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Mike Howell (00:08):
The Dirt with me, Mike Howell. An eKonomics podcast where I present the down and dirty agronomic science to help grow crops and bottom lines. Inspired by eKonomics.com, farming’s go-to informational resource, I’m here to break down the latest crop nutrition research, news, and issues helping farmers make better business decisions through actionable insights. Let’s dig in.
(00:38):
Well, hello again everyone. Welcome back to The Dirt. We’ve got a familiar guest with us here today. We’ve got Dr. Alan Blaylock, Senior Agronomist with Nutrien, joining us again today. Alan, thanks for being with us.
Alan Blaylock (00:49):
Well, thanks for the invitation to be back on the program, Mike.
Mike Howell (00:52):
Alan, it’s getting toward the end of October. Harvest is in full swing. Already finished up a lot of the crops down in my part of the world, but what’s going on in the field where you’ve been lately? What are growers talking about as far as yields and how are things looking?
Alan Blaylock (01:05):
Well, I’ve been both in the Midwest and out in the Pacific Northwest in the last couple of months, and I think the best way to describe yields is variability. I’ve seen some pretty good crops and I’ve seen some pretty bad crops. It just depends on how the weather was in your particular area. Pacific Northwest crops are not too bad, but yields are down a bit and quality somewhat too because of some early spring conditions, a late planting and cool weather early in the spring has slowed everything down in the beginning. Condition of the crops has look good, but yields are going to be down some. In the Midwest, it all depends on your rainfall. Some areas got good rainfall and I’ve seen some really good corn and I’ve seen some really severely stressed corn that’s not going to yield very well. So it is really all over the board this year. One of the more variable years that I can remember in recent years.
Mike Howell (02:04):
It seems to be that way everywhere I’ve been as well, Alan. Here at home, we had record heat, had very little rainfall during the summer, and from what I can gather, it looks like we’re going to set a state record in Mississippi for corn and soybean yields despite having the terrible conditions during the growing season. So irrigation sure makes that go a lot better where growers have the luxury of having that. So Alan, with this crop, getting in the bins in a hurry, harvest is going along really nicely from what everybody’s telling me, what kind of conversations are you having with growers? A lot of these growers are thinking about 2024 already. What’s on your mind?
Alan Blaylock (02:39):
Well, the big concern that growers are expressing is the same concern that we always hear. It’s about input costs. Now, input costs have come down some. Particularly fertilizer prices have come down some from where they were, say a year ago, the last couple of years, but they’re still fairly high so that’s a big concern with growers. You and I, Mike, can’t do anything about that. The grower doesn’t have a lot of control over that. So the key next conversation is how do we plan to manage the best way we can for the most profitable crop that we can get? And in our world, soil fertility, nutrient management, that involves soil testing, doing a good job with your soil tests, knowing what you have in the soil, what’s going to be available for the crop the next year, and then budgeting appropriately to produce the best yield possible within the environment that you have.
Mike Howell (03:34):
Well Alan, I think that’s a great lead in to what we wanted to talk about today. We always mention our website during this podcast, that’s Nutrien-eKonomics.com. But was looking at some of the hits on the website recently and was surprised to see that the most popular article that we have on there is one talking about Liebig’s Law of the Minimum. Now that’s a pretty basic concept, and we actually did one of our famous agronomist sections on Dr. Liebig a while back, but we really haven’t spent much time on the podcast talking about this law. So thought today we would spend a few minutes and go through this and let everybody get caught up on what Liebig’s Law is. So Alan, if you will, let’s start off and talk about Liebig’s Law and just exactly what is in this law.
Alan Blaylock (04:18):
Well, Liebig’s Law is this concept from Dr. Justus von Liebig, German scientist. And the law basically says that the yield that you can produce or the outcome that you can get is dependent on the most limiting factors. So basically to say that another way, the yield that you’re able to produce will be driven by the most limiting factor. So as you think about management, the idea that follows from that is to identify that most limiting factor and then adjust that factor.
Mike Howell (04:50):
Alan, I’m sure most of our listeners that’s ever had any soil fertility training at all are familiar with the barrel and the stave concept, the lowest stave. And that’s how Liebig depicted his interpretation of this. So talk a little bit about the barrel and what those staves represent in that barrel.
