Fertilizers explained (2-part presentation) -- with 6/2023 update

[Steve Johnson]

Steve, if it helps I nave a table of all the commonly used fertilizers and their percentages of available nutrient elements. You can probably also find it on line.

Plants take up nutrients as ions (such as nitrate or sulphate or ammonium) not necessarily as naked elements, and ions always come in pairs. So, if you are formulating a fertilizer, you need the percentage of the element in the compound (molecule)
Eg - the percent of Ca and the percent of N in calcium nitrate = 17% Ca and 12% N. From there you can work out how much Calcium nitrate to include in your formulation etc.

Hi Mike,

That I can understand, and you're explaining it concisely. I'll go back and redo the spreadsheet calculations. Thanks!

[Steve Johnson]

Your final answer of 14 ppm NH4 in the fertilizer is correct, but you add it to the 2 ppm N obtained from the 0.65 ml of fertilizer. You are adding apples and oranges. The 14 ppm NH4 contains about 11 ppm N (10.75).[/color]

See this:

The left side of the spreadsheet has a breakdown for US growers, and the right side is for the rest of the world running on the metric system. I'm trying to do this for all growers regardless of where they live.

0.65 ml refers to the metric side of the spreadsheet for non-US growers. For US growers, I use metric only for measuring the amount of ammonium sulfate, potassium sulfate, and sodium molybdate powders going into the stock solutions. By the way, I did change the spreadsheet from 0.65 to 0.7 mL/L on the right side of the spreadsheet -- I do agree that the non-US folks will make it easier. Where any of the ppm numbers changed at all, they changed by only 1 or 2 ppm.

[Steve Johnson]

Okay, now I remember what the spreadsheet is supposed to be showing...

Since I'm replacing the Dyna-Go 7-7-7 with the GH FloraMicro 5-0-1 and FloraBloom 0-5-4 ferts, I need to supplement the FloraMicro's 5% N so that it matches the Dyna-Gro's 7% N. Diluted at 1/2 tsp. per gallon, the 7-7-7 is 14 ppm NH4 and 32 ppm NO3. FloraMicro at the same dilution rate = 2 ppm NH4 and 31 ppm NO3. In order to match the 7-7-7, we need an additional 12 ppm NH4 in the watering solution. I had to calculate the right amount of ammonium sulfate for an ammonium sulfate-potassium sulfate stock solution, and the right amount of stock solution going into the watering solution to arrive at the additional 12 ppm NH4. The final amount I get in the watering solution is 14 ppm NH4 -- the match is as close as we can get, and the extra 2 ppm isn't worth mentioning.

Based on our recent conversations with Mike regarding phosphorus, it became pretty clear that FloraMicro 5-0-1 and FloraBloom 0-5-4 are superior to the Dyna-Gro 7-7-7 I had been using for years because:

• The P in FloraBloom is lower than the 7-7-7's P.

• FloraMicro can be supplemented with ammonium sulfate, giving us a more favorable N-P ratio of 1-0.3 compared to the 7-7-7's ratio of 1-0.44.

• Ammonium sulfate and potassium sulfate can be combined in the same stock solution, giving us the ability to bring K up to an ideal NPK ratio in the watering solution.

The only reason why I wanted y'all to check my math -- ppm calculations by volume are easy with liquid ferts, but I wasn't sure if my calculations were right going by weight for the ammonium sulfate, potassium sulfate, and sodium molybdate powders going into stock solutions. If they were indeed right, the rest of the ppm numbers in the spreadsheet fall into place.

I'll admit that I was the author of confusion when I put the calculations for US and non-US growers in the same spreadsheet. We'll try again, but with 2 spreadsheets -- for US growers...



...and non-US growers:



FloraMicro and FloraBloom are sold under the Terra Aquatica brand name in Europe, although it's possible that they're being sold under different brand names in countries outside of Europe. If not, but you find a 5-5-5 liquid fert matching this...



...you'll have a recipe you can follow using the spreadsheet for non-US growers.

In regards to this whole conversation where I'm trying to show you an error at your request, forget about Nitrate ratios and Mo. It just does not fit in with this conversation.

There has to be a reason why Mike recommends .05 ppm Mo when NO3 is higher than NH4 and .03 ppm Mo when NH4 is higher than NO3. If it's not about specific NH4-NO3 ratios, I won't bring this up again -- his recommendations are good enough without me having to know why he's making them. Also, I'm breaking down N to NH4 and NO3 in the spreadsheets because those numbers come from the fert's guaranteed analysis. I'm keeping them in there regardless of whether we need them or not. The point is to make sure that total ppm N in the watering solution stays within acceptable limits for cacti.

