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6278172 
Book/Book Chapter 
Chapter 12 - Carbon Cycling: The Dynamics and Formation of Organic Matter 
Horwath, W 
2015 
Academic Press 
Boston 
Soil Microbiology, Ecology and Biochemistry (Fourth Edition) 
339-382 
The chapter examines the global carbon cycle with an emphasis on soil organic matter (SOM). The most up-to-date information on its formation, structure, and function is presented. It is now recognized that SOM is composed primarily of microbial products consisting of aliphatic substances, carbohydrates, and nitrogen containing compounds dismissing the previous notion of significant aromatic content. SOM formation relies on the interaction of individual compounds with mineral surfaces and bridging metals, particularly iron to form colloids with micellar features that exhibit hydrophobic properties. The hydrophobic properties explain the sorption of nonpolar pesticides and pollutants. Once stabilized, SOM has a varying turnover rate depending on fraction from less than a year to thousands of years. SOM influences many soil processes, particularly the production and consumption of greenhouse gases, such as methane and nitrous oxide. Rising carbon dioxide and temperatures will influence the turnover of SOM and its influence on biogeochemical processes globally. 
Carbon cycle; Geological cycle; Biological cycle; Soil organic matter; Climate change; Elevated carbon dioxide; Carbon pools; Organic matter formation; Methane 
Paul, Eldor A.