Fertilizer application

The most common way to maintain or to restore soil fertility or to replace minerals that are essential for plant growth is through the application of commercial fertilizers. A fertilizer is any material added to the soil to supply one or more essential minerals for plant growth. A soil amendment on the other hand is used to alter physical and chemical properties of the soil e.g. (using lime to improve the physical characteristics of a clay a soil and to lower its acidity). Fertilizer allows a crop producer to apply a specific essential mineral or group of minerals in precise concentrations to attain maximum yield. Commercial fertilizers like urea, sulphate of ammonia, calcium nitrate - supply Nitrogen to plants.
Single super phosphate supply phosphorous and muriate of potash supply potassium. A mixed fertilizer will supply all the three elements, that is NPK, fertilizer e.g. 15-15-15 i.e. contain 15 percent of by weight of each of N. P and K. the remaining 55 percent represent inert carrier for the useful nutrients . Fertilizer contains additional elements like magnesium e.g. (NPKMg 18-15-14-2).