Top Dressing Nitrogen

(Jim) I’m Jim Shroyer your host. And we’re in luck because we’re going to be speaking to Dr. Dorivar Ruiz Diaz, our Extension Soil Fertility Specialist on top dressing nitrogen. He’s going to be talking to us about very important topics to be thinking about when top dressing. So, get your cup of coffee, come on back and we’ll get this show on the road.

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(Jim) Good morning folks. Welcome to That’s My Farm. I’m Jim Shroyer your host and we’re in luck because we’re going to be speaking to Dr. Dorivar Ruiz Diaz and Dr. Dorivar is our Soil Fertility Extension Specialist and this time of year Dorivar we’re thinking about top dressing nitrogen. So, what are some things farmers have to think about in preparing for top dressing? (Dorivar) There are several key points we need to take into account as we are getting ready for top dressing. One of those is obviously timing of that nitrogen application. But also what kind of rates are we going to be putting? The placement of that fertilizer and the source of that fertilizer that we’re going to be using. Those are probably perhaps one of the keys points that we need to consider. One other thing that we may also think, depending on the situation is what else we may be thinking in terms of nutrients? Are we going to put something else… (Jim) Boron, zinc or sulfur. (Dorivar) Yes. So, those are also some questions that we need to keep in mind. (Jim) OK. So, let’s talk about the first two, the timing and the rate, cause those kind of go together. If you put all your nitrogen on in the Fall, well you don’t have to worry about too much this Spring, this Winter and Spring. So, they kind of go together. Let’s talk about those for a second. (Dorivar) Yes, yes, they kind of go together and obviously again ideally, when it comes to rates you want to have a good soil sample ready, a profile nitrogen sample in the Fall, that will give you an estimation of how much more nitrogen you may need to be putting on this Fall. So, that will give you a good idea. But also the timing of that has implications in terms of how much you really plan and how much more are you going to need to be putting here in the top dressing application. We usually require some level of nitrogen at planting, at least. And that’s very important to keep in mind obviously. Top dressing could be one of the main nitrogen application times but we still need to have some of that nitrogen apply at planting, so we are assuming you already have some of that nitrogen applied. (Jim) So, let’s talk a little bit more, shift a little bit more back more toward timing. At this point anytime on, til when? When is the farmer going to get the biggest bang for the buck related to top dress nitrogen? (Dorivar) Yes, there’s a couple of things we need to keep in mind there. Obviously we want to have the nitrogen early enough to make sure easing the roots on when their uptake happens later this Spring. So, that would be a key component that we need to keep in mind. So, we really need to be thinking about that fairly soon here and for sure we don’t want to be after jointing which is really kind of the latest you can be thinking about application. (Jim) OK, so what happens if I run into a wet spell? I put it on before jointing, and there’s a two to three week period there that I could have, should have put it on, but I can’t. Now it’s dry and it’s after jointing. What do I do? (Dorivar) I think obviously still it would be a value applying nitrogen at that point, but the risk at that stage is that you may not get the full benefit from that nitrogen application. You still have the risk of that nitrogen not moving in the root. So, obviously you want to be looking at the conditions in the next few weeks and if at all possible move forward with the application at this point. (Jim) Hang on. We’ve got to take a word from our sponsors. So, folks grab your cup of coffee, come on back and we’ll talk to Dorivar some more.

