Measuring Ammonia Emissions from Hog Anaerobic Lagoon Effluent Applied with Traveling Gun and Drag Hose Systems

Abstract

Substantial ammonia losses can occur when hog anaerobic lagoon effluent is land-applied. Ammonia, thus lost during application may not only impact public health and environment but will affect the plantavailable nitrogen (N). In addition to uncertainty of ammonia losses as affected by weather, there is very little research on the impact of application method on ammonia losses. In this study, swine lagoon effluent was applied to Coastal Bermuda grass on Cainhoy sand in eastern North Carolina using a traveling gun and the aerator-equipped drag hose. Vertical ammonia flux was measured from the traveling gun (85 m dia.) and drag hose (31.7 × 31.7 m) plots using the integrated horizontal flux (IHF) method for 5 d during October 17-22, 2005. Ammonia-N concentrations were measured in the middle of the two plots at five heights (0.2, 0.6, 1.2, 2.2, and 3.4 m) using acid scrubbers (3% boric acid) for six durations (0-4, 4-24, 24-48, 48-72, 72-96, and 96-120 h). Background ammonia-N concentrations were measured between the two plots at the same height and for the same durations. While hourly temperature, relative humidity, precipitation, and wind direction, and solar radiation were measured at a single height, wind speeds were measured at the same heights as the ammonia-N concentrations. Further, to evaluate ammonia-N losses during application as well as to determine uniformity of application with the traveling gun, 32 rain gauges (16 gauges had 50 mL each of 3% boric acid) were deployed along two axes. In addition to sampling the effluent from the gun (prior to release) and drag hose, lagoon effluent samples were also analyzed in quadruplicate. Of the 25.2 kg of total ammoniacal-N (TAN) applied to the traveling gun plot, 17.1% was lost through ammonia volatilization during the study; of the total ammonia- N lost, 96% was lost during the first 4 h. Based on ammonia-N concentrations in the effluent before being released from the gun and collected in the rain gauges, ammonia-N losses could not be detected during application. Of the 5.4 kg of TAN applied to the drag hose plot, 3.3% was lost through ammonia volatilization during the study; however, no data could be collected during the 4-24 h period due to battery power failure. Ammonia losses will be measured from the two treatments during mid-May and mid-July 2006.