Sugarbeet nutrient management: Best practices, guidelines & new research for MN growers
Hello and welcome back to University of Minnesota Extension's Nutrient Management Podcast. I'm Jack Wilcox in communications here with Extension.
Jack Wilcox:Minnesota is the top producer of sugar beets in the nation in terms of acreage. Today, we'll talk about sugar beet nutrient management.
Jack Wilcox:We have three specialists joining us. Can you introduce yourselves, please?
Dan Kaiser:This is Daniel Kaiser. I'm a nutrient management specialist with the University of Minnesota. After John Lamb retired, I kind of took on some of the role for doing some of the sugar beet research here related to nutrient management at the University of Minnesota. So I spent a little bit of my time actually working on some of the nutrient guidelines and working with some of the coops and going through some of the current data out there to see whether or not we need to be making any modifications to the fertilizer guidelines.
Melissa Wilson:My name is Melissa Wilson. I am an associate professor at the University of Minnesota, and I'm the minerals specialist. So in my case, I've been basically trying to figure out how to put the smelly stuff to make sugar.
John Lamb:I'm John Lamb, professor emeritus in nutrient management. In my career with the University of Minnesota, I worked with sugar beets for over thirty years.
Jack Wilcox:Let's talk about the fertilizer recommendations right now for sugar beet. Are there any revisions coming up that you're aware of?
John Lamb:The recommendations for for sugar beet nutrient management, actually have a long history going back into the the seventies, when, the coops were put together, and they've been a activity between the the university and the sugar industry that has been supported by their checkoff fund. Over the years, they've been updated, and we've tried to continue updating them particularly in the area of nitrogen management because nitrogen affects quality directly in beets. Too much nitrogen actually hurts the amount of sugar in them. So right now, a short answer long is basically, I know the Southern Minnesota Beet Sugar Cooperative has updated their nitrogen, recommendations, this last fall using data that that has been generated in their growing area. Dan can speak to the rest of them, but I think those recommendations were reviewed in 2023.
Dan Kaiser:Yeah. And we went through and I looked at some of these. Normally, I do is I I try to maintain some contact with the the cooperatives when we're looking at the the guidelines because, they are a pretty good source in terms of getting information out to the growers, working with them. And if you know Minnesota, there are three major cooperatives. Southern Minnesota Beet Sugar Cooperative.
Dan Kaiser:It's located out of Renville. Minn-Dak, that's at Wapton, John, up in that area.
John Lamb:Minn-Dak's Farmers Co op. Yep.
Dan Kaiser:And then you've got American Crystal, which has a number of locations up in the Red River Valley. And, traditionally, the guidelines are split where you've got the Northern locations, Minn-Dak and Crystal, kind of on their own in terms of their guidelines. And then Southern Min has had separate nitrogen guidelines, which, until this last year I mean, that's the first time I've had they've changed base, and I've known unless you did it at some point, John, before you, you retired, and I took over some of this. So they've been kind of, with the same guidelines, which I think was close to, like, a 110 to a 130 at that point in time when I first started. So, you know, I've been doing a number of studies the last, oh, we'll say since I don't know.
Dan Kaiser:When did you retire, John? Around 2015, 2016, 2017, somewhere in there?
John Lamb:2015. Yeah.
Dan Kaiser:So I've had a number of locate where we're doing some nitrogen trials. Mainly, a lot of the stuff I've been looking at, I've been looking at timing. We're we've been doing some work in the North and the South. Looking at some of these issues with spring urea, which I know, John, there's still a few questions that will come up with that on growers because we do see some stand loss with spraying application of urea. It's it's not necessarily anything I worry about because most of the, the loss is compensated by just you get a bigger beet root if you're missing a few plants.
Dan Kaiser:So we haven't seen anything where it's been drastically different with that. So, you know, the the big thing for me, though, is trying to keep up with it. And having the northern sites, you know, it's kind of been a challenge because, NDSU also was doing some work with Crystal up in that area. And then we had Albert Sims also working out of Crookston where we're able to maintain some sites in the North and the South, and it's you know, with retirements, it's been getting kinda harder to to do that. We we've made some updates here.
