What is K₂O and K?
- K₂O is potassium oxide, a common way to express potassium content on fertilizer labels.
- K stands for elemental potassium, the actual nutrient plants need.
Why convert K₂O to K?
Fertilizers show potassium as K₂O, but plants use potassium in elemental form (K). So, to know how much actual potassium you’re applying, you convert K₂O to K.
How to convert K₂O to K?
- The formula weight of K₂O is about 94 (39 for each K × 2 + 16 for O).
- The atomic weight of K is 39.
In K₂O, potassium makes up about 83% by weight:
So,
Amount of K=Amount of K₂O×0.83
Example
If your fertilizer label says 100 kg of K₂O:
100 kg K₂O×0.83=83 kg of K
You are actually applying 83 kg of elemental potassium.
Summary Table
| Given | Multiply by | Result |
|---|---|---|
| K₂O | 0.83 | K |
You can find more agriculture conversion calculators here.