Greenhouse gas emissions and final compost properties from co-composting bovine specified risk material and mortalities with manure Xiying Hao Æ Kim Stanford Æ Tim A. McAllister Æ Francis J. Larney Æ Shanwei Xu Received: 3 June 2008 / Accepted: 1 October 2008 / Published online: 18 October 2008 Ó Springer Science+Business Media B.V. 2008 Abstract The increased disposal costs of cattle spec- ified risk materials (SRM) have reduced the competitiveness of the Canadian beef industry. The SRM materials include the skull, brain, trigeminal ganglia, eyes, palatine tonsils, spinal cord and dorsal root ganglia. This study investigates greenhouse gas (GHG) emissions and final compost properties from open windrow co-composting of manure with bovine SRM and mortalities. There were two compost treat- ments with four replications: SRMC consisting of SRM, cattle manure and barley straw and COWC consisting of cattle mortalities, cattle manure and barley straw. Average windrow temperature was higher (P \ 0.05) for SRMC (47.1°C) than for COWC (44.1°C) over the first 139 days. The final compost coliform count, moisture, pH and TC contents were not significantly different between treatments while TN and available N (NH 4 ? ? NO 3 - ? NO 2 - ) were lower for SRMC than for COWC. The average surface GHG flux from SRMC were 24.3 g C day -1 m -2 and 0.17 g N day -1 m -2 for CO 2 and N 2 O, respectively, and were not significantly different from those from COWC (31.6 g C day -1 m -2 and 0.17 g N day -1 m -2 for CO 2 and N 2 O, respectively), but CH 4 emissions from SRMC (0.47 g C day -1 m -2 ) were lower than from COWC (1.57 g C day -1 m -2 ). While a few large bones were left in the cattle mortality treatment, composting decomposed all SRM suggesting that it may be a viable alternative to rendering for SRM disposal. Keywords Beef feedlot manure Á Cattle mortality Á E. coli Á Greenhouse gas emissions Á Specified risk materials Á Compost properties Abbreviations ECD Electron capture detector FID Flame ionization detector GHG Greenhouse gas SRM Specified risk materials TCD Thermal conductivity detector WC Water content Introduction Specified risk materials (SRM) include the skull, brain, trigeminal ganglia, eyes, palatine tonsils, spinal cord and dorsal root ganglia of cattle aged 30 months or older, as well as the distal ileum of cattle of all ages (CFIA 1990). Currently, SRM are rendered to separate fat which can be used in products such as biodiesel while the remaining X. Hao (&) Á T. A. McAllister Á F. J. Larney Á S. Xu Agriculture and Agri-Food Canada, Lethbridge Research Centre, 5403 – 1st Avenue South, Lethbridge, AB, Canada T1J 4B1 e-mail: haoxy@agr.gc.ca K. Stanford Alberta Agriculture and Rural Development, 5401 – 1st Avenue South, Lethbridge, AB, Canada T1J 4C7 123 Nutr Cycl Agroecosyst (2009) 83:289–299 DOI 10.1007/s10705-008-9219-6