Alan Blaylock (05:06):
Yeah. So if we think about our inputs as a stave in this barrel, in a barrel, we had the wooden staves. Those are the slats of wood that form the barrel. And if you cut those off at different heights, you can only fill the barrel up to the height of the shortest stave. So if you want to fill the barrel higher, you have to extend that shortest stave. In other words, if we equate our crop yield to the water or fluid that might be contained in that barrel, then we can only produce yield up to the height of that shortest stave, that shortest stave being our most limiting factor. The concept behind this is you extend those staves one by one, starting with the most limiting, raise that stave up, then go to the next most limiting, raise that one up until you get them all up to the top of the barrel, and then theoretically you would be able to produce the maximum yield. So that’s the idea behind that barrel and the expression, that analogy with Liebig’s Law of the Minimum.
Mike Howell (06:04):
When I studied about this way back in school, all that was mentioned when we looked at this barrel was fertility and the nutrients that are required for plants to grow and develop. And I think that’s the way Dr. Liebig depicted it when he laid out this concept. But there’s a lot more to yield than just nutrients and nutrient management. I think that’s one thing that we may be missing on this barrel is what about water? What about sunlight? What about insect control? Weed control? I think we may need to look at some more staves in that barrel.
Alan Blaylock (06:32):
Exactly. And Mike, you and I have talked about this many times, but yes, and Dr. Liebig really was applying this law to nutrients, but really we should think of the staves in that barrel as all the different inputs and even all these soil and weather environmental factors that we have to deal with because each of those different factors can limit yield. It could be sunlight, it could be water, it could be temperature, it could be insect pressure, it could be diseases or weeds or whatever the case may be. All of those factors contribute to the crop’s ability to produce yield. And so when we think of that barrel, we really need to think beyond just nutrients. And a great example of that, we take nitrogen for example, or really take any nutrient. If we don’t have water to grow a high yield, we can put nitrogen out there and continue to add nitrogen, and we don’t get any more yield if water is our most limiting factor. Or if we have lots of cloudy days, we don’t get the sunlight, we’re not going to be able to utilize those nutrients as efficiently as we would if all of those things are not limiting.
Mike Howell (07:36):
Well, Alan, we know there’s a lot of interactions that go on between different nutrients and you just mentioned we’ve got to have the water as well as the nitrogen in order to get these yields. And recently there’s more and more talk about The Dam Theory and relating the nutrient management or the yields to a dam instead of the barrel concept. Talk a little bit about The Dam Theory and how it differs from the barrel concept.
Alan Blaylock (07:59):
This is actually probably a better way to express this concept of limiting factors. And the idea behind using an analogy of a dam is that we may have multiple leaks in that dam. For example, the water behind the dam is our yield potential, and if we have multiple leaks in that dam, we might plug one leak, but we still have other things that are leaking yield potential. So that concept differs from the barrel example in that we have these leaks in the dam, and if we don’t try to plug all of them, we’re still not going to be able to fill that dam up to the top. Whereas with the barrel, we look at them one at a time. We look at them individually and one factor is the most limiting and we try to fix that and then we try to fix the next one where the concept of this leaky dam is that we try to fix them all in proportion, in balance.
(08:55):
And a great example is nitrogen. For most farmers, nitrogen will be their most limiting nutrient. Maybe other factors obviously, but nitrogen will be the most limiting nutrient. So we’re thinking about nutrients. We can put more nitrogen on, and maybe we don’t get the full response to that nitrogen if something like potassium or sulfur or some other nutrient is limiting. So applying more nitrogen without fixing the say potassium leak or the sulfur leak in that dam may not get us the response that we need. It’s still not going to allow us to fill up to the top of the dam. So by plugging all of those leaks together, we can capture more of our yield potential. I think that concept recognizes that all of these different factors are interacting together and while in concept the law of the minimum, it’s a real law. We see that in action all the time. With that concept we tend to think about it as individual factors in treating them individually. But with this idea of a leaky dam and trying to plug all of the various leaks, it draws our focus more towards the interaction of all of these things and trying to fix the different yields, limiting factors in combination. Understanding their interactions, understanding plant physiology and how these things work together and try to keep them in balance more than with the concept of a barrel and staves of various lengths.
