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6254496 
Book/Book Chapter 
12 - CARBON CYCLING AND FORMATION OF SOIL ORGANIC MATTER 
Horwath, W 
2007 
Academic Press 
San Diego 
Soil Microbiology, Ecology and Biochemistry (Third Edition) 
303-339 
Publisher Summary This chapter discusses carbon (C) cycling and formation of soil organic matter. C was deposited on earth from carbonaceous comets and asteroids in both organic and inorganic forms. The extraterrestrial C contained complex compounds including hydrocarbons, organic acids, and amino compounds essential to the evolution of cellular life forms. The “Carbon cycle” is the transfer of C among the atmosphere, oceans, land, and life. The C cycle is composed of both long-term and short-term cycles. The short-term C cycle is dominated by the interplay of terrestrial and marine photosynthesis, respiration, and organic matter formation. The short-term C cycle is dependent on two principle gases: CO2 and methane (CH4). Perturbations of the short-term C cycle causing changes in the concentration of these two gases in the atmosphere cause potential changes in climate because both are greenhouse gases. The chapter describes the long-term carbon cycle, short-term C cycle, and ecosystem C cycling in detail. The composition and turnover of C inputs to soil is explained along with soil organic matter and role of methane in the C cycle. 
Paul, Eldor A.