Speaking of, I think Davide has been patiently waiting for this:



That's not a typo -- NH4 is indeed higher than NO3. My experience is confined to using liquid ferts, so I'd be interested to find out if dry ferts usually tilt in favor of Ammonium N. If they do, .03 ppm Mo is the target number for a watering solution. (And yes, Ferty 3 is a dry fertilizer.)

[Fohat85]

Great, thank you so much for taking the time. I'll let you know the results!

[Steve Johnson]

Okay, we're learning more about Molybdenum...

I asked Mike a PM question about why he recommends 0.05 ppm Mo for some situations and 0.03 ppm for others. Didn't want to broadcast the answer without his permission first (just a matter of courtesy), and it was granted. For your consideration:

I'm trying to understand the relationship between Mo and NO3. More specifically, why is .05 ppm Mo good when NO3 is higher than NH4, and .03 ppm Mo is good when NH4 is higher than NO3? If a 1-2 or 2-1 ratio of NH4 and NO3 isn't the determining factor, then Jerry was right. If so, I'd like to know why the NH4-NO3 ratio has nothing to do with it. If I made an incorrect statement, I'd like to correct it for the record.

Steve

Hi Steve. The only reason I say 0.05ppm Mo is that that seems to be the standard amount used in most commercial hydroponic set ups. (remember these use no humus or soil in the medium so there is basically no Mo other that what is added in fertilizers) These usually use 100% nitrate nitrogen and zero ammonium. So it follows that the need for Mo is greater for those formulations than it would be if 50/50 ammonium/nitrate or greater were used. I also read somewhere long ago that when the Dutch hydro people supplemented their crops with 100% Calcium nitrate for whatever reason, that they often add Mo along with it after finding that un-used nitrate would build up without it. I have no idea where I read that but it stuck in my mind. So to sum up, the 0.05ppm Mo seems optimal for soil-less media using mainly nitrate - N and the Mo is less important when using a mix of nitrate and ammonium or only ammonium or urea, and/or the mix contains soil. The 0.03 figure is just a working one and is quite flexible. It could be zero in a soil based medium where ammonium or urea was the main source of N.

Do you need an Mo supplement if your fert doesn't have enough (or maybe no Mo at all)? If so, how much? The answers are right there. Thanks, Mike!

[jerrytheplater]

Okay, we're learning more about Molybdenum...

I asked Mike a PM question about why he recommends 0.05 ppm Mo for some situations and 0.03 ppm for others. Didn't want to broadcast the answer without his permission first (just a matter of courtesy), and it was granted. For your consideration:

I'm trying to understand the relationship between Mo and NO3. More specifically, why is .05 ppm Mo good when NO3 is higher than NH4, and .03 ppm Mo is good when NH4 is higher than NO3? If a 1-2 or 2-1 ratio of NH4 and NO3 isn't the determining factor, then Jerry was right. If so, I'd like to know why the NH4-NO3 ratio has nothing to do with it. If I made an incorrect statement, I'd like to correct it for the record.

Steve

Hi Steve. The only reason I say 0.05ppm Mo is that that seems to be the standard amount used in most commercial hydroponic set ups. (remember these use no humus or soil in the medium so there is basically no Mo other that what is added in fertilizers) These usually use 100% nitrate nitrogen and zero ammonium. So it follows that the need for Mo is greater for those formulations than it would be if 50/50 ammonium/nitrate or greater were used. I also read somewhere long ago that when the Dutch hydro people supplemented their crops with 100% Calcium nitrate for whatever reason, that they often add Mo along with it after finding that un-used nitrate would build up without it. I have no idea where I read that but it stuck in my mind. So to sum up, the 0.05ppm Mo seems optimal for soil-less media using mainly nitrate - N and the Mo is less important when using a mix of nitrate and ammonium or only ammonium or urea, and/or the mix contains soil. The 0.03 figure is just a working one and is quite flexible. It could be zero in a soil based medium where ammonium or urea was the main source of N.

Do you need an Mo supplement if your fert doesn't have enough (or maybe no Mo at all)? If so, how much? The answers are right there. Thanks, Mike!

Steve, I can honestly say that I never even considered any effect on Mo concentrations when I was pointing out the mistake I found in your calculations. I don't know how you got that impression, and it does not really matter now. The mistake was and still is that you are calculating Ammonium, NH4, instead of Ammoniacal-Nitrogen, N obtained from Ammonium compounds. Look at the label you posted for the GH FloraMicro products. It does not say anything about Ammonium. It says "0.3% Ammoniacal Nitrogen".

