 The first three presentation of the morning are going to be dealing with not only nitrogen but PNK placement, I would say the four arcs, right timing, right placement and right location. So I would like to invite our first speaker of this morning, Dr. Steve Phillips with IP and I, and he will be discussing on the importance of PNK and micronutrients. Thank you, Steve. Thank you, Brenda. Good morning. It's like we lost a few from yesterday. Yeah, eight o'clock's always a tough spot. First in the morning and right after lunch and right before happy hour. So we'll see what we can do to get through. PNK and micronutrients, that's quite a bit to cover in 40 minutes. So what we're going to do is just kind of hit a general overview of fertilizer management with some specific examples and kind of some cool things that we can say about these three nutrients. Before I get started, I want to tell you a little bit about IP&I. I work for the International Plant Nutrition Institute. For those of you that are not familiar with IP&I, we're a not-for-profit scientific organization. We're funded by membership dues paid by fertilizer manufacturing companies and industry associations around the world. We employ 34 PhD level scientists in regions literally covering everywhere in the world except for western Europe. Our mission is to develop and deliver science-based information on the responsible management of plant nutrition. And as Brenda mentioned, when we talk about responsible management, we're talking about what we've defined as four-hour nutrient stewardship, applying the right nutrient source at the right rate, at the right time, and in the right place. Now how this differs from traditional soil fertility management, you may look at these components and say, well, that's obvious what's new about that. But it's the way that we work it into an entire framework, a holistic approach recognizing that every fertilizer management decision includes all of the four hours, source rate, time, and place, and that everyone affects and is affected by the other three. And so often in nutrient management we get caught up focusing on one single aspect of fertilizer management, usually rate, because it's the one where we can see the most direct relationship to profitability and production. It's also the one that gets the most attention from the environmental stakeholders as that's the ones that we see N and P most often directly affecting environmental quality when mismanaged. And so we need to remember that these are all interdependent on one another and that we need to look at them holistically when we talk about nutrient management. Now what's right in terms of the decision we make varies depending on climate, location, cropping system, soil characteristics, logistics, resource availability. This is very site specific and so recognizing that within for our nutrient stewardship one size does not fit all. But what is universal are the scientific principles that guide the decision making process. So while we may come up with what seem to be very different nitrogen recommendations for corn, for example, as we look around at different regions in the U.S. and in the world, but what we'll find is that the scientific principles guiding that rate recommendation are the same. And so within the context of a cropping system giving equal weight to social, environmental, and economic sustainability of the production system, that's what we're really trying to establish with for our stewardship. And so to spend a little time talking about some of these principles, I'm going to start with rate. Now as I mentioned, what we do with rate depends on what we're doing with source, timing, and placement. But specifically some of the principles regarding rate is the most obvious is that plants require a certain amount of nutrient. 17 essential nutrients, each equally important in optimizing yield. Here's an example of some of the amounts of nutrients that need to be taken up to produce a certain level of yield. Now some of these nutrients will be supplied by the soil, others we're going to have to add in fertilizer. Now often we see these types of numbers, but what I'm going to point out is we're showing uptake. This is not nutrient removal. A lot of times when we start talking about nutrient balancing and trying to use these types of numbers to calculate changes in soil fertility, we're talking about removal. Now these are very different than uptake, and I'll show you this a little bit later. There are also factors affecting the soil supply of nutrients. As I mentioned, some of these will come from the soil. We have inherent nutrient sources within the soil, as organic matter, insoluble, inorganic compounds. And there are several chemical processes that control the amount and availability of these nutrients to the plants. And this varies regionally and according to climate, there are temporal and spatial factors affecting nutrient availability. And so when we go to making rate recommendations, we need to take some of these into consideration. There are also plant factors that affect nutrients. Nutrients are taken up differently by plants. Some of the mobile nutrients like nitrogen and sulfur are taken up with water as the plant roots transpire and draw water in. Nutrients come with it. Other immobile nutrients like phosphorus, the roots actually have to grow out and come in contact with the fertilizer. And so understanding the different nutrient behaviors in soil helps us understand more about how to manage those in terms of plant availability. One example is potassium. Potassium is one of the nutrients that we find on the exchange site. You've heard of cation exchange capacity. Soils have different levels of the nutrients they can