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Biogeochemical cycles of urban and livestock production wastes: Why do we continue to mine nutrients in a world awash in surplus?
Cooperband, Leslie1, 1 University of Wisconsin-Madison, Madison, WI
ABSTRACT- There are over 142 million Mg of municipal organic wastes or by-products produced annually in the U.S., or 75% of the total amount of municipal wastes generated. They include sewage sludge or biosolids (7 million Mg), food scraps (20 million Mg), paper (73 million Mg), textiles (7 million), wood (10 million Mg) and yard trimmings (25 million Mg). Of this total, only 32% are recovered for reuse and over 60% are land filled. Almost 9 million Mg of carbon and 325,000 Mg of nitrogen are produced in yard trimmings alone. Livestock wastes include animal manure, livestock mortalities and meat processing by-products. Total manure produced in the US for confined livestock facilities exceeds 144 million Mg, representing 7 million Mg of N and 1 million Mg P. Trends toward concentration and vertical integration of livestock production and processing enterprises have resulted in large disparities between where organic livestock wastes are generated and where they are needed for land application. In this presentation, I will describe current fates of these waste streams and the implications for atmospheric C and N losses and P loss to surface waters. I will contrast the current unidirectional flow of mined nutrients (including C) that are used in typical livestock and crop production systems with scenarios that promote recycling and soil sequestration of waste-derived sources of C, N and P. Lastly, I will link organic waste recycling to building organic matter in grass and shrub lands and describe the potential for use of organic wastes to restore degraded, desertified grass and shrub lands.
Key words: urban wastes, carbon, nitrogen, phosphorus, biogeochemical cycles, livestock wastes