus, let's let's go to our trace elements, our zinc, our boron, our sulfur, and et cetera. They're often overlooked, but yet they're critical. How do you know if foliar or granular is the best application? Do you want to start there?

SPEAKER_02 1:56

I mean, I I think uh obviously, since we've got Dr. Roberts on here, we ought to at least probably listen to him more than us, but you know, just to kind of start with the question that Abigail started with, Trent, what about, you know, when we think of sulfur, zinc, or boron, when you think of those three specific micronutrients, you know, what what forms do you like, timings do you like on those three specifically?

SPEAKER_01 2:24

Okay. Well, so what I would start with is we have to think about macro and micronutrients differently. So I would throw sulfur in with the macronutrients. And when we look at macronutrients, I think we have to focus on granular soil-applied methods for our macronutrients. And it really just comes back to the demand by the plant. So when you consider your macronutrients like NPK, uh, especially like nitrogen and potassium, you need hundreds of pounds per acre in the plant to maximize yield. When you move down to something like sulfur, depending on the crop, you know, you still need 30 to 40 pounds of sulfur in the plant to maximize yield. And it's very, very hard uh to use foliar sources and be able to get that rate of nutrient effectively into the plant, right? So it's it's the magnitude of the nutrient that's required that limits the ability to use foliar sources for our macronutrients. When we switch to our micros, it's a completely different story. And what I mean by that is it's specific to the element. So for something like zinc, we can be very effective with both foliar and granular sources. What it comes down to is do we want to impact soil test concentrations? So for something like zinc, if we use a granular source, we're gonna feed the crop, but we're also gonna build our soil test zinc levels. So, right, in that case, we're producing a crop, but we're banking zinc in the soil that we can take advantage of down the road. Now, we can also be very effective with foliar zinc, but what we have to remember is that foliar zinc isn't gonna do anything to help our soil test zinc levels, right? So that's just a decision that that the producer has to make. Uh, boron also, uh foliar is a great approach that can be used. The difference between boron and zinc is that uh using a granular boron source doesn't necessarily build soil test boron. And so that's something that you just make the decision. Do I want to go with granular boron, you know, like pre-plant, or do I want to do like a foliar boron with a herbicide application? And so to me, each of those three elements, it's kind of different, right? The impact of uh the source that you choose. Um, and that's that's kind of the way that I approach it.

unknown 5:07

Yeah.

SPEAKER_02 5:08

Carrie, do you have anything?

SPEAKER_00 5:11

Oh no, I just kind of uh a factor that we deal with is the the reason I don't particularly like uh micros and and blends is we're so far from pore, so a lot of those blends are heavier, those micros are heavier and they they get lost in the blend.

SPEAKER_02 5:35

Yeah, we run into a lot of that too. Uh just whenever I think about some things specifically, you know, comparing say like a zinc to a boron timing-wise, you know. Um I I'll just start with zinc, you know, currently, you know, and and I'll I'll use corn as an example, but it could go for rice too, for that matter. But you know, a lot of times uh if we don't have a enough soil test zinc and we know we need to make that application, um, you know, what I found is if we a lot of times that zinc deficiency will show up early, but then if we're waiting and and kind of counting on making a foliar application, you know, leaf area so often is come becomes an issue. You know, if we're not if we don't have the leaf area to get coverage for the plant to take it up, it just seems like that uh that sometimes that that runs into a little bit of a trouble to, you know, as far as if we're gonna uh kind of recommend or or you know give our grower the best the best possible start. You know, sometimes putting it in with our blend is uh is gonna give us our our best results if we run into that issue.

SPEAKER_01 6:51

I don't know if that's something that you agree with or if that if that makes sense where I it definitely makes sense, and I think it it really comes down to proper source selection. And so when we're looking at like foliar zinc products in particular, um you've got chelated and non-chelated sources, right? So a nutrient-like zinc is pretty immobile in the soil. So what that means is anytime I put zinc on the soil, it's gonna typically attach to the soil and it's not gonna move. So I've either got to incorporate it, right, and get it in the root zone, or that plant's never really gonna take advantage of it. And so, similarly, when I talk about foliar sources in zinc, if I use a non-chelated source, that's when that leaf area really, really matters. Because for non-chelated zinc sources, anything that doesn't contact the leaf is essentially useless because once it hits the soil surface, the plant can't ever take advantage of it. Now, on the opposite end, the nice thing about chelated zinc sources is I get both foliar and soil activity, and so I can spray that, you know, pretty much at any time post-emergence, because with that chelated zinc source, whatever doesn't touch the leaf will be mobile in the soil, and so it allows that that zinc to move down into the root zone to where the plant can't take or to where the plant can take advantage of it. And so that's to me where source selection becomes very important when you're talking about foliar sources.

SPEAKER_02 8:36

Right. That's awesome. That's that's kind of I was hoping that's where we were going. That's what I was trying to, I was trying to key that up, but I I I guess I could have put that a different way. And so then if we if I think about boron on the on the next next page, we think about boron, it it's it's it's major importance, if I'm saying this right, would be more toward the reproductive side of of the plant, whether it be corn, soybeans, rice, any of that, right? I mean, it's it's gonna be more so so does that allow us a little more time and and possibly give us the ability to think to lean more toward that foliarification if if boron is the issue?