retain on the soil surface. And then those nutrients are freely exchanged in and out of soil solution where the plant roots are taking them up. Now potassium is one that is on the exchange sites. And so these will go into solution and become plant available. But we also have potassium fixed within clay layers. And so the amount and type of clay that we have will also affect potassium availability. And so this is why it's important to use the correct soil extraction chemicals when we're doing a soil test for available potassium. Because we want to be able to extract a good representative amount of the potassium that's going to become plant available. And so that's when we get into some of the differences that we see with laboratory methods and different recommendations coming out of one lab or the other. Is it might very well be a difference in the laboratory methods that they're using. We'll talk a little bit more about that. Phosphorus is another one that the soil environment has a great deal to do with the plant availability of this nutrient. If you've studied any soil fertility in school you'll recognize the solubility diagram. This is not the intent of this lecture. But what we know about phosphorus is it's very strongly controlled by soil pH. Phosphorus, the phosphate ion doesn't exist as free phosphate. It's always going to be in a compound with something else in the soil. At high pHs it's going to be precipitated as calcium or magnesium phosphate. At low pHs it's going to be as an iron or aluminum phosphate. And so there are many different forms that phosphorus will take in the soil. And what we're concerned with is where can the plant take it up from. And that would be the labial form in solution. But most of our soil phosphorus is in these non-labial forms. And so again the soil extraction method that we choose is very important for identifying the amount of soil phosphorus that will become available to the plant during the growing season. Soil pH we've talked about clay type and amount with potassium. But as you can see there are many, many factors that affect the nutrient supply in soil. Soil pH is probably the most dominant chemical characteristic in soils that affects nutrient availability. We especially see this with our micronutrients in terms of changes in soil pH affecting the availability of these nutrients. But as you look down through here take for example phosphorus just about anything that's going on in the soil physical or chemical is going to affect phosphorus availability to plants. Nitrogen a lot of these not so much again that has to do with the more mobile nature of nitrogen. Micronutrients you can just go across the board and see that just about anything moisture, temperature, aeration, type and amount of organic matter, clays, crop residues. So this is where we get into the 4Rs being very site specific and very unique to the cropping system is that the decisions we make regarding fertilizer management and recommendations there are a lot of things that are beyond our control that affect what we do in terms of a recommendation. So this is why it's very important for us to understand soil nutrients. Now I can't give a fertility talk to a group of advisors and growers without stressing the importance of soil testing. This really can't be overstated. It to date remains our best tool available for assessing soil nutrient supply. What we get into now is a lot of concern over the accuracy of soil testing particularly in terms of our recommendation. I think there was a talk yesterday or maybe this afternoon on some changes in nutrient requirements with some of the newer hybrids or varieties that we have coming out. Certainly we have as I've mentioned spatial and temporal issues. And so there are a lot of precautions we need to take when collecting our soil sample to make sure that it's representative and able to give us a good number in terms of nutrient requirement. Now potassium gets a lot of attention because that's the nutrient when we get our soil test. If we do annual soil test and we look at those, it's not uncommon for us to see that potassium number having much more fluctuation in it than some of the other nutrients. There are various reasons. One of these we can see that soil test potassium is affected by both soil moisture and temporal variability. Simply changes in the time of the year. As we look at this figure across four years of soil samples, the blue line represents soil moisture and the black line represents soil test potassium. As you can see, there's fluctuation. It seems that often lower soil moisture will result in higher soil test potassium, but that's not necessarily always the case. Sometimes they tend to run together. There also seems to be a trend for lower soil test K going into the fall here in each of these years. Again, these are data from the Midwest. These seasonal variations will be different in the South than they are in the North, but what you'll find is that if you keep good records of soil testing, you'll be able to begin to see some of these trends that are occurring with changes in season. We also know that soil test potassium is greatly affected by the depth of sample. As you can see, if we take a seven-inch sample across this range of dates, and we saw a lot of variability, we can quiet a lot of that seasonal noise by taking a deeper sample. When we start getting into these surface samples, one to two inches, which would be consistent with the no-till farming system, which we're seeing more and more of down through different parts of the South, is that we get a lot more variation through the year in that surface layer. The important thing is to be consistent in the depth you're taking, because a lot of times we get guys that