ARS | Publication request: Ammonia and greenhouse gas emissions in swine mortality composts of sawdust, broiler litter, and swine lagoon effluent

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 4, 2012
Publication Date: N/A

Technical Abstract: Animal agriculture is looking for innovative means to dispose of mortalities. Composting is an environmentally friendly option that retains the nutrients of the animal and organic materials. Southern U.S. swine farrowing operations often use sawdust as a C source for mortality composting. The objective of this study was to compare the farm standard mortality composting procedure (using sawdust and water) with other mixtures having supplementary C and N provided by broiler litter and by replacing water with swine lagoon effluent. Covered, heavy duty plastic recycling bins (227 L) contained three replications of four treatments: sawdust/water, sawdust/litter/water, sawdust/effluent, and sawdust/litter/effluent. Temperature, water content, nutrients, bacterial survival and emissions of ammonia, carbon dioxide, methane, and nitrous oxide were measured intermittently during the 4 month composting period. Relative to duration, ammonia flux was greatest just after the start of the experiment (up to 100 mg m-2 h-1) and was evident after the first turn or mixing within each bin (1 month later). Carbon dioxide flux followed a similar trend to ammonia, apparent initially (up to 50 mg m-2 h-1), after the first turn, and also after the second turn. Methane emissions were most pronounced after the second turn (up to 200 mg m-2 h-1) while nitrous oxide emissions were greatest after the first turn. Treatments containing lagoon effluent were associated with the highest emissions for each gas species. Considering only the results of emission estimates from this study, replacing water with effluent is not recommended for emission reduction from swine mortality composts.