What Are the Main Chemicals in Fertilizers?

Some fertilizers can be used in a spray form.Hemera Technologies/Photos.com/Getty Images

Fertilizers are substances used to improve the growth rate and quality of various types of plants. Fertilizers are composed of varying combinations of nitrogen, phosphorous and potassium. When you purchase fertilizer, the label usually has three numbers, such as 10--20--10. These numbers indicate the percentages of nitrogen, phosphorous and potassium in the fertilizer. You can buy fertilizers with various concentrations of these chemicals, depending on the specific needs of the plants.

Nitrogen

One function of nitrogen within plants is to assist the formation of enzymes. These enzymes are critical for most activities within plants that require energy, such as the synthesizing or breaking down of certain compounds. Nitrogen also plays an important role in cell division and reproduction. Plants need nitrogen to make chlorophyll molecules, which act as receptors for light energy that is transformed into chemical energy within the plant during photosynthesis. Nitrogen also is the primary chemical for leaf production. If plants do not receive enough nitrogen, they may become yellow in appearance and stunted in growth.

Phosphorous enters plants through the root systems and plays a major role in fruit production. Energy transfer processes, such as photosynthesis, require phosphorous. Phosphorous also helps compose genes and chromosomes within plants, which guide plant growth and development. An inadequate supply of phosphorous can cause plants to produce seeds that are few in number and small in size. Phosphorous also helps move nutrients within plants. If a plant lacks phosphorous, it will show through a discoloration of leaves, delayed growth and reduced fruit and foliage. The plant will also be more susceptible to disease.

Potassium is the primary ingredient that assists the flowering of plants. Plants also require potassium for photosynthesis, protein and water usage. This mineral, which is commonly referred to as "potash," is commonly added to food bearing crops. The life cycle of plants is dramatically impacted by the absence or presence of potassium. Without it, plants may suffer from thin cell walls, weak stems and stalks, insufficient root growth and decreased resistance to disease. Proper supplies of potassium can increase the yield of many plants. Potassium can also help mature fruits and vegetables resist rot and decay.