go out and, well, there's a hard spot, so there may be a two or three-inch core here. Maybe you'll get right in next to an old plant residue where the roots have really worked that soil. We might go seven or eight inches, and then you mix all those together in the same sample. It's not representative, so we really need to be consistent in our sampling and make sure that we're getting a representative sample. To summarize that, temporal variability exists, particularly with regard to soil test potassium. Let's get in a habit of sampling each year at the same time, whether it's going to be after harvest in the fall, whether it's going to be just prior to the corn going in in the spring. Whenever that's going to be, be consistent and keep records and begin to identify some of those trends on your farm. We've mentioned the importance of a representative sample. Spatial variability is a problem or an issue that we need to deal with in farms of all sizes and all fertility levels. People assume that some of these smaller fields, 10, 15 acres, not going to be that variable. They're just as variable, if not more than some of the larger fields. Soils with high average fertility levels have just as much variability as soils with low fertility levels. We need to make sure that if we're using any type of management zone sampling strategy or if we're going to do an initial grid to establish some of these zones, that we begin to represent those different areas of the field. We don't really even need to go all the way into precision ag. A lot of times, growers know where certain areas of their field are, whether it be from just yield history or knowledge of the site. Maybe it was an old farm site. Maybe it's the site where they always load the spreader. And so the farmer understands where these zones are that need to be sampled as independent management units. We mentioned the depth issue. A select and stable, the quality lab. Sometimes we hear these debates between private and public labs that they're making different recommendations. Well, as I mentioned, it's very possible the number might be different. But the way the number corresponds to the fertilizer recommendation should be consistent because there's correlation and then there's calibration. We're making what does this number mean in terms of the probability of a response to added fertilizer. And so pick a lab that you trust, that you understand their philosophy. There are different ways to do this. And we get this question a lot when growers start asking, well, fertilizer prices are really high. My soil test came back and it's recommending 20 pounds of P205. Do I really need that 20 pounds? Well, there are a lot of factors that go into that. Our favorite answer to give a scientist, and certainly the farmer's favorite to hear is, well, it depends, but really it does. And a lot of it depends on the recommendation philosophy of the lab, whether they're on a crop removal basis, whether they're just putting back what the estimate is coming off in yield, whether it's trying to build up to a certain level, because ideally we'll bring all these soils up to an optimum level and then keep them there with maintenance amounts of fertilizer. But the time that the lab has decided they want to take, is it a four-year build up? Is it an eight-year build up? There's crop requirement with some additional maintenance fertilizer to get it up. All of these things will vary and that's why those rates will be different. So in years where economics are tight, understanding the recommendation philosophy of your lab will go a long way in explaining why certain recommendations are made and whether or not you can skip a year or not. Moving on to some of the principles guarding timing of fertilizer. Fertilizer's not taken up by the plant linearly. It doesn't just start taking up fertilizer and keep growing. Most all crops will follow this sigmoid type pattern where the uptake rates are much lower early in the season and then they tend to peak during a heavy vegetative growth and then they tend to taper off. This is nitrogen in corn. And so ideally to optimize the efficiency of fertilizer uptake and maybe Tony talked about some of this yesterday. You may have seen these type of figures in either Tony or Wade's talk yesterday, but ideally we'll apply fertilizer at times just prior to these periods of maximum uptake rate. We want to get the nutrient in the field when the plant is going to take it up most rapidly and that prevents excess nutrient from sitting in the field, having the potential to be lost through various mechanisms and it also ensures that we don't run short. Nutrient patterns for different, the uptake patterns for different nutrients follow a similar curve but what we sometimes see is a shift in the timing of the uptake. For example, we saw in the nitrogen pattern that this by about V12 or as we get into tasseling here we're at about 65% of the total in has been taken up so we're going to continue to take up quite a bit of in during the reproductive stages of corn growth but if we look at potassium, we'll see that by that same growth stage about almost 85% of the potassium is already in the plant. And so understanding the uptake patterns, we saw this happen with cotton with a lot of the earlier bull setting varieties in that they were concerned that we weren't recommending enough potassium but what was actually happening was a shift in the potassium uptake pattern of some of these newer varieties and so the demand was the same but the time in the season when the plant needed it now earlier and so the natural mineralization of soil potassium wasn't occurring rapidly enough to meet the needs of these newer cotton varieties and so that's when we get into