SPEAKER_01 9:16

Well, so the the tricky part about boron is it's primarily involved in cell division. And so if you think about like really extreme boron deficiencies and soybean, you know, the apical meristem will die and fall off. And so early in the season, if you've got severe boron deficiency in something like soybean, you know, plants are very stunned, they just don't grow. If it gets real bad, that apical meristem will die and fall off, and you'll start to get a lot of lateral branching. And so when you think about cell division, it just goes back to how severe the deficiency is. Because it when you talk about like waiting later in the season, then what you could be dealing with is a hidden hunger scenario where all season that plant is kind of starving and it's not really growing optimally, and you're just kind of slowly losing yield, but you're not getting these drastic symptoms, you know, like apical meristem death or something like that. And so I think first off, if you know you're gonna have a boron deficiency, you know, treat it early because you don't want to have to be dealing with that hidden hunger potential scenario. Obviously, we think about the reproductive side of it because that's where we're visibly losing yield and those types of things. But if it's bad enough, it's affected that plant the entire season. Um, so to me, that's just one of those things that if you're in an area where you feel like you're gonna have boron issues, you know, try to take care of it as early in the season as possible.

SPEAKER_02 10:59

You know, so pH affects uh our zinc availability. Does it affect how how does pH affect boron or does it? And it may not.

SPEAKER_01 11:11

I just I yeah, so so boron is a little tricky. Boron is the only element that the plant takes up uncharged, right? So zinc is a cation, the plant takes it up as a positively charged ion. You think it's something like sulfur, right? So sulfate, the plant takes it up as a negatively charged anion. So boron actually is taken up as boric acid, which is uncharged. So pH doesn't impact it as much as the other elements, but we tend to see more boron deficiencies on higher pH or alkaline soils.

SPEAKER_02 11:49

Okay. Um, that's kind of uh we we had a uh a meeting this spring in uh in my area with uh with the store locations, and one of the locations kind of charged us with a with a little test, I guess, for boron. And we actually me and Carrie have a uh we have a a boron trial going out now where like we we did we treated part of the field with boron with our dry fertilizer, and and then in corn we're gonna come back and add boron with our herbicide and part of it, then we're gonna add part of it with a an I would call a an early fungicide application where you know probably pre-tassel, you know, just right right at tassel, and then with the normal fungicide timing. And then on our soybeans, we're gonna come in and do we've we've got the we've got the pre-plant down, the same as corn, but then we'll do one with our last herbicide application and then one with our fungicide application. We just, you know, like I said, just I don't know that it'll tell us a whole lot uh between the three or four, but but it's something that we're doing on farm this year to try to I don't know, give us some answers of maybe when a a good timing may be.

SPEAKER_01 13:11

Well, not you know, boron is kind of tricky. Um, you know, I've I've seen some reports of boron response in corn. Um, you know, we've tested it quite a bit, and we've we've just never seen that. And you know, part of what I try to remind people is grass crops tend to respond to zinc, and broadleaf crops tend to respond to boron. And and all it is is just the uptake mechanisms of broadleafs versus cereals. And so, you know, we'll have a a study location where we'll plant soybean and we'll get a highly significant response to boron. But if I plant corn in that same area, you know, on an area that should respond to boron, the corn or the rice doesn't respond. And then we see the opposite effect for zinc. And so really what it comes down to is when I think about boron, I want to focus on corn, cotton, peanuts. And when I think about zinc, I want to focus on rice and corn. You know, to me, that's kind of how you want to approach it is you know, micronutrients in soybean, boron's gonna be the big one. Micronutrients in our cereal crop, zinc is gonna be the big one. But I think the approach that you're using, uh like in the corn study you mentioned, is really good because what it's gonna say is like, okay, a lot of times we think of boron as being immobile in the plant. And so by getting those later timings in the season, you're able to say, okay, like if we applied it early, maybe you know it didn't mobilize in the plant during grain fill. And so we saw a yield drop, right? So by doing some of those later timings, you're applying that boron closer to grain fill, so you may see a response.

SPEAKER_02 15:12

So what you're telling me is I need to tissue sample throughout the year.

SPEAKER_01 15:16

Well, to me, that's the only way you can confirm, right? Like if uh if you would expect a a response or or not.

SPEAKER_00 15:26

Real real quick while we're on this, uh Dr. Trent, is there I know in Mississippi every now and then it's not often we see uh manganese deficiencies. Are there any deficiencies y'all are seeing that we're missing on that we besides boron and zinc that we've already hit? Is there something else we need to really be concentrating on?

SPEAKER_01 15:50

Um, well, so in soybean, we've been doing um kind of like a monitoring project where we're trying to just get samples from all the soybean producing counties. And I would say manganese is the one that's popped up on that. So we used to have a few pockets in the state that uh we kind of knew we were gonna have manganese issues, but it's starting to show up in different areas. So, as far as soybean goes, I do think manganese is one that is becoming, I don't want to say a greater concern, but it's showing up in areas that historically we had never seen it before. Um, we get a lot of questions about sulfur. And on most of our, you know, what we would call rice soils, we don't ever get sulfur responses. Um on a lot of our sandier ground, we'll we'll see some sulfur responses. I think the big thing that people miss in Arkansas is the amount of sulfur they get from their irrigation water. And so even on some of our sandier ground where you think, okay, I should get a sulfur response, we don't get a sulfur response because every time they irrigate, they're just you know adding sulfur through their irrigation water. Uh but to me, the ones, the ones we want to be on the lookout for are sulfur, zinc, boron, and manganese, right? Like if we're gonna tissue test to try to look for those things that maybe a hidden hunger or kind of robbing yield, those are the ones that I think are popping up and are gonna become more of an issue kind of as time goes on.

SPEAKER_03 17:42

That's great. Well, guys, I think we're coming to a close on our time, but we will have Mr. Trent with us for another episode. So you'll have to stay tuned for that. Um, but thank you again for joining us. Thank you all so much for um Curtis and Carrie, Mr. Trent, for helping um just talk with us today and educate us. Um so this is going to be a close to our filled notes podcast today. I'm your host, Abigail Waller, and look forward to being with you next time.