I made up a spreadsheet to do the calculations and I used your numbers throughout. I did omit some of the nutrients from the spreadsheet for clarity. These don't change as they are contained in the liquid fertilizer as purchased.

The red lines are the Ammonium calculations. You will notice also a red line for Nitrate, NO3 right under Nitrate-Nitrogen, NO3-N. Notice how great an impact the same error there produces. Thankfully, it was not made for Nitrate-N. Your numbers end up with a fertilizer solution that contains 6.5% N- 2.18% P- 10.65% K at 46 ppm N.

Steve Johnson's Calculations.jpg (121.33 KiB) Viewed 2169 times

Here is the same spreadsheet corrected to calculate using Ammoniacal-Nitrogen, rather than Ammonium. These corrections require increasing the volume of stock solution used to 53 ml and reducing the amount of K2SO4 added to the stock solution to 1.9 grams. The areas where the changes have been made are in red. These changes produce a fertilizer solution that contains 7.08% N- 2.18% P- 10.60% K at 50 ppm N. Your Mo calculations are not changed.

Jerry Smith's Corrections.jpg (120.47 KiB) Viewed 2169 times

Please do not take this as a personal attack on you. You asked for someone to check your calculations, "Everyone, please check my math -- if any of the calculations are in error, I'd appreciate it if you could give me the right calculations. I'll update my spreadsheet accordingly." I have done what you have asked. I hope you can see the error.

Who am I to make these posts? I am not a chemist, as I said before. I have a BS in Biology from Florida Institute of Technology where I had to take three years of college chemistry. I worked my last 29 years in Electroplating where calculations like these were almost every day parts of my job. So you can say I have a lot of practical on the job training in applying a portion of my degree.

Edit: sorry about the way the spreadsheets are sideways. If you can tell me how to rotate them, I'd be glad to. It is unfortunate. Also, the red font does not show up very well. Bummer.

[Steve Johnson]

Hi Jerry,

I pulled out the JPGs and archived them on my computer, so all I need to do is flip them clockwise -- easy enough. Unfortunately they're too small to read well, so I just wanted to double-check on something:

• Your version of my spreadsheet -- 1.8 grams ammonium sulfate and 2.6 grams potassium sulfate per liter of stock solution.

• Your spreadsheet showing the corrections -- 1.3 grams ammonium sulfate and 1.9 grams potassium sulfate per liter.

Looks like I was way off on the potassium sulfate, so I'll go with your 1.9 grams per liter. On the ammonium sulfate, did I have it down as 1.8 grams? If I did, I was way off on that too. As I said, hard to read the numbers in the JPGs you posted, so please verify that these numbers are right. If they are, I'll fly with your corrected numbers.

[jerrytheplater]

It is not 1.8, it is 1.3 grams of Ammonium Sulfate. It is also 1.9 grams of Potassium Sulfate. I did not change the amount of Ammonium Sulfate being used. I reduced the Potassium Sulfate.

You were not off on the potassium. You got those numbers correct. The reason the K2SO4 has to be reduced is because I had to increase the volume of the stock solution used to get more Ammonium Sulfate to increase the Ammoniacal-Nitrogen. Since the two chemicals are mixed in the stock, once I increase the volume used, I'm increasing the amount of both chemicals being taken out. The K2SO4 concentration of the stock needed to be reduced so that you still get the same amount of K2SO4 in the increased volume of stock solution.

[jerrytheplater]

PS. If it is worth it, I could scan them over at a higher resolution and try to manipulate the colors to make it clearer. I was disappointed that the red did not show well.

[Steve Johnson]

PS. If it is worth it, I could scan them over at a higher resolution and try to manipulate the colors to make it clearer. I was disappointed that the red did not show well.

Not necessary -- you verified the numbers I need to use, so many thanks. While we're here...

Just an FYI as we continue to learn more about Mo. On 2/26, I posted an article from the Pro-Mix website (https://www.pthorticulture.com/en/train ... t-culture/) -- here's a quote:

• "Molybdenum is an essential component in two enzymes that convert nitrate into nitrite (a toxic form of nitrogen) and then into ammonia before it is used to synthesize amino acids within the plant."

Thanks to a University of Nebraska-Lincoln article Jerry posted on 3/4, I now know the difference between nitrate-N and nitrate. Then I got confused -- is Mo converting nitrate-N or nitrate into ammonia? The Pro-Mix article says nitrate, but the real answer is here:

Molybdenum02a.jpg (60.17 KiB) Viewed 2135 times

An obscure bit of information, granted -- but for those of us who like to know how and why things work the way they do, this is kinda fascinating.

