Though urea's origins may be unsavory -- it derives from mammalian urine -- it is a core component of plant fertiliser when synthesised with ammonia and carbon dioxide. Urea fertiliser promotes healthy growth by providing essential nitrogen to plants. For the most part, farmers use urea fertiliser on crops and pastures, but green fingers can put it work on the lawn at home.
Urea comes in the form of a solid white crystal. It contains 46 per cent nitrogen, hence its qualification as a nitrogen fertiliser. Urea fertilisers contain prills -- tiny dry spheres -- or granulated urea elements, mostly the latter as urea granules resist moisture more efficiently than prills. Like ammonium nitrate and ammonium sulphate fertilisers, urea-based fertiliser is a fast-release fertiliser.
Farmers and gardeners apply urea fertiliser as a solid compound or as a spray that targets foliage. Farmers commonly use urea fertiliser on sod crops such as winter wheat, potatoes, soybeans and small grains during the cool seasons. It can be used on grass during summer seasons, provided there is plentiful rainfall. This type of fertiliser accommodates blending with other fertiliser types, including monoammonium phosphate and diammonium phosphate. It also can be incorporated into an irrigation system.
Urea fertiliser generally comes at the lowest per-pound nitrogen cost when compared with other single-element nitrogen fertilisers. This type of fertiliser usually exhibits a greening effect fairly quickly. It produces crop yield increase equal to other forms of nitrogen, according to research from soil specialists at the University of Minnesota's agricultural extension. As the fertiliser decomposes, it releases few environmental pollutants. Urea fertiliser poses little or no fire hazard. Because of its high nitrogen content, urea fertiliser stores easily and doesn't cost much to transport.
If urea fertiliser stagnates on the soil's surface for too long during warm weather, its nitrogen content can evaporate into the atmosphere. Loses decrease when soil is cool. It gives off ammonia when it evaporates, so urea fertiliser should not be applied to vegetative plants during warm seasons. Urea fertiliser contains the chemical compound biuret, which leads to agronomic problems if the fertiliser is used too close to seeds. When applied to small lawns, it may burn grass. Urea fertiliser does not accommodate blending with superphosphate-based soil.