Greenhouse gas emissions and carbon footprint

Authors: Franzluebbers, Alan

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/12/2019
Publication Date: 8/24/2019
Citation: Franzluebbers, A.J. 2019. Greenhouse gas emissions and carbon footprint. In Rouquette, Jr., M. and Aiken, G. (eds.) Management Strategies for Sustainable Cattle, Academic Press pp. 11-34. Book Chapter.

Interpretive Summary: Pastureland in the southeastern USA supports a large segment of cow-calf operations. Knowing the greenhouse gas emissions and carbon footprint of these operations is needed to make informed decisions as to how to improve efficiency. A scientist with USDA Agricultural Research Service in Raleigh NC reviewed literature on greenhouse gas emissions associated with beef production. Although few studies were conducted specifically in the southeastern USA, studies from other regions of the country and around the world served to guide understanding in the region. Enteric methane emissions from ruminant livestock and soil nitrous oxide emissions from fertilized pastures and crops are the two largest sources of greenhouse gas emissions in agriculture. Enhancing nutritive value of feedstuffs and wisely utilizing on-farm sources of nitrogen are two important strategies to reduce greenhouse gas emissions and sequester more carbon in soil as organic matter. This information will be useful to farmers, agricultural advisors, and scientists in the region to design more efficient pasture-based production systems.

Technical Abstract: Perennial pastures are an important component of beef cattle production for cow-calf operations in the southeastern USA. Greenhouse gas emissions are dominated by enteric methane (CH4) emission, accounting for ~60% of total emissions from beef production. With significant N fertilization of pastures, nitrous oxide (N2O) emission is often the second most important greenhouse gas, accounting for ~30% of total emissions from beef production. Region-specific data on greenhouse gas emissions from beef production are lacking, and yet these data are essential to design southern pastures for improved resource efficiency. Forages with high nutritive value can reduce CH4 emissions by grazing cattle, as consequence of greater feed efficiency and shorter time to gain maturity. In addition, forages with significant tannins, saponins, and other biochemical components may have potential to mitigate against enteric CH4 emission. Nitrogen fertilization of pastures often leads to greater soil N2O emission. Establishing and maintaining legumes in pastures can limit the need for external N inputs. Forage production systems that rely on farm-derived nutrients (e.g. precision litter decomposition with management-intensive grazing, application of additional manure sources, composts, etc.), keep brood cows healthy and productive, and get calves to finishing weight faster are keys to reducing greenhouse gas emissions from southern pastures. Significant soil organic C sequestration should also be a focus to reduce overall C footprint of animal agriculture in the region.