Ammonia volatilization from freshwater fish ponds

This study evaluated ammonia (NH3) emissions to the atmosphere from fishpond waters and uneaten, floating feed, Channel catfish (Ictalurus punctatus) were stocked at 550 pond(-1) in four, 400-m(2) ponds at the Auburn University Fisheries Research (AUFRU), Auburn, AL, on 30 May 1997, Feed (28% crude protein), prepared as floating pellets was applied daily, Ponds were harvested between 7 and 9 Oct. 1997, Ammonia traps were placed in ponds on a weather vane sampler. Ammonia emissions were measured from June through September 1997, In addition, NH, volatilization from wetted catfish feed was measured in a laboratory experiment. Average NH3 volatilization from ponds ranged between 8.8 to 71.0 mg NH3-N m(2) d(-1), and averaged 3.75% of total NH, nitrogen (TAN) concentration in water, Positive linear correlations were found between the amount of feed applied and TAN concentration in the water and between TAN and NH, volatilization, Volatilization from wetted feed was not a major NH3 loss to the atmosphere. The study suggested that 24 kg ha(-1) of N were lost to the atmosphere between 23 June 1997 and 30 Sept. 1997 from ponds into which 158 kg ha(-1) N were applied. In the USA, there are about 66 000 ha of catfish ponds. Extrapolation from this study suggests that 1584 t of NH3 could volatilize from catfish ponds each summer.