Field crop agriculture and greenhouse gas emissions

About 6% of total greenhouse gas emissions in the US are associated with the agricultural sector. The three major greenhouse gases from agriculture are carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Carbon dioxide is emitted through fossil fuel use on and off the farm (eg. vehicle use and fertilizer production). It can also be emitted or sequestered depending on the type of land and crop management practice used (eg tillage and residue management). Methane emissions predominate in animal agriculture, and are produced during enteric fermentation and through manure management. Nitrous oxide is the major greenhouse gas emitted from crop agriculture, primarily through soil management activities such as nitrogen fertilizer application. Quantifying all three of these greenhouse gases is necessary to determine the importance of farm mitigation options. By altering or adopting management practices, farmers have the potential to reduce their greenhouse gas footprint, and make a substantial contribution to mitigating climate change both regionally and at the global scale.

Calculate and compare the greenhouse gas impact of different cropping systems

To calculate the greenhouse gas impact of different crop rotations and varying management practices, begin by moving your cursor over the map of the US below and click on a county. The next screen will show an estimate of the greenhouse gas cost (CO2 equivalents) of a ‘baseline scenario’ corn-soybean rotation in that county, based upon data from the USDA. To see how different management practices and farm conditions alter the greenhouse gas cost of the system, you can then change the crop, tillage type, fertilizer rate and environmental variables to create new scenarios.