Dan Kaiser:I think the main change will be, especially that southern MN data that we're off to be changing the grower, just the grower guide that goes out every year that Neil need to be updated in. But, other than that, though, I really haven't seen any changes or anything on my my research that would make me, you know, think that what we have in place right now really is any different, from where we should be in terms of management. But I guess that's where I'm at. I mean, you know, I you know, John, I mean, mostly, I think the bulk of the stuff right now has been looking at nitrogen, and I know you've worked a lot on timing too. And I think that's one of the things that growers have been really, you know, kinda questioning is whether or not we need to be looking at any in season applications of nitrogen.
Melissa Wilson:For folks who are thinking about putting manure on sugar beet, it's basically the same rates. It's just making sure you're using the plant available nitrogen conversion to see how much of it you'll apply.
John Lamb:We've done a a lot of work on over the years on split applications. And when we're on heavy textured soils, we have not seen any gains by putting it on, splitting it between a pre plant and a side dress. And there's a lot of activity out there trying to push that way, but we haven't seen any any gains. Now if you're on irrigated sands, which we have a bunch in the Bonanza Valley area and off towards Morris in that area, and, yeah, you'd have to split because you're on a very sandy soil that will leach nitrogen, and a grower needs to be aware of that so as they don't put everything on at once.
Dan Kaiser:You think that topic comes up one because it's a lot easier now? And I don't know, John. I'm assuming a lot of these growers, they culture injection or wide probably wide drops, I would assume, something like that where they have equipment or is it just kinda split?
John Lamb:There are even some that are just spreading urea over and maybe cultivating it in too. I think some of it comes from the fact that there's been a lot of push in the corn growing, areas to split on corn. And so I think growers are thinking, well, if it's good for corn, it's probably good for beets. The one thing I would caution is is least from the principles, you got too much nitrogen on on July 1, it will be detrimental to your quality.
Dan Kaiser:Well, that's one of the things too, the difference really. The beet, you look at the taproot, it is and they're just factories for extracting nitrate and converting it to sugar. I mean, it's really what that beet is out there doing that they're pretty efficient, and that taproot will go down quite a ways where you can extract a fair amount of nitrate even if it's moved a little bit deeper in the profile. And some of the studies I've been looking at tissue testing, you know, John, you kind of cautioned me against that. And, you know, I will say that it is somewhat problematic using, a petiole test.
Dan Kaiser:You know, we're kinda targeting some different times, but, you know, I think the if you're gonna do it, the ideal time would be the the July 1. The problem is, though, it really didn't do a good job of predicting where I needed a response with it. And a lot of that's because if you're dealing with petioles, it's the nitrate is transient in it, so it isn't necessarily that. It's it's not a storage structure, so you can be impacted by conditions around the time you're sampling if it's translocating nitrate or not. So it's it kinda makes me somewhat skeptical in whether we can use that in combination with, like, in season or in season applications to try to correct for some deficiencies.
Dan Kaiser:And I think it's where a lot of growers are looking at are situations where we might be getting to I know, John, some of these higher tonnages, get up to 40 tons and maybe worried about being a little short on end that they really wanna kinda pump some additional in in for, you know, potentially for sugar. But if you overdo it, you know, really, as John said, the problem is is you get you start to see decreases in quality. So it's really what makes sugar beet interesting. It you know, corn, when it comes down to a lot of the research, it's it's somewhat boring because I can overapply nitrogen, and I don't see a a negative response. If you get into some of these crops like beets or other crops where your overapplication can negatively affect crops, becomes a whole different animal when it comes to management.
Dan Kaiser:It's a lot more of an emphasis for growers really to try to manage things a little bit closer to the optimal rates within a given field.
Jack Wilcox:What are some of the active studies that the University of Minnesota has on sugar beet nutrient management? Melissa, I know you have one on liquid separated dairy manure in a sugar beet rotation. Can you tell us about that?
Melissa Wilson:Yeah. We've been applying manure in the sugar beet rotation, and we've actually had kind of we're rotating three crops, corn, soybean, and sugar beet, and just seeing where in that rotation it's best to apply manure. As we get more and more of these larger dairies moving up into the sugar beet growing regions, I've been having more questions asking if they can fit it into the rotation or if that's detrimental to the sugar production. Like Dan said, you don't want a lot of late nitrogen available or that will affect the sugar beet quality, the sugar quality. And manure tends to have that highly mineralizable nitrogen, so it really fluctuates from year to year on the weather conditions, basically.