Mike Howell (10:21):
And Alan, this theory, The Law of the Minimum has been around for years and years way before the current concepts. And one thing we talk a lot about here is the four Rs and how we implement the four Rs on a farm. But even way back when Dr. Liebig introduced The Law of the Minimum, the four R principles were still taken into account. He may not have called it the four Rs, but it relates back to the four Rs as well.
Alan Blaylock (10:42):
Yeah. They’re similar concepts and when we think about the four Rs of nutrient management, using the right source at the right rate, right time, and in the right place, that’s a model to guide our thinking. It’s a thought process and thinking about all the different factors in nutrient management. And when we’re thinking about the four Rs, we can easily get off track and think about them one at a time, individually acting independently, but they don’t really act independently. We need to consider those four Rs in how they interact together. Just as we talked about with nutrients interacting and plugging all the different leaks in the dam. With our four R concepts, we want to think about nutrient management in much of the same way. If we change our placement, for example, we may want to change the source of a nutrient. If we change the source, we may need to change placement. Or if we change placement, maybe we need to think about a different timing. Or if we use different combinations of those that get greater nutrient use efficiency, we may be able to change the rate.
(11:47):
So none of those things really work independently. They all work together to optimize nutrient use efficiency. Just as with nutrient balance, if we can supply all of the nutrients in balance, we can get maximum efficiency out of all of them working together. Without all of them working together in the right proportions, in proper balance, it’s hard to get to optimize the efficiency of those nutrients. It’s hard to optimize crop performance without thinking about the many interactions. And it is complicated. There are many interactions. It’s hard to isolate just one or two things because everything works together in the physiology of the plant and in the natural environment in which that plant is growing.
Mike Howell (12:28):
And that’s one of the reasons research in an agriculture system is so difficult. We can’t always account for all of these extra variables, and you may think you’ve got a good test and then it’s hard to get it repeated sometimes. A lot of times we don’t know what some of these other variables are.
Alan Blaylock (12:42):
That’s a good point, Mike. I’m glad you brought that up because in research, historically at least, we have often tried to control a set of variables and then manipulate one variable to see how the crop responds to the manipulation of that variable. I think if you look at a lot of the research being today, we’re moving more to a study of the interactions. The term people use is systems research. But it’s really just an example of looking at those interactions and studying how they work in an entire system. And it’s more complicated research. It’s easy to put out a bunch of plots and apply all the nutrients except one at the same level in the same way and then we manipulate, say nitrogen, for example. That’s fairly easy research to do. But if we’re trying to look at how these interactions behave, we can’t just manipulate one. So the studies become more complex. We have to collect more data, and maybe the study design is entirely different. Instead of doing a bunch of factorial combinations of different treatments in small plots, we may need to look at an entire system and compare how one system performs to how a different system may perform. So the research and data collection and data management become more complex, but our computers today allow us to do many things with that data that we couldn’t do before.
Mike Howell (14:02):
Alan, we started this conversation off talking about what growers need to look for going forward or planning for 2024, and you were mentioning the high cost of inputs, and that’s something that we constantly have to deal with. But going along with that, one of the questions I always get from growers is, “Can I cut back on my fertility rates?” They like to look at Liebig’s Law of the Minimum and say, “Well, I’ve got plenty of potassium out there, maybe I can cut back this year.” Is that something that growers can do or should they do? And if so, how do they go about determining if it’s safe to do that and how much they can cut back?
Alan Blaylock (14:36):
Well, there again, Mike, I would start with a soil test. So start with that basic information. What does the soil test indicate about the available nutrient supply in your soil? Now, understand that it’s an index of availability. We express the soil test in certain units with certain values, but think of it as an index of nutrient availability. A way I like to describe it is a probability indicator. That soil test indicates a probability of getting a response to certain nutrients. Now, to your question, can I cut back? Well, we all know that nutrients play a really important role in crop yield potential. We also know that economically speaking yield is a huge component of that profit equation. It’s often the biggest driver of profitability. Lots of studies have been done on that. And so when I think about the impact of nutrients on yield, and I look at that soil test and I say, have I done a good job of maintaining soil fertility levels, those things that I’m able to build and maintain in the soil, like phosphorus, potassium, the micronutrients, some of those things? If I’ve done a good job of maintaining those nutrient levels in the soil, I have a certain amount of reserve capacity or reserve nutrient storage in that soil.
