Agriculture’s Role in Greenhouse Gas Emissions and Capture

The American Society of Agronomy, the Crop Science Society of A

The effort summarizes current knowledge of Greenhouse Gas (GHG) emissions and capture as influenced by cropping system, tillage management, and nutrient source (including manure) in six US agricultural regions. The six regions are the Northeast, Southeast, Cornbelt, Northern Great Plains, Southern Great Plains and the Pacific. The Pacific region includes California, Nevada, Oregon, Washington and Idaho. Additionally, topics requiring further research have been identified.

The report's interpretive summary states that: "Approximately 6% of all greenhouse gas (GHG) emissions originating in the United States (U.S.) come from agricultural activities. These gases are in the form of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). However, by employing proper management techniques, agricultural lands can both sequester carbon and reduce CO2, CH4, and N2O emissions, thereby reducing their GHG footprint.

Cap-and-trade climate change legislation, currently under discussion in the legislative and executive branches, may have broad and long-term implications for the agricultural sector. In order to determine the role of agriculture in GHG emissions and capture, a full life cycle accounting of GHG sources and sinks is needed."

The report does a great job in explaining the effects of GHG on climate change and documents the rise in each of the three GHG's. It further offers methods of reducing agriculture's production of GHG or sequestering carbon including:

• Reducing fuel consumption;
• Enhancing soil carbon sequestration;
• Improving nitrogen-use efficiency (NUE);
• Increasing ruminant digestion efficiency;  and
• Capturing gaseous emissions from manure and other wastes.

Livestock producers, rangeland managers and hay producers will value many of the specific suggestions for them in both reducing GHG’s and sequestering carbon.  A few of these include:

• Harvesting forage by livestock grazing rather than mechanically - reducing fuel consumption;
• Using legume-based rotations or organic agricultural systems to reduce N fertilizer applications - reducing fuel consumption;
• Conservation tillage, winter cover crops and perennial pastures - enhancing soil carbon sequestration;
• Leguminous green manures (like clovers) can convert nitrogen gas from the atmosphere to plant available N for crop use (like hay and pasture or between vineyards) - improving nitrogen-use efficiency (NUE);
• Adjusting the portions of animal feed to decrease digestion time - increasing ruminant digestion efficiency;
• Using edible oils or other feed additives to reduce metabolic activity of rumen bacteria that produce CH4 - increasing ruminant digestion efficiency;
• Capturing CH4 emissions from livestock waste using covered lagoons and converting to electricity – capturing gaseous emissions from manure; and
• Applying manure to the soil as a nutrient source rather than storing it as waste – capturing gaseous emissions from manure.

It's encouraging to know that grazing livestock and some of the typical practices we presently employ can have a positive impact on our environment. I hope all of you will download and read the entire report.