In this episode Joe and Nick talk about plant nutrients, NPK, and source water.
More about Joe Swartz:
More about Nick Greens:
Polygreens Podcast Episode 49
[00:00:00] Joe Swartz: Hey everyone. Welcome to the poly greens podcast. I'm Joe Swartz from am hydro, along with Nick greens of the Nick greens grow team. And we're talking today, Nick and I were talking this morning about a lot of the emails and online inquiries that we've been getting related to different aspects of growing and really overwhelmingly one of the most important topics in a lot of growers, mine all relates around Ruth root health and planning.
And, uh, when we're talking about the different technologies out there, sometimes we actually forget about the root systems, which is a shame because that's really the basis of all of our crop production. So, Hey, how's everything going this
[00:00:41] Nick Greens: Everything's going, I'm really good. Um, you know, the weather's starting to frost up.
We're getting those, uh, 30 degree, a, you know, you know, below the thirties, something, I think I hit, we had 20 something the other night, 29, maybe. So that frost is coming on and the grass is, is starting to get the frost. [00:01:00]
[00:01:00] Joe Swartz: Yeah, everything's dying off except inside the greenhouse. So
[00:01:03] Nick Greens: the healthy root system, you have nothing to worry about.
And that's why today we're talking about it.
[00:01:09] Joe Swartz: Yeah, really it, you know, plant nutrition in hydroponics is one of the things that a lot of people take for granted. Sometimes we'll mix up a nutrient solution that should kind of take care of everything or, uh, in a lot of cases, it's an afterthought and that's usually where.
Growers tend to have some, some drill challenges. Usually when someone reaches out to me and they're having a challenge with their crop, obviously, you know, one of the first things to do is look at any historical, uh, analysis of both their nutrient solution and their plant tissue, but also then to look at.
What's going on currently. So if there's a, uh, an issue with, uh, the physical appearance of the plant, whether it's just slow or stunted growth, misshapen leaves, um, discolored leaves, obviously one of the big things that people always notice is, is either yellowing or some type of [00:02:00] chlorosis or necrotic spots.
So obviously we have to look at our environment and a lot of the kind of more obvious causes, but you're looking at nutrition. Is a, is a big issue. And I often tell growers to send me a picture right away of their root systems. Pull the plan up. Let's see what the root systems look like, because if there's any physical damage or other types of, um, issues with the roots, that's going to be your first red flag that there's obviously some type of inability of the plant to absorb good nutrition, but then once, once that's been taken care of.
There are certainly a lot of other factors that that will go into the plants properly absorbing and utilizing nutrients. So I think we should start
[00:02:44] Nick Greens: it from the goal from the beginning, right? The beginning of, uh, of, uh, of MPK, I guess. Right. Understanding and PK and why hydroponics, uh, are all about their NPK.
But then, uh, one thing they do forget is they forget their, [00:03:00] their, their micronutrients too, as well.
[00:03:02] Joe Swartz: Yeah, yeah. Coming from a conventional field, agricultural background NPK, uh, if people don't, aren't familiar with that term, it refers to the three primary elements used for, for crop growth, nitrogen, potassium, and phosphorus, and then, excuse me, nitrogen phosphorus and potassium
[00:03:21] Nick Greens: correctly.
I know it was kind of where I was kind of thought that was weird. K is potassium. I was like, Like, I w I would think the P would stand for potassium, but it's, you know,
[00:03:32] Joe Swartz: yeah. You got to go back to your high school chemistry class and look at the three on the table. And, uh, uh, I definitely, uh, the periodic table is, is certainly something that, uh, that kicks a memories for me.
When I was in high school. I remember very distinctly in my junior year taking the basic chemistry class and our, um, our instructor had us, uh, with the periodic table. And we were looking at. Molecular weights and atomic weights and things like that. And [00:04:00] I remember, of course I was in 11th grade. So of course I knew everything at the time.
And I remember arguing with my, uh, science teacher about the practicality of that and whether, how, where, where in my life am I ever going to need the periodic table or need to know what an, a molecular weight of something is. And, uh, and I think of her every time I pull out. Periodic table that I use now, when I'm working on a nutrient formulation or, or anything like that, I always think of Mrs.
