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[00:00:08] Mike Howell:
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, news, and issues, helping farmers make better business decisions through actionable insights. Let’s dig in.
[00:00:39] Mike Howell:
Well, hello again, everyone. Welcome back to The Dirt. Spring is here, and a lot of people are already in the field planting corn. It’s still kind of cold in some areas, but I thought today would be a good day to talk about corn planting and things we need to do to get it prepared for this upcoming season. To help us do that, we’ve got Dr. Erick Larson with us. Erick, welcome to The Dirt. And if you will, introduce yourself to our listeners, let them know what you do.
[00:01:01] Erick Larson:
First of all, I appreciate the invitation, and hopefully I’ll be able to share some information that everybody will be interested in for this corn growing season and planting season coming up. I’m an extension specialist at Mississippi State University. My background is in agronomy and I have responsibilities in corn and a couple other grain crops down here. I’ve got statewide responsibilities and been doing this for 30 years now. Got a good deal of experience associated with that. And I also grew up in the Midwest. I grew up in Kansas, on a farm out there, and went to school at Kansas State of Nebraska.
[00:01:36] Mike Howell:
Erick, I knew you’d been here a long time. I didn’t know it’d been quite 30 years yet. You’re making me feel old this morning.
[00:01:41] Erick Larson:
Yeah, it’s gone by in a hurry.
[00:01:44] Mike Howell:
Erick, can you recall what the state corn yields were when you started 30 years ago?
[00:01:48] Erick Larson:
The year before I started, I think was the first year that Mississippi had over a 100 bushel acre state average yield. And now they’re nearly twofold that. We’ve been pushing 190 bushels an acre for a state average yield. Really the last seven or eight years, Mississippi, as well as probably the other southern states, have basically caught up to or now produce similar yields as throughout the corn belt as far as state average yields.
[00:02:15] Mike Howell:
Yeah, there’s a lot of people when I travel do not realize that we can grow just as good a corn here in the South as they do up in the Midwest. We have to work a lot harder to get there, but we can grow some good corn in the South as well.
[00:02:26] Mike Howell:
Erick, it’s springtime here in the South, and it came a little early this year. My son’s got a lawn care business, and I help him get his lawnmowers up and running every year. And we always put a little sticker on it when we service the mowers every year. And somehow we always end up doing that the day before he starts mowing grass. We started servicing them this year, and he asked me to come help him get his lawnmowers ready. And I said, “Yeah, we’ll do that.” I said, “You’re starting a little early this year, trying to get ready early.” He said, “No, the phone’s ringing off the hook. We got to go.”
[00:02:54] Mike Howell:
When we were changing the oil, I looked at it and the date on it last year was March 25th. That was within a day or two of when he started mowing grass last year. This year, he started mowing grass March the 3rd. So we’re almost a month early. And I know folks are planting corn a lot earlier this year. Talk a little bit about the effects of planting corn that early here in Mississippi.
[00:03:13] Erick Larson:
We got a rare opportunity this year, and really I was checking precipitation estimates across the United States. And most of the greater corn growing area in the United States is well below normal in terms of precipitation over the last 90 to 120 days. In the South, the primary limiting factor on when we can usually start planting is not soil temperatures as much as it is rainfall and wet soils that limit the opportunity to get in the field and plant. And we had dry conditions this year. We had some tillage work that was done during the month of February. And I remember we were doing counting extension meetings, and finished those up sometime after the 20th of February, and had some low temperatures in the 20 to 30-degree range, and soils were drying out. And as soon as the temperatures warmed up substantially after that, there was growers literally going to the field to start planting.
[00:04:08] Erick Larson:
The two environmental factors which affect corn emergence and planting conditions are soil moisture, as I already mentioned, and then soil temperatures, which is a big limiting factor across much of the greater United States as well. Corn requires a minimal soil temperature of 50 degrees, and we were achieving temperatures well above that minimal soil temperature, because we had nighttime temperatures well into the 60s, and daytime temperatures pushing 80 degrees the last week of February and the first week of March. We had a rare opportunity to get in the field and actually plant when soil conditions were very conducive to emergence. Now, the biggest threat is a freeze coming along and doing substantial damage to the sand if we get cold enough temperatures to do so sometime during the next several weeks.
