Read Full Transcript
Mike Howell (00:08):
The Dirt. With me, Mike Howell. An eKonomics podcast where I present the down and dirty agronomic science to help grow crops and bottom lines. Inspired by eKonomics.com, farming’s go-to informational resource, I’m here to break down the latest crop nutrition research, use, and issues, helping farmers make better business decisions through actionable insights. Let’s dig in.
(00:38):
Welcome back to The Dirt everyone, we’re glad you’re joining us here today. We have Dr. Brian Arnall with the Oklahoma State University joining us. Dr. Arnall, welcome to The Dirt.
Dr. Brian Arnall (00:47):
Thanks for having me here, Mike, excited to have the conversation.
Mike Howell (00:50):
We look forward to it. Before we get started, if you would, tell us a little bit about yourself and what you do at Oklahoma State.
Dr. Brian Arnall (00:56):
Absolutely. So I’m an extension specialist at Oklahoma State University. I have a three-way appointment extension, teaching and research. I teach soil fertility class and precision ag. My research is focused on nutrient management timing specifically of a lot of our nutrients. I really like digging into the spatial aspects, spatial distribution, spatial response, and my extension program kind of focuses on everything from what is nitrogen and why should pH be maintained at a six to use of drones, and computer learning, and agriculture. My program covers all crops that receive commercial fertilizer in the state of Oklahoma so, of course, I have a lot of wheat. I also get to work in sorghum, corn, sunflower, sesame, forage crops, and fiber crops. Cotton is another one. I grew up in northeast Oklahoma, didn’t really have a whole lot of production ag in my background. Came to Oklahoma State and I keep getting drawn back here and I’ve never really left.
Mike Howell (01:55):
Well I tell you, I’ve visited Oklahoma State several times. Used to bring a bunch of 4Hers out there for the National Land Judging Contest, and if I had to live somewhere else Oklahoma would be one of the places I would look at. Really enjoyed coming out there and have enjoyed my time in Oklahoma over the years. Dr. Arnall, tell us a little bit about the current crop situation in Oklahoma, what’s going on, how’s harvest coming and that kind of stuff.
Dr. Brian Arnall (02:16):
Well, harvest was expedited on our summer crops. We have ended up swathing a whole lot of soybean, sorghum, and corn ground. We’ve got a couple pockets that made some grain but the number of folks that are bailing up soybean, bailing up corn and sorghum is pretty big. A lot of beans are going down. It’s just been miserable, hot and dry, Mike. In fact, we’re flirting with triple digits as we record this in the middle of September coming up the end of the week and so we’re awfully hot and dry. The wheat is starting to go in the ground. Typically, our graze out wheat would be going in right now, heavy, heavily planted but the problem is, we’ve had one or two showers in a few locations so what we’re looking at is a band of moisture that might go four to six inches deep with nothing below it to three or four foot deep. So a lot of folks got wheat in the ground, they got it up to prep for grazing but if it doesn’t get rain in the next week or so, we see mid-90s, we’re going to have wheat going backwards. We’re already getting some army worms starting to march from the south coming up off the Red River.
Mike Howell (03:17):
Wow, that’s just not a good scenario at all. I’ve been talking about my little farm here. We started a little farm about two months ago and we needed to cut the hay when we started and haven’t had a dry time to cut hay yet. The hay’s just about ruined by now and I don’t know if we’re ever going to get a hay cutting off of this. We’re in the total opposite situation from what y’all are in, just can’t get a break, just not a good situation. Well, let’s get to the dirt and jump in on today’s topic. I thought we would continue our series on our essential plant nutrients today and talk about iron for a little bit. Dr. Arnall, if you would, tell us about iron and what the role of iron is within a plant.