this issue of needing to recalibrate sometimes and so we've got a good bit of that going on in various states across the southeast and mid-south looking at do we need to shift some of these rates because of timing again we get into this four-hour connection the interconnectivity of rates and timings is that we may find ourselves recommending more because of the timing issue and having to do with the genetics and so again these things all work together some crops benefit more than others from split timing certainly in the south leaching losses is a concern for us particularly with nitrogen and so most of our crops will have a split recommendation for splitting nitrogen potassium some states recommend splitting potassium as well where we have in a lot of our southern coastal plain soils very low CECs low organic matter a lot of potential for nutrient loss including potassium especially nitrogen and sulfur but we can lose some potassium as well wheat is one that we see not so much here because we're growing softweeds but in a lot of the regions of the country where they're going bread wheats and protein is a premium we'll see some late season nitrogen applications which won't increase yield but will increase grain protein I mentioned the issue of splitting in cotton logistics I mean this this is something that is a very real factor in determining nutrient management and a lot of our traditional nutrient management planning efforts have completely neglected this issue and so they assume that the farmer can just go apply the fertilizer whenever they say to do it well why can't you just do do it all at v6 well because I have 4,000 acres of corn that I've got to get over and by the time I start at v6 I'm tasseling in some so you know these logistics and that's that's where for our nutrient stewardship is unique compared to a lot of our traditional management is that it's the decision making lies in the hands of the farmer and the advisor the sustainability goals are established with a group of stakeholders which will include those policy making organizations but the actual in the field decision remains in the hands of the farmer and so that this is very important as farm size and logistics and diversity of farming operations continues to increase is that we need to work continue to work to keep that flexibility and decision making at the farm level not at the policy level we mentioned the interconnectivity several times again if timing is an issue we can do things with sources a lot of our enhanced efficiency products give us more flexibility they widen those windows of application where we're still going to have that nutrient availability at that time of rapid uptake but we might be able to get it out there a little earlier at a more convenient time we might be able to go at v3 v4 and then have that nutrient becoming plant available as we come into v6 v8 that more rapid period of uptake a few comments about place we mentioned the difference in root uptake with mass flow diffusion root interception here's an example they have a three month old corn plant and a two month old sugar beet plant and you think those are drawing nutrients from the same zones of the soil again we've got to put the nutrients where they can be most accessible by the plant we also roots have a plasticity characteristic where when we enrich a certain zone of soil we'll see a proliferation of roots within that zone this is especially true with some of the immobile nutrients like p and k and that's why we typically will localize placement of those immobile nutrients also have changes in uptake again we're talking early in the season when we're doing these localized placements we're talking about very small immature new root systems so in terms of nutrient uptake per unit of root mass we see that being significantly greater in those early roots and so those early young roots have a very high nutrient requirement relative to as we get on into later in the growing season two three months down the road when we have a much more mature broad root system when placement is not as much of an issue I also mentioned earlier about the affinity of fertilizer phosphorus for various compounds and other nutrients in the soil this is again when we localize placement with a band application we're minimizing that fertilizer soil contact we're keeping that fertilizer concentrated in the band where we know that those roots will proliferate within that band and so we get a much more efficient utilization of the fertilizer by the plant it puts it in there at the high concentrations early and then increases the rate of diffusion on some of these immobile nutrients now banding is not always beneficial compared to a broadcast application it really has to do again with the nutrient requirement in that soil this is just a generalized illustration of what we expect to happen with band this is broadcast applications as we see as we increase the soil fertility up to a medium to high level we don't typically see the benefits to banding that we do at the lower soil test levels there are a lot of recommendations that suggest banding starter starter P with a lot of crops you know we don't really have a lot of data that support that when we start getting into higher soil test levels of P what we do see sometimes is a benefit to mixing nutrients in the band this shows an increase in fertilizer P uptake this is using labeled P when we're mixing nitrogen in the band again we get some chemical things going on with the nitrogen and the phosphorus some schools of thought or that it's actually a heating effect as these nutrients chemically react that warms that rhizosphere and those young roots that's why sometimes we see where we do see a response to starter P even