Buck out. And if you're out there somewhere, Mrs. Buck, I'm very sorry for being a smart Alec because I use it on a regular basis now. So I was very well
[00:04:38] Nick Greens: chemistry. We cannot have. A complete macro and micro together nutrients because somehow the chemistry will react if sits over time.
[00:04:49] Joe Swartz: Oh, when we're making yeah.
There's there's issues, certainly when we're making a nutrient solution concentrates. And we can talk about that when we start talking about mixing. Preparation of [00:05:00] nutrients, but, but certainly when we are in the soil in general, most micronutrient, uh, issues are not as noticeable. Uh, not as prevalent, uh, doesn't mean that.
Incredibly important when we were, for example, growing in the field, uh, we would have soil tests and in general, most fertilizer recommendations were based on, um, the needs of, of the heavy, uh, nutrients, the nitrogen, the phosphorous, the potassium, uh, sometimes for pH control, um, limestone would need to be added to the field.
Rarely if there was a micro. Uh, issue, there were different types of micronutrient fertilizers that would be used, but by and large people think about kind of the big, the big three, if you will. And when we look at hydroponics, obviously we don't have the soil, we don't have everything going on in it in terms of nutrient inputs.
So we're, we're [00:06:00] responsible for all those, the boron, the manganese, and the molybdenum and all that. And so referring to the. The periodic table and things like that, you can go as deeply as you want in, um, in terms of the plant chemistry, Howard Rush's book, hydroponic food production is an amazing resource and you can go very, very deeply into plant nutrition, to calculate values for nutrient formulations.
And I know we've got plenty of growers will really like to do that. And some growers will make their own nutrient formulations and they will dial in, you know, to a very high level. What they're, what they're, um, adding or not adding
[00:06:41] Nick Greens: and some growers take it far too, uh, designing their own soils, correct.
To certain. I
[00:06:46] Joe Swartz: see. Yeah, I've seen that as well. Sure. Um, so again, and that's, that's where the understanding that. Plant nutrition is so critically important and sometimes overlooked with that said though, [00:07:00] most growers that I've worked with and myself included, there are a number of different nutrient formulations, kind of commercially available hydroponic formulas.
And we can talk about a few of them. Is, is that there for most applications? They're not only more than adequate. Some of them are, are very, very high performing nutrients. So you don't necessarily have to understand, um, you know, how many grams per liter of, uh, molybdenum acid you have in a nutrient formulation or, um, you know, manganese, sulfate, you know, in relation to magnesium sulfate, you know, you don't necessarily have to understand that, but you do have to understand really the importance of the nutrients and understanding.
How to one, evaluate your water, prepare your nutrient solution, and then monitor your crop growth accordingly. So, so we're going to kind of take a little bit of a, of more of an overview, um, walk through the process a little bit and see if that makes a lot more sense.
[00:07:59] Nick Greens: Yeah. And [00:08:00] can, um, fertilizer spoil, like, or say organic fertilizer?
That's not cell based. It's liquid based is there, is there, there is a shelf life to that.
[00:08:12] Joe Swartz: Well, there is in my experience now I have very limited experience with long-term storage of a lot of these nutrients. I, you know, as far as, uh, nutrients and fertilizers that are manufactured, um, or, or gathered and prepared, or what have you usually utilized pretty quickly.
So that's normally not too big of an issue, but certainly especially when you're dealing with organic materials, uh, there can be some challenges for sure. Um, As it relates to hydroponics. Obviously we want to step back. And first and foremost, we want to understand the source water composition of the source water is really the most important step because you can take your water, whether it's from your tap or your well, and throw in some hydroponic, nutrients and hope for the best, but it's not a really a sound approach.
So, so one of the things that we always do [00:09:00] is look at the source water. Um, NMI labs in Georgia is an amazing lab. There, there are a number of, uh, different laboratories across, uh, across the world that can do a very inexpensive and simple, uh,
[00:09:13] Nick Greens: analysis. And sometimes some of those labs will give you the first one for free.
Yeah, and you probably won't get a super full-out rating, but you can get like a basic reading for free. Yeah,
[00:09:24] Joe Swartz: I've seen, I've seen some that do that. And certainly just understanding, um, everything from the natural pH of the water growers that are using municipal water in general, the water in a municipal system is treated.