Dr. Brian Arnall (03:53):
Iron, of course, is one of our considered micronutrients and we always say most soil fertility specialists will tell you it’s not micro because of the power it has, it’s micro because of the quantity that we’re utilizing it and removing it in the crop. And so, iron is critical and essential throughout the plant and we’re still learning about all of iron’s roles but, heavily, it’s involved with the synthesis of chlorophyll so it’s a big part about chlorophyll. It’s essential for the maintenance of chloroplast and the structure and function of chlorophyll so it’s a big part of photosynthesis. It also has a big aspect and interaction with enzymes. It’s utilized heavily in a lot of the enzymatic activity within the plant. When it comes to roles in plants, iron is a critical compound when it comes to the plant. It is not mobile in the plant so it’s immobile in the plant so, therefore, we’ll typically find the iron deficiencies in new growth.
Mike Howell (04:50):
Okay. Well, you mentioned that it has a lot to do with chlorophyll production so I’m assuming if we start seeing deficiencies we’re going to lose that dark green color we’re looking for. Tell us a little more about the iron deficiency symptoms.
Dr. Brian Arnall (05:01):
Iron deficiency is one of the most, as far as symptoms goes, it’s a very classic symptomology that doesn’t veer of from itself too often. It’s always found in the new tissue and it’s interveinal chlorosis so it’s that yellowing between the veins where you get that beautiful John Deere striping on a corn or sorghum leaf. On soy and on cotton you still get that interveinal. Same thing on alfalfa and all of our crops but it’s a very yellowing. Not a lot of necrosis, we’ll typically see a studding. Beans might be more of a general yellowing on some of the leaf, almost indicative of a sulfur yellowing but you still have a strong interveinal chlorosis, pretty consistent across the board when you get into that.
Mike Howell (05:43):
Okay, and I’m assuming that if we start seeing these deficiency symptoms that’s going to result in yield loss, that’s why we call it an essential element. What kind of yield losses could we expect to see if we have iron deficiencies?
Dr. Brian Arnall (05:54):
So in some of our extreme cases, Mike, if I go into the high plains where we have some of our biggest challenges with iron deficiency, on a soybean crop, if it’s untreated we’re talking the difference between 50, 60 bushel and five bushel. We can lose 30 to 40 bushel in severe iron deficiency chlorosis or IDC as we’ll typically call it in the soybean system. In severe cases, a 50% yield reduction is not out of the question, that’s the really extreme cases. Just marginal cases, we’ll see it strip a couple bushels off if you just start having a little bit of the deficiency symptomology. In our bad cases, it takes us almost down to zero in some of our pockets.
Mike Howell (06:33):
Wow, that’s a big loss just from one small nutrient like that. One thing that a lot of growers have trouble with is determining do I have an iron deficiency or is it a nitrogen deficiency or a sulfur deficiency? Is there any way we can tell this deficiency from something else without actually doing tissue sampling and knowing for sure?
Dr. Brian Arnall (06:50):
The tissue sample is helpful but it’s not always the best when it comes to identifying iron. Typically, our iron deficiencies can be associated with certain soil characteristics. And so, if I’m going to a field, if I know a couple things about that field I can quickly associate it with certain nutrients, opposed to a nitrogen sulfur. For just the deficiency symptomology, nitrogen’s going to typically be older lower leaf, sulfur’s going to be newer growth, more of a general yellowing, while the iron deficiency will be interveinal chlorosis. The iron, the way it acts in the soil, so iron is immobile in the soil in forms of FE2, FE3. It’s a heavy positive so that soil negative charge and this iron positive charge, it’s really a strong bond, along with it’s highly chemically reactive. It’s much like phosphorus or aluminum that is really trying to bond with a lot of the other elements that are in the soil with it as far as anions.
(07:46):
And so, iron deficiency is going to more commonly occur in higher pHs. If I have a soil pH below a six, five or below a six, it’s almost never going to be iron just because the way that soil pH and the free hydrogen with those lower pHs are going to have more free iron in the system, and so, the soil pH is the first indicator of potential iron deficiency. The second one is free calcium so we’ll see a lot of that in the high plains. The North Dakota and Minnesota region really gets a lot of this free calcium or calcium carbonate or free lime. Soil test lab calls it different things in our western states, and so it’s a combination of high pH, free lime, along with sodium. And so, if we have a salt problem. We can have high pH but not have a problem with iron, but if we combine high pH by a high sodium concentration, now that’s going to push the potential chances for iron even higher.
