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USDA NRCS

U.S. Department of Agriculture Natural Resources Conservation Service (NRCS) is a key developer of the Voluntary Reporting Carbon Management Evaluation Tool (COMET 2) which helps farmers and ranchers report the effectiveness of various land management systems for agricultural soil carbon sequestration.  The Century Soil Organic Matter model developed at Colorado State University was chosen as the method to assess soil carbon stock changes occurring on non-federal cropland, rangeland and pasture lands in the conterminous U.S.  The Century model output from COMET 2 provides an estimate of soil C changes specific for land management alternatives within US Regions.  Currently, management descriptions are available at the MLRA level.

The current USDA NRCS effort related to quantifying the change in greenhouse gas emissions due to natural resource conservation practice application began in 1999 with statewide studies in Indiana, Iowa, and Nebraska.  These studies developed the methodology that is the foundation of COMET 2.

In 2002 - 2003, NRCS began preliminary development of COMET 2 by gathering resource and management information at the Land Resource Level.  A team of NRCS experts was assembled to input information into the Carbon Sequestration Rural Appraisal (CSRA) of land management and cropping histories for these 20 regions.  The CSRA is a joint development of NRCS and CSU that grew out of work in Iowa and was refined for other studies.

This information along with data generated using Geographic Information System (GIS) processing was used to build the Century Run files and SQL database.  The information on historical cropping practices needed for Century simulations were gathered from a variety of sources with differing scales of coverage, from the experiences of a single farmer to national level databases (NRI, NASS, STATSGO). The goal was to gain as much knowledge as possible from the time of plow out and the "pioneer" stage of subsistence farming until modern farming regions and practices. Information on individual crops and early crop rotations was gathered from literature dating as far back as the horse-drawn era of the late 1890s  through the emergence and eventual dominance of today's technologies. Data was also accumulated on the changing uses of manure and inorganic fertilizers.

The interface development began in June of 2004.  John Brenner, USDA NRCS and Jill Schuler, former USDA NRCS GIS/WEB Programmer were key NRCS players in this tools development.  John and Jill worked closely with the scientist at Colorado State University, Natural Resource Ecology Lab (NREL) in a collaborative research effort.

Other staff with USDA, USDA GCPO, USDA ARS, USDA USFS,  and DOE also participated in the development of this tool giving guidance on policy and management decisions.

CSU NREL

NREL scientists are among the world leaders in terrestrial greenhouse gas assessment and mitigation. Their expertise spans agricultural, grassland, and forest ecosystems and they work closely with agronomists, foresters, atmospheric scientists, remote sensing experts, economists, and social scientists across CSU and around the world.

For over 30 years NREL has led the development of ecosystem biogeochemical modeling and basic research on soil carbon and nitrogen dynamics. In addition, NREL is leading numerous efforts to provide terrestrial greenhouse gas inventories at national, region and state levels within the US and abroad, working with representatives of industries, state and federal agencies, and non-governmental organizations to help them integrate greenhouse gas mitigation into their activities.

More than 30 senior scientists are associated with the Natural Resource Ecology Laboratory. They are joined in their work by many post doctoral fellows and graduate students. An outstanding group of support staff and accounting and clerical staff help make NREL research possible.  Key personnel for NREL involved with the development of COMET 2 are Dr. Keith Paustian, Dr. Steve Ogle, Kendrick Killian, Mark Easter, and Steve Williams.

One of the primary missions of NREL is the Mitigation of Greenhouse Gas through Natural Resource Management.  Research is focused on facilitating the adoption of improved land management practices to mitigate greenhouse gas emissions in an economically and environmentally sustainable fashion.

The CENTURY Model used by the COMET 2 Interface provides a comprehensive description of the  biogeochemistry of Carbon, Nitrogen, Phosphorus, and Sulphur in the environment. The primary purposes of the model are to provide a tool for ecosystem analysis, to test the consistency of data and to evaluate the effects of changes in management and climate on ecosystems.

The CENTURY model simulates the long-term dynamics of Carbon (C), Nitrogen (N), Phosphorus (P), and Sulfur (S) for different Plant-Soil Systems. The model can simulate the dynamics of grassland systems, agricultural crop systems, forest systems, and savanna systems. The grassland/crop and forest systems, have different plant production submodels which are linked to a common soil organic matter submodel. The savanna model uses the grassland/crop and forest subsystems and allows for the two subsystems to interact through shading effects and nitrogen competition. The soil organic matter submodel simulates the flow of C, N, P, and S through plant litter and the different inorganic and organic pools in the soil. The model runs using a monthly time step and the major input variables for the model include:

• monthly average maximum and minimum air temperature,
• monthly precipitation,
• lignin content of plant material,
• plant N, P, and S content,
• soil texture
• atmospheric and soil N inputs, and
• initial soil C, N, P, and S levels.

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