Fertilizers enhance the growth of plants. This goal is met in two 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, like many on fertilizers, emphasises the nutritional aspect. Fertilizers typically provide, in varying proportions:
three main macronutrients: Nitrogen (N): leaf growth; Phosphorus (P): Development of roots, flowers, seeds, fruit; Potassium (K): Strong stem growth, movement of water in plants, promotion of flowering and fruiting;
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.