Management of Dryland Cropping Systems in the U.S. Great Plains: Effects on Soil Organic Carbon

Authors: Liebig, Mark; Mikha, Maysoon; Potter, Kenneth

Submitted to: Soil Science Society of America Special Publication Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/25/2007
Publication Date: 3/6/2009
Citation: Liebig, M.A., Mikha, M.M., Potter, K.N. 2009. Management of Dryland Cropping Systems in the U.S. Great Plains: Effects on Soil Organic Carbon. Soil Science Society of America Special Publication Book Chapter. P. 97-113. In: R. Lal and R.F. Follett (Eds.) Soil carbon sequestration and the greenhouse effect, 2nd Ed. SSSA Spec. Publ. 57. ASA-CSSA-SSSA, Madison, WI.

Interpretive Summary: Mitigation of greenhouse gas emissions from land management practices requires increasing soil organic carbon (SOC), decreasing methane and nitrous oxide emission, or increasing soil methane oxidation. To date, much emphasis has been placed on identifying and employing land management practices that sequester SOC. In that regard, a literature review was conducted to summarize the effects of management on SOC within dryland cropping systems of the U.S. Great Plains. This region possesses significant expanses of land used for agricultural production. Accordingly, identification and application of dryland cropping systems that sequester SOC can have a significant impact on the overall greenhouse gas balance from U.S. agriculture. Management practices in the region with the greatest capacity to increase SOC or mitigate SOC loss included adoption of no-tillage and increased cropping intensity (i.e., reduced frequency of fallow). Increases in SOC in dryland cropping systems have concomitant benefits to agroecosystem performance through improvements in soil quality and increased crop productivity. Additional benefits to agricultural producers from SOC sequestration include supplementary farm income through involvement in carbon trading programs. Despite these benefits, the effectiveness of dryland cropping systems in the U.S. Great Plains to mitigate global climate change remains uncertain due to estimated rates of nitrous oxide emission.

Technical Abstract: The U.S. Great Plains possesses significant expanses of agricultural land containing large reserves of soil organic carbon (SOC). Identification and application of dryland cropping systems in the region known to sequester SOC can significantly affect the greenhouse gas (GHG) balance from U.S. agriculture. In this paper, we review the effect of dryland cropping systems on SOC in the U.S. Great Plains. Change in SOC for continuous cropping no-till management ranged from -0.05 to 0.23 Mg C/ha/yr for time-series data and 0.16 to 0.56 Mg C/ha/yr for data where a tilled treatment was used as a baseline. Increasing cropping intensity (i.e., reducing fallow frequency) in the region either increased SOC or mitigated SOC loss. Converting crop-fallow to continuous cropping under no-till management increased SOC accrual by 0.28 Mg C/ha/yr. Accrual of SOC in dryland cropping systems has accompanying benefits to agroecosystem performance through improvements in soil quality and increased crop productivity. Additional benefits to agricultural producers from SOC accrual include increased farm income through involvement in carbon trading programs. Such programs are poised to expand in the future, and in doing so, will likely undergo increased scrutiny to ensure GHG reduction benefits are realized. Given this context, presumptions regarding the capacity of continuous cropping no-till management systems in the U.S. Great Plains to reduce atmospheric radiative forcing are tenuous, due mainly to uncertainties associated with nitrous oxide emission from these systems. [GRACEnet Publication]