(08:45):
And then, one-third on top of that, and there’s been some cool work done throughout the soybean belt, is if you combined high pH by high nitrate so high residual nitrate, that’s also going to push the deficiency worse. It’s not that desalt creates it or the high nitrate creates the deficiency, it’s that it makes an already small deficiency exceptionally worse. And so, some really cool pictures out there on bean crops is where you’ll see a wheel track that’s really green and outside the wheel track is iron chlorotic. The deal is, that wheel track held water and had denitrification and so it actually had lower nitrate values where that water had held, and so it was still green, while outside of it had a high pH and high salt content through a really classic iron chlorosis.
Mike Howell (09:29):
Wow, amazing that just a tractor track can make that much different. Dr. Arnall, you mentioned soil pH and the importance of pH. I think that’s something that listeners are getting accustomed to on this show. We did one episode strictly on pH and I think everybody else has talked about the importance of pH and these nutrients and making sure that pH is in the right range for the crops we’re growing, making sure nutrients are available with that certain pH so I appreciate you touching on pH again. What are some of the common fertilizer sources? If a grower knows he’s going to need to add some iron, what are some sources he can use to get that out there?
Dr. Brian Arnall (10:02):
When it comes to iron management or the fertilizer sources, we can of course have the traditional sources, which might be an iron chloride, an iron nitrate. It’s basically that iron cation combined with an anion that’s highly soluble, and so very historic, we’ve used those as foliar sources for a long time. However, one of the challenge with those, especially if you’re going into an environment that has very high pH, which is that free calcium, the calcium magnesium that’s in that soil solution is going to also have a lot of OH, that hydroxide. That OH is going to want to bond with iron really rapidly. And so, it’s chemically a quick process so if you put iron chloride into the soil it’s going to bond and basically create an iron oxide or rust pretty rapidly. So what we do is we use a chelated product that aids in the holding of that iron.
(10:52):
It basically is like an organic claw that holds that iron and keeps it from being bound by the hydroxyls in the soil solution. And so, we look at EDTA and EDDHA products and so what you have is two different chelate forms. The challenge is that one form is cheaper and the other form is much more expensive. It’s about two times as expensive but you use half as much. And so, the EDDHA is typically a little more capable of holding this iron in, in these high pH systems. Now, when it comes to fertilizer management, we’ve all been able to do foliar iron for a long time, but in these soils that are really binding it is almost always better to go in as a starter or a pop-up and get the iron with the seed.
(11:38):
The application of foliar hardly ever comes back to the same yield level as those starters so it’s one of those scenarios we want to take care of upfront. We can recover with a foliar but we’re usually more successful to take care of it at planting, that most important pass. Just go ahead in those scenarios where you know you might have iron problems, a high pH, high salt, high nitrate. Go ahead and handle that in a starter system. It almost nine times out of 10 is going to be better off than trying to catch up later with foliars.
Mike Howell (12:06):
Right, and that’s the case with most of our nutrients. We’d much rather address it early in the season than have to try to play catch up later in the year. Dr. Arnall, I know we’ve talked a lot about iron and the role of iron in the plants, but iron is also something that’s important for humans. This really came to my attention a few months ago. I’ve got a sister-in-law that was having some health problems and it turned out she was anemic. They told her she needed more iron in her diet and she said, “Well, I eat a lot of red meat and that’s a good source of iron.” But I did not understand it until she started talking about it that we actually have two different types of iron. You can get iron from the red meat as well as a different type of iron coming from the plants. I know that there’s been a lot of work going on recently about iron fortification in some of our crops, I know wheat is one of those. Can you talk a little bit more about that and what research is going on in that realm?
Dr. Brian Arnall (12:54):
So one thing, a lot of our wheats, if you look at just the bread which you buy at the grocery store, you’ll see fortified. If it says fortified, it’s almost always got some iron in it. Now, those are minerals, some of them chelated irons that they’re actually adding in the breads to build it up. A pretty cool study that just came out of Colorado State in 2022, so this year, was analyzing their bread wheats and some of their wheat production and like what we see in protein and wheat. With protein, when we make bigger yields in wheat we typically see lower protein, it’s this dilution effect. They’re seeing the exact same thing when it comes to iron and zinc in our bread wheats, that as we’re pushing yield you see with higher yielding in environments we’re seeing a dilution of the amount of iron in those wheats.
