(Jim) Good morning folks and welcome to That’s My Farm. I’m Jim Shroyer your host and we are here in Manhattan, Kansas, and we are going to be talking to an Extension Soil Fertility Specialist here in just a second because really now’s the time to be thinking, if you haven’t already done it, to put top dressed nitrogen on the wheat. So stay with us, we’re going to be talking with Dr. Dorivar Ruiz Diaz when we get back. See you in a minute.
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(Jim) Good morning folks and welcome to That’s My Farm. I’m Jim Shroyer your host and we’re going to be visiting today with Dorivar Ruiz Diaz. He is our Extension Soil Fertility Specialist. Dorivar, thanks for being on the show with us. It’s top dress time for wheat, if you haven’t already done it. So what do producers need to be thinking about? (Dorivar) Yes Jim you are right, its the time of the year we need to be thinking about top dressing for nitrogen and actually other nutrients for wheat. I think one way to think about the key points for top dressing would be to think about the 4 R concept of nutrient management. That would be the right placement, the right time, the right source and the right rate of fertilizer. And this is something that applies for any nutrient management but for top dressing would be one excellent way to do that. If we start with the right rate of fertilizer obviously we need to keep in mind what we need in terms of the pre-plant application rate and basically what’s left in terms of how much we need to put for for top dressing wheat to meet that requirement. (Jim) So what if you put on a minimal amount, less than 20 pounds of nitrogen prior to planting? (Dorivar) That’s probably a pretty good option actually because obviously we don’t need a lot of nitrogen in the fold because we don’t get a lot of growth. So having some nitrogen there basically as a starter for to be sure they grow early on, that’s a good option. Many people would come back at this time of the year and put the balance of that nitrogen again, with most of that nitrogen going this time of the year. First of all, to minimize any potential nitrogen losses, but also we can estimate what kind of moisture we have, what kind of yield potential and we can still make some adjustments to that rate based on the potential yield that we expect this year. (Jim) OK, so how do you figure out the rate that we need to use? (Dorivar) A recommendation at K-State we have an equation to come up with the rate where we take into account the yield potential, that’s a key factor. So we have the yield potential as one of the components. And then we start to take credit for any residual profile nitrogen we already have from the previous crops. And that could be quite significant. We see in some cases after a failed corn or some crop with very low yields we may have actually a significant amount of nitrogen left from that season. We’ve seen some cases coming into the testing lab where we have easily 100 pounds plus of nitrogen already in the soil. In those cases you may need very little if any nitrogen applied to the wheat. So that would be another key factor, or components, we have in that equation to take into account any credits from previous crops. As well as legumes for example that may be providing some nitrogen as well as any organic source like manure application. (Jim) In the organic matter level. (Dorivar) And in the organic matter as well. That’s a key factor actually. And we are saying usually about 10 pounds of nitrogen is coming from each per cent of organic matter that you have in the soil. Its also very important to have organic matter tested to account for that. (Jim) So really last summer we should have soil tested to know what was in the profile, should have taken a profile and test. (Dorivar) Yes, before planting. Ideally in the fall before planting we should have that information. If we don’t have that information at this point, unfortunately there’s not much we can do because we’re ring to have to use a default value which is about, we say a default value of 30 pounds of nitrogen. But like I say, in some cases we’re seeing 100 plus pounds of nitrogen already there. (Jim) The 30 pounds you’re talking about that’s in the soil. (Dorivar) That’s in the soil, yes. (Jim) so then you go from there. (Dorivar) So then you go from there in terms of yield potential and taking into account any other credits that you may have. (Jim) Well I know that when I first go here we were talking about one and a half pounds per bushel. And really its 1.75, I’ve heard some consultants say over 2 pounds of nitrogen for every bushel that you’re hoping for. But really what you’re saying is that formula is the best way to go. (Dorivar) that formula is really the best way to go. (Jim) Dorivar, we’re going to have to stop right now and hear a word from our sponsors, so don’t go anywhere. And you folks at home, you don’t go anywhere either, except maybe for a cup of coffee, and come right back.
