Science needs and new technology for increasing soil carbon sequestration

Fossil fuel use and land use change that began over 200 years ago are drivi ng the rapid increase in atmospheric content of CO2 and other greenhouse ga ses that may be impacting climatic change (Houghton et al., 1996). Enhanced terrestrial uptake of CO2 over the next 50 to 100 years has been suggested as a way to reclaim the 150 or more Pg carbon (C) lost to the atmosphere f rom vegetation and soil since 1850 as a consequence of land use change (Bat jes, 1999; Lal et al., 1998a; Houghton, 1995), thus effectively 'buying tim e' for the development and implementation of new longer term technical solu tions, such as C-free fuels. The ultimate potential for terrestrial C seque stration is not known, however, because we lack adequate understanding of ( 1) the biogeochemical mechanisms responsible for C fluxes and storage poten tial on the molecular, landscape, regional, and global scales, and (2) the complex genetic and physiological processes controlling key biological and ecological phenomena. Specifically, the structure and dynamics of the below ground component of terrestrial carbon pools, which accounts for two-thirds of global terrestrial organic C stocks, is poorly understood. Focusing pri marily on forests, croplands and grasslands, the purpose of this chapter is to consider innovative technology for enhancing C sequestration in terrest rial ecosystems and address the scientific issues related to better underst anding of soil C sequestration potential through appropriate and effective approaches to ecosystem management.