Another possibility is to mix the dry fertilizer into water, and store the concentrated solution. With a little forethought you can select units of measure that will make it easy to dilute in the future.
The fertilizer will probably not dissolve completely into a volume of water small enough to yield the same volume as that of the fertilizer in the container. And, when stored in the refrigerator, solutions will not hold as much dissolved as they would at room temperature.
Measure the volume of dry fertilizer you have. Figure out how many units of small measure you use that volume represents. There are 16 tablespoons in a cup and 3 teaspoons in a tablespoon.
For example, if you use 1/4 teaspoon per gallon of water, you know that one cup of fertilizer granules will yield (1 quarter teaspoon / gallon x 4 quarter teaspoons / teaspoon x 3 teaspoons / tablespoon x 16 tablespoon / cup) = 192 gallons of your final concentrate.
You could dilute the powder so you would add 1 teaspoon of concentrate to a gallon of water to give you a final concentration of 1/4 teaspoon of powder per gallon. To reach this you would put one cup of fertilizer powder into 192 teaspoons of water. Since there are 16 tablespoons per cup, and 3 teaspoons per tablespoon, 192 teaspoons divided by 3 teaspoons per tablespoon divided by 16 tablespoons per cup equals 4 cups of water, or one quart. The way to get it right would be to add the powder to 3 cups of water, dissolve completely, and add water to make 1 quart (4 cups) exactly.
You may be able to dissolve more than a cup of fertilizer powder in a quart of water. Two cups of powder in a quart of water would yield a concentration such that a half teaspoon of concentrate added to a quart of water would yield a quarter teaspoon of powder per gallon of water.
You can also buy a siphon injector for your garden hose bibb. It screws onto the bibb; then you screw the hose onto the siphon. The injector has a rubber tube coming off the side that you drop into a bucket of concentrated fertilizer solution. When the hose is turned on at something more than a trickle, the injector uses the Venturi principle to suck concentrate out of the bucket. It mixes with the water coming from the hose bibb.
The injectors sold in the US make a 1:16 final dilution. This is because there are sixteen tablespoons per cup, and most fertilizer granules sold in the US are applied to outside plants at 1 tablespoon per gallon. So, if you put one cup of fertilizer granules per gallon of water in the concentrate bucket, the final yield out your hose will be 1 tablespoon of fertilizer per gallon.
If you wanted one teaspoon per gallon, and not one tablespoon, you would add 16 teaspoons of fertilizer granules for each gallon in the concentrate bucket.
Last edited by estación seca; 05-27-2017 at 04:46 PM..
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