Grassland Soil and Water Research Laboratory 1 article published in JoVE Environment A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function Philip A. Fay1, Lara G. Reichmann2, Michael J. Aspinwall2, Albina R. Khasanova1, H. Wayne Polley1 1USDA-ARS, Grassland Soil and Water Research Laboratory, 2Department of Integrative Biology, University of Texas at Austin The Lysimeter Carbon Dioxide Gradient Facility creates a 250 to 500 µl L-1 linear carbon dioxide gradient in temperature-controlled chambers housing grassland plant communities on clay, silty clay, and sandy soil monoliths. The facility is used to determine how past and future carbon dioxide levels affect grassland carbon cycling.