Temperature and Water Content Effects on Carbon Mineralization for Sapric Soil Material

Histosols, often formed in wetland environments, provide an important global soil carbon (C) stock. Mineralization of soil organic C is an important process with broad implications for nutrient availability, soil quality, and global change. Temperature and moisture effects on C mineralization have been widely studied, but little information is available for temperature and moisture effects on C mineralization from recalcitrant sapric soil materials of warm climate Histosols. Our objectives were to determine Q (10) values (the factor by which the reaction rate increases with each 10 A degrees C rise in temperature) for sapric soil material collected from a warm climate Histosol, to examine the influence of water content on Q (10), and to assess the optimum soil moisture condition for C mineralization. A laboratory incubation (48 h duration) was conducted including sapric soil material at three moisture conditions; approximately 0.15, 0.30, and 0.45 m(3) m(-3) water content by volume; and two temperatures; 25 and 37 A degrees C. Calculated values for Q (10) were generally consistent with previous studies for other soil materials. Results indicated highest mineralization rates for both temperatures occurred at 0.30 m(3) m(-3) volumetric water content, corresponding to approximately 50 % water-filled pore space. But values for Q (10) increased as water content increased, demonstrating the important relationship between moisture and temperature effects for C mineralization for these organic soil materials.