Greenhouse gas emissions during co-composting of cattle feedlot manure with construction and demolition (C&D) waste

Abstract

Manure management strategies should reflect current animal feeding practices and encourage recycling of organic waste to help protect our environment. This research investigated greenhouse gas (GHG) emissions during cattle manure stockpiling or composting with and without construction and demolition (C&D) waste. Manure was collected from cattle fed a typical finishing diet (CK manure) and from cattle on diets which included 30%dried distillers grains with solubles (DG manure). The CK and DG manures were co-composted with (4:1) C&D waste (treatments: CK_CD, DG_CD), composted alone (treatments: CK and DG) in 13 m3 bins or stockpiled without C&D waste (treatments: CK_ST and DG_ST) for 99 days. Manure type (CK vs. DG manure) had no effect on GHG emissions over the 99 day manure composting or stockpiling. Composting with C&D waste produced similar CO2 emissions, about double that from manure stockpiling (7.0 kgC•m–2). In contrast, CH4 emissions were reduced by the inclusion of C&D waste (64 gC•m–2 with C&D vs. 244 gC•m–2 without C&D) while the manure stockpile emitted the greatest amount of CH4 (464 gC•m–2). Additionally, only 0.48% of C was emitted in CH4 form with C&D waste, compared to 1.68% when composting without C&D waste and 7.00% when cattle manure was stockpiled. The N2O emissions (12.4 to 18.0 gN•m–2) were similar across all treatments. The lower CH4 emissions with C&D waste are beneficial in reducing overall GHG emissions from manure composting, while reducing the amount of material entering landfills.