(13:39):
It is a problem as we’re trying to push production. We’re trying to get as much per acre as we can out but that is, in a way, starting to dilute it so we are looking, there’s a lot of folks looking at research about iron application, foliar applications, application of soil applied. [inaudible 00:13:57] a little bit mixed as far as the foliar is making it into the grain. It is a immobile nutrient and so it’s not going to be re-immobilized from the plant tissue to the grain like say nitrogen can or phosphorus or potassium that can be re-immobilized and sent up to the new growth so we’ve really got to be a timing factor on that. It’s got to be taking into the plant at the time that you’re making the berries, and so that’s why we don’t always see a foliar application making it into increase in the grain content because it may be too early and it just gets stuck in that tissue.
(14:31):
We see the pre-plant applications that typically have higher rates. Now, that tends to end up in the grain, especially when that source is available to be there until the end because the plant’s still taken it up by root interception and bringing it up into the plant and depositing it straight into the grain. There are some folks looking at a late application, a flowering application of an iron product to see if we can’t boost that grain iron content. I know with nitrogen I can put on nitrogen right at flowering and get a pretty good boost in protein. Seeing if we can do the same thing with iron to really fortify, bio-fortify that crop so it may not have to be done at the Miller point.
Mike Howell (15:09):
Okay. Well, Dr. Arnall, we really appreciate all the information you’ve given us. Before we move on, is there anything else about iron that we need to touch on?
Dr. Brian Arnall (15:16):
No, I think it’s a big take home, it’s an extremely important nutrient. It’s one of those that’s best to be managed upfront, it’s the most economically managed, but it typically tied to some kind of soil property so if you know your soils well, you have an idea. The only thing I did not mention is that when we get into soybean, corn, and et cetera, there are varieties that are more sensitive to iron deficiency than others so there’s also a genetic aspect. Make sure you know what cultivars and what varieties you have and what are IDC tolerant and which are not.
Mike Howell (15:46):
Okay, great information. Dr. Arnall, it’s fall time here in the south and across the country and we’ve been talking a lot about football and those kids have been out all summer pumping this iron, trying to bulk up and get ready for football season. But we’ve been talking about our tailgates here at the local football game and have you got a favorite football team?
Dr. Brian Arnall (16:04):
Go pokes, baby, Oklahoma State Cowboys.
Mike Howell (16:07):
I understand. Being from Oklahoma, I can see that. At least it’s not Oklahoma fan. What about tailgating? Do y’all do any tailgating at Oklahoma State? What’s your favorite tailgate food?
Dr. Brian Arnall (16:16):
Yeah, tailgating is a pretty big deal for Oklahoma State and we do a heck of a lot better tailgating than the Sooners do so our tailgate blows them out of the water and even they’ll admit that. I’m a fan of smoked things, I love me some good smoked meats, we roll that smoker dry rub quite a bit. But if you just have to pick one for a quick tailgate, it’s a smoked queso so throw that meat, throw that cheese, maybe some brisket, some cheese, some onion in that smoker and let that melt down for a couple hours and have that smoked.
Mike Howell (16:44):
Okay, sounds good. That’s kind of the direction we’re going with our tailgate this week. Last week we put a few Boston butts in the air fryer and pulled that pork out of there, had pulled pork and barbecued it up real good, put it in a slow cooker and had pulled pork sandwiches. Well, we had a little bit extra this week so we’re going to do some pulled pork nachos with the leftover Boston butts from this week so we’re going to do just plain nachos. We’re going to have any kind of topping you can possibly imagine. Have not thought about smoking that queso but you gave me an idea there, we may try to do a little bit of that as well. It’s homecoming this week at Poplarville so we’re going to do a few more things and try to keep it interesting and let the kids have a lot of fun.
