An adequate potassium supply ensures a higher sugar yield, by reducing the sugarcane fibre content.
Very high levels of potassium can however, reduce sucrose levels. Trials show that foliar potassium applied to the plant 6-8 weeks prior to harvest, reduced cane fiber by 28%.
Sugar is also influenced by magnesium supply and sucrose content is reduced where magnesium nutrition is inadequate. It is important to balance the levels of potassium and magnesium, as high levels of potassium can restrict and compete with uptake of magnesium.