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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 310-324 in the Ninth International Animal, Agricultural and Food Processing Wastes Proceedings of the 12-15 October 2003 Symposium (Research Triangle Park, North Carolina USA), Publication Date 12 October 2003.  701P1203.(doi:10.13031/2013.15266)
Authors:   H. M. Keener, J. A. Pecchia, G. L. Reid, F. C. Michel Jr., and D. L. Elwell
Keywords:   aeration, composting, dairy manure, design, feedstock, optimization, parameters, systems

Manure management has become a major issue on dairy farms as they have expanded and required a larger land base for application. With increased hauling distances, liquid manure systems become less economical. Dairy farmers are adopting composting as a method to process manure, which reduces transportation cost and facilitates utilization while protecting the environment. Full scale studies in 2001-2002 for dairy manure (free stall, 85% moisture wb) mixed with sawdust or straw using turned windrows showed total weight losses of 82 and 80% w/w and volume reductions of 81 and 89% v/v for the compost mixes, respectively, over a time period of 150 days. Normalized to the original manure weights and volumes, reductions from composting were 77 and 73.5% w/w and 42 and 58% v/v. Dry matter losses were approximately 72%. Nitrogen losses were 26-42% w/w. However, 2001 pilot scale studies using intermittent aeration had 16% NH3-N losses, while maintaining a rate of decomposition of about 0.015 kg/kgvs-day. These latter results imply by day 42-44 a 50% reduction in organic matter would occur for the compost mix and it may be stable enough to be piled for curing. Optimization studies using Excel. spreadsheets and parameters evaluated from the pilot scale and full scale windrow composting were done. Dry matter and moisture loss, compost pad area and energy cost were evaluated as functions of, materials used and mixing ratio, fan sizing and on/off operation, pile shape and size and consolidation frequency. Results showed composting manure in two stages reduced cost significantly. For example, composting 28 days using windrows and then curing for 152 days using large blocks reduced pad area by 15% compared to composting in windrows for 35 days and curing 145 days.

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