Emissions of NMVOC and HS from field-applied manure measured by PTR-TOF-MS and wind tunnels.

Field application of animal manure is a source of volatile organic compounds (VOC) and hydrogen sulfide (HS) emission that contribute to air pollution and odor nuisance in local surroundings. In this study the non-methane volatile organic compounds (NMVOC) and HS emission and odor activity dynamics over time after field application of pig and cattle manure were investigated. Furthermore, three different application techniques, trailing hoses, trailing shoes, and trailing hoses applying manure 20 cm above canopy, was compared. With a flexible system combining dynamic chambers and Proton-Transfer-Reaction Time-of-Flight Mass Spectroscopy (PTR-TOF-MS), HS and 22 different NMVOC were measured, identified, and quantified. From pig manure high amounts of HS was measured right after application, resulting in high odor activity values (OAV). During the first 10 h 4-methylphenol accounted for most of the cumulative emissions and OAV. Carboxylic acids were emitted for a longer period, and accounted for most of the long-term emissions and OAV. Acetic acid alone accounted for 33-57% of the total cumulative emissions. Trailing shoes were found to reduce NMVOC emission under certain conditions. It is suggested to use updated ratios from this study to calculate NMVOC emissions relative to ammonia emissions. The average ratios of cumulated NMVOC emission divided by cumulated ammonia emission 90 h after application of pig manure is 1.15±0.55 and 0.72±0.26 for trailing hoses and trailing shoes respectively, whereas the equivalent numbers for cattle manure is 0.43±0.11 and 0.18±0.04.