ABSTRACT
Fertilizers provide plants with the nutrients they need for growth and development. To maintain soil fertility and productivity and prevent land degradation, nutrients taken up by crops must be replenished through the application of fertilizers. Rapid increases in food production must be achieved if future world requirements are to be met. Agriculture must be relied upon as the primary source of an increase in food production. A commercial fertilizer is a material that contains at least one of the plant nutrients in chemical form that, when applied to the soil, is soluble in the soil solution phase and assimilable or "available" by plant roots. The primary raw materials for nitrogen fertilizers are natural gas, naphtha, fuel oil, and coal. Nitrogen fertilizers via ammonia synthesis account for more than 90% of the world's nitrogen fertilizers. Animal and human wastes have long been used as fertilizers, especially in Europe and Asia, particularly China.
