Coating materials for slow release of nitrogen from urea fertilizer: a review

Presently, about 200 million tons of urea fertilizer is produced worldwide to meet supply and demand. However, a quarter of the urea applied to soils is lost to the environment due to poor efficiency. Poor efficiency can be prevented by slowing the release of urea - nitrogen. One mechanism to do this is ‘Encapsulation’. Encapsulation allows for higher urea efficiency, synchronization with plants ongoing nutrient needs. This review covers an extensive study on ordinary urea usage including the different materials used for coating, which can be natural or artificial, and the different coating processes. Also included are the methods of employing different substances with the pros and cons of each.