[jerrytheplater]

Another PS. When I'm making my own stock solutions, I make it so I will use it up quickly. I'll calculate the weight of the nutrient needed in the final container of fertilizer and multiply it by 10 and add that to the stock container. Then I take out 1/10th of the stock container for the final fertilizer. This way I'll have fresher solutions to mix up new batches of fertilizer. This is very important when using Nitrogen containing fertilizers (Ammonium or Nitrate) in the stock solution.

But that won't always work due to the limitations of the scale I have. You can play around and vary the combinations infinitely really I suppose.

[jerrytheplater]

Just an FYI as we continue to learn more about Mo. On 2/26, I posted an article from the Pro-Mix website (https://www.pthorticulture.com/en/train ... t-culture/) -- here's a quote:

• "Molybdenum is an essential component in two enzymes that convert nitrate into nitrite (a toxic form of nitrogen) and then into ammonia before it is used to synthesize amino acids within the plant."

Thanks to a University of Nebraska-Lincoln article Jerry posted on 3/4, I now know the difference between nitrate-N and nitrate. Then I got confused -- is Mo converting nitrate-N or nitrate into ammonia? The Pro-Mix article says nitrate, but the real answer is here:
Molybdenum02a.jpg

An obscure bit of information, granted -- but for those of us who like to know how and why things work the way they do, this is kinda fascinating.

Steve, I hope I can explain this without confusing you or anyone else. The term "Nitrate-Nitrogen" is a term used when looking at lab reports or fertilizer bags. No chemical exists that is called Potassium Nitrate-Nitrogen. It would be Potassium Nitrate KNO3. As it dissolves it splits into two ions: Potassium K+ and Nitrate NO3-. Not Nitrate-Nitrogen ion NO3-N-. That last ion does not exist in reality. Nitrate-Nitrogen just tells you that the Nitrogen being talked about is derived from Nitrate ions only.

The nitrogen in Potassium Nitrate can be analyzed and reported as % Nitrate or % Nitrate-Nitrogen. Both numbers are describing the same compound. Both numbers can be used to calculate how much is in the bag of fertilizer. You just have to make sure you know what the manufacturer is saying.

The Mo is being used to convert Nitrate ions. It is being used on that part of the fertilizer that is made from Nitrate containing chemicals. The bag would list the concentration of them as % Nitrate-Nitrogen. It is a term that farmers use a lot. And greenhouse growers. And us now.

I don't know the fertilizer industry well enough to be able to say all bags of fertilizer make a distinction between the forms of Nitrogen they contain. I have a container of Espoma Organic Cactus fertilizer. The label says the 1.00% Nitrogen it contains is comprised of 0.10% Ammoniacal Nitrogen, 0.87% Other Water Soluble Nitrogen, and 0.03% Water Insoluble Nitrogen. So here are even more terms!

[Steve Johnson]

Steve, I hope I can explain this without confusing you or anyone else. The term "Nitrate-Nitrogen" is a term used when looking at lab reports or fertilizer bags. No chemical exists that is called Potassium Nitrate-Nitrogen. It would be Potassium Nitrate KNO3. As it dissolves it splits into two ions: Potassium K+ and Nitrate NO3-. Not Nitrate-Nitrogen ion NO3-N-. That last ion does not exist in reality. Nitrate-Nitrogen just tells you that the Nitrogen being talked about is derived from Nitrate ions only.

The nitrogen in Potassium Nitrate can be analyzed and reported as % Nitrate or % Nitrate-Nitrogen. Both numbers are describing the same compound. Both numbers can be used to calculate how much is in the bag of fertilizer. You just have to make sure you know what the manufacturer is saying.

What you said is quite understandable, so all I needed was an explanation -- which you just did. Thanks.

With that in mind, Davide PM'd me about a fertilizer he's considering in place of Ferty 3:

Cifo Idrofloral Tech 15-10-30 (1-0.29-1.66)

Total nitrogen (N) 15%,
Nitric nitrogen (N) 8.5%,
Nitrogen (N) ammoniacal 4%,
Nitrogen (N) urea 2.5%,

Phosphorus pentoxide (P2O5) soluble in neutral ammonium citrate and in water 10%,
Phosphorus pentoxide (P2O5) soluble in water 10%,
[Not sure why it's listed twice.]

