Southern Plains

Who operates and manages this LTAR site?

The Grazinglands Research Laboratory (GRL) of USDA-ARS manages the Southern Plains LTAR site.


The GRL consists of the Forage and Livestock Research Unit and the Great Plains Agroclimate and Natural Resources Research Unit, who jointly conduct LTAR research. GRL also houses the USDA Southern Plains Climate Hub, which develops and delivers regional, science-based information to partners and producers in Kansas, Oklahoma, and Texas that enables climate-smart decision-making.

The GLR is located on the former Fort Reno property, which was transferred from the U.S. Army to the USDA by Congress in 1948.  Research was initially led from USDA headquarters and implemented through cooperative agreements with the Oklahoma Agricultural Experiment Station.  The ARS began assigning in-house staffing and research 1970.

The GRL conducts long-term watershed research in the Upper Washita Basin as part of the Conservation Effects Assessment Project (CEAP). Research began on the Little Washita River Experimental Watershed (LWREW) in 1961, and on the Fort Cobb Reservoir Experimental Watershed (FCREW) in 2005.


Located in the southern part of the Great Plains, about twenty-five miles west of Oklahoma City, the site (35.59⁰ N, 98.04⁰ W 419 m asl)  lies within the Central Rolling Red Plains (Major Land Resource Area 78C).  Land use is primarily agricultural, including native prairie pasture, cropland, and pastureland.


The Southern Plains LTAR sees an average temperature of 14.9˚C, with an average high of 34.4˚C in July and an average low of -5˚ C in January.  The average annual rainfall is 869 mm.

Download SP Climate Syntheses PDF


  • Twelve eddy covariance systems
  • Two Green Feed systems
  • Twelve soil moisture sensor arrays
  • Mesonet weather station
  • LTAR weather station
  • Multiple soil (microbial) flux sites
  • Multiple sampling flumes
  • Thirty five soil microclimate (ARS Micronet) monitoring sites
  • Genomics lab and greenhouse
  • Chemistry labs
  • NRCS SCAN site
  • Eight instrumented unit source watersheds: neutron access tubes, ground water level wells, V-notch weirs, tipping bucket rain gages, automated water samplers
  • Four COSMOS soil moisture measurement sites
  • Field portable multi-band, and hyperspectral spectroradiometers

Classification System

Farm Resource Regions:  Prairie Gateway
Major Farm Region:  Beef cattle, winter wheat, pasture, forages, prairie
Hydrologic Unit Codes (HUC-2): 11–Arkansas-White-Red, 13–Washita River Basin
National Ecological Observatory Network (NEON):  Domain D11 (Southern Plains)
NRCS Major Land:  Central Rolling Red Plains

LTAR Research Emphases

  • Integrated crop-livestock systems
  • Rangeland (prairie)-beef cattle systems
  • Forage breeding and diversification of forage base
  • Carbon, water, and energy measurements with flux towers
  • Cropping system, hydrologic and erosion modelling
  • Climate downscaling, and climate impacts assessment, and mitigation strategies
  • Remote sensing of ET, drought, and vegetation
  • Soil biology and ecology
  • Reservoir sedimentation research

Muti-site Initiatives

  • Common experiment synthesis (Spiegal/Bestelmeyer)
  • Sustainable intensification review (Kleinman)
  •  Water balance/budgets (Baffaut)
  •  Farm modeling – IFSM (Kleinman)
  • Wind erosion network (Webb)
  • Soil Biology Group/DET for soil biology modeling (Kleinman)

Major Accomplishments

List of accomplishments

Other Networks (where data is shared)

  • Oklahoma Mesonet
  • ARS Micronet
  • National Wind Erosion Network
  • Grazing CAP  (Kansas State University led, NIFA funded)
  • Cosmos
  • Cropland CEAP
  • Pasture CEAP
  • SCAN

USDA Climate Hub

Southern Plains Hub

Site Name

Southern Plains




Central to Southwest Oklahoma



Area (km2)

Grazinglands Research Laboratory (GRL):  27 km2
The Little Washita River Experimental Watershed: 611 km2
The Fort Cobb Reservoir Experimental Watershed:  813 km2


Jean Steiner (LD, RL), Prasanna Gowda (RL), Daniel Moriasi, Jurgen Garbrecht, Patrick Starks, John Zhang, Ken Turner, Brian Northup, Jim Neel