NH3 traps placed in ponds on a weather vane sampler were used to measure NH3 emissions from June to September 1997 to study such emissions to the atmosphere from fishpond waters and uneaten, floating feed. Channel catfish (Ictalurus punctatus) were stocked at 500/pond in four 400 sq m ponds at the Auburn University Fisheries Research, Auburn, AL, on 5/30/97, and feed (28% crude protein), prepared as floating pellets, was applied daily. Ponds were harvested 10/7-9/97. Also, NH3 volatilization from wetted catfish feed was measured in a laboratory experiment. Average NH3 volatilization in ponds was 8.8-71.0 mg NH3-N sq m/day, and averaged 3.75% of total NH3 nitrogen (TAN) level in water. Positive linear correlations were found between feed quantity and TAN concentration in the water and between TAN and NH3 volatilization. Volatilization from wetted feed was not a key loss to the atmosphere. It was suggested that 24 kg/ha N were lost to the atmosphere from 6/23/97 to 9/30/97 from ponds in which 158 kg/ha N were applied. Extrapolation from this work suggested that 1584 ton NH3 could volatilize from catfish ponds each summer.
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis