Converting Dyna-Gro fertilizers to a 1.0-0.4-1.5 elemental ratio.

[jerrytheplater]

Steve Johnson started a discussion on fertilizers in his blog back on Oct. 20, 2020 (or maybe earlier in another post) viewtopic.php?f=31&t=34730&start=600 which is page 41 on my computer. I went over his calculations and discovered an error in the amount of Potassium Sulfate to add to reach his goal. Minor issue, but the cause of it was due to using volume calculations rather than weight. The density of ground fertilizers varies greatly from water and this led to an error, but not one which will harm your plants. We have been discussing this via PM's and it led to me making a spreadsheet to calculate how to convert selected Dyna-Gro liquid fertilizers into the 1.0-0.4-1.5 elemental nutrient ratio pointed out to Steve by MikeinOz.

Since I can't attach Excel spreadsheets on the Forum, if anyone wants a copy I would be glad to send it via email if you PM your email address to me. I will also scan the calculation pages and attach them as photos if it works.

I will try and copy over the first tab in this spreadsheet where I go over the calculations needed.

Directions for converting Dyna-Gro All-Pro to a cactus formulation in a 1.0-0.4-1.5 ratio.

Equipment needed, with selected sources:

An electronic balance which will give you one decimal place in the weights, as in 5.8 or 10.7 grams. Example from Carolina Biological Supply:
https://www.carolina.com/lab-balances-s ... /702357.pr

10 and 100 ml plastic graduated cylinders to get an accurate volume from your stock solution. An example from Carolina Biological Supply: https://www.carolina.com/lab-cylinders/ ... _721600.pr

Disposable micro pipets to measure out Dyna-Gro concentrate. An example from Carolina Biological Supply: https://www.carolina.com/lab-pipets/mic ... /736984.pr

To make all of the conversions, you will need Potassium Sulfate, Potassium Nitrate, Mono Potassium Phosphate, and Ammonium Nitrate. The only one you can't buy from aquarium fertilizer online sellers like https://aquariumfertilizer.com/ is Ammonium Nitrate. You may know that as the ingredient in terrorist bombs using Fuel Oil and Ammonium Nitrate. You can buy one pound quantities of Ammonium Nitrate though, and you will not need to give ID and jump through hoops with Homeland Security. Here is one site I found, there may be more. https://sciencekitstore.com/ammonium-nitrate-99/

You must use Distilled or Deionized or Rain or Reverse Osmosis Water. The hardness chemicals of Calcium and Magnesium in most tap water will react with the Phosphates in the Dyna-Gro fertilizer and in the Mono Potassium Phosphate and precipitate out. You don't want that to happen.
Any time I refer to adding water, it will always be any one of the above waters. Always. Always.

Step by step directions to make the conversion:

You will be making a stock solution and using some of it to make a final gallon which will be used to fertilize the cactus. This is a method to obtain much finer weights than your scale will allow. Instead of 0.1 gram accuracy, you can get 0.0001 gram accuracy. More or less. The example below uses the weights from the Dyna-Gro All-Pro sheet. The others are similar.

Calculation example:

To determine weights of chemicals needed to make the stock solution, follow this procedure:

Add the weight of one teaspoon of the fertilizer chemical first on the list to a gallon container 3/4 filled with water as explained above. It really does not matter which chemical you choose first, but I needed to start somewhere. At the bottom of this page are the weights of one teaspoon of the fertilizers as I determined them. Your results will definitely differ as explained below.

(5.8 gm KNO3 in a gal. stock solution container) x (??? ml to use from stock) = (0.1182 gm KNO3 in final gal. from column "E" ) x (3785 ml per gal.) Unknown ml to take from stock solution to add to the final gallon. = 0.1182 x 3785 / 5.8 which is 77.1 ml stock solution to be used.

To calculate the weight of Potassium Sulfate you need to add to the stock solution so that 77.1 ml of it contains the required final weight of K2SO4,
you calculate like so:

(??? gram K2SO4 to add to stock sol.) x (77.1 ml stock sol.) = (0.2178 gram K2SO4 in final gal. from column "E") x (3785 ml/gal.). ??? gm K2SO4 to add to the stock solution = (0.2178 x 3785 / 77.1) which is 10.7 gm K2SO4 to be added to the stock sol. or a little more than 1.5 US tsp.

If there is a third chemical to add to the stock solution, repeat the Potassium Sulfate calculation using the appropriate values.

Directions for making the solutions once the weights needed are calculated as above.

1. In a 1 gallon plastic container which you can cap, like a milk container, add about 3/4 gallon Water as above.

2. Add 5.8 gram Potassium Nitrate, KNO3, and 10.7 gram Potassium Sulfate, K2SO4 to the gallon container. Cap and shake to dissolve. Keep the stock solution out of the sun to prevent algae growth. Use within one month because of the KNO3 stimulating bacterial or algae growth. Pour out the expired stock solution in your garden or lawn over a large area.

3. In a second labeled gallon container add 3/4 gallon Water as above. This container is what you will apply to your cactus once made up.

4. Add 77 ml of the stock solution by filling the 100 ml graduated cylinder to 70 ml and the 10 ml graduated cylinder to 7 ml. Pour both into the second gallon and mix well.

