These pictures are from a field near Talmage, Nebraska.  The untreated corn was shorter and showed potassium deficiencies.  The corn that was treated was taller and showed no nutrient deficiency symptoms.  PRO CAL 40 will increase nutrient availability of the nutrients already present in the soil.  There is not potassium found in PRO CAL 40.  Availability is enhanced by improving soil structure, increasing air/water exchange, improving root growth, etc.