Controlled Release Nitrogen Fertilizers

Abstract

In North America, nitrogen (N) fertilizer is largely applied as anhydrous ammonia, UAN solutions or urea. However, these forms of N can be lost if wet weather conditions precede their uptake by crops. Controlled-release N fertilizers can reduce these losses by delaying the initial release of N and providing it gradually to coincide with crop uptake needs. Controlled-release (also called slow-release or delayedrelease) N fertilizers include coated ureas, non-coated “chemical-release” forms and other products.