Straw Covers to Reduce Gas Emissions from Liquid Dairy Manure Storage

摘要

The objective of this study was to investigate the effect of floating straw covers on gas emissions from liquid dairy manure during undisturbed storage and during agitation. Emissions of carbon dioxide (C0_2), methane (CH_4), nitrous oxide (N_2O), andammonia (NH_3) were measured between June and October 2007 from six tanks (6.6 m~2) containing liquid dairy manure in Nova Scotia, Canada. Straw was added to four of the tanks at two thicknesses (15 and 30 cm), while two tanks remained uncovered. Concentrations were measured using tunable diode lasers, an infra-red gas analyzer, and acid traps, while fluxes were measured using steady-state chambers. At the end of the study one tank from each treatment was agitated. During 122 d of undisturbed storage the 15 and 30 cm straw cover treatments both reduced total greenhouse gas (GHG) emissions by 20% and NH_3 emissions by 78 and 90%, respectively. During 5 d of agitation, substantial releases ofCO_2, CH_4 and NH_3 were observed from all treatments and thisdecreased the overall reduction ofNH_3 emissions provided by the 15 and 30 cm straw cover treatments to 68 and 76%, respectively. The results suggest floating straw covers can reduce both GHG and NH_3 emissions from liquid dairy manure and that agitation contributes to overall storage losses, especially for NH_3.