(15:50):
And if I’ve done that, then I do have the possibility of maybe reducing some of those a little bit for a short time. Maybe a year, maybe a couple of years, but I need to be paying attention to my soil test. If I’m suboptimal on any of those nutrients, then I should not be cutting back because if I cut back from something that’s already suboptimal, then I simply increase my risk of reducing yield and therefore increase the risk of reducing profits. And almost always when you do the arithmetic on yield versus costs, yes, costs are an important part of the equation, but when we start cutting costs, the amount that we save is usually less than the amount that we lose when we start losing yield. So you want to keep that in mind. Do some arithmetic, study your soil tests, look at your crop rotations, crop requirements, and make sure you’re keeping that in balance. Because once you are cutting to the point where it starts to affect yield, then you’re also cutting into profitability.
(16:52):
So you have to do some study with those numbers and price things out. Sometimes there’s just not enough money to go around. So then you have to evaluate where do I best put that investment in nutrients? And most farmers will gravitate towards maintaining the nitrogen, but maybe cutting on other things when in reality, cutting some of those other things may be affecting the value of their nitrogen, may be affecting the efficiency of nitrogen use. If I cut my potassium and I’m not getting full utilisation of the nitrogen, well that’s maybe not the place to cut. Maybe you should be looking at balancing those nutrients or maybe in some cases even diverting to a field that’s more productive, putting the resources into the fields that can produce the most return for that fertilizer dollar.
Mike Howell (17:37):
Alan, one thing you said a couple of times in that response there, you said you could cut back on some of the nutrients. Talk a little bit about which nutrients you may be able to cut back on, and some like nitrogen, we don’t want to cut back on. Some that are going to stay in the soil and be there, some that have the potential to move away from where we need it to be.
Alan Blaylock (17:56):
Yeah. Mike, especially what we call mobile nutrients. Those nutrients that can be lost from the soil like nitrogen. It’s hard to build those up. It’s hard to maintain some background storage of those nutrients in the soil. So it’s very difficult to cut back on those without affecting yield. Other nutrients that are what we call immobile in the soil, like potassium, phosphorus, we can build up a reserve of those nutrients in the soil. They may not be in immediately available forms, but we build up that reserve and they become available over the growing season. If we have, like I said, maintained that reserve or built up an optimum level in the soil, there’s a reserve there that can supply nutrients to the crop even if we don’t have enough fertilizer. So I like to advocate maintaining that optimum level. Not an excessive level, but a high enough level that if I do have cashflow problems, costs increase and I can’t afford all the fertilizer that I really need, again, I like to maintain that level in the soil that will allow me flexibility managing my immediate fertilizer costs for that growing season. That may allow me to cut back on some of those nutrients for which I can create reserves in the soil like P and K and some of the micronutrients. Hard to do with the mobile nutrients like nitrogen and sulfur.
Mike Howell (19:17):
So if we have cashflow issues and decide we need to cut back on some fertility, we first want to look at the ones that are immobile in the soil before we start thinking about the mobile nutrients. Am I hearing you right?
Alan Blaylock (19:27):
Yes. And also in conjunction with that, look at those nutrients on the soil test for which you have high levels in the soil. Those that are, as I said before, suboptimal on my soil test, I don’t want to be cutting those back. But if I have others that are high, then those are the ones where I might be able to cut back a little bit.
Mike Howell (19:50):
Okay. Alan, we always appreciate you taking time to join us. I know our listeners always get a lot out of our discussions. So do you have any closing comments, anything you want to leave the listeners with before we sign off today?
