ARS | Publication request: Carbon sequestration and greenhouse gas fluxes in agriculture: Challenges and opportunities

Submitted to: Council for Agricultural Science and Technology Issue Paper
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 12, 2011
Publication Date: October 12, 2011
Citation: Follett, R.F., Mooney, S., Morgan, J.A., Paustian, K., Allen Jr, L.H., Archibeque, S., Del Grosso, S.J., Derner, J.D., Dijkstra, F., Franzluebbers, A.J., Kurkalova, L., Mccarl, B., Ogle, S., Parton, W., Petersen, J., G. Philip, R., Schoeneberger, M., West, T., Williams, J. 2011. Carbon sequestration and greenhouse gas fluxes in agriculture: Challenges and opportunities. Council for Agricultural Science and Technology Issue Paper. 112 p.

Interpretive Summary: To abate climate change is one of the most pressing modern-day environmental issues. As a signatory country to the United Nations Framework Convention on Climate Change, the United States is actively engaged in a critical international effort to find solutions to the problems posed by climate change. The particular challenges for agriculture include adapting management and land use to cope with the changing climate and adopting mitigation strategies to decrease agriculture’s net contributions to three of the greenhouse gases (GHGs)—carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). These challenges are additional to agriculture’s pivotal roles—to produce food, feed, and fiber as well as bioenergy feedstocks and to provide for conservation and protection of natural resources. This 112 page report outlines a number of practices for which increased C sequestration and decreased emissions of GHGs have been established or, in some instances, are presently under investigation. The practices are evaluated and presented in separate sections that cover annual cropland, pasture and range, horticultural crops, agroforestry systems, wetlands and organic soils, confined livestock, and biofuel feedstock production. There are two principal opportunities for C sequestration in agricultural ecosystems: 1. Improved management of permanent agricultural land through practices that enhance C storage, and 2. Conversion and/or restoration of marginal and degraded agricultural lands to alternative, C-sequestering uses Emissions from N2O can be decreased mainly through more efficient use of N additions to soils, and the main opportunities for CH4 reductions in U.S. agriculture are through improved livestock and manure management practices.

Technical Abstract: Globally, agriculture accounts for 13.5% of GHG emissions. In the United States, agriculture is a small but significant component of the country’s and world’s GHG emissions. We are moving into an uncertain and changing climate pattern that could affect agriculture production, sea levels, and human health. This report’s primary focus is on agriculture’s role in the land-atmosphere exchanges of GHGs as well as agriculture’s ability to decrease GHG emissions or sequester additional carbon in agricultural soils while continuing to supply the necessary food, feed, and fiber required for the world’s growing population. Emissions of CO2, CH4 (methane), and N2O (nitrous oxide) from agriculture are the result of both human-induced and natural processes in the ecosystem carbon (C) and nitrogen (N) cycles. Although these causes of GHG emissions cannot be completely eliminated, they can be lowered through modified land use and management. In general, agricultural activities can mitigate emissions by 1. Decreasing emissions of GHGs due to agricultural causes; 2. Increasing sequestration of C in soil organic matter and plant biomass to result in net removal of CO2 from the atmosphere; and 3. Using sustainable agricultural biofuels with their capacity to offset CO2 emissions from fossil fuels. [GRACEnet publication].