How is urea used as both a component of urine and a fertilizer?

Urea is a chemical compound that functions as both a biological byproduct and a vital agricultural resource.

Biological Role

In mammals, urea is the primary nitrogenous end product resulting from the metabolic breakdown of proteins. During this process, amino groups are removed from amino acids and converted into ammonia, which is toxic. To protect the body, the liver converts this ammonia into urea, which is then transported to the kidneys and excreted in urine.1

Agricultural Use

As a fertilizer, urea is highly valued for its high nitrogen content. When applied to soil, it is readily converted into ammonia, providing essential nutrients for plant growth. Commercially, it is produced by reacting liquid ammonia with liquid carbon dioxide under high pressure. Because it is inexpensive and effective, it is used as a standalone fertilizer or incorporated into mixed fertilizers to support agricultural productivity.1