Quote:
Originally Posted by KristofferNgo
I don't know the mineral content of my water... I have to test it yet..
What is the formula that you used to get 100 ppm N for teaspoons and tablespoons? I am wondering why you used 9.2 for ml/L (ml is the same as teaspoons?) while 8 for teaspoons/gallon. What about tablespoons? Reason I'd like to know is so that I could use the formula and manipulate it depending on my needs.
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I remembered incorrectly... 1 ml/L is 1/1000, 1 tsp/gal is 1/768, so the ratio is 1000/768=1.3 (not the 1.2 I used).
Fertilizer measurement should be done in mass, not volume, especially when dealing with granular products, whose bulk density can vary. However, there is a reasonable, though not entirely accurate, estimator using a "standard, estimated" bulk density of 1 g/cc that says 2/%N = tsp/gal for 25 ppm N, or 1.3x that or 2.6/%N= ml/L, making 100 ppm N 10.4/%N (not the 9.2 I stated earlier)
Nitrogen concentrations are given in weight % on labels. so if you dissolve 100 g of a 20% N product in a liter of water, your solution will contain 20g of N in 1100g of liquid, making it a 1.8182 %N solution.
The specific gravity of that solution will be slightly higher than 1, but that is close enough for our purposes. So let's say you want to aim for the 100 ppm N final solution. 1.8182% is 1818.2 ppm, so you'd want to mix 100/1818.2=0.0055 or 5.5 ml of that solution in a liter.
Going back to the estimator, 10.4/1.818=5.72, which would really give us a 5.72/5.5=104 ppm N solution, which is pretty close!