(Jim) Welcome back to That’s My Farm, I’m Jim Shroyer, and Dorivar Ruiz Diaz is still with us here and we’re going to be talking a little bit more about rate. There’s some new technologies out that might help with that. (Dorivar) Absolutely Jim, and one of those is the sensor technology that works really well for wheat in particular. We do a lot of work here at K-State looking at calibrations of those sensors. And the way these work is basically the sensor measures the level of ??? and the level of biomass that you have early in the season wheat and based on those measurements its basically providing a recommendation for application rate. These sensors also give you an estimate of potential yield, yield potential for that field. These are really good, very accurate, taking into account all the factors that we mentioned already in terms of residual nitrogen, yield potential, organic matter, everything, so its an excellent tool. Its becoming more affordable for producers and something that can work very well for wheat. (Jim) OK, we’ve talked about the rate, the 4 R’s, what do you want to go to next, the source? (Dorivar) Let’s talk about the source, that’s the next one. And again in terms of source, we do have many options and the main one would be liquid or dry fertilizer. A lot of that depends on the farm and what is easier for the farm, as well as economics. Economics is a big part. (Jim) Well dry is obviously cheaper. (Dorivar) Obviously cheaper, but many times liquid may be more convenient for some producers. In terms of availability, in terms of efficiency of each fertilizer in theory they should be equal, however, there are some challenges with each of the different types of fertilizer. For example, dry fertilizer may be subject to some quality losses. (Jim) On high evaporative days. (Dorivar) Absolutely. In the case of liquids, since we are talking about UAN, only 50% is urea, in that kind of situation obviously the potential is much lower. Again, if you have some moisture, some rainfall, some snow after application its very likely you’re going to have a good infiltration of nitrogen into the soil and that shouldn’t be an issue. (Jim) So also an advantage to liquid is weed control as well. (Dorivar) Yes, and that’s what many producers do, and again, maybe a more convenient option for many of them because they are doing herbicide application at the same time and liquid would be a better option for them in that kind of situation. (Jim) One thing, driving around the countryside, in early spring after a foliar application, this liquid, is that you see this burning out there. (Dorivar) Yes, and that’s a big concern in that case. Actually not just the burning of the leaves, but we have the potential for ??? if we are spraying the UAN on top of residue, so that could be a concern for example for no-till producers where there’s a good level of residue where tie-up could be a concern. (Jim) So dry wouldn’t be a bad idea? (Dorivar) Dry wouldn’t be that bad because dry would probably move through that residue and get into the soil. And here we are already basically talking about one of the other 4 R’s which is placement. (Jim) OK, hold that thought. We’ve got to take a word from our sponsors. Folks, we’ll be right back.
(Jim) Welcome back to That’s My Farm and we have Dorivar Ruiz Diaz and Dorivar, let’s continue with those 4 R’s. (Dorivar) The next one would be placement, a key one. We were just talking about the different sources, dry, liquid, and that’s where placement can help us with minimizing any potential losses, potential tie up with the residue. (Jim) Like in no-till? (Dorivar) Absolutely in the case of no-till. Again if we have that kind of situation where we have heavy residue and we are concerned with potential tie up, using streamer bars for liquids. try to stream that fertilizer, concentrate it. (Jim) Reduce the tie up. (Dorivar) Reduce the tie up, that would be a good way to also improve efficiency. there are other considerations for applications, for placement we have some people who actually even do some anhydrous application as a top dress application, which would be an option. Again we do have some issues with damaging the wheat and that could be a concern, but its also one alternative. (Jim) What about timing? The last R, right timing? (Dorivar) Yes, the last but not least is obviously timing and this is very important. When we’re thinking about the development of that growth we want to have the nitrogen there but in time to be able to produce the yields that we need. (Jim) the tillering? (Dorivar) The tillering and in the case of top dressing you want to be there for sure before jointing to make sure that nitrogen is in the roots and its available to the crops. On the other hand, we don’t want to go too early and be subject to some run off or potential losses from snow or anything like that. (Jim) OK let’s talk a little bit about that with timing. Why do we say don’t put on frozen ground? Or over the top of snow? (Dorivar) There’s a few things, there’s an agronomic and environmental side to that. On the agronomic side we’re putting fertilizer on top of snow or frozen ground and one concern is we’re going to have a lot of that nutrient moving around and you may have ares short of nitrogen and other areas may be high in nitrogen. So distribution and efficiency will be lower as well as getting some of that nutrient into water bodies. (Jim) In the field, and then down the river. (Dorivar) Which is inefficiency in terms of agronomically use of that nutrient because its leaving the field. (Jim) Stay with us, we want to talk a little bit about some other nutrients as well. Folks we’ll be right back after these words form our sponsors.
