Modified ureas: for more effective and environmentally safer use

摘要

There is considerable interest in North America with the new controlled release urea (CRU) introduced by Agrium into the broad acre crop market. The CRU is a plastic (polymer) coating on urea which, based on temperature and available water supply, regulates the release of urea from the product. This product has a long history, starting originally in the golf course, turf and vegetable market, where long-terra N release has great economic value. Further refinement of the coating thickness for field crops has provided products which release their N after 30-60 days post-application. Even longer release profiles are available, but the cost usually limits these products to the turf and horticulture market. The principle market for these 30-60 day products has been areas where high rainfall leads to leaching losses of N, and for crops which have a long, or late season, N demand. The product has been shown to work very well, reducing N losses and maintaining or increasing current yields with reduced N rates relative to untreated urea.