Co-composting of Beef Cattle Feedlot Manure with Construction and Demolition Waste

With increased availability of dried distillers' grains with solubles (DDGS) as cattle feed and the need to recycle organic wastes, this research investigated the feasibility of co-composting DDGS cattle feedlot manure with construction and demolition (C&D) waste. Manure was collected from cattle fed a typical western Canadian finishing diet (CK) of 860 g rolled barley (Hordeum vulgare L.) grain, 100 g barley silage, and 40 g vitamin and mineral supplement kg(-1) dry matter (DM) and from cattle fed the same diet but (DG manure) with 300 g kg(-1) DM barley grain being replaced by DDGS. The CK and DG manures were co-composted with and without C&D waste in 13 m(3) bins. Compost materials were turned on Days 14, 37, and 64, and terminated on Day 99. Adding C&D waste led to higher compost temperatures (0.4 to 16.3 degrees C, average 7.2 degrees C) than manure alone. Final composts had similar total C, total N, C/N ratios, and water-extractable K, Mg, and NO3-content across all treatments. However, adding C&D waste increased delta C-13, delta N-15, water-extractable SO42-, and Ca+ contents and decreased pH, total P (TP), water-extractable C, N, and P and most volatile fatty acids (VFA). The higher C&D compost temperatures should reduce pathogens while reduced VFA content should reduce odors. When using the final compost product, the increased SO42- and reduced TP and available N and P content in C&D waste compost should be taken into consideration. Increased S content in C&D compost may be beneficial for some crops grown on S-deficient soils.