Pedospheric Processes and Climate Change.

PEDOSPHERIC PROCESSES AND CLIMATE CHANGE Rattan Lal Carbon Management and Sequestration Center, The Ohio State University, Columbus, OH 43210 USA ABSTRACT Climate affects and is affected by numerous pedospheric processes. Key among interactive processes between the pedosphere and climate are: rate of weathering of silicates; rate of decomposition and accretion of soil organic carbon (SOC); aggregation and stabilization of aggregates; erosion, sedimentation and deposition; illuviation and transfer of C into the sub-soil; elemental transformation; anaerobiosis affecting methanogenesis and nitrification/denitrification; wetting/drying and freezing/thawing cycles, and formation of pedogenic carbonates and soil inorganic C (SIC) sequestration. These processes moderate emission of greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O); the radiative forcing, and the energy balance at micro, meso and macro scale. Thus, there may be positive or negative feedbacks affecting atmospheric chemistry, radiative forcing, and the magnitude of climate change. Therefore, a judicious management of pedosphere can enhance its resilience against climate volatility. Climate-strategic pedospheric management includes enhancing processes that accentuate drawndown of atmospheric CO2 such as increasing rate of weathering of silicates (Olivine); creating positive soil C budget through land use and soil/water/plant/animal management; decreasing risks of accelerated erosion; increasing aggregation; enhancing oxidation or soil uptake of CH4; moderating nitrification/denitrification and reducing emission of N2O; accentuating leaching of bicarbonates and formation of secondary carbonates; increasing translocation of SOC into the sub-soil etc. The aim is to enhance and sustain C pool (both SOC and SIC) to 2-m depth or more to its maximum potential for the specific climate while improving soil quality and strengthening numerous ecosystem functions and services.