5. Fill the second gallon almost full and mix well. Add 2.5 ml (1/2 tsp) of Dyna-Gro All-Pro Concentrate as found in cell "I3" in all of the sheets. Fill to one gallon and mix well. Apply to your plants.

Reason why you should use weight measurements rather than volume, as in teaspoon measurements.

All of the fertilizers below were sifted through the same sieve to ensure uniform particle size for the weighing trials. None of the measures were packed down. All were leveled with the same straight edge. The same teaspoon was used in each case.

Wt. of KNO3 depends on size of tsp. measure; if it is shaken and packed down; and how leveled off it is. Avg 5.772 gm/tsp. Range: 5.65-5.86 gm Density of crystal KNO3 is 2.109 gm/cc. Density of fertilizer grade ground KNO3 range 1.130 to 1.172 gm/cc, depending on packing and particle size.

Wt. of NH4NO3 depends on size of tsp. measure; if it is shaken and packed down; and how leveled off it is. Avg. 3.586 gm/tsp. Range: 3.459-3.766 gm Density of crystal NH4NO3 is 1.725 gm/cc. Density of fertilizer grade ground NH4NO3 range 0.692-0.753 gm/cc, depending on packing and particle size.

Wt. of KH2PO4 depends on size of tsp. measure; if it is shaken and packed down; and how leveled off it is. Avg. 5.419 gm/tsp. Range: 5.35-5.59 gm/tsp. Density of crystal KH2PO4 is 2.338 gm/cc. Density of fertilizer grade ground KH2PO4 range 1.070-1.118 gm/cc, depending on packing and particle size.

Wt. of K2SO4 depends on size of tsp. measure; if it is shaken and packed down; and how leveled off it is. Avg. 7.0 gm/tsp. 7.5 gm if packed. Density of crystal K2SO4 is 2.662 gm/cc. Density of fertilizer grade ground K2SO4 range 1.396 to 1.5 gm/cc, depending on packing and particle size.

[jerrytheplater]

Before scanning, I realized I can also add in the conversion for the other Dyna-Gro products I calculated. All of these are available in 8 ounce containers. I am pretty sure you can buy direct from Dyna-Gro, but I didn't see a cart on their site. Maybe Steve can shed some light on this for us.

Each one of these conversions will yield a fertilizer strength of about 50 ppm Total Nitrogen in the fertilizer you will use on your plants. The other nutrients will follow that concentration in the same ratio as the concentrate and the stock solution you add.

Dyna-Gro All-Pro: Stock solution: Add 5.8 gm Potassium Nitrate and 10.7 gm Potassium Sulfate to the 3/4 gallon water. Final solution for use: 3/4 full water. Add 77.1 ml stock solution. Mix. Fill almost to top. Mix. Add 2.5 ml Dyna-Gro All-Pro. Mix. Use.

Dyna-Gro Orchid-Pro: Stock solution: Add 5.8 gm. Potassium Nitrate, 6.1 gm Ammonium Nitrate, and 25.7 gm Potassium Sulfate to the 3/4 gallon water. Final solution for use: 3/4 full water. Add 49.8 ml stock solution. Mix. Fill almost to top. Mix. Add 2.2 ml Dyna-Gro Orchid-Pro. Mix. Use.

Dyna-Gro Foliage-Pro: Stock solution: 7.0 gm Potassium Sulfate, and 5.6 gm Mono Potassium Phosphate to the 3/4 gallon water. Final solution for use: 3/4 full water. Add 144.8 ml stock solution. Mix. Fill almost to top. Mix. Add 2.1 ml Dyna-Gro Foliage Pro. Mix. Use.

Dyna-Gro Grow: Stock solution: Add 5.8 gm. Potassium Nitrate, 2.4 gm Ammonium Nitrate, and 8.7 gm Potassium Sulfate to the 3/4 gallon water. Final solution for use: 3/4 full water. Add 125.8 ml stock solution. Mix. Fill almost to top. Mix. Add 1.9 ml Dyna-Gro Grow. Mix. Use.

Dyna-Gro Bloom: Stock solution: Add 5.8 gm. Potassium Nitrate, 2.9 gm Ammonium Nitrate, and 0.8 gm Potassium Sulfate to the 3/4 gallon water. Final solution for use: 3/4 full water. Add 301 ml stock solution. Mix. Fill almost to top. Mix. Add 1.4 ml Dyna-Gro Bloom. Mix. Use.

Dyna-Gro Bonsai-Pro: Stock solution: Add 5.8 gm. Potassium Nitrate, 2.4 gm Ammonium Nitrate, and 8.7 gm Potassium Sulfate to the 3/4 gallon water. Final solution for use: 3/4 full water. Add 125.8 ml stock solution. Mix. Fill almost to top. Mix. Add 1.9 ml Dyna-Gro Bonsai-Pro. Mix. Use.

rsz Dyna-Gro All-Pro conversion.jpg (134.64 KiB) Viewed 1257 times

[jerrytheplater]

In case anyone has copied out the directions for converting Foliage-Pro, I just noticed a mistake I made when copying in text and correcting the numbers. I never did that for the Foliage-Pro and had the incorrect information. I have just edited it above to correct it.

And, if any of you wanted to buy Dyna-Gro's Grow or Bonsai-Pro, you only need to buy one. They are identical. Dyna-Gro just confirmed that for me.