To raise the pH. So a higher pH in the actual water itself is, is usually most common. So obviously how we're adjusting the nutrient solution in terms of pH is, is contingent on what the source water is looking like. So, so obviously if you have a municipal water, chances are good. You're going to need to [00:10:00] lower the pH for hydroponic production.
And, uh, well, water can be in terms of pH can be all over the place I've seen. Um, water sources in limestone areas that are, you know, pretty high pH and then other wealth sources that are acidic. So understanding the pH is really important. And we'll talk in a little bit about the using pH control of the nutrient solution.
That's a very different issue, but just looking at the source water first, understanding the pH level, uh, is, is very important. And then we
[00:10:31] Nick Greens: will, water can be hard water as well. Yeah, there are
[00:10:34] Joe Swartz: different lands.
[00:10:35] Nick Greens: And I think there's, I think there's a fertilizer out there that some fertilizer companies design, um, a fertilizer specially for hard water.
Um, I did, I have, I have seen that back in the day.
[00:10:49] Joe Swartz: Yeah. Yeah. The, the actual composition of a nutrient fertilizer program really should be built around the source water. Because if, if in my installation, for [00:11:00] example, I have really high magnesium levels or high manganese levels, how I'm going to. Formulate the nutrient and, and then use, it may be very different than yours, where you have extremely high sulfur levels, you know, self esteem
[00:11:16] Nick Greens: as well to
[00:11:17] Joe Swartz: know for sure.
And, and understanding, uh, calcium in terms of soluble, soluble, calcium. Um, so-so so those are all factors that we have to take a look at and understand understanding. Uh, the base pH level and then the composition of the water. What, what, what are in it for bicarbonate? How does that affect how we make the nutrient solution?
And then the actual elements themselves, everything from nitrogen all the way does zinc and molybdenum, you know, the tiniest of micronutrients. And so in general, most, uh, municipal water pH can be an issue, but in most cases, there, there are issues as it relates to sodium or chloride. Uh, calcium, [00:12:00] magnesium.
And that's another thing is looking at, um, ions that are used by the plant, like calcium or nitrogen, but then also other ions such as sodium and chloride, which essentially for lack of better term take up space and the nutrient solution, they don't actually add to the crop growth. And so those are things that,
[00:12:21] Nick Greens: okay, I get my, a full water report.
Now, can I send my water report to am hydro to. Uh, a specific formula for me. So, yeah.
[00:12:32] Joe Swartz: Yeah. What we do is we, we have a water analysis kit where we can take your source water, and then we would forward it to the labs. And then based on the results, get. You'll make recommendations specifically in, in many cases we've actually formulated, uh, different nutrient solutions.
Um, or we have, I mean, we have a whole line of, of different nutrient fertilizers for different props and, and how we manage them [00:13:00] can also impact, uh, You know, the, the suitability. So, so we don't necessarily always have to make a custom nutrient formulation, for example. And most of our growers now most commercial growers go directly.
They all have labs that they work with. Um, so we don't even necessarily have to handle that. Uh, we'll just, you know, ask that a grower would forward the results from the
[00:13:23] Nick Greens: analysis now would another decision. Okay. Finalized. We, we understand the water. Um, you understand what kind of formula for my water?
Can I choose South's over liquid organic fertilizers? Is that, is that an option as well? Is that like the next
[00:13:42] Joe Swartz: step? Well, there are certainly a number of, of even components and even in just what you said. So we're looking at, um, more conventional hydroponic, uh, nutrients. Uh, most of them are fertilizer salts and they're highly soluble.
You know, in the home hobby market and the canvas market, [00:14:00] we see a lot of liquid nutrients and liquid nutrient is much easier to incorporate into your nutrient solution in use, but it can be very, very expensive. So if you're buying a liquid fertilizer, say from a hydroponic store, you're buying mostly water.
So most commercial operations we manufacture or other growers will use. A powdered, uh, nutrient formulation that for ease of use will then take it at their facility or at their home. And they will mix it with water and make a liquid fertilizer concentrate. So ultimately in hydroponics, obviously we're always using a liquid formula, but how those nutrients come, you know, can, can vary quite a bit.