(Jim) Welcome back to That’s My farm, and Dorivar is still with us here and he’s still talking about nitrogen and top dressing. Let’s talk about some other things other than nitrogen. Let’s talk about sulfur and chloride, which seems to be gaining al little bit of importance in our wheat crop. (Dorivar) Yes, that’s a very good point Jim. Especially sulfur seems to becoming more and more of an issue for us in Kansas. We’ve been seeing a lot of sulfur deficiency showing up in recent years. And top dressing would actually be a very good timing to go out and put that sulfur especially in regions where we expect to have some sulfur problems. (Jim) But how do you know you’ve got sulfur problems? Do you take a soil test or just see the plants or what? (Dorivar) You can do soil tests and we actually talked earlier about the profile nitrate test and that would be an excellent time to also go out and have that soil analyzed for sulfur. Again both nitrogen and sulfur are mobile in the soil so getting that profile you can get a good idea about both nutrients at that point. So that would be one good way. now there’s also situations where early in the season you’re already seeing some sulfur deficiency. We’ve been doing some research that you can still recover some of that if you go ahead and put some sulfur at that point. (Jim) And we’re talking at a point near flag leaf emergence, and that’s that point, right? That’s when you really see it. (Dorivar) You can see it much earlier sometimes, you’re getting too late around flag leaf stage. That may be a little difficult to do much about it for sulfur. (Jim) OK, so how much sulfur do you need? (Dorivar) Its usually smoothing that we don’t need any high amount. Usually about 20 pounds should be enough for our crop. Now one thing about sulfur that we
need to keep in mind is the source will really make a difference. It really needs to be in a viable form so we want to have a sulphate form of sulfur. We’re talking liquid, ammonium sulphate would be one way we could put some of that sulfur. Dry fertilizer could be ammonium sulfate, its becoming more available now. but also I think gypsum, calcium sulfate, those all are going to be available to that crop immediately. (Jim) So if we’re top dressing with a liquid we’re going to be using what? (Dorivar) Ammonium thiosulfate is going to be the option in that case, in liquid. Now one concern with that is if the wheat has already greened up we may have some leaf damage. (Jim) that will burn the leaves even more. (Dorivar) That will burn even more, so we have to be careful there. We want to go early enough or make sure we use streamer bars to minimize any potential leaf burn. (Jim) What about chloride? (Dorivar) Chloride is another one that could go at top dressing time. It’s again a mobile nutrient so you can put it at top dressing time and there would be enough movement of that nutrient that’s going to be available to the roots. Seems like here in Kansas we see more response to chloride in the central part of the state. Obviously in the eastern part of the state we have history of potassium chloride applications so we usually have enough. And in western Kansas we don’t have a lot of rainfall to leach that chloride so we usually tend to have enough in the system. but in the central part of the state we see very consistent response to chloride application. (Jim) thanks Dorivar, we’ll be back in just a second so don’t go away. Folks, don’t go away we’ll be right back.
(Jim) Welcome back to That’s My Farm. Dorivar, finish up on some micro-nutrients. (Dorivar) Yes, Jim, that’s a study we worked together in the past. We have done quite a bit of research now on micro-nutrients. In addition to the chloride, and maybe the sulfur that we mentioned already, we haven’t seen any consistent benefit to any of the micro-nutrients. the ones we are evaluating in our study were manganese, copper, zinc, iron and boron as well. So we focused on those and again in multiple locations, farmers fields, we haven’t seen a lot of consistent response in wheat. (Jim) Is there any way that you can tell you’re going to get a response to these micro-nutrients? (Dorivar) That’s an excellent question because we do see some sites that would show some benefit. It goes back again to the soil condition. Soils that tend to be pretty sandy, very low organic matter, perhaps high pH, those may be candidates to see some benefits. Now if you go ahead and put it across all fields without looking at your soil, may not get any benefit from those nutrients. So the key is again, look at your soil and try to make a decision based on the soil types. (Jim) Dorivar, I want to thank you for taking time to talk to us about top dressing our wheat because now’s the time to be it. Folks, thanks for being with us as well. And don’t forget next Friday we’ll be back with another session of That’s My Farm.
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