title: A reservoir of nitrate beneath desert soils.
abstract: A large reservoir of bioavailable nitrogen (up to approximately 10(4) kilograms of nitrogen per hectare, as nitrate) has been previously overlooked in studies of global nitrogen distribution. The reservoir has been accumulating in subsoil zones of arid regions throughout the Holocene. Consideration of the subsoil reservoir raises estimates of vadose-zone nitrogen inventories by 14 to 71% for warm deserts and arid shrublands worldwide and by 3 to 16% globally. Subsoil nitrate accumulation indicates long-term leaching from desert soils, impelling further evaluation of nutrient dynamics in xeric ecosystems. Evidence that subsoil accumulations are readily mobilized raises concern about groundwater contamination after land-use or climate change.
authors: U.S. Geological Survey, Lakewood, CO 80225, USA. walvoord@usgs.gov
authors: Michelle A
authors: MA
authors: Walvoord
authors: Fred M
authors: FM
authors: Phillips
authors: David A
authors: DA
authors: Stonestrom
authors: R Dave
authors: RD
authors: Evans
authors: Peter C
authors: PC
authors: Hartsough
authors: Brent D
authors: BD
authors: Newman
authors: Robert G
authors: RG
authors: Striegl
mesh_terms: D001272:Atmosphere; D002712:Chlorides / Q000032:analysis / Q000378:metabolism; D003889:Desert Climate; D017753:Ecosystem; D009566:Nitrates / Q000032:analysis* / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D010944:Plants / Q000378:metabolism; D012987:Soil / Q000032:analysis*; D015206:Southwestern United States; D014867:Water / Q000737:chemistry
chemical_list: D002712:Chlorides; D009566:Nitrates; D012987:Soil; D014867:Water