Alan Blaylock (20:00):
I would remind growers that these are complex interactions and so get with an agronomist, discuss your situation, sit down with your soil test and say, what are my most limiting factors? Do I have multiple limiting factors? Is it more than just nitrogen? Where can I get the best bang for my buck with my inputs? And also think about variability in the field because soils are not uniform across the field, and we may have some areas of the field where maybe potassium is more limiting than phosphorus or other areas where that’s reversed. So take that into consideration too, and that’s really how we’re going to optimize nutrient balance. I think we throw this term nutrient balance around a lot, but I think it’s really important to maintain proper nutrient balance. The plant wants these nutrients in certain proportions, and so when we’re looking at limiting factors and whether it’s Liebig’s Law or the dam concept that we talked about, look at those limiting factors and think about how can I best balance those to get the biggest response to the nutrients that I do put in the field.
Mike Howell (21:00):
Okay, Alan, we sure appreciate it. Listeners, as you know, it’s now time that we move into our second segment today where we talk about somebody famous in agriculture. Now, Alan and I, along with several other people on the agronomy team will be in St. Louis in the next couple of weeks. We will be attending the Tri Society’s meeting. That’s the American Society of Agronomy, the Soil Society of America, and the Crop Science Society of America. Those three organizations will be meeting in St. Louis and one thing that we always look forward to is the Dr. Leo Walsh lecture. I got to thinking today who we would talk about, and I got to wondering who was Leo Walsh? I know I always like to attend these lectures, but I didn’t really know who Dr. Walsh was. So did a little research, and Dr. Walsh was born into an agriculture family near Barnum, Iowa. He planned on farming as a career, and he entered the Farm Operations Certificate Program at Iowa State University in 1948.
(21:58):
He then decided to continue his college focusing on agriculture education. After he graduated, he served two years of active duty in the United States Air Force, and then he went to work as a vocational ag teacher in Iowa until his love of learning and agriculture swayed him to again continue his education. He earned his PhD in 1959 at the University of Wisconsin at Madison, and started a career in a faculty position there as soon as he graduated. He was a professor in the soil science department. This enabled him to teach and conduct research in soil fertility and nutrient management. This opened the door to his appointment as Dean of the College of Agriculture and Life Sciences at the University of Wisconsin from 1979 to 1991.
(22:43):
Now, throughout his career, Dr. Walsh promoted nutrient management practices to optimize production and preserve natural resources for future generations. He is described as an innovator of soil testing technology by one of his former students. Early in his career, Dr. Walsh recognized the rapidly developing fertilizer industry was creating a new era in agriculture, shifting production from small diversified farms to large scale specialized crop producers. Dr. Walsh developed innovative science-based educational program for farmers and their suppliers. His program centered around soil testing and his impact on efficient nutrient use resulting in optimal yields while minimizing environmental impact. Dr. Walsh collected and summarized electronic soil test data to project where problems and opportunities might develop and shared his information through extension program.
(23:35):
Now, Dr. Walsh was one of the first extension specialists in the United States to hold a research position in addition to an extension appointment. This allowed him to tie his extension and research specialties together into one position, and it not only garnered more respect and attention, but it also resulted in the development of practical research program and direct response to the problems faced by the questions asked by those working the land. Walsh is credited with the development of the Wisconsin Fertilizer and Chemical Association. Translating complex data into usable information, he worked with producers, industry, and soil and plant analysis labs to improve soil management practices and crop production, and addressed water quality and environmental concerns. Drawn to research that had practical applications, Walsh was one of the first scientists to look at the hazards and possible benefits of applying municipal waste to agriculture land leading to recommendations and regulations for sewage sludge use.
(24:32):
In 1987, he was appointed by President Reagan to the Board of International Food and Agriculture Development, where he advised the board on program to promote sustainable agriculture and protect natural resources in developing countries. So we want to extend our gratitude to Dr. Walsh and all of his contributions made to the field of soil science.
(24:52):
So listeners, if you want to find out more information on this or any of the topics we talk about, you can visit our website. That’s nutrien-eKonomics.com. Listeners, we also want to let everybody know that many of our episodes are now available for CCA credits. So if you’re a certified crop advisor and looking for some ways to get your credit hours, you can go to our website. That’s nutrien-eKonomics.com. Follow the links there to The Dirt, and find out more information about how to get CCA credits for listening to these podcasts. Until next time, this has been Mike Howell with The Dirt.
