Ammonia loss following urea addition to sugar cane trash blankets

Extent of ammonia loss and factors controlling loss when urea is broadcast onto sugar cane trash are described. Usefulness of a number of management practices designed to reduce ammonia loss is considered. These include irrigation, use of urease inhibitors, addition of urea/salt mixtures, delaying urea application until the crop developed a substantial canopy, and fertiliser placement. Investigations show conclusively that application of urea to sugar cane by broadcasting or banding on the surface of a trash blanket results in significant losses of ammonia by volatilisation, typically 40% of the nitrogen applied. Most management practices reduced loss to varying degrees, but none completely prevented loss. For economic and environmental reasons it is imperative that techniques be implemented to control loss of ammonia and other nitrogenous species generated following fertiliser application. The need for r¢search into the environmental impact of the volatilised ammonia is urgent.