Melissa Wilson:So we applied liquid separated dairy manure. A lot of these bigger dairies are using this technology to separate the liquids from the solids. So we applied the liquid separated manure in the fall in front of sugar beet or corn or soybean and then rotated each of those crops over the three years to see, again, would it be better to put it in the year before sugar beets, two years before sugar beet, three years, etcetera. But overall, I was kind of expecting there to be a lot of differences with treatments, and we actually didn't find any. So the first set of three years that we did this, there had not been a manure history in the field.
Melissa Wilson:And the only time we actually saw yield differences in root yield and sugar yield was in the second year, and we had different application rates of manure. And the higher rate of manure had significantly higher sugar yield than any of the other treatments, including just like a standard fertilizer only practice. But other than that, yields were very consistent from year to year, and then percent sugar really only changed in that first year, and even then it wasn't statistically different, but it was 15.6% in the fertilizer only plot. And in the sugar beets where manure had been applied in the previous fall for that high rate of manure, it was down to 15.2%. So it was not a drastic change in sugar, but we definitely saw a little bit of a decline that first year.
Melissa Wilson:And then after that, even when we applied manure again in that rotation after the three years and started the rotation again, we didn't see that decline. So it seems like we've been pretty excited to see that it hasn't had the negative effect that we were potentially anticipating. And then I know John's done some research in the past too with things other than just liquid separated dairy manure, so maybe he can fill in on that.
John Lamb:The story about manure, the principles would say that if you have something that's mineralizing late in the season, you might see a quality problem. None of our work has shown that. In fact, if anything, when you put it into into the quality based payment systems, you might see a two to three ton increase in yield with the use of manure compared to like fertilizer. And the quality does not seem to take the hit that we expected. And and that's basically what what Melissa has shown in hers.
John Lamb:And so I guess if a farmer was to ask me, you know, well, what do you do? And I say, if you have manure and need to use it, just don't get too wild with the amount that you put on because maybe it won't hurt you the first time you do it but if you continue to do it, it will come back. Another interesting thing in the the manure work that that I did was as we always took a deep nitrate sample after the study and the study had nitrogen urea put on and incorporated up to 240 pounds of nitrogen. And then we had some swine manure and some turkey litter put on there. And at the end of the season, the beet growing season, those nitrates were all the same.
John Lamb:And that just tells me that, beets, the roots will take up any nitrate you got sitting there in the soil. Yeah. Some of it will be recycled in the in the tops eventually, but there's a lot of it has that ability to suck up nitrogen like no plant that I've known of.
Melissa Wilson:The other thing going on with manure is that it has a lot of the secondary nutrients as well that you might not be applying regularly in your fields, you know, sulfur, calcium, etcetera. Dan has done some work on that in the past too with fertilizers.
Jack Wilcox:That's a great segue to switch over to micros. Dan, could you bring us up to speed?
Dan Kaiser:Yeah. And we just haven't really seen a lot with fertilizers. I mean, we looked at boron for a few years in the southern part of the state on some non irrigated high high organic matter soils. And, I mean, the only thing that it seemed like it could see is that some of the higher rates seemed like, you know, some of like, some of the other crops where we started to see a little bit of yield drag at the rate was too high, and that's not uncommon because boron can have toxicity issues. I mean, normally, beet should be, you know, a little bit more tolerant to it versus some other crops.
Dan Kaiser:I mean, soybeans is probably the worst. You know, I kind of cringe when I hear people talking about boron applications in soybean, but, I haven't seen it. I mean, sulfur, I haven't really seen it. It's just that mysterious manure bump we get about with any crop, and it it's kinda hard to pin down what's going on there. I mean, it could be just a nutrient availability over time thing.
Dan Kaiser:Although, you know, John said with some of the work with fertilizer, especially with nitrogen timing, really split applications haven't shown any benefit, but you really can't rule out some of these things. You know, when I look at a lot of our data, I just don't see much of a benefit, you know, on the on the micro side. I mean, the only ex the exception to that would be dry year sandy sites. Boron could be an issue. A few years back, I know up around Manoomin in that area, one grower that I'm in contact with, he sent some pictures that looked like some boron deficiency on some sandier ground that they had in that area, which would make sense.
