HR: 0800h
AN: B41B-0181    [Abstracts]
TI: Estimating Soil Erosion and Carbon Mineralization by Rainfall Erosion for Select Management Practices in Corn-based Cropping Rotations: A Case Study for Iowa
AU: * Nelson, R G
EM: rnelson@ksu.edu
AF: Richard G. Nelson, Engineering Extension 133 Ward Hall Kansas State University, Manhattan, KS 66506-2508 United States
AU: Sheehan, J J
EM: john_sheehan@nrel.gov
AF: John J. Sheehan, National Renewable Energy Laboratory 1617 Cole Blvd. , Golden, CO 80401-3393 United States
AU: West, T O
EM: westto@ornl.gov
AF: Tristram O. West, P.O. Box 2008 Environmental Sciences Division Oak Ridge National Laboratory, Oak Ridge, TN 37831-6335 United States
AB: This paper presents estimates of changes in rainfall-induced soil erosion and soil carbon mineralization of individual land capability class I-VIII soil types in Iowa. Land management considered in this analysis includes various quantities of corn stover removal on continuous corn and corn-soybean rotations that are subject to conventional, reduced, and no-till tillage practices. For each rotation and tillage scenario, calculations of soil erosion and carbon mineralization were made for: 1) a ``baseline'' case (e.g., the annual quantity of rainfall-induced soil erosion (tons per acre) that would have occurred with no corn stover removal), 2) a minimum residue level at harvest such that the USDA-NRCS prescribed tolerable soil loss limit (T) is not exceeded for each individual soil type, and 3) a minimum residue at harvest set at 50 bushels corn stover equivalent. Results indicate a large variation in soil erosion and soil carbon mineralization, with this variation depending on rotation, tillage, residue level at harvest, stover removal, physical characteristics of individual soil types, field topology (average % slope), and localized climate. For each county, soil erosion and carbon mineralization increased within a set tillage practice in the corn-soybean rotation versus continuous corn with a range of 11.5% to nearly 600%. Also, an expected decrease in soil erosion and carbon mineralization occurred as tillage decreased in intensity from conventional to conservation/reduced to no-till. Moving from conventional to no-till in continuous corn and corn/soybean rotations with no stover removal, for example, resulted in average decreases of soil erosion of 60% and 88% respectively, and an average decrease of 0.084 tons of carbon dioxide efflux per acre between the two rotations. Allowing a minimum stover level at harvest based either on T or 50 bushels per acre stover equivalent resulted in average increases in soil erosion and carbon mineralization between 27% to over 1,000%, depending upon rotation and tillage practice. A case study at the individual soil type level for Adair County, Iowa is presented to demonstrate differences in soil erosion and carbon mineralization within a single county subject to differing crop rotations, tillage management, and residue removal. This case study will illustrate the significance of including estimates of carbon dioxide efflux from soil erosion in regional carbon accounting and in bottom-up carbon modeling scenarios.
DE: 0402 Agricultural systems
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0430 Computational methods and data processing
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: Fall Meeting 2005