Ammonia volatilisation losses from nitrogen fertilisers surface-applied to Vertosols

Abstract

Key findings • Between April and July 2013, nitrogen volatilised from fertilisers applied to four fallow paddocks ranged from 3.5–16% of the N applied. • In medium to heavy clay soils of northwest NSW, measured N losses from urea were less than 20% of the applied N in bare-fallows, and less than 10% when applied to mid-tillering wheat. • Less N was volatilised from ammonium sulphate, unless the soil contained calcium carbonate. • Reduction in urea N loss with a urease inhibitor was inconsistent, possibly due to temperature.