[00:04:58] Mike Howell:
Erick, that’s going to be my next question. All the old timers have always said you get a thunder in February, you’re going to get a freeze in April. It thundered at my house on the 21st day of February. I sure hope we don’t get a frost on the 21st of April. That’s going to be disastrous this far south. I really don’t think we’re going to be in danger of that, but what happens to this corn coming out of the ground if we do get a frost on it?
[00:05:20] Erick Larson:
I think the biggest factor that determines the extent of injury is how cold the temperatures actually get. We all know that growing corn is underground until it gets to about V5, V6 growth stage. And normally in the South, that’s not going to occur until late April sometime. Obviously, conditions are a little bit different in terms of planting progress this year and temperatures thus far. Most of our corn is still well smaller than that. But in my experience over the years, temperatures that get down below say 25 or 26 degrees are going to start moving that frost level below the soil surface, where it may get to a point where it’ll actually contact the groin point, or get close to the groin point and disrupt the movement of the tissue in the development where it’s going to stunt the plant and cause issues that are going to jeopardize the stand.
[00:06:14] Erick Larson:
Temperatures 28 degrees and above, particularly if they don’t occur for more than a couple hours, are going to frost the above ground vegetation off above the soil surface. But if we have warm conditions and particularly sunny conditions thereafter, the growing point will regenerate leaves, which will emerge, and the plant will begin feeding itself again as soon as it got green leaf tissue emerged. So, it’ll be fine.
[00:06:39] Mike Howell:
Erick, if we’re planting into these cool soils, naturally the corn’s not going to come up and start growing quite as quick as if we can plant into some warmer soils. A lot of people are thinking about putting fertilizer out, starter fertilizers or pop-up fertilizers. What do you think about putting these fertilizers in with the seed? Does that do any benefit for us?
[00:06:57] Erick Larson:
I like starter fertilizers as a general supplement. It’s probably a practice that has subsided a little bit, considering that the profit margins are so slim right now, but it certainly will help stimulate growth. What I would urge folks to realize is they think that the fertilizer won’t overcome the effects of soil temperature. You got to realize that, I guess. But it will stimulate growth and nutrition obviously to the young plants and make them healthier during the early stages.
[00:07:28] Erick Larson:
The general research results that we’ve had over the years is that starter fertilizers are a lot more likely to produce a nice response and benefits in a closer we are to a no-till system, minimum till, where we don’t have good distribution of immobile nutrients through the soil profile, or have heavy crop residue on the soil surface. Putting those immobile nutrients in the root zone will provide a nice response to stimulate the early growth of the plants, which will stimulate maturity and hopefully improve yield potential as well.
[00:08:02] Mike Howell:
Erick, what about some micronutrients in that starter package? Do you see a benefit of adding the micronutrients in at that time?
[00:08:08] Erick Larson:
We typically see a nice response from zinc. That’s just a common nutrient that we have seen some issues with over the years in the South. You can provide it in that band, put it in the seed zone and see a nice response, as well as your traditional starter fertilizer nutrients, which is primarily phosphorus oriented.
[00:08:28] Mike Howell:
Erick, we talked about some of the risk of planting early. What are some of the benefits of getting this crop in early?
[00:08:34] Erick Larson:
Corn, as well as most other crops, is extremely responsive to early planting. It allows the crop to hopefully mature earlier in the year, which is going to put it in a more environmentally favorable time zone for it to reach tasseling and go through its early reproductive stages. When it’s hopefully cooler, particularly the nighttime temperatures will be cooler, there’s more chances of stored soil moisture for dryland producers, which is critically important, and more rainfall during the earlier part of the summer, as opposed to the later part of the summer as well. And generally, your pest issues will continue to pick up and be cumulative in nature during the season too.
[00:09:12] Erick Larson:
As long as you can get a good stand, which isn’t a given, corn as well as most other crops is generally considered to be very responsive to early planting and more productive. It’s obviously a huge advantage and something that growers will strive to do if they are given the opportunity to do so.