So we normally don't recommend people purchasing, unless it's just for a small, you know, home hobbies. And we don't recommend purchasing pre-made liquid fertilizers. So, so we usually, uh, there are a number of, of good manufacturers out there [00:15:00] and, um, and taking those formulas and then mixing them into a, uh, a nutrient concentrate that then can be a liquid concentrate that then can be added to your nutrient solution.
And to your earlier question about mixing different nutrients. Um, we do in most cases will make two par, two parts or two different nutrient concentrates, a part a, and a part B most common two-part, uh, solutions. Um,
[00:15:25] Nick Greens: in the common question that I get is why can't I just develop a one all in one? Like, yeah,
[00:15:34] Joe Swartz: well, there certainly are a few, one part solutions out there.
My experience in the experience of a lot of my growers. That is as good or provides as good results obviously. And if independent ones out there using a one part and they have great results, I'd love to hear about it. That's
[00:15:52] Nick Greens: more control when you have a two-part correct. Is that what it is?
[00:15:55] Joe Swartz: Yeah. And when you're making a concentrate.
So, so again, so let's, let's say [00:16:00] where, where you're growing lettuce in your greenhouse and you've got a thousand gallons. Nutrient reservoir that you're running through your system. So you start with a thousand gallons, you're making up a new solution. You start with a thousand gallons of water, um, and you are adding liquid, uh, concentrate to that, to dilute, to make a full strength nutrient solution.
So Faye is for example, in Sheboygan and your lettuce greenhouse, you want to run a, a pH. Five points six and a, an ISI of 1.2. So you will, of course the gesture pH, and then you will add nutrient concentrate until the sea level is up to 1.2 and then you can manage it accordingly so that the fertilizer liquid fertilizers that you have are, are quite strong and concentration in that initial concentrate form.
And at those levels of those concentrations, if you are mixing, say calcium nitrogen, Um, with potassium nitrate or magnesium sulfate, magnesium sulfate, calcium [00:17:00] nitrate. If you ever mix those two together, you're going to have, uh, what looks like clunky milk and, uh, and what happens is, um, certain elements can become, um, insoluble.
Uh, precipitate out or become unavailable to the plant. So we don't want to have those chemical interactions. Um, when we add them to a nutrient solution that that thousand gallon nutrient tank I was talking about at those concentrations, you don't have that reaction. So everything stays soluble. So that's just a, really a handling issue.
So, so we'll make a two-part nutrient concentrate. One part, uh, say for example, in our part a is calcium nitrate and some potassium nitrate, and a part B, there may be all mano potassium, phosphate, um, uh, magnesium sulfate, different micronutrients, and they're specifically mixed that way. So they don't have any interaction there until they're added to their nutrient solution in a more dilute form.
[00:18:00] And that's usually the most common way. And so, so you don't, again, you don't have to necessarily understand. Um, a nutrient solution con you know, composition to a high level. Um, but, but understanding, uh, one what basic concentrations are in your new chain or in a correct nutrient solution is important. Um, and then managing your environment around that to get you your crop
[00:18:26] Nick Greens: size and injecting system that you see.
Cause I know it varies, right? Like you can have a, a three-part injector for your baby. Type commercial style facility up to like an eight part, uh, injecting system,
[00:18:40] Joe Swartz: right? Correct. Yep. Yeah. And that's a great question. So. When you're adding nutrients to a nutrient solution, the level of technology and the, and the level of control that you have in there varies quite a bit.
And I'm, uh, fully admit, uh, for many years as a grower, I added the nutrients manually. [00:19:00] I added nutrients. I mix them and I tested it and I felt that that gave me the best control because I was monitoring. Twice three times a day, sometimes adding it, um, gave me a high level control. I sometimes didn't realize how much time I was spending doing it.
And then, so the next level up from that hand dosing is, is a low level automation control. So you can have a two or a three part peristaltic pump controller, like when we had Kelly Nicholson from auto grow, um, the intellidose, which is, uh, a unit that will monitor. The pH and EDC of a nutrient solution and then make adjustments accordingly.
So the peristaltic pumps, if, if the solution is low in, um, uh, strange electrical connectivity, so electrical connectivity is a measure of the strength of the nutrient solution. It's a matter, it's like adding a sugar to your tea and if the concentration is not high enough, I'm sure. Your taste buds will be the monitor and tell you [00:20:00] to go ahead and add some more sugar to it.
