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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.
(00:38)
In previous episodes of The Dirt, we have mentioned different nutrients that plants require to grow and develop. Today, I would like to begin a series of programs looking at each of the essential nutrients, how the plants obtain them, the different forms of these nutrients and what they do inside the plants.
(00:54)
To kick off this series, today we will be talking about the essential nutrients, we’ll define exactly what is meant by this term, and then break down these nutrients into different categories. Finally, we’ll dig a little deeper on three of these major nutrients. To help us go through all of this, I’m pleased to welcome Dr. Alan Blaylock, interim director of agronomy with Nutrien. Alan, before we begin, tell our listeners a little bit about yourself.
Dr. Alan Blaylock (01:19):
Yeah. I grew up on a farm in Eastern Oregon. Through that experience, agriculture got in my blood. We had a small dairy and some real crops. I went to school, got a bachelor’s degree and master’s degree at Brigham Young University in agronomy and horticulture. Then had some persuasive professors that convinced me to go on for a PhD. Completed that at Iowa State University.
(01:43)
After spending a few years at University of Wyoming as an extension soil specialist, I was approached by some people in Agrium, a predecessor company of Nutrien, and talked about joining the company as an agronomist. And the rest, shall we say, is history. I’ve been with the company now for about 25 years.
Mike Howell (02:01):
Okay, thanks, Alan. Let’s get to the dirt. Tell our listeners what we mean when we talk about essential plant nutrients.
Dr. Alan Blaylock (02:08):
Yeah, Mike. All plants require certain nutrients to complete their life cycle for growth and development. There are 17 of these essential nutrients. By definition, they’re nutrients that the plant requires, that it has to have. There may be some other elements that can be beneficial, but these nutrients that we’re talking about or elements the plant has to have to complete its growth.
Mike Howell (02:30):
17 essential nutrients. It seems like when I was in school and learning all of this, there were only 16, but I know they’ve added one along the way. But Alan, that’s a lot to remember. The way I try to keep track of it is break these down into smaller groups to help me keep track of them. Is there a good way to break these down? I kind of like to look at nonmineral nutrients and mineral nutrients. Can you explain the difference in these?
Dr. Alan Blaylock (02:53):
Yeah, exactly. There are three nutrients, carbon, hydrogen, and oxygen, that we consider nonmineral nutrients. The plant gets these from air and water. We don’t add them as fertilizer. We don’t manage them. They’re abundant. These are the structural components of the plant. They make up the cells, the cell walls. They’re the key elements in all of the compounds that the plant is composed of, the proteins, the starches, all of that arc.
(03:20)
Carbon hydrogen, and oxygen are those three key structural nonmineral elements. Then there’s another group of elements we call the primary nutrients. That’s nitrogen, phosphorus, and potassium. When you see a fertilizer label, you see that listed on the label. Those three numbers, N, P, and K, are nitrogen, phosphorus, and potassium, and those have to be on the fertilizer label.
(03:41)
The primary nutrients are called primary nutrients because they’re the nutrients that we most often have to apply as fertilizer and in the greatest quantities typically. They’re most frequently deficient in soils, most frequently needed to be added. Hence, the term primary nutrients. The next group is called the secondary nutrients. These are nutrients that are taken up in fairly large quantities, not as great as the primary nutrients.
(04:09)
They’re less commonly needed as fertilizer, but they are nonetheless very important. Those secondary nutrients are calcium, magnesium, and sulphur. Now, calcium is taken up in fairly large quantities, but we don’t often add it as a nutrient. There may be exceptions to that, but typically we don’t add it as fertilizer. It’s in that category of secondary nutrients.
(04:30)
And then magnesium, sulphur are taken up more or less similar quantities to the amount of phosphorus the plant takes up, but not added as often as fertilizers or in as larger quantities. Then the last group of nutrients that we talk about is what we call micronutrients. Some people use the term trace elements or minor elements. These are elements the plant takes up in very small quantities.
(04:53)
In comparison to say nitrogen and potassium, where the crop may take up a couple hundred pounds per acre of those two, in the micronutrients, the plant uptake is only in parts per million. It’s a much lower level. Now, that doesn’t mean they’re less important. It just means that the plant needs very small quantities of these. They’re absolutely essential to the plant growth, but they’re needed in very small quantities.
(05:16)
We don’t add them as fertilizer as often as we would add nitrogen, phosphorus, and potassium, but they are absolutely essential. Those are the main groups of nutrients that we talk about.
Mike Howell (05:26):
Okay, thanks, Alan. You actually answered several of my next questions going through that. That’s a great job explaining how we break these categories down and what we’re talking about on essential nutrients. Now, there is one other category that people are talking about over the last few years. Talk a little bit about what they’re terming beneficial nutrients, some nutrients that may not necessarily be required, but may benefit the plant.