under optimum soil test P levels is typically in some of the very cold seeded crops some very early seeded corn maybe potatoes we see this in several different states with potatoes when they're going into really cold soils that we will get this what we call a starter effect it's not truly a nutritional response but there is what we defined as a starter effect sometimes in certain environments right place is more than just proximity to the root it's also the right place in the field I talked a little bit about establishing zones and managing that and this is a great example of how the spatial distribution of fertilizer P improves our overall efficiency for this field if we would have taken a traditional composite sample one course various course from throughout the field compiled them we would have recommended about a ton of product on this field to meet the phosphorus requirement well what we found is if we did this by management zone we're still going to put out a ton of product with an average application rate of about a hundred pounds P205 but what we found is that we actually had about a third of the field that didn't require any fertilizer at all while another portion of it required 130 pounds and so if we'd have went with the uniform application of about a hundred pounds P205 we would have applied the same amount of fertilizer but we would have over applied by a hundred pounds into however many acres didn't even need it and then we would have under fertilized a significant portion of the field too so we don't always save fertilizer cost with variable rate or precision ag but what we do is by redistributing that fertilizer to where it's needed in the field we get a much more efficient use of it and we'll see some increased yields and also some better environmental quality by not over applying wrap up here with just a little bit on micronutrients I mentioned 17 essential nutrients each one just as important as the other but what you can see is when we start talking about comparing some of our micronutrients again this is example is 180 bushel corn crop big difference between the amount of N and K compared to zinc and copper this is pounds uptake and then here's removal that'll give you you know I mentioned nutrients in uptake and removal this is a good example you know if you just are calculating I need about 33 pounds of K to make 180 bushels of corn I actually need 150 pounds in that plant a lot of K left in corn stover and residue in the field so again I mentioned not much in terms of quantity required by these but maybe you've heard of one of the scientific laws of soil fertility is the law of the minimum that yield potential will be restricted by the nutrient in the most limiting amount so whether that be nitrogen which often they are the macronutrients because of the higher quantity of requirement but if we have a zinc deficiency it doesn't matter how much nitrogen phosphorus or potassium fertilizer we apply if we don't fix that zinc problem yield will be limited one nutrient an excess of one nutrient can't compensate for the shortage of another so that's why the balance fertility is very very important we look here again the importance of which micronutrient varies with crop you can see in the case of soybeans iron is very significant compared to the others boron and cotton a lot of you grow cotton you understand the importance you know about the importance and probably are making improvements to that crop zinc very important in wheat, corn, cotton kind of across the board zinc and iron but again you know they're all important even though the plant needs them in very tiny amounts and you'll get your soil test and there's just a few pounds the fertilizer recommendation will likely just be a few pounds especially if it's a banded application but it's amazing what will happen if we don't make that again zinc no different these micronutrients no different than the secondary or macronutrients is that the uptake is not consistent zinc tends to follow the uptake pattern more closely with this would would be again right around tasseling so more closely related to that of potassium as opposed to nitrogen what we typically find with micronutrients is that a lot of times our soil test will say that we're adequate for a certain micronutrient but then we'll get these little hot spots popping up I don't know if you can see on this but you might be able to see that kind of yellow patch right there that's a localized zinc deficiency and this is pretty common with micronutrients that we'd see this these patchy spots showing up in the field micronutrients are affected by a lot of the things the others are temperature, pH, texture topsoil, organic matter cropping system zinc in particular has a strong interaction with soil P levels but when we're talking about very very small amounts it doesn't take as big a fluctuation in some of these chemical and physical characteristics to affect availability and that's why we tend to get these little micro environments within the field of deficiencies showing up. I mentioned this P-zinc interaction this one's pretty interesting in fact it is so important that some states actually consider soil P when they make a zinc recommendation because they understand how applying zinc in a very phosphorous rich environment it goes back again to the balance between the two nutrients you can see in this field which was marginal zinc with a P requirement here's the image this is the recommended amount of P-205 banded or broadcast you can see again still not getting it done we can look at the yield data the check yields about 100 bushels just adding the zinc again about 100 bushels increased leaf tissue concentration if we just meet the P-requirement without adding zinc