Robertson, G. P., S. K. Hamilton, S. J. Del Grosso, and W. J. Parton. 2010. Growing plants for fuel: Predicting effects on water, soil, and the atmosphere. Biofuels and Sustainability Reports. Ecological Society of America, Washington, D.C., USA.
As society confronts dwindling supplies of fossil fuels to meet energy needs, alternative fuels from renewable resources are capturing the attention of farmers, conservationists, and policy makers. Gasoline blended with corn-based ethanol, one of several biofuels (liquid