[00:09:30] Mike Howell:
Erick, you mentioned soil moisture, and I couldn’t agree more. We need to do anything we can, especially in these dry land situations to help conserve that soil moisture. Last year, we did not have that problem across the Mid-South. It started raining shortly after we got this crop planted, and I don’t think it quit until the middle of June. It made nitrogen management really challenging. Some guys put out a little bit of nitrogen when they planted, and some were waiting to come back and put some in after the crop came up. And that proved to be challenging last year, getting in and getting that nitrogen put out. Sidedress applications were late. I think we lost a good bit of yield last year because we had some delayed or late applications of nitrogen.
[00:10:08] Mike Howell:
I hear you talk about nitrogen management quite often. Talk a little bit about how we need to manage this nitrogen to make sure we don’t get behind the eight-ball on feeding this crop.
[00:10:17] Erick Larson:
Nitrogen was definitely a huge limitation for us last year, and it’s always a limitation or something that we have a lot of challenge with in the South, because we have warm winter conditions, so our nitrogen is not stable over the winter, like it is in a lot of the corn belt region of the United States. So we have very low carryover from last year. And then we have high rainfall during the season as well. We’re putting out a hundred percent of our nitrogen from the time we plant and through the growing season, trying to minimize the risk and the exposure that nitrogen to those wet conditions, which are conducive to loss.
[00:10:53] Erick Larson:
Last year we had the rare condition where the entire month of May was almost too wet to get in the field until… There’s one week right at the end of May where growers had the opportunity, but we went a full three weeks, three and a half weeks probably of the month of May with no opportunity to get in the field and perform any field operations, whether it’s planting soybeans and cotton, or sidedressing corn.
[00:11:18] Erick Larson:
There was a pretty substantial percentage of the corn acreage that was planted in mid-April last year. So it went through the early growth stages and past V6, which is considered to be the ideal sidedress timing when we’re starting rapid growth stages, without an opportunity to get in the field and side dress during that timeframe. A lot of the state, we have aerial application capability where growers went to a plan B, you might say, and applied nitrogen by air when we couldn’t get into the field with ground rigs.
[00:11:51] Mike Howell:
That’s an awful expensive plan B, Erick.
[00:11:53] Erick Larson:
Well, it’s better than the alternative of not applying nitrogen during those stages and falling behind the crop, which unfortunately we had some of those problems too. And that’s not normally a problem. Normally, we’ll get a window or an opportunity to get in the field where we’re not really falling behind, but the more we can do to match the crops nitrogen needs over the course of the season, the better our efficiency will be. And regardless of where you’re growing corn in the United States, nitrogen is a large part of your budget for growing corn. And if we can grow a bushel of corn per pound in nitrogen or even do better than that, which is kind of what our best managers can do, then that can certainly help our profitability potential, which all of our growers are trying to do in their programs.
[00:12:44] Mike Howell:
Erick, you mentioned that pound of nitrogen per bushel, and that kind of triggered a remembrance. Back when you first started, I was just getting out of school about the same time you started there at Mississippi State. And if I remember right, the recommendation then was 1.2 or 1.3 pounds of nitrogen per bushel for the first 100 pounds anyway, and then it came back down a little bit. But we’ve backed off of those nitrogen recommendations a good bit over the last 30 years.
[00:13:08] Erick Larson:
We’ve still got those recommendations, but it’s difficult to apply those. What I like to focus on, and I think our growers are moving towards focusing on is the timing of the nitrogen fertilizer, using appropriate sources, which hopefully are going to be more efficient than methods that we used in the past and other things to increase our efficiency. We talk about increasing efficiency in a lot of ways, and this is certainly one of them that is very practical method to enhance our profitability, you might say.
[00:13:41] Mike Howell:
Erick, another thing I hear you talk a lot about at the winter meetings is cover crops. And I know you’ve spent a lot of time doing some research on cover crops. I travel all over the country, and some people love cover crops, some people hate them, don’t want to talk about cover crops. I’ve seen benefits of cover crops in places, I’ve seen where it can be a detriment in places. But talk a little bit about your research with cover crops and what you’re finding.
[00:14:03] Erick Larson:
I realized that there’s both end of the spectrums out there. Cover crops have been around for a long time. And there was a couple things that are interesting when you look at research over the years. Cover crops for all the benefits associated with cover crops in terms of soil and water health improvements and things like that, it’s very rare that we see short-term yield increases associated with cover cropping systems. When we started doing research projects on cover crops, we were keenly aware of what other folks had found as far as various limitations associated with cover crops, but we were keenly interested in identifying what the limitations were, because from a crop management standpoint, if we don’t know what those limitations are, then we will certainly encounter challenges and stumbles associated with the system, and we can’t afford that in today’s marketplace.
