HR: 17:00h
AN: B44B-05    [Abstracts]
TI: Transitioning from Corn to Switchgrass in the US Great Plains: Implications for Climate and Water Resource
AU: * Oglesby, R J
EM: roglesby2@unl.edu
AF: Department of Geosciences and School of Natural Resources University of Nebraska, Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340, United States
AU: Rowe, C M
EM: crowe1@unl.edu
AF: Department of Geosciences University of Nebraska, Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340, United States
AU: Erickson, D J
EM: ericksondj@ornl.gov
AF: CSM/ORNL, Oak Ridge National Laboratory PO Box 2008 MS6016, Oak Ridge, TN 37831-6016, United States
AB: Much attention has been paid to the use of corn as a biofuel, in large part because corn is already grown throughout much of the US and technology is in place to convert it to ethanol. Increasingly, however, it is recognized that other types of vegetation are likely to be more efficient producers of biofuel. In particular, switchgrass (the primary component of prairie long grass) may be a very efficient producer in the Great Plains (as well as portions of the Midwest and Southeast), where it is an indigenous species. The dominant agricultural planting in the Great Plains at present is corn. A transition from corn to switchgrass may have numerous benefits, both because it may be a better source of biofuels, and because in the water-scarce Great Plains it would likely make better use of available water resources. In addition to these positive benefits, however, there may be effects on the climate of this region that can be deleterious. While switchgrass, with its deep and extensive root system may be less subject to drought, and less needing of irrigation, than corn, it also cycles much less water during its growing season. This reduction in water input to the atmosphere means less water available for local and regional precipitation, and also dramatically affects the surface energy balance, resulting in more sensible and longwave heating of the atmosphere. This may cause a significant increase in surface air temperature and stabilization of the atmosphere, leading to a reduction in precipitation as well as increased evaporative potential (both of which would help negate any increased water efficiency of switchgrass). We use the MM5 and WRF regional climate models to investigate these effects over the Great Plains. Simulations were made assuming all corn ('irrigated cropland') and all switchgrass ('grassland') and compared to a control using present-day land use types that is largely a mix of the two. Model runs are being made for three years with normal precipitation, plus years with precipitation above and below normal (as based on observations). The high-resolution North American Regional Reanalysis provides lateral and initial conditions for the model simulations. Preliminary results suggest that a transition from corn to switchgrass can increase daily maximum temperatures by up to 4 C, with smaller increases in daily minimums. Precipitation decreases by 15-25%. Overall, the tendency is for warmer and drier conditions. These results also suggest that effects due to global warming may be exacerbated by a large-scale change to switchgrass.
DE: 0402 Agricultural systems
DE: 0416 Biogeophysics
DE: 1620 Climate dynamics (0429, 3309)
DE: 1833 Hydroclimatology
SC: Biogeosciences [B]
MN: 2007 Fall Meeting