Previous work (Lal et al.,1998) described greenhouse gas processes, global warming concerns, and the potential of U.S. cropland soils to sequester C and mitigate the greenhouse effect. That work was based on the potential C sequestration that results from land conversion, land restoration, and intensification through the use of conservation tillage, improved water and fertility management, and improved cropping systems. The estimates were that 75 to 208 (mean = 142) MMTC/yr could be sequestered in cropland soils.