Potassium oxide (K2O) soluble in water 30%,

Sulfur trioxide (SO3) soluble in water 5%,
Boron (B) soluble in water 0.02%,
Copper (Cu) soluble in water 0.02%,
Copper (Cu) chelated with EDTA 0.02%,
Iron (Fe) soluble in water 0.05%,
Iron ( Fe) chelated with EDTA 0.05%,
Manganese (Mn) soluble in water 0.02%,
Manganese (Mn) chelated with EDTA 0.02%,
Molybdenum (Mo) soluble in water 0.01%,
Zinc (Zn) water soluble 0.02%,
Zinc (Zn) chelated with EDTA 0.02%

This is a dry fert, and I'm recommending 0.4 grams per liter for the watering solution. If you and Mike could do an evaluation including the ppm numbers, it'll tell us whether or not Davide will be getting what I think he's getting -- a fert with everything all in one bag, no stock solution required. All that's missing is Ca, but he can add limestone or gypsum to his mix depending on species.

[jerrytheplater]

Steve, I hope I can explain this without confusing you or anyone else. The term "Nitrate-Nitrogen" is a term used when looking at lab reports or fertilizer bags. No chemical exists that is called Potassium Nitrate-Nitrogen. It would be Potassium Nitrate KNO3. As it dissolves it splits into two ions: Potassium K+ and Nitrate NO3-. Not Nitrate-Nitrogen ion NO3-N-. That last ion does not exist in reality. Nitrate-Nitrogen just tells you that the Nitrogen being talked about is derived from Nitrate ions only.

The nitrogen in Potassium Nitrate can be analyzed and reported as % Nitrate or % Nitrate-Nitrogen. Both numbers are describing the same compound. Both numbers can be used to calculate how much is in the bag of fertilizer. You just have to make sure you know what the manufacturer is saying.

What you said is quite understandable, so all I needed was an explanation -- which you just did. Thanks.

With that in mind, Davide PM'd me about a fertilizer he's considering in place of Ferty 3:

Cifo Idrofloral Tech 15-10-30 (1-0.29-1.66)

Total nitrogen (N) 15%,
Nitric nitrogen (N) 8.5%,
Nitrogen (N) ammoniacal 4%,
Nitrogen (N) urea 2.5%,

Phosphorus pentoxide (P2O5) soluble in neutral ammonium citrate and in water 10%,
Phosphorus pentoxide (P2O5) soluble in water 10%,
[Not sure why it's listed twice.]

Potassium oxide (K2O) soluble in water 30%,

Sulfur trioxide (SO3) soluble in water 5%,
Boron (B) soluble in water 0.02%,
Copper (Cu) soluble in water 0.02%,
Copper (Cu) chelated with EDTA 0.02%,
Iron (Fe) soluble in water 0.05%,
Iron ( Fe) chelated with EDTA 0.05%,
Manganese (Mn) soluble in water 0.02%,
Manganese (Mn) chelated with EDTA 0.02%,
Molybdenum (Mo) soluble in water 0.01%,
Zinc (Zn) water soluble 0.02%,
Zinc (Zn) chelated with EDTA 0.02%

This is a dry fert, and I'm recommending 0.4 grams per liter for the watering solution. If you and Mike could do an evaluation including the ppm numbers, it'll tell us whether or not Davide will be getting what I think he's getting -- a fert with everything all in one bag, no stock solution required. All that's missing is Ca, but he can add limestone or gypsum to his mix depending on species.

I just came on to say that I didn't do any checking on the Ferty ferts you posted recently and was going to suggest you check the calculations you did to see if the Nitrate Nitrate-Nitrogen issue is there too.

Now when I read what you just posted alarm bells went off. I'm sure its translation issues, but I see "Nitric Nitrogen" and "Urea-Nitrogen". The Nitric could mean from the "Nitrite NO2-" ion which is not good. Or it might mean it came from Nitric acid, but in that case it would be Nitrate-Nitrogen. (That last statement is my guess and it could be wrong) The urea-nitrogen is a slowly available nitrogen and requires time for it to be available. I believe I have seen cautions against it, but again I could be wrong.

Sulfur Trioxide SO3- Just read about it and have to doubt that it is actually there. I just don't know.

It would be helpful to see the derived from statement, if there. That tells you the ingredients in the fertilizer.

[jerrytheplater]

Here is the product label from an English website. I was not able to see a Derived From statement on the Italian site or the product sheet. http://www.royalagroscience.com/en/powd ... 0-301.html

Guaranteed Content (W / W)
Total Nitrogen (N) 15%
Nitrate Nitrogen (N) 8,50%
Ammonia Nitrogen (N) 4%
Urea Nitrogen (N) 2,5%
Water Soluble Phosphorus PentaOxide (P2O5) 10%
Water Soluble Potassium Oxide (K2O) 30%
Water Soluble Sulfur tri oxide (SO3) 5%
Physical Information
pH 4 - 5 (in 10% solution)
EC 1,781 mS / cm (1 g / lt)