AMMONIA VOLATILIZATION FROM TALL FESCUE PASTURES FERTILIZED WITH BROILER LITTER

Ammonia (NH3) volatilization is an important and often overlooked comp onent of the N budget in many agricultural systems involving land appl ication of animal wastes. We quantified the amount and rate of NH3 vol atilization from broiler Litter applied to established tall fescue pas tures (Festuca arundinacea Schreb.). Study sites were located in the C oastal Plain (Alabama), Piedmont (Georgia), and Cumberland Plateau (Te nnessee) Major Land Resource Areas (MLRA) of the southeast USA. Litter was applied to supply 70 kg of available N ha(-1) based on equations developed by the U.S. Department of Agriculture (USDA) and the U.S. En vironmental Protection Agency (USEPA). Measurements of NH3-N volatiliz ation were taken using a micrometeorological, field-scale technique fo r 14 d immediately following litter application during the spring of 1 995 and 1996. Ammonia flux for the study period ranged from 3.7 to 10. 6 kg N ha(-1) in 1995, and from 3.5 to 8.0 kg N ha(-1) in 1996. A shar p increase in volatilization rate occurred 1 to 3 d after litter appli cation at all three sites is both years. However, volatilization rates rapidly decreased to normal levels,within 10 d. Volatilization rates peaked at 2.8 kg NH3-N ha(-1) d(-1) in 1995 and 2.2 kg NH3-N ha(-1) d( -1) in 1996. Overall, N losses due to NH3 volatilization were less tha n expected based on previous studies. These data suggest that for thes e conditions, NH3 volatilization was a relatively minor component of t he N cycle and was not a major pathway for N loss.