Anyone have a recipe for making liquid fertilizer from stock chemicals like potassium nitrate?

[Horseflesh]

Because I grow plants in my aquarium I have all the basic macronutrients as dry chemicals. It's easy enough to figure out how much of each chemical to add to a tank of water to get to a desired concentration of that nutrient.

But when I looked for a guide on how to mix your own liquid fertilizers for potted plants, I struck out. I'll feel dumb if I buy a bottle of fertilizer from the store when I have pounds of all the same chemicals in jars.

If anyone has a cool reference, thanks for the pointer.

 

[YumYum]

It is all based on weight percentages, not volume. Fertilizer, whether liquid or solid, is based on percentage of the weight of the product. 10% N means 1 lb of nitrogen in 10 lbs of product.

Is that what you are asking?

I'm not sure how you are calculating things to add to water as opposed to dirt because water weighs something and dirt weighs something.

 

[Horseflesh]

> Fertilizer, whether liquid or solid, is based on percentage of the weight of the product. 10% N means 1 lb of nitrogen in 10 lbs of product.

Sure, so let me put it another way:

I have a jar of potassium nitrite: how much does my 10 liter bay laurel pot need? A gram? A hundred grams? It's the same question for potassium sulfate, magnesium sulfate, and monopotassium phosphate.

I can calculate what percent of the chemical weight is the nutrient of interest, but I cannot find how much nutrient (or bulk chemical) we actually want to add to a pot of a given size. When I look up fertilizers the application instructions are per 100 square feet, which does not apply easily to feeding single potted plants.

 

[YumYum]

https://www.omnicalculator.com/biology/water-soluble-fertilizer

Imagine you are using a 20-20-20 water soluble fertilzier. You want and end product of 150 ppm N in a gallon of water.

Desired element: N
Mass concentration: 150 ppm
Volume of diluted solution: 1 US gal
Answer is 2.839 g of fertilizer per gallon of water.

There is a custom selection where you can input different fertilizer numbers.

 

[YumYum]

Here is a calculator for non water soluble fertilizers:
https://www.omnicalculator.com/biology/fertilizer

 

[YumYum]

Here is a calculator for non water soluble fertilizers:
https://www.omnicalculator.com/biology/fertilizer

That one goes by the surface area which you can figure up how many square feet are in a 10" round pot.

 

[Horseflesh]

That is a handy calculator, thanks, that will help a lot.

I'm still trying to figure out how to dose a potted plant. I can figure out its surface area but it is something like 6.88705e-6 acres, haha.

 

[YumYum]

All that means is move the decimal point to the left 6 places so 6.88705e-6 = 0.00000688705 acres.

 

[YumYum]

Try figuring it in square feet instead of acres.

50 lbs/acre of N is a good starting point for fertilization.

 

[Horseflesh]

I know what it means, it's just an absurd measure (and it also has an unrealistic number of sig figs).

I remain surprised that there isn't some kind of chart that summarizes the info I am looking for, but I guess I am the first person that ever had a jar of nitrite and wanted to fertilize a pot with it!

 

[YumYum]

Oh ok. Well when you are trying to figure a small amount in large units, it happens.

Don't nitrites convert to nitrates? There may be a reason potassium nitrate is used instead of potassium nitrite.

 

[Horseflesh]

You are correct! I misspoke.

 

[DirtMechanic]

Oh ok. Well when you are trying to figure a small amount in large units, it happens.

Don't nitrites convert to nitrates? There may be a reason potassium nitrate is used instead of potassium nitrite.

Nitrates in sausage break down into nitrites and thus give the longer shelf life to charcuterie meats is how I remember it.

Dont forget the metric system is water based and if one does not compensate for the specific gravity of the material against the mass of water the fertilizer can come out hot.

 

[gary350]

Don't waste money of over priced $5 boxes of plant food.

Go to a Farmers supply store you can buy any type fertilizer $20 per 50 lb. bag. Most of the plant food in a bottles and 5 lb. boxes and bags cost $20 also. In TN we have, Farmers Co-op and TSC = tractor supply. I buy, 21-0-0, 46-0-0, 6-12-12, 15-15-15, 0-20-20,

Each plants need its own type food. Onions need 21-0-0 for 6 weeks then 0-20-20 for 6 weeks.

Potatoes and tomatoes need, 15-15-15 for 1 month then 6-12-12 for a month, then 0-20-20.

Corn needs 15-15-15 and 46-0-0 a week before planting seeds then 46-0-0 when corn is knee high, again when plants are 4 ft tall, again when ears have silks.

Beans, strawberry plants and garlic like, 15-15-15.

 

[DirtMechanic]

Don't waste money of over priced $5 boxes of plant food.

Go to a Farmers supply store you can buy any type fertilizer $20 per 50 lb. bag. Most of the plant food in a bottles and 5 lb. boxes and bags cost $20 also. In TN we have, Farmers Co-op and TSC = tractor supply. I buy, 21-0-0, 46-0-0, 6-12-12, 15-15-15, 0-20-20,

Each plants need its own type food. Onions need 21-0-0 for 6 weeks then 0-20-20 for 6 weeks.

Potatoes and tomatoes need, 15-15-15 for 1 month then 6-12-12 for a month, then 0-20-20.

Corn needs 15-15-15 and 46-0-0 a week before planting seeds then 46-0-0 when corn is knee high, again when plants are 4 ft tall, again when ears have silks.

Beans, strawberry plants and garlic like, 15-15-15.




View attachment 103454

I had to take a screenshot of this post. Might have my wife print it out and have it framed!