Urea: From Biological Waste Product to World's Most Important Fertilizer
Urea is the primary nitrogen waste product of mammalian metabolism and the world's most widely used nitrogen fertilizer (~180M tonnes/year), also used as diesel exhaust fluid.
Urea (CO(NH₂)₂) is a simple organic compound serving dual roles: the primary nitrogen waste product of mammalian protein metabolism (excreted in urine) and the world's most important synthetic fertilizer. ## Industrial Production Urea is synthesized via the Bosch-Meiser process from ammonia and CO₂ at high pressure and temperature. Global production exceeds 200 million tonnes annually, making it the most widely used nitrogen fertilizer — containing 46% nitrogen by weight, the highest of any solid fertilizer. ## Diesel Exhaust Fluid Urea solution (marketed as AdBlue/DEF) is injected into diesel exhaust in selective catalytic reduction (SCR) systems, converting toxic nitrogen oxides (NOₓ) to harmless nitrogen gas and water. This is required on virtually all modern diesel trucks and many passenger diesels to meet emissions standards. ## Other Uses Urea appears in cosmetics (moisturizer), resins and adhesives (urea-formaldehyde), laboratory reagents, and as a de-icing agent. In medicine, it's used topically for skin conditions and as a diagnostic marker (blood urea nitrogen/BUN for kidney function). **See also:** LNG (Liquefied Natural Gas): How Gas Crosses Oceans