C
Corbin
Guest
I have been doing some research and found the following formula for calculating the amount of fertilizer to add to reach a desired ppm of nitrogen. The formula is from David Mellard's article in the August 04 issue of the Atlanta Orchid Society's newsletter. See also Part 5 of Bill Argo's article in the Sept. AtOS newsletter.
step 1) Multiply the desired nitrogen concentration by the gallons of fertilizer you want.
step 2) Multiply the percent nitrogen in the formula by 75
step 3) Divide the value from Step 1 by the value from Step 2
Amount of fert. to add = (desired nitrogen concentration) X (# gallons of water) / (% nitrogen in the fertilizer) X (75)
Example: If you want 125 ppm nitrogen in one gallon of water and the fertilizer is 20-10-10
(125) X (1) / (20) X (75) = 0.083 ounces
Since 1 tsp holds about 0.2 ounces then 0.083 ounces divided by 0.2 ounces per tsp = 0.4 tsp
step 1) Multiply the desired nitrogen concentration by the gallons of fertilizer you want.
step 2) Multiply the percent nitrogen in the formula by 75
step 3) Divide the value from Step 1 by the value from Step 2
Amount of fert. to add = (desired nitrogen concentration) X (# gallons of water) / (% nitrogen in the fertilizer) X (75)
Example: If you want 125 ppm nitrogen in one gallon of water and the fertilizer is 20-10-10
(125) X (1) / (20) X (75) = 0.083 ounces
Since 1 tsp holds about 0.2 ounces then 0.083 ounces divided by 0.2 ounces per tsp = 0.4 tsp