The story
From the chemical symbols for each element, hence K being used for potassium (formerly known as kalium).
Etymology from Wiktionary, CC BY-SA 4.0.
NPK
Today it means: Nitrogen, Phosphorus, Potassium (or Potash) Full definition →
Today it means: Nitrogen, Phosphorus, Potassium (or Potash) Full definition →
From the chemical symbols for each element, hence K being used for potassium (formerly known as kalium).
Etymology from Wiktionary, CC BY-SA 4.0.