Fertilizer

Fertilizer (or fertiliser) is any material of natural or synthetic origin (other than liming materials) that is applied to soils or to plant tissues (usually leaves) to supply one or more plant nutrients essential to the growth of plants. Conservative estimates report 50 to 70% of crop yields are attributed to natural or synthetic commercial fertilizer.

Fertilizers enhance the growth of plants. This goal is met in two broad ways, the traditional one being additives that provide nutrients. The second mode by which some fertilizers act is to enhance the effectiveness of the soil by modifying its water retention and aeration. This article, emphasizes the nutritional aspect. Fertilizers typically provide, in varying proportions: The nutrients required for healthy plant life are classified according to the elements, but the elements are not used as fertilizers. Instead compounds containing these elements are the basis of fertilizers.
 * three main macronutrients: nitrogen (N), phosphorus (P), potassium (K);
 * three secondary macronutrients: calcium (Ca), magnesium (Mg), and sulfur (S);
 * micronutrients: copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B), and of occasional significance there are silicon (Si), cobalt (Co), and vanadium (V) plus rare mineral catalysts.