Dr. Alan Blaylock (05:49):
Yes. There are some elements that may be beneficial for some crops, maybe not all crops. Some crops may respond to those nutrients, those elements. They’re not considered essential, but may provide some benefit. Now, a great example of that is silicon. Silicon is considered to be beneficial to certain crops, particularly rice has a very high silicon content.
(06:11)
There may be some other crops that have higher silicon content, or maybe a crop with a high requirement for silicon, is grown in a soil that maybe doesn’t have as high levels of soluble silicon, so there may be benefits to applying these. Sometimes we see that, but they’re not universally recognized as essential.
Mike Howell (06:29):
Right. I also want to point out that some of these that they’re looking at as beneficial nutrients, it doesn’t take very much of them to get into a toxic environment, and that toxicity could be to the plant or to whatever other animal that may be eating that, whether it be an animal grazing on that or us eating the crops. I want to caution everybody, don’t just go out and start adding some of these “beneficial nutrients.”
(06:52)
We really need to understand these before we make any broad applications of those, but did want to mention them today and let growers be aware of some other nutrients that may be out there.
Dr. Alan Blaylock (07:01):
Yeah, Mike. A great example of what you’re talking about is selenium. Selenium is required for animals, but it’s not essential for plants as a nutrient. We as humans need a certain amount of selenium in our diet. But as you say, too much selenium can be toxic, and there are some soils that are extremely low in selenium. If we’re growing forage crops for animal feed, then we may need to supplement that animal feed with selenium.
(07:26)
Or in some cases, some people have even applied selenium as a fertilizer, but these are nutrients we need to be or elements with which we need to be very careful. Another example is cobalt. It’s not identified as an essential nutrient for plants, although it’s required for nitrogen fixing bacteria, and it is required in animal nutrition. There are some of these things. We have to keep in mind this relationship between what’s crop nutrient, what’s an animal nutrient.
(07:51)
And when we’re feeding a crop to animals, they may become more important. But yeah, you’re right. We need to be very careful in the management of those.
Mike Howell (07:58):
Alan, another topic that comes up from time to time is we can also add some different nutrients that we require to these crops. They really don’t do anything to the crop, but the crops can actually take them up and we can get them into our diet that way. Do you have any examples of things like that that we may be looking at?
Dr. Alan Blaylock (08:15):
Well, I just mentioned selenium and cobalt, which at very low levels are essential for human nutrition. But this topic of what’s called biofortification is a topic of growing interest around the world and even some nutrients that are considered essential nutrients in plants. Zinc is a great example. It’s been identified as an element that’s widely deficient in human nutrition and many of our crops, because they’re grown in soils that may be zinc poor, not enough zinc in the soil to meet that requirement.
(08:47)
Some of the international health organizations have proposed this idea of biofortification, fertilizing the crop with those nutrients, and zinc I mentioned, iron is another one, to increase the amount of those elements in the crop and thereby enhance human nutrition in those areas where soils may be poor in those nutrients or the particular crop or the portion that’s edible is low in those nutrients.
(09:09)
Rice, for example, very low in zinc and iron. In diets where rice is the predominant component of the diet, they don’t get a lot of these mineral nutrients. But by boosting the plant nutrition, we can also boost human nutrition.
Mike Howell (09:22):
Alan, we’ve talked about a lot of stuff today. We’ve talked about the essential nutrients. We’ve broken them down into smaller categories, looked at a few of the beneficial nutrients. We also talked about the function of carbon, hydrogen, and oxygen, how they work in the plants. Is there anything else that we need to talk about today before we wrap this up?
Dr. Alan Blaylock (09:40):
Mike, I know you’re going to talk about all the individual nutrients in future broadcasts, but let’s think about the importance of these nutrients to growing adequate food and food of adequate quality to feed a growing global population. These nutrients are essential to achieving that objective, growing high quality food in sufficient quantities.
(10:03)
The demand for food is increasing as the population grows, and that means the demand for nutrients is increasing. Our responsibility as agronomists is to help people understand how to manage those nutrients in the best way possible to get the best result, while minimizing the undesirable impacts of those nutrients on the environment. Everyone’s heard about those things, but I’m sure those topics will be discussed in your future broadcasts.
Mike Howell (10:29):
Yep. We’re planning on talking about each one of those in depth and individually, and we’ll also get into the four R concepts. You alluded to that a little bit in your comments there, but make sure we get these nutrients applied at the right time and the right source, the right amounts. What was the fourth one?
Dr. Alan Blaylock (10:46):
The right place.
Mike Howell (10:47):
The right place. There we go. Alan, again, thanks for being part of today’s discussion. I’m sure our listeners will get a lot out of this. I want to also thank our listeners for tuning in today. Hope you’ve enjoyed today’s episode, and we look forward to having you again next time when we continue our series of discussions on the nutrients, and we’ll be focusing in on nitrogen next time. Thanks a lot. Have a great day.
