What is Potassium Meq/100g and Potassium ppm?
- Potassium Meq/100g: This shows the amount of potassium based on its chemical charge in the soil. It measures how many milliequivalents (mEq) of potassium are present in 100 grams of soil.
- Potassium ppm: This shows the weight of potassium in milligrams per kilogram (mg/kg) of soil. Since 1 ppm = 1 mg/kg, it reflects the actual concentration of potassium in the soil.
Why convert Meq/100g to ppm?
- Farmers often get soil test results in Meq/100g, but fertilizer recommendations and nutrient management plans are easier to understand in ppm.
- Converting helps in better planning of fertilizer application based on available potassium.
How to convert Potassium Meq/100g to Potassium ppm
Step 1: Understand the atomic weight and charge of potassium
- Atomic weight of potassium (K) = 39 g/mol
- Potassium has a charge of +1 (valence = 1)
Step 2: Use the formula
ppm=Meq/100g×Atomic weight of K/Charge of K×10
- Multiply by 10 because Meq is per 100g soil, but ppm is per kg (1000g). So, 1000/100=10.
Step 3: Plug in values
Potassium ppm=Potassium Meq/100g×39/1×10=Potassium Meq/100g×390
Example:
If your soil test shows potassium as 0.2 Meq/100g,
Potassium ppm=0.2×390=78 ppm
Summary Table
| Potassium Meq/100g | Potassium ppm (approx.) |
|---|---|
| 0.1 | 39 |
| 0.2 | 78 |
| 0.3 | 117 |
| 0.5 | 195 |
You can find more agriculture conversion calculators here.