ARB Research Seminar

This page updated June 19, 2013

Agricultural Strategies for Mitigating GHG Emission: DNDC Model and Case Studies

William A. Salas, Ph.D., President, Applied GeoSolutions, LLC, New Hampshire

February 18, 2010
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Presentation

Overview

Agriculture represents an important near-term opportunity for GHG mitigation. Given that nitrous oxide and methane emissions from agriculture can be extremely variable in space and time, quantification of mitigation opportunities using emission factors is difficult. Process-based biogeochemical models that capture the spatial and temporal variability in the processes and drivers that cause nitrous oxide and methane emissions from agriculture can play an important role in developing emission inventories and strategies for mitigation. Integration of these models with GIS databases of climate conditions, soil properties, cropping systems and management practices can be useful for regional inventories and assessment of spatial variability in effectiveness of mitigation opportunities. The DNDC (DeNitrification-DeComposition) model was originally developed for quantifying C sequestration and greenhouse gas emissions for the U.S. agricultural lands in 1989. During the past 20 years, with support from Federal and State agencies, several versions of the DNDC have been developed, tested and applied to a wide range of terrestrial ecosystems- croplands, animal feeding operations, pastures, forests and wetlands. DNDC predicts C and N transport and transformation by converting primary drivers (e.g., climate, topography, vegetation, soil, and anthropogenic activity) into environmental factors (e.g., temperature, moisture, pH, redox potential and substrate concentration gradients), which then determine the rates biochemical and geochemical reactions. DNDC possesses a relatively complete set of biogeochemical processes for simulating C and N biogeochemistry by tracking vegetation biomass, soil climate, and soil microbial activities (e.g., decomposition, nitrification, denitrification, fermentation). DNDC has been linked to regional datasets generated from statistics or remote sensing analysis for North America, Asia, Europe and Oceania for quantifying impacts of changes in climate or management on C sequestration and trace gas emissions at the regional scales. Dr. Salas will present an overview the DNDC models, summary of on-going efforts for model validation for California agro-ecosystems, discuss sources of uncertainty in scaling up from the site to regional scale, and a present a case study in using the model for GHG inventories and development of strategies for mitigating GHG emissions from agriculture.

Speaker Biography

William A. Salas, Ph.D., is President and Chief Scientist of Applied Geosolutions (AGS), LLC, a small business consulting firm in New Hampshire. His research interests include biogeochemical modeling applications in agriculture and forestry, remote sensing of land use and land cover change, and development of geospatial decision support tools. Dr. Salas work also includes collaboration with private companies, universities, NGOs, and State and Federal agencies in development of decision support tools for quantification of greenhouse gas emissions from agro-ecosystems. Prior to forming AGS in 2000, Dr. Salas was a research scientist at Complex Systems Research Center at University of New Hampshire and a Member of Technical Staff at NASA's Jet Propulsion Laboratory. Dr. Salas has a B.S. in Mathematics from University of Vermont, and an M.S. in Forestry and Ph.D. in Natural Resources from the New Hampshire, respectively.


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