we actually reduced yield a lot of this is a metabolic issue look at the increase in percent P tissue the plant took the P up but once it was in there missing that micronutrient affects the physiology within the plant and so this is actually a plant physiology issue between P and zinc when we get both of them in there increased yield by 60 percent got a more appropriate tissue P and again increased zinc tissue a misconception is that it's a precipitation issue that it's a zinc phosphate precipitating out making the zinc plant unavailable actually zinc phosphate is just as soluble as calcium phosphate which is the form that a lot of our fertilizer P is going to be in and so this is actually happening in the plant and so there may be some issues at the root with uptake but these data suggest that a lot of this is going on in the plant so again it gets back to the importance of balance fertility in the soil that way it can take up the appropriate amounts and then we don't end up with these high concentrations in the tissue not making it into harvested product here's another visual of basically the same story again you can see the phosphorus deficiency symptoms leave here that purpling then when we but you see there's no visual zinc deficiency we come with a 30 pound P205 starter application no phosphorus deficiency but look what happens here now we're starting to see some zinc deficiency in that seedling so again you know we can we can create our own problems with fertilizer management if we don't think holistically about what we're doing in terms of plant requirements and all the essential nutrients in a balanced program and so hopefully that gives you kind of an overview you know didn't really get into a lot of detail I just wanted to familiarize you with the 4R concept with the holistic management with the importance of not neglecting timing or placement or source selection at the expense of rate but understanding that they all are interconnected that any decision we make affects and is affected by the other components of nutrient management we have several materials available again as I mentioned today I just didn't have time to really go into detail about any of this but you're welcome to visit our website we have printed books, electronic books, videos power point presentations that grow through several different aspects and in fact all of the slides that I showed today were taken from some of those 4R presentations on there so you're welcome to view anything that I talked about in much more detail if you visit our website with that that concludes my presentation I appreciate your attention and I'm happy to take a question or two if there's a few minutes yes sir there are some toxicity issues it depends on crop certainly there are ok there are a couple of things there are some toxicities with certain crops and then when you get excessive with one it tends to throw the chemistry out of balance and so then you can you know it affects uptake and some of your soil chemistry so yes it is possible to over apply micronutrients again it depends on the crop the soil the levels of other nutrients in the soil a lot of factors go into it but the short answer is yes you can over apply yes sir you mentioned taking soil samples at the depth do you concentrate more on the plant that you're planting and it's depth of root of where you're specifying what levels or is it a generalized or use more plants considered the instructions will come from the lab that's going to do the analysis because all of their calculations will be based on you know in terms of calculating a nutrition and nutrient will be based on depth so depending on tillage practices tillage practices is probably a more predominant decision maker than the actual crop you're going to grow but what crop you're growing depends on root development and so as the roots explore a greater volume of soil that increases aeration and the ability for those nutrients to move and so the crop you choose will affect how the nutrients can move in the soil but the depth of sample is typically what we'd call the plow depth or however deep you're incorporating fertilizer and mixing that soil is typically what the depth will be usually six to eight inches to one and a half to two inches in no till or turf but you'll be you'll be given those instructions from the soil test lab where you're ripping the nutrient rows yeah and especially what we're getting into now especially with a lot of the precision ag when we got RTK guidance we're putting those bands right in the exact spot every time and so we're creating those striations in the field and so you want to be consistent that's the biggest thing in a strip till system is just be consistent you don't want to go out one year and sample in the row and the other out in the middles you need to establish a pattern of consistency and then you'll be able to start to see those fertility trends across time that's it alright one more you mentioned method of extraction there's a couple of different ways to do the phosphorus right that's right you're a favor of well the main thing is whether you have alkaline alkaline soils and so there's a method called Olsen P extraction which they typically use more out in the Great Plains area where they have a higher free calcium carbonate down here most all of the labs around here are using an acid extraction either Malik 1 or Malik 3 both of those are calibrated the same Mississippi uses, has their own based on their soil types it's called the Lancaster method and that's specific to their it's calibrated for their soil environments and so in the south most all labs are going to be using mostly Malik 3 some use Malik 1 but those are good extraction procedures for this environment