(17:23):
Kids always like these fried Oreos so I’m going to have the fryer out this week. We’re going to fry up some Oreos, let them get started on a good sugar high with the fried Oreos, and for dessert this week I’m going to cook a few beignets. Now, for people that don’t know what beignets are, that is kind of like a French donut, real popular in New Orleans so we’re going to fry up some beignets. We’re going to coat those down as soon as we get them out of the grease with some powdered sugar. And then, we’re going to have some strawberries and peaches and that kind of stuff that we can put on them as a little fruit topping so kind of excited about the tailgate menu this week.
(17:56):
Dr. Arnall, one thing we always like to do is focus on one commodity. Since you’re from Oklahoma and wheat is a big crop in Oklahoma and we’re going to be using the wheat in our beignets, thought we would focus a little bit on wheat. The US is fourth in terms of total production of wheat. Canada, another one of our big listening audiences, ranked sixth in total production of wheat so any comments about wheat production in general?
Dr. Brian Arnall (18:20):
Wheat is one of those crops that often ends up in some of the more unforgivable lands because it’s a very forgivable crop. A lot of the wheat farmers throughout the plain states, they handle a lot of diversity and they put a crop in that has a lot of diversity. That’s an amazing thing I’ve always appreciated about wheat is that you stick that seed in the ground that may not always be capable of growing 300 bushel corn and that’s why you put wheat seed in the ground and it will kick and it will strive to grow. Given the proper environment and the proper management, we have the capability now to really blow the top out of some yields with some really good quality wheat.
Mike Howell (18:54):
You mentioned the Great Plains area. I’m looking at the list of the top five production states in the United States. Four of those five are in the Great Plains. The only one that’s not is the state of Washington and I really don’t think about Washington when I think about wheat producers but I realize that they do grow a lot of wheat out in Washington. It’s a little different type of wheat than we typically grow though. That brings up that there are different types of wheat. I think, what is it, seven different types of wheat that we can grow in the United States, depending on what the end use is going to be for that.
Dr. Brian Arnall (19:22):
Yeah, it ranges. You go from our reds and our whites, we have our softs and we have our hards. Then we start getting into, we consider the Triticales, and the pastas, and the Durhams and all that stuff. So yeah, every region has a lot of their specialty, whether that’s because of end use or because of environment, but even now we’re seeing those geographies change as we’re getting better genetics and we’re seeing more of the softs make their way into the Central Plains that were historically dominated by the hard red wheats. And so, it’s interesting to see this change as we learn and we grow and we get better genetics behind us.
Mike Howell (20:00):
The last fact that I’m going to throw out there about wheat has to do with consumption. One statistic I found shows that the average American is going to eat between somewhere between 125 and 150 pounds of wheat per year. That’s a big part of American’s diet when you look at how much total wheat they’re consuming. Dr. Arnall, we really appreciate you being part of the show today, we’ve all learned a lot from this. I hope we can have you back on the program sometime here in the future.
Dr. Brian Arnall (20:24):
Appreciate the opportunity, Mike, and any chance I get I’m happy to talk.
Mike Howell (20:30):
Listeners, we appreciate you tuning into this week’s episode. We’ve hoped you’ve learned a lot and enjoying this program. If you are enjoying the program, we highly encourage you to pass this on to your friends and neighbors and also give us a rating on your favorite app store. Let us know how we’re doing. Let us know what we can do to improve. If you’ll do this, we’re giving away some skull candy earbuds to the first 75 people that do this, I believe that’s still up and going. If you have not done that, go ahead and check out our website. That’s www.nutrient-eKonomics.com, and find all the details to get your skull candy earbuds.
(21:09):
Well listeners, another Friday night is in the record books. Poplarville has defeated the Terry Bulldogs by a score of 48 to six. The Hornets are really on a roll right now, they’ve won three games in a row and it’s homecoming this week. We’ve got Pass Christian coming to town, lot of activity going on this week. We’ll be bringing you another episode next week talking about our tailgate, let you know how the ballgame turned out, as well as bringing you some new and exciting agronomic information here on the show. I hope you’ll all tune in next week and, until then, this has been Mike Howell with The Dirt.
