Water Soluble Potassium using Tobacco Stems

Hello All, I have referred the CGNF India recipe to make Water Soluble Potassium using Tobacco stems. The dry tobacco stems are cut into small pieces and soaked into water for 7 days (No charring). However, I see some are suggesting that it should be charred. Can some experts guide me here? I have already put 2 Kilos into 10 liters of water as per the dry tobacco stems method (Recipe: http://www.cgnfindia.com/wsk.html) Thanks!