From Prairies to Corn Fields for Fuel

A Tale of Lost Carbon

Author:	Glenna M. Malcolm Department of Biology Pennsylvania State University gmm193@psu.edu
Abstract:	With increasing U.S. government support for biofuel production in the late 2000s came increased pressure to convert more land to cornfields for ethanol. To make way for more corn, millions of acres of prairie grassland were plowed under, destroying an extremely diverse wildlife habitat that also served as a large carbon reservoir. This case study focuses on the reasons for and consequences of large carbon losses when prairie grasslands are converted to agricultural lands. Many students are challenged when faced with linking together energy flows, decomposition, and nutrient cycles. This case gives students the opportunity to consider different pools in the carbon cycle and the fluxes between them in order to model (on paper) an integrated picture of why carbon is lost when prairie grasslands are plowed and planted to cornfields. Students also consider ways that carbon loss from land conversion due to ethanol production might be avoided via government incentive programs or mitigated via changes to farming practices. This case study was developed for an introductory ecology, environmental science, soil science, or agriculture course.
Objectives:	Describe differences in soil appearance, plant life cycle (annual vs. perennial), and plant biomass production for prairie grasslands vs. cornfields. Consider differences in biomass inputs for prairie grasslands vs. cornfields. Link conversion of prairie grasslands to cornfields as a driver of climate change. Draw the terrestrial carbon pools and fluxes between them for a prairie grassland. Describe the forms of carbon as it moves through the cycle between pools. Model the changes in the sizes of prairie grassland carbon pools and fluxes following a disturbance, such as plowing, to the environment. Develop ecosystems thinking skills, which includes the ability to integrate knowledge in the ways described in the bullets above.
Keywords:	Corn ethanol; biofuel; carbon cycle; nutrient cycle; decomposition; energy flow; carbon reservoir; carbon sink; pools; fluxes
Topical Area:	Science and the media
Educational Level:	Undergraduate lower division, Undergraduate upper division
Formats:	PDF
Type/Method:	Analysis (Issues), Dilemma/Decision, Interrupted
Language:	English
Subject Headings:	Agriculture Biochemistry Biology (General) Earth Science Ecology Environmental Science Natural Resource Management
Date Posted:	8/6/2015
Date Modified:	N/A
Copyright:	Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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