Dan Kaiser:I mean, I haven't really seen it consistently. So, I mean, if you're a grower, you're gonna do it. I would just at least try to keep the rate low. And I can't remember what our max rates were in their studies. If we had upwards of 10 pounds broadcast, I mean, it did look like the yield went down.
Dan Kaiser:And most crops, they just don't eat a lot. And I think, with a lot of micros, I mean, a lot of the issue really is related to environmental conditions more than anything. We just get situations where, you know, especially with boron, if it gets dry, you don't get it released from the soil. So then the question is, you know, if I getting a low boron tissue concentration, if it is dry, is it really worth applying it? Because you get moisture.
Dan Kaiser:We've seen this with alfalfa, and it'll it'll come out of it. So that's kind of the the problem with it is is fixing some of those issues whether or not it's really worth it. I just don't know if I'd use tissue testing. I one of the first studies I did with, sugar beets was, we looked at comparative tissue testing among different varieties in the at different times. We were looking at around, somewhere around mid to late June.
Dan Kaiser:And we're I think we're doing them in, I was roughly looking at, like, forty, sixty, and eighty days, I think. Somewhere thirty, fifty, and seventy, something like that. One thing I did remember is it the joy of trying to sample sugar beets at about thirty to forty days wasn't a lot of fun being on my hands and knees, trying to not pull them out of the ground as I'm trying to pluck petioles. You know, if you're a grower I mean, if I think diagnostic, I think it's around 50. I mean, around early July is probably a good time.
Dan Kaiser:But, again, the data really hasn't been in anything that we can utilize for for any of our nutrient guidelines. So that's been the problem with it. And it's a thing. I mean, if you're a grower, you know, whether any crop you're doing, you gotta wade through the information that you're getting from a lot of these companies that are trying to market stuff to you because there's some things that do make sense from what we know about physiology for some of these crops, but in effect, I mean, some of our soils I mean, my data really hasn't been consistent where, you know, some of these things, especially these microsulfur, some of those things have really benefited beets outside of some situations. I think, John, you know, sandier ground, maybe there's some benefit, but, you know, not in most of our heavy textured soils.
Jack Wilcox:What else should growers know about sugar beet nutrient management? Any advice or best practices? I heard exercise caution with micronutrients. Also heard if you have the neuro need to use it, don't get too wild with the amount that you put on. Anything else?
Dan Kaiser:Nitrogen timing. I mean, we've done fall versus spring. I think, you know, it in the South, it worries me a little bit as fall urea is becoming more commonplace. So we've looked at that. I mean, certainly, we haven't had the issues with fall application and as much stand reduction.
Dan Kaiser:Sometimes you get it, sometimes you don't. But if you look at, you know, our data, about 50% of the time, the tonnages are less with fall application versus spring. Now if I go to the North, I go to Crookston, some of that data, it's that shows relatively little difference. There's situations in the actual fall looked a little bit better up there. So timing wise, I think spring is still a a good option for urea.
Dan Kaiser:I mean, manure and anhydrous are a different story altogether, I mean, in terms of timing on that. But at least for urea that, at least in the South, it seems like spring is a little bit better. And I know that kinda doesn't fit with a lot of growers in terms of what's going on there, and we've been looking at some of these, inhibitors to try to counteract that. I just don't have any straight answer on that in terms of what's a good option right now other than the fact that, you know, consistently, at least about half the time, we're seeing the spring application do better than the fall.
John Lamb:When I started working in the Southern Minnesota beet growing area in the late nineteen nineties, I started out looking at fall versus spring. And most of the time, the fall when when I did the correlation calibration on that data, the fall actually predicted the response better than the spring, but then we'd have some wild swings in the amount of nitrate in the soil between fall and spring that we couldn't explain. So I what Dan's finding is very similar in the ways of the fact that the you know, you would think that the spring would always be a better time because you're closer to the time that the plant needs it. The other thing I would tell you about nitrogen management on sugar beets. The most important application is the pre plant application because what the beet needs, it needs enough nitrogen so as it will develop leaves that cover the row because it's the leaves that are acting like a solar panel to bring in energy and converting it to sugar.
