A fertiliser is composed of chemical salts through which essential plant nutrients are added to the soil.To obtain the maximum benefit of its properties it should be applied at the proper time and at the proper place. The requirement of nutrients by plants varies according to individual needs and stages of growth. Crops that have high economic value such as sugarcane, cotton, potato, etc., can be fertilised heavily. For e.g., Potato requires 80 kg of nitrogen, 60 kg of phosphoric acid and 60 kg of potassium per acre land for satisfactory yield.