Potassium fertilizer was applied to Shiraz grapevines in two different vineyards for four years. In the hot vineyard, using KCl fertilizer increased certain nutrient concentrations in the plants, while no change was seen in the cool vineyard. Wine potassium levels were higher in the cool vineyard wines that received KCl fertilizer. The study found that soil potassium levels did not directly correlate with potassium levels in the grapes.