[00:14:58] Erick Larson:
Most research shows that cover crops need to be terminated with herbicides or using mechanical tillage maybe in some areas of the United States prior to planting corn. We know corn is very responsive to early planting, we know it’s very responsive to uniformity of the stand. By terminating that cover crop prior to planting, hopefully we will allow the sunlight to warm the soil surface and prevent the vegetation and physical issues associated with planting a very responsive crop like corn into that cover by killing it several weeks in front of planting.
[00:15:38] Erick Larson:
Like most research protocols, we had a certain date range starting as far as six weeks in front of planting that we employed. And basically what we found was that the cover crops needed to be terminated at least two weeks or more in front of planting at two weeks, or when we terminated at planting, or if we terminated after planting, we certainly see yield decreases associated with all the times that we allow the cover crops, or we’d plant into green cover crops, or even kill them as few as two weeks in front of planting.
[00:16:10] Erick Larson:
So the magic number was at least two weeks, which means three to four weeks in front of planting is what we needed to do to optimize our seedbed conditions and limit the interference associated with that cover crop.
[00:16:23] Mike Howell:
Erick, are you using grass species, or legumes, or a mixture of both?
[00:16:27] Erick Larson:
We actually used a mixture of both as our standard, and then we also used the grass species in the legume separately so we could identify whether there’s benefits or advantages of the singular species, as opposed to the combination. And it was interesting that we found that we had more interference associated with the grass species as opposed to legume species. And I think that’s primarily because of the higher carbon and nitrogen ratio associated with the cereal species, was shading the soil, and frankly limiting soil temperature, which was the other novel finding that we found in our cover crop work, is that most of the yield problems that we had our various treatments were associated with the cover crop retarding the soil temperature if we killed that cover crop late in relationship to corn planting.
[00:17:18] Erick Larson:
The other interesting thing that we found was that full week time period relative to corn planting time. And for us in the South, our target planting date was April the 1st, which would put the kill date on the cover crop at March the 1st. And as you know, most of our cereal species start stem elongation sometime shortly after March the 1st normally. I think the bigger key associated with cover crop management is to try to terminate the cover crop near or shortly after the time period when stem elongation starts on the cereal species.
[00:17:52] Mike Howell:
Erick, another thing I hear people debating is, with legumes, are you getting any benefit from the nitrogen on those legumes? Is it going to release that nitrogen in time for the crop to take it up that year?
[00:18:03] Erick Larson:
I certainly hear plenty of that as well. And obviously, if you let the legume go and not kill it quite so early, you’re going to get more contribution. We definitely see contribution of the legume cover crop, where we compare a cereal species like cereal rye or wheat or oats, whatever it is, when you plant that species without the legume compared to in a mixture with the legume, you can see a dramatic difference in the health of the cereal species when it’s planted with the legume. So it’s definitely contributing nitin to the system even if you kill it well before flouring, or before it generates a lot of biomass during the spring, which again, is typically going to occur in the South sometime after March the 10th. It’s definitely contributing. I wouldn’t plant a cover crop without a legume for that reason.
[00:18:57] Mike Howell:
Well, Erick, we’ve hit a little bit on a lot of different topics this morning, a lot of things that I think growers need to pay attention to before they get the crop in the field this year. Is there anything else we need to talk about before we wrap this episode up?
[00:19:08] Erick Larson:
Just take some time. Corn is a crop that’s extremely responsive to planting. So, be diligent with your management decisions and your preparation prior to planting corn, in the South, and elsewhere across the United States probably too. Soil moisture is marginally abundant for us every year, basically. So, one of the compounding effects that we see a lot of is soil compaction associated with tire traffic patterns if you plant wind conditions are marginally wet. And that’s something that’s going to stick with you all year. A lot of our planters are wider row planters than what are used in the other areas of the United States, but most of our corn growers have 12 row planters, and have dual wheel tractors, and that’s going to affect as many as six of the 12 rows on the planter. And we’ve actually went in and harvested individual single rows and found over 40 bushel an acre yield difference between those rows that are underneath the tractor where there’s soil compaction occurring, as opposed to those out on the wing of the planter that are not affected by that.
