Understanding the concentration of nutrients in your fertilizer mix is essential for optimal plant growth. This article will teach you how to calculate the parts per million (ppm) of your fertilizer or fertilizer mix, and how to create a custom NPK mix to meet your specific needs.
grams of fert per liter = A / B
Where:
your ppm = C x B
Where:
The final mix will provide 188 ppm N, 124 ppm P, and 220 ppm K in one liter of water. For greater precision, consider mixing larger batches or using a more accurate scale.
Understanding Fertilizer Labels
On the side of a fertilizer bag, you will find three numbers representing the percentage content of Nitrogen (N), Phosphorus (P), and Potassium (K) in the mix. These are the primary macronutrients required for plant growth. For every gram of fertilizer in one liter of water, it contributes 10 ppm of the given nutrient per percentage point. For example, a 20-20-20 fertilizer mix will provide 200 ppm of each nutrient for each gram in a liter of water.Calculating PPM of Fertilizer Mix
To determine the ppm of your fertilizer mix, you can use the following formula:grams of fert per liter = A / B
Where:
- A = your desired ppm
- B = 10 ppm x the % of nutrient in mix
your ppm = C x B
Where:
- B = 10 ppm x the % of nutrient in mix
- C = grams of fert per liter
Example: Creating a Custom NPK Mix
Let's say you want to create a 200 ppm N, 100 ppm P, and 200 ppm K mix using the following fertilizers:- 13-0-44 (potassium nitrate)
- 12-62-0 (monoammonium phosphate)
- 33-0-0 (ammonium nitrate)
- 0.5 g of potassium nitrate (200 ppm / (10 ppm x 44 K))
- 0.2 g of monoammonium phosphate (100 ppm / (10 ppm x 62 P))
- 89 ppm N
- 124 ppm P
- 220 ppm K
The final mix will provide 188 ppm N, 124 ppm P, and 220 ppm K in one liter of water. For greater precision, consider mixing larger batches or using a more accurate scale.