Fertilizers are chemicals added to soil for the purpose of improving plant growth quality and yield. First discovered by ancient farmers, fertilizer technology has significantly improved as the chemical needs of growing plants were discovered. Synthetic fertilizers are composed primarily of nitrogen, phosphorous, and potassium compounds. Secondary nutrients that are important for plant growth are also included. The use of fertilizers has had an important impact on civilization, significantly improving the quality and quantity of the food available today.

The technique of increasing growing capacity by adding materials to soil has been used since the early days of agriculture. Ancient farmers discovered that plant yield could be increased on a plot of land by spreading animal manure throughout. As humans became more experienced, fertilizer technology improved. Other materials were added to soil. For example, the Egyptians added ashes from burnt weeds. The ancient Greeks and Romans added various...