This study investigates the effects of potassium fertilizers on sugarcane sucrose content in Japan. Focusing on the negative correlation between potassium and sucrose content in Okinawa, the research explores the impact of counter ions (Cl-, SO42-) on sugar accumulation in sugarcane juice. Pot experiments with different potassium fertilizers were conducted to analyze sugar accumulation, emphasizing the essential role of potassium in sugarcane growth and sugar content.