So in this case, the, the dose controller will, um, you know, have you, you can preset in what you want, your, your strength of your nutrient solution to be. And if the solution drops below that the dozer will then add it and it does it automatically. So basically it's monitoring in real time. The composition of the nutrients.
[00:20:25] Nick Greens: One size don't fit all.
[00:20:27] Joe Swartz: Oh yeah, absolutely not for sure. Um, the, the, the size, the scope, the crops that you
[00:20:36] Nick Greens: are trusting, the adjusting the calibrating.
[00:20:39] Joe Swartz: Uh, yeah, so there's many different applications in different sizes. So if you're using a simple. Uh, dozer. And that would be one part would be to adjust the pH.
And then the other two would be to add nutrients and that's the most inexpensive, but on a commercial level, effective, uh, tool Michael Christian, who found that [00:21:00] American hydroponics tried for years to get me to try the dosing system. And I was very resistant. But, uh, actually once I, once I incorporated and it's a godsend, because one, it does take a lot of a way, a lot of the time, obviously you've got a touch screen, you got to read out.
And I, as a grower, checked it all the time. Anyway. Um, The unit is handling the actual monitoring and dosing for you. You didn't
[00:21:26] Nick Greens: lose. And I think that you could probably feel that Joe is you lost the art of doing that.
[00:21:32] Joe Swartz: Well, when you're being
[00:21:33] Nick Greens: the dosing system, it's
[00:21:35] Joe Swartz: kind of like an. Yeah, but I, but I still, uh, and again, it, because, you know, I'm never, I've never been a proponent of the set it and forget it mentality.
Uh, I would still go in and check all the time, which is why they're great to have, you know, a readout screen on the dosing unit. So I can check anytime and believe me, I checked all the time. What the, the temperature of the solution was, what the pH was, what the EDC was, [00:22:00] and, and you can adjust
[00:22:01] Nick Greens: them, want to put flow meters on those, uh, Those units.
So that way you can see how fast the flow is coming from back from the system, because that will help to get an accurate reading as well too, as the monitor, the flow rates, correct? Yeah.
[00:22:16] Joe Swartz: Some growers definitely. Um, we'll, we'll look at flow rate and volume in terms of what's going into the system and what's coming up for sure, but, but really the, the automated dosing.
You can get on a commercial scale, you know, fairly low level, reasonably inexpensive equipment that provides real value. I think the dosing systems for most commercial growers are probably one of the most valuable tools that you have. And so you had asked earlier, You know, the different levels and, you know, two-part dosing up to eight or nine or 10 part dosing.
And certainly a lot of them ever saw first. Uh, I actually I've seen, uh, I think it was, I think it was nine or 10, uh, components. Yeah. And, and it, to be honest in [00:23:00] most applications, I don't think that's really necessary, but every grower is different and especially in the cannabis space, uh, we've done a lot of laws.
[00:23:08] Nick Greens: Secret sauce is in the cannabis space.
[00:23:10] Joe Swartz: Yeah. So I w I want, I think one of the real challenge, so as far as dosing, so if you have a liquid concentrates and you have dosing units, and these could be either just simple, um, injectors that work off the water, they're, they're basically water pump, uh, injectors, um, or peristaltic pumps.
Adding nutrient when needed is very simple and very straightforward. The real-time inline monitoring of the solution is a little, little more difficult, a little more challenging. So if you're, if you're measuring just something as simple as what the pH is and what the electrical conductivity is, that's pretty straightforward.
When you start measuring specific ions, how much. Is in the solution and then maybe adding nitrate if needed or potassium or phosphorus that gets a [00:24:00] little more expensive and a little more difficult to do. Certainly can be done. Lots of growers use that very successfully. I think that
[00:24:07] Nick Greens: somebody should do that in the beginning.
You know, like when you're starting a farm, you should water test a lot and fix it up and correct it and water test and water test and spend the money in the beginning. And then over time you can dial it in and then just use what you dialed in and then do that every season, right? You, because the season's going to change.