(Jim) Welcome back to That’s My Farm and with us we have Dr. Dorivar Ruiz Diaz. And Dorivar we were talking about timing and rate of top dressing just a second ago. Let’s kind of continue that a little bit more. I was asking you a little bit at the end there about what happens if it’s too wet and you have to go past jointing. What happens if you have frozen, ice, snow covered fields out there? (Dorivar) Yea, those are some of our challenges and of course to avoid those conditions. If we have frozen ground or snow covered conditions, we want to avoid putting nitrogen down in that kind of scenario because we can have significant account of runoff and in some cases the nitrogen may not leave the field. However that distribution is going to be affected significantly. So, we want to look for some days when we don’t have those conditions ideally for nitrogen application. (Jim) So, let’s talk about rate again. I know we’re past the pre-plant time, we’re thinking about top dressing. But do we normally think about the distribution or the amount we apply in the Fall versus what we apply in the Springtime? Is it 50/50 or 20/80 percent? What do we normally think about? (Dorivar) Yes. Ideally I would like to see most of the nitrogen applied as a top dress, especially in soils that can have potential for nitrogen losses, sandy soils for example… (Jim) Sure. (Dorivar) …could be a concern. So, in that case again, I would like to put just small amounts in the Fall. Remember we don’t take a lot of nitrogen in the Fall. Also the nitrogen… (Jim) There’s no roots, no plants. (Dorivar) There’s no roots, there’s no growth much, so you just need a little bit of starter. Sometimes it’s enough. And then come back with the full, with most of the nitrogen application in the top dress time. Again, minimizing losses for some of those problematic soils, in particular could be very important. (Jim) OK. So, we’ve talked about timing and rate a little bit. There’s a formula for rate that we talk about the profile nitrogen being important so kind of, can you tell me a little bit about that formula? (Dorivar) Yes. We think about that formula. The key in that formula is really yield potential. So, that’s something that is very important. And again, I know many producers also like to do more of their application as a top dress for a reason. Because it’s pretty difficult to have a yield expectation in the Fall when you don’t know if you are going to get the moisture, you don’t know what’s going to happen. At this point we’ll hopefully have a better idea. We also kind of know what happened last year in terms of yield potential, if we didn’t get a profile nitrogen. If we have a failed crop, sometimes the probability of seeing more residual nitrogen is higher. (Jim) Right. (Dorivar) So, we can take that into account also when it comes to rates. In many cases last year we had some pretty good yields. Chances of seeing residual nitrogen, nitrogen in that kind of situation would be lower. (Jim) Right. There’s been some, there’s been some soil profiles in that south central, central Kansas, that 60-80 pounds of nitrogen left over from the previous year. So the soil profile test is really important. (Dorivar) It’s very important, yes. (Jim) Dorivar again, don’t go away, we’ve got to have some we gotta take a break here. Folks, come right back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm. I’m Jim Shroyer. With us we have Dr. Dorivar Ruiz Diaz. Dorivar didn’t run off during that break and we’re happy for that. Dorivar, let’s continue our conversation about top dressing nitrogen. We talked about timing and rate. Let’s talk about source. (Dorivar) Yes, source obviously is another key component and many producers obviously will choose the source of fertilizer based on convenience, how they are set up, how they usually do their programs. But you know… (Jim) Cost. (Dorivar) Yes, but also, that’s a key point. The cost is a big, big factor and it’s something that we need to be looking at, especially this year. The grain prices are not… (Jim) They’re bad. (Dorivar) They are bad. So we need to be looking at that very closely. And in terms of source typically for top dressing we can use dry urea fertilizer UAN liquid, obviously is a popular one. But actually many producers that would do top dressing with anhydrous as well, which is something that is a possibility. We do have some research on that as well to evaluate that source. (Jim) OK. (Dorivar) And again, one thing, a few considerations that we need to keep that in mind when you are choosing those different sources is what potential you have for efficiency, potential for losses for that nitrogen. Again, as we are thinking about improving efficiency in general. Typically if we are talking about broadcasting for example a liquid fertilizer, we can have some concerns in terms of tie up. (Jim) On the residue you’re saying. (Dorivar) On the residue. If we have no till tie up, no till system tie up that could be a potential factor. So, we need to be thinking about that, especially where we’re talking about how we place that fertilizer as well. So in that case, for example, the use of dry urea fertilizer that can move through that residue and into that soil may be a better choice. May be a better alternative compared to broadcast liquid fertilizer. Like I say, anhydrous application as well is something that we’ve been looking at. And like I said many producers use it. Sometimes you do have some damage to the stand, to the wheel. (Jim) Do you go with the row or across the row how do you do that? (Dorivar) One thing that we’ve been doing is going in at an angle and that seems to work pretty well for us. We inject the anhydrous in about 20 inches or so, that seems to be also a very good distance. If we go out much further than that, 30 inches, we may start to see some waving later on and that sort of thing. But about 20 inches seems to work pretty well. Going in at an angle, we don’t see a lot of damage to the wheat, with very good results. (Jim) You can’t cover as much ground can you? With anhydrous because you’re…as opposed to broadcast or using a liquid it’s a much slower process going. (Dorivar) Absolutely and that’s part of the decision that the producer needs to make of course, what’s going to be more convenient in terms of the speed that they need and again the availability of equipment as well. And also whether they put on herbicide. (Dorivar) Yes. And that’s another good choice, another good point. And again, the reason why many people choose UAN because again, many people will be putting herbicide. (Jim) Carrier. (Dorivar) That’s a carrier. Those are different factors that we need to be thinking about as we choose the right source. (Jim) Well with UAN also you’re probably going to get a little burn, that’s always shows up. (Dorivar) That always shows up. Obviously depending on conditions, if we have warmer temperatures a little bit of green in the leaves, then we start to see obviously, more of a burn. But again a lot of times that seems to be also more cosmetic at this point. (Jim) Sure. (Dorivar) We don’t have still a lot of biomass to really cause a problem. (Jim) OK. Hang on here. Folks, stay right with us. We’ll be back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm. I’m Jim Shroyer. Dorivar stayed with us again and I appreciate that. Dorivar we talked about timing, rate and source. The last one of course is, placement. OK, let’s continue our conversation. (Dorivar) One thing that we also need to keep in mind when it comes to nitrogen application now is the place of that nitrogen, how we put in that. A lot of that is related to what we were just talking about the source of that nitrogen, source of fertilizer, obviously depending on what we are using we have different options. If we are using anhydrous, obviously we are injecting that. That usually tends to be a pretty efficient way of putting in nitrogen. But then if we are talking about liquid, we have multiple options really. Very often we do a broadcast application, again with herbicide that could be one alternative. But again, thinking about potential for losses and especially tie up, we have a heavy residue situation we may really want to think about using streamer bars, streaming that nitrogen can definitely help us to minimize contact with the residue and minimize tie up losses. (Jim) So that doesn’t cause any kind of a streaking through the field? What settings are those on? Are they on like eight or ten inches? (Dorivar) Yes and there are different types of nozzles that we can use for that. But essentially what we are trying to do is we basically try to concentrate, we basically try to stream that fertilizer and concentrate it so we minimize contact with the residue. And we can look at different type of nozzles that basically do that. But again, that would be one alternative in terms of trying to minimize potential losses. In the case of dry urea obviously we are typically going to be broadcasting that. And the advantage of dry urea is that again that you should also move through the residue in getting to soil, minimizing potential tie up problems. One thing that we…potential for losses at this point that may not necessarily be a concern but many times we get these questions, what about volatilization when you talk about urea… (Jim) Volatility. (Dorivar) Volatility or urea and UA in particular. That’s usually something that traditionally we say is not a big concern given these conditions, cold temperatures. (Jim) But… (Dorivar) But there could be some days that we can have higher temperatures and we can have some volatilization there. So there is that possibility. And again, obviously placing the fertilizer for example using streamer bars can also help to minimize that. (Jim) So a situation that would cause volatility losses would be what? (Dorivar) Situations that would contribute to that will usually be a good soil moisture combined with high temperature. A high temperature again, above 60 close to 70 that’s where you start to see volatilization happening. The other thing also is that we’re ideally going to have some moisture, some type of moisture to move that nitrogen in the soil to minimize any potential losses. (Jim) So, if it’s laying on top of the surface, it hasn’t gone into the soil solution yet, then it’s subject to volatility. (Dorivar) It’s subject to volatilization if that’s standing there for a very long time and we have higher temperatures. (Jim) Right. But if it’s worked in by snow or rain or what have you then basically we’re scott free. (Dorivar) Yes, that’s what we want, yes. (Jim) OK. We’ve got one more section to do. Folks, stay with us as well. We’ll be right back after these words from our sponsors.

