Potassium Sources:

• Potassium Sulfate: Very soluble, 50% K.
• Potassium Silicate: Very soluble, 32% K. Contains silica. Much more expensive than Potassium sulfate.
• Langbeinite: Usually used as a source of magnesium.
• Greensand: Broad spectrum mineral content, low solubility of K.
• Wood ash or Sunflower ash.
• Composts and manure products.