[00:24:28] Joe Swartz: Yeah, I'm a big proponent of, uh, so if you're just starting out, testing your source water, making up a base nutrient solution, testing that, and then testing that same nutrient solution again, after a certain period of time, maybe every three or four or five weeks. Test that solution. So just those three tests though, the source water test, a new nutrient solution test, and then a test of a nutrient solution that's been running for awhile.
That's going to tell you a lot about what's going on in your nutrient solution. So [00:25:00] at the end, when you're testing the, the, the old solution or the youth solution, if you will, you know, are your, are your levels still where they need to be is maybe sodium or chlorides getting too high. Um, is, you know, if you still have really good nitrogen levels, but very low potassium levels, it tells us a lot about what's going on.
And then, you know, making adjustments or changes to the nutrient obviously
[00:25:27] Nick Greens: is low, right? The dissolve oxygen. Throw off everything else too, as
[00:25:31] Joe Swartz: well. Yeah, absolutely. And that's, that was when we were, when I was going to talk about microbials, the dissolved oxygen is a very big piece. So one of the things we might as well talk about it now, then one of the big things that people sometimes forget is they look at the nutrient solution because basically you're taking the, the perception is you're taking water and you're adding chemicals to it.
And you're just dumping in some fertilizers. And then going from there. I've always [00:26:00] been very adamant that the nutrient solution in a properly run hydroponic system is literally a living, breathing entity. So we have a whole host of different beneficial microbes. Uh, in any, any situation, um, that, that, that performed many, many different functions in the roots, uh, roots on plant from breaking down, uh, nutrients in the soil, um, helping make them available to the plant, stimulating root growth, um, uh, being, uh, beneficial to the plant growth, both in terms of stimulation, but also blocking out or inhibiting.
Different harmful pathogens. So like healthy microbes, like Trico Derma or streptomyces that are in soil, do a lot of things. They stimulate root growth. They help metabolize waste products that are coming from the roots. They also help block out or inhibit the growth of pathogenic, fungus, like Pythian refuse cerium [00:27:00] so, so they do, oh, hold,
[00:27:02] Nick Greens: hold another term for that.
The, uh, uh, like, um, um, like a medium agent, like a medium cleaner.
[00:27:10] Joe Swartz: I haven't heard that term used, but I mean, I guess that, that you certainly couldn't use that. Um, but it, again, it's, it's a living healthy biology and, and unfortunately in hydroponics for many years, that that has, has been kind of overlooked.
And in many cases, you know, erroneously left out, um, people have to this day, Talk to me about hydroponics being kind of this laboratory sterile environment kind of thing. And I always just, you know, cringe with that because nothing could be further from the truth. Um, just recently was reading our article about an indoor vertical farm and, you know, a big part of the article was how this is modern high-tech food.
That kind of is removed from the natural biology that you'd see outside. And again, I'm yelling at the computer screen while I'm reading it because, um, [00:28:00] no, as hydroponic growers, we have to understand we are managing many different living ecosystems within our greenhouse or inside our grow space. But one of the most important ones is the living ecosystem in our nutrient solution.
It's not an inert, um, uh, entity. It is. Water and nutrients and. A whole host of, uh, different beneficial microbes, like strike streptomyces, Miko, riser, Trico Derma, and we, we grow or sometimes we'll add them. You can commercially purchase them. But also, and we see this in aquaponics is that these microbes are in the environment.
And so what we're doing is we're stimulating their growth by providing them with a good environment. So think about this when you're in a greenhouse, you're providing temperature, light, carbon dioxide levels, air movement, all to optimize the conditions for plants, looking at what plants need. And if you do that, [00:29:00] that will stimulate the plants to grow well and grow properly.
And so. As a manager of the environment, we also have to manage our nutrient solution. And so in order to stimulate and to encourage and, and, um, Promote the growth of all these different beneficial microbes, just as in soil, we have to provide that proper environment. And temperature is one, um, the pH of a nutrient solution, the composition of source water.
Those are all important factors. And as you said, the dissolved oxygen level, so here's a really important, uh,
[00:29:38] Nick Greens: And, you know, there's a big group of people, growers, I should say. There's a really huge, big growers that do the opposite. They actually kill all the beneficial bacteria. They kill all the bacteria because they think that their plant will have a more successful, uh, finish if there's nothing [00:30:00] there to try to take it out.
So they're playing defense and not offense, I guess that would be called right.