(Jim) Welcome back to That’s My Farm. I’m Jim Shroyer, your host and with us we have Dorivar Ruiz Diaz. Dorivar, we’ve talked about top dressing nitrogen. What are some other nutrients that can be put in with that, or we should be thinking about this time of year? (Dorivar) Yes, typically we like to look at the mobile nutrients and a couple of nutrients that can be applied at this time of course are chloride and sulfur. For some of those soils in some regions we are seeing benefits from these nutrients. In the case of chloride it’s something that we see quite a bit, especially if we are in kind of the central part of the state where we don’t have a lot of history of potassium chloride application. Because we usually have enough potassium labeled. So, chloride is definitely beneficial in that case. We still need to look at that profile sample. Not just nitrogen but also chloride and sulfur. (Jim) Because those chloride and sulfur are mobile. (Dorivar) They are mobile, so we really need to look at that profile, 24 inches ideally to have a good idea. But it works pretty well for chloride, so based on that information, we can decide whether we need to be putting some chloride also with the nitrogen this time of the year. In terms of rates for that, the maximum rate that we’ve seen in our research is up to 20 pounds. That’s all we need to put. We’ve never really seen any more, more than 20 pounds. In terms of the type of chloride that we can use, pretty much all of the sources are good. It could be liquid. It could be potash, potash and chloride dry fertilizer. That would work well. Again, it’s highly mobile. So, once you put it in the soil, it will move into the soil pretty easily. The other nutrient that I can mention is sulfur and that’s also something that we are seeing quite a bit show up in recent years in some parts of the state. (Jim) It looks kind of like nitrogen deficiency, doesn’t it? (Dorivar) It looks like nitrogen and that’s been one of the challenges actually because sometimes we say, well it looks like nitrogen may put more nitrogen to it but actually that being sulfur. And we’ve seen some of those situations. Now in the case of sulfur, we really…the source can make a difference. (Jim) Really? (Dorivar) And we really need to be thinking about sulfate form of sulfur to apply because that is a form that is going to be valuable immediately. (Jim) As opposed to elemental? (Dorivar) As opposed to elemental sulfur which is something that could be a good price, you usually see a good one in terms of price. However, you need more time for that to basically hydrolyze and become available to the crop. (Jim) Lastly here, what do you have in your hand and how can it be used? (Dorivar) Yes this is another tool that we use quite a bit in our research program in general and many producers are using, is basically a sensor. It’s a hand held sensor. This is obviously…you can get one that has… (Jim) More bells and whistles. (Dorivar) More bells and whistles, but this is a very simple one that you can use. And basically what you’re doing with this is you go over the canopy and take a reading. And it will give you an index, a value that is an indication of how green the plant is, how much biomass you have. And this is correlated very well to nitrogen and potentially nitrogen recommendation. So, we talked earlier about the importance of soil testing for nitrogen. This is one alternative to soil testing and if we don’t have that information we can do well if we use sensors. (Jim) Soil testing is very important but this is another tool to use. (Dorivar) It is another tool to use that can help us to fine tune nitrogen recommendations, yes. (Jim) Dorivar, thank you again. Thank you as always for being on the show with us. Folks, thank you, thank you for being with us. And don’t forget next week about this same time, we’re going to have another issue of That’s My Farm. See you then.

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