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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF MODELS AND CONSERVATION PRACTICES FOR WATER QUALITY MANAGEMENT AND RESOURCE ASSESSMENTS Title: Biofuels and water use: Comparison of maize and switchgrass and general perspectives

Authors
item Kiniry, James
item Lynd, Lee - DARTMOUTH COLLEGE
item Greene, Nathanel - NAT RES DEFENSE COUNCIL
item Johnson, Mari-Vaughn
item Casler, Michael
item Laser, Mark - DARTMOUTH COLLEGE

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: March 10, 2008
Publication Date: December 10, 2008
Citation: Kiniry, J.R., Lynd, L., Greene, N., Johnson, M., Casler, M.D., Laser, M.S. 2008. Biofuels and water use: Comparison of maize and switchgrass and general perspectives. In: Wright, J.H., Evans, D.A., editors. New Research on Biofuels. Nova Science Publishers, Inc. p. 17-30.

Interpretive Summary: Switchgrass and corn are two of the main plants currently being considered as potential biofuel feedstocks in the U.S. Recent expanded production of both has raised serious questions about natural resource utilization, notably, soil carbon, soil nutrients, and water. Water is often limiting for crop and grass productivity. The objective of this study was to calculate and compare water use and water use efficiency of corn and switchgrass. We used the calibrated and validated ALMANAC computer simulation model for five sites representing the southern Great Plains (Stephenville, TX), the northern Great Plains (Mead, NE), and two locations in the Corn Belt (Ames, IA and Columbia, MO). Ten years of weather data were used. Average values for water use and water use efficiency were calculated for corn and switchgrass. Results from this work will give guidance to policy planners, producers, and economists. These results show the relative impact of expanded corn production, expanded switchgrass production, and use of improved switchgrass varieties, on the water balance in these regions. The water use efficiency (WUE) of four switchgrass types showed means ranging from 3 to 5 mg g**-1. Switchgrass WUE values were much greater than WUE of corn grain, but such was not always the case when compared to WUE of whole corn plants.

Technical Abstract: Two of the main plants currently being considered as potential biofuel feedstocks in the U.S. are switchgrass (Panicum virgatum L.) and maize (Zea mays L.). Recent expanded production of both has raised serious questions about natural resource utilization, notably, soil carbon, soil nutrients, and water. Water is often the limiting resource for crop and grass productivity. The objective of this study was to calculate and compare water use and water use efficiency of maize with current growth characteristics, switchgrass with current growth characteristics, and switchgrass with characteristics improved by normal plant breeding selection techniques. We used the calibrated and validated ALMANAC model for five sites representing the southern Great Plains (Stephenville, TX), the northern Great Plains (Mead, NE), and two locations in the Corn Belt (Ames, IA and Columbia, MO). Ten years of historical weather data were used. Mean values for water use and water use efficiency calculated for maize, switchgrass with currently growth characteristics, and switchgrass with anticipated improved growth characteristics. Results from this simulation work will give guidance to policy planners, producers, and economists. These results show the relative impact of expanded maize production, expanded switchgrass production, and use of improved switchgrass varieties, on the water balance in these regions. The water use efficiency (WUE) of four switchgrass types showed means ranging from 3 to 5 mg g**-1. Switchgrass WUE values were much greater than WUE of maize grain, but such was not always the case when compared to WUE of maize plants. Changes in switchgrass light extinction coefficients (k) and in switchgrass radiation use efficiency (RUE) showed the expected trends. Increased RUE caused increases in dry matter yield and in WUE, but not usually as great as the percentage increase in RUE.

Last Modified: 11/28/2014
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