Abstract
Currently, the plant-available nitrogen (PAN) coefficient of hog anaerobic lagoon effluent does not differentiate for land application by broadcast (e.g. drag hose) or irrigation (e.g. traveling gun). There is a need to determine PAN coefficients for traveling gun and drag hose by measuring ammonia (NH3) emissions, and accounting for partial nitrogen (N) mineralization. Ammonia emissions were measured for four application periods (fall, spring, 2 summer) with the integrated horizontal flux (IHF) method on Bermudagrass grown on Cainhoy sand in Garland, NC. Ammonia concentration was measured using acid scrubbers. Nitrogen mineralization was estimated based on published literature. During application by traveling gun 3 to 9% of applied-N was lost as NH3 before it hit the ground (soil or canopy surface). Total NH3 emission from the ground ranged from 13 to 26% of applied-N, 96 h after start of the application. The first 4 h accounted for 65 to 81% of the NH3 emission. The N loss during application (in the trajectory) ranged from 4 to 11%. Due to uncertainties in the NH3 emission measurement, additional studies are needed with improved methods to account for losses in the trajectory and subsequent mist formation during application. Ammonia-N emission using the drag hose, ranged from 1 to 5%. Based on literature, the organic-N mineralization rate was assumed to be 50%. The PAN, thus obtained, was 0.65 for traveling gun, and 0.85 for drag hose. A model was used to simulate NH3 emission from hog lagoon effluent applied with both the traveling gun and drag hose. The model underestimated NH3 emission from traveling gun treated plot for all four periods. The model overestimated emissions from drag hose treated plot in two of the three periods. The model was sensitive to increase in soil pH and moderately sensitive to changes in all other selected parameters (total ammoniacal-N concentration and pH of effluent, linear partition coefficient of soil, and wind speed).
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