Modelling C and N Emissions from Livestock Using Comet Farm.

In this presentation we present real-world examples from U.S. dairies and beef feeding operations to show how the COMET Tools may be used to assess how straightforward management changes can reduce greenhouse gas emissions.  The USDA-NRCS COMET-Farm and COMET-Planner tools give producers and natural resource professionals the capacity to assess how conservation activities reduce the net greenhouse gas emissions from agricultural operations.  Trace Gases from livestock production are a significant source of greenhouse gas emissions, accounting for one-third of direct greenhouse gas emissions from the U.S. agricultural sector, or 3% of total annual U.S. emissions from 1990-2012 and 18% of total worldwide emissions.  Major emissions sources are enteric methane from ruminants as well as methane and nitrous oxide from livestock manure.  Without emissions reductions in the agricultural sector, the proportion of emissions from the livestock sector is likely to rise, as renewable energy and emissions reductions technologies infuse the energy and transportation sectors.  Livestock emissions sources represent an important conservation opportunity for the agricultural sector.  In the COMET tools, users describe their current livestock operation and superimpose conservation scenarios on their current operations by adjusting feed rations and/or modifying manure management methods to gauge the potential greenhouse gas reduction benefits of management changes.