The raw materials that make up the bulk of fertilizer are nitrogen, phosphorus and potassium. A dozen or more secondary but essential components are included in smaller amounts, not all of which are listed on the label.
Nitrogen synthesizes proteins, nucleic acids and hormones to prevent leaf yellowing and maximize plant growth. Phosphorus energizes the plant’s metabolic chemical reactions. Potassium synthesizes proteins and enables other vital plant processes, which stimulates the growth of strong stems and roots and prevents leaf yellowing and dead spots.
Most fertilizer includes only small amounts of magnesium, sulfur and calcium, because most soils naturally have these elements. Micronutrients include copper, iron, manganese, molybdenum, boron, zinc, chlorine and iron, which primarily act as cofactors in enzymatic reactions. Although present in only trace amounts, these compounds are vital. Without them, the plants can die.
Other essential fertilizer nutrients are compounds that can be mined or isolated from naturally occurring sources, including sodium nitrate, seaweed, bones, guano, potash and phosphate rock. These compounds are also chemically synthesized from basic raw materials such as ammonia, urea, nitric acid and ammonium phosphate.
Fertilizers replace the nutrients that soil loses from growing plants. Properly fertilized soil can bear beyond its natural capacity or be tailored to support specific crops.