[00:20:08] Erick Larson:
There’s plenty other things to try to do to obviously achieve the type of picket fence stand that you want to with corn, even as simply as thinking about manipulating seeding rates and making sure that we’re not overseeding. We know that corn is responsive to higher seeding rates, just like it is to nitrogen. But with both of those factors, at some point the response is going to level off and plateau, or even decline. It can decline because of dry land systems as opposed to irrigated, but planting date is one factor that definitely affects the dynamics of seeding rate that corn growers need to keep aware of as well. Early planted corn is generally going to be shorter because it progresses through its early vegetative growth stages when conditions are cooler. Using higher seeding rates would be more pertinent for early planting specifically because of that. And as you get pushed into later planting dates, conversely, it progresses through the vegetative stages when conditions are a lot warmer.
[00:21:07] Erick Larson:
And you may have plants we commonly see down here that there may be a foot and a half difference in plant height and plant canopy associated with planting date strung out over a six or an eight-week period like we often have in some years. Planting rate is a tool for us to manage light interception, and that’s what we need to think about in terms of management goals. Some folks may go out there and set the planter at 34,000, plant the entire crop with it over a large timeframe, or different hybrids for that matter, but adjusting to fit your conditions is extremely important.
[00:21:43] Mike Howell:
Erick, a lot of great information. We really appreciate you taking time to visit with us today. I’m sure our listeners have got a lot out of this episode. Listeners, we appreciate you tuning in. If you will, hang around for just a couple of moments and we’ll be right back with segment two.
[00:21:57] Mike Howell:
Farming isn’t farming without questions, and now there’s a place to go for answers. At eKonomics, an entire team of agronomists is waiting and ready to help. For free. No question is too big or too small. Visit nutrient-ekonomics.com, and submit your question with the ask an agronomist feature.
[00:22:20] Mike Howell:
Listeners, welcome back for segment two, where we have an agronomist in the studio and ask them a question of the week. Today, we’ve got Lyle Cowell back in the studio, our Canadian agronomist. Lyle, welcome back to the dirt.
[00:22:31] Lyle Cowell:
Thanks a lot. Always great to be part of the show, Mike.
[00:22:33] Mike Howell:
Lyle, today’s question is, what is the difference between banding and broadcasting? And how do I know what’s right for my situation?
[00:22:41] Lyle Cowell:
That depends. It depends on the nutrient. Why do we band fertilizer? Why do we band it under the soil? Well, there can be two primary reasons. One, it may reduce the risk of loss, especially for nitrogen fertilizer. Placing it under the soil, creating that barrier of soil between the fertilizer and the atmosphere can reduce losses of nitrogen due to volatile losses of ammonia. It can reduce the risk of losses to denitrification later in the nitrogen cycle. And actually, it can reduce the risk of nitrogen being tied up in the surface residue. You separate that nitrogen from the surface residue, then you have less nitrogen tied up, or immobilized, as the crop residue decays. That’s the primary reason that we think about banding nitrogen fertilizer.
[00:23:31] Lyle Cowell:
Now, why do we band other nutrients? In some cases, especially if you’re using relatively low rates of nutrients like phosphorus or potassium, there can be some advantage to applying that low rate of a band near the sealing root system. So rather than broadcasting a low rate of phosphorous or potassium and mixing throughout the soil, putting that starter band near the sealing root system intensifies the supply of that nutrient to the developing sealing root system, and also tends to help minimize the risk of that fertilizer nutrients being used by other plants, the weeds in the field.
[00:24:13] Lyle Cowell:
Really two reasons that we do utilize bands, but ultimately it improves the efficiency and the economics of the fertilizer that we use.
[00:24:22] Mike Howell:
Lyle, we really appreciate it. Listeners, thank you for tuning in this week. If you need more information on anything we’ve talked about today, please visit our website, that’s nutrient-ekonomics.com. Until next time, this has been Mike Howell with The Dirt.
[00:24:39] Mike Howell:
Hey, guys. If you like what you heard today, do us a favor and share this podcast with someone else. It could be your neighbor, your friend, your crop advisor, or whoever you think would enjoy it. Your support helps ensure future episodes. So please like, subscribe, share, and rate the show wherever you’re listening from.