John Lamb:By the time you get to July 1, in most years, you have the rows closed and there's enough mineralization in the soil to take care of the nitrogen needs to harvest to have a good quality beet.
Dan Kaiser:The other thing I'd say too is phosphorus. Right now, I know that is a big issue because of price. Phosphate DAP/MAP prices are relatively high. That a lot of the older data would show that, you know, you can get away with a small amount or smaller rate of phosphate if applied in furrow. And I know, John, that was a lot of that work was with 10- 34 -0 , I think, that Albert Sims did.
John Lamb:Yep.
Dan Kaiser:Then a lot of growers now have switched to some of these low salt sources. So I don't know how applicable I mean, the same gallon rate would be if I'd say of, like, a 6 24 6 versus 10 34 0 , if that difference in the amount of phosphate matters. So that's one of the things that I've been trying to get some funding for just to do some comparisons, just to see. Because if it is related to the the pounds of nutrient, then there could be some issues essentially if you're using, like, say, three gallon rate, which I think is was the going rate, which is what Albert found what could replace some of the higher broadcast rates. There's some things out there on the cost cutting side, I think, that could be done, especially with beets, and that would be one of them is, you know, in-furrow starter versus the broadcast, phosphorus.
Dan Kaiser:And, K, I haven't done a whole lot of work with that. You know, John, you've done some work in the past, but that seemed to be more limited too to some of the the lighter grounds, the irrigated grounds we're seeing more of a response to k.
John Lamb:My work on K basically said it didn't make any difference. And we used, you know, K rates from zero to 500 pounds per acre just to see if we could cause other issues with other nutrients, and we really didn't see a difference between that or any interaction with nitrogen. As for the phosphorus, Al Sims found that that three gallons of 10 34 0 would perform like a 60 pound P205 application broadcast. We did just a little bit of work with with George Rhem on some of that looking at at different 10 34 0. And I don't remember the exact mixtures, but there were other mixtures and we really didn't see much difference.
John Lamb:But that was like a that was a three year study and and we didn't always show a response to phosphorus in those sites. With with our experience with phosphorus, you have to be in the bargain basement. And I mean, an Olsen salt test of less than six to get a response to phosphorus. And when you get a response to phosphorus, it's it's in tonnage. Phosphorus does not hurt quality.
John Lamb:And there's some preliminary data starting that we're starting to work on out of Southern MN that shows that you gotta have really low sites and those are hard to find.
Melissa Wilson:Just wanted to add that manure obviously comes with phosphorus and potassium as well. And typically because of the way manure is stored and handled, if you're applying in a nitrogen based rate, you're applying more than enough phosphorus and potassium. So that's another thing. If you're looking for cost saving measures this spring, something to consider is manure.
Jack Wilcox:John, you said something interesting earlier. Beets will take up whatever nitrogen is sitting there like no other plant you know. Do you have any idea why that is?
John Lamb:I have no idea. I'm sorry. I'm not a very good physiologist, but that's just the nature of sugar beets. It it scavenges for nitrate.
Dan Kaiser:The taproot on that, John, though, will go down quite a ways. Correct?
John Lamb:Well, yeah. See, a lot even in the drought of eighty eight now see, I'm talking like an old man here, but the drought of eighty eight, we saw roots down at eight and nine feet. In other times when we've done studies to look how deep they go looking at the water withdrawal, by the July 4 or the July 1, they're down about four feet already. It's quite a root.
Jack Wilcox:John Lamb, Professor Emeritus of Nutrient Management. Melissa Wilson, manure nutrient management specialist and water quality expert. And of course, Daniel Kaiser, nutrient management specialist, all with the University of Minnesota. Thank you all for being here.
Melissa Wilson:Thanks for having us.
Jack Wilcox:Do you have a question about something on your farm? Just send us an email here at nutmgmt@umn.edu. Thanks a lot for listening, and we look forward to seeing you next time.
Jack Wilcox:We'd like to thank the Agricultural Fertilizer Research and Education Council, or AFREC, for supporting the podcast.
