Farm-scale full GHG accounting with the COMET-Farm tool

The COMET-Farm system is an integrated web-based platform, for quantification and assessment of conservation scenarios in whole farm, ranch, and forest plot greenhouse gas (GHG) emissions, using tate-of-the-art computation methods but in an environment that enables farmers, ranchers, and foresters (as well as ag consultants and land management agency personnel) to manage their data and produce high-quality estimates and reports of their emissions, and the GHG reduction potential of conservation practices. COMET-Farm includes five estimation modules: soil and biomass related (field-based) emissions, livestock emissions, agroforestry emssions, forestry emissions, and energy emissions. For field-based emissions, the system includes a full spatial interface that allows management to be specified for individual fields and pastures (and subdivided by within-field soil type using Web Soil Survey). Biomass CO₂ and soil CO₂ and N₂O emissions/removals are calculated dynamically using the DayCent simulation model, with optional empirical models for biomass stocks in agroforestry systems. Livestock emissions, for enteric CH₄ and CH₄ and N₂O emissions from manure management are estimated from empirical models using basic livestock characteristics or with more detailed information on feeding regimes. Agroforestry greenhouse gas balance is calculated using regional regression models based on the U.S. Forest Service Forest Inventory and Analysis (FIA) database, and calculates carbon sequestered due to plant growth and losses from tree removals. Other emission source categories, including biomass burning, liming and urea applications are included in the system. Scenarios for different farm-types and management systems are presented and emission estimates are compared to results from relevant field experiments.