Volatilized Nitrogen from a Tropical Pennisetum clandestinum Pasture in South Africa

A micrometeorological mass balance was used to determine nitrogen volatilised as ammonia from dryland Pennistetum clandestinum (kikuyu) pasture. Treatments included 2 levels of N {ISO and 300 kgN/ha, applied in 3 dressings) from limestone ammonium nitrate and urea. Volatilised N was measured after N application and during subsequent grazing periods. Overall, volatilised N was lower than expected for subtropical conditions (4.4% of applied N). Higher losses were recorded when sward height was reduced from IO cm to 3 cm. The mean difference was 764±109 gN/ha {P��.05) for 33 h after the application of urea at 50 kg N/ha.