ENHANCED MIDWESTERN CROPPING SYSTEMS FOR SUSTAINABILITY AND ENVIRONMENTAL QUALITY
Location: Agroecosystems Management Research Unit
Title: Soil carbon sequestration in central USA agroecosystems
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: December 20, 2011
Publication Date: June 8, 2012
Citation: Cambardella, C.A., Johnson, J.M., Varvel, G.E. 2012. Soil carbon sequestration in central USA agroecosystems. In Liebig, M.A., Franzluebbers, A.J., Follett, R.F., editors. Managing Agricultural Greenhouse Gases: Coordinated Agricultural Research through GRACEnet to Address our Changing Climate. San Diego, CA: Elsevier Publ. p. 41-58.
Cropland soils of the central USA represent a large potential sink for atmospheric carbon (C). This chapter reviews recent literature related to C storage in cropland soils of the central USA to define the current state of knowledge of agricultural management impacts on soil C sequestration. The most widely adopted management practice to enhance C sequestration in this region is conservation tillage. Recent research has demonstrated that no tillage (NT) management of increased surface soil organic carbon (SOC) compared to plow tillage but in many studies, subsoil C content was higher under plow tillage. There is evidence that changes in tillage management can alter C cycling processes resulting in greater retention of corn-derived C in NT compared to plowed systems. Enhancing crop rotation complexity is another successful strategy to foster C sequestration in corn-based cropping systems of the Midwest, especially by including small grains and forage legumes in extended rotations and through planting of perennial grasses and trees on marginally productive cropland. Planting cover crops is a viable option for increasing C sequestration in this region, although it is difficult to measure significant changes in SOC due to cover cropping in corn-based cropping systems. Nitrogen (N) fertilizer application has been reported to increase SOC content in some but not all Midwest agroecosystems, because C sequestration in response to N fertilizer application depends on interactive processes that simultaneously increase crop C inputs while enhancing the decomposition rate of crop residues and soil organic matter. Significant progress has been made in the past decade towards defining the effects of crop rotation complexity, tillage, N fertilizer application, and planting perennial grasses on surface and subsurface SOC. Further research is needed to increase our understanding of the interactive effects of agricultural management practices, increased atmospheric carbon dioxide (CO2), and changing climate variables on C sequestration in central USA agroecosystems.