title: National-scale estimation of changes in soil carbon stocks on agricultural lands.
abstract: Average annual net change in soil carbon stocks under past and current management is needed as part of national reporting of greenhouse gas emissions and to evaluate the potential for soils as sinks to mitigate increasing atmospheric CO2. We estimated net soil C stock changes for US agricultural soils during the period from 1982 to 1997 using the IPCC (Intergovernmental Panel on Climate Change) method for greenhouse gas inventories. Land use data from the NRI (National Resources Inventory; USDA-NRCS) were used as input along with ancillary data sets on climate, soils, and agricultural management. Our results show that, overall, changes in land use and agricultural management have resulted in a net gain of 21.2 MMT C year(-1) in US agricultural soils during this period. Cropped lands account for 15.1 MMT C year(-1), while grazing land soil C increased 6.1 MMT C year(-1). The land use and management changes that have contributed the most to increasing soil C during this period are (1) adoption of conservation tillage practices on cropland, (2) enrollment of cropland in the Conservation Reserve Program, and (3) cropping intensification that has resulted in reduced use of bare fallow.
authors.affiliation: US Department of Agriculture, Agricultural Research Service Soil Plant Nutrient Research Unit, Fort Collins, CO 80523-1499, USA. meve@nrel.colostate.edu
authors.forename: Marlen D
authors.initials: MD
authors.lastname: Eve
authors.forename: Mark
authors.initials: M
authors.lastname: Sperow
authors.forename: Keith
authors.initials: K
authors.lastname: Paustian
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Follett
mesh_terms: D000383:Agriculture; D002244:Carbon / Q000032:analysis* / Q000378:metabolism; D002980:Climate; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D017752:Greenhouse Effect; D011640:Public Policy; D012016:Reference Values; D012987:Soil
chemical_list: D012987:Soil; D002244:Carbon