Potassium (K) is one of the essential nutrients in plants and in recent years is one of three that are commonly in sufficiently short supply in the soil to limit crop yields on many soil types in Western Australia. Potassium is commonly found in plants at levels above all other macro nutrients except carbon, oxygen, hydrogen and occasionally nitrogen. Potassium has many functions including the regulation of the opening and closing of stomata which are the breathing holes found on plant leaves and therefore regulate moisture loss from the plant. Consequently, potassium is known as the poor mans irrigation because it improves the crops finishing ability.