Ammonia volatilisation was measured from two 65 m x 360 m bays of irrigated dairy pasture in south-eastern Australia. Atmospheric ammonia concentrations were measured with passive samplers and a backward Lagrangian dispersion model (WindTrax) used to calculate emissions from the areas grazed. Experiments were conducted in the summer and autumn of 2004, during grazing events that were followed by urea application and irrigation. Emissions from the pastures before grazing were negligible. Emissions from the whole herd were measured during the grazing phases. In summer, emissions from grazing were 14.8 kgN and in autumn, 2 kgN. Only 1% of the urea-N was lost when irrigation followed fertilization immediately, but 6% was lost when irrigation was delayed for 3 days. A computer model has been developed to simulate the ammonia volatilisation from this acidic pasture soil.
See more of Biogeochemistry of Agricultural Soils/Div. S-2 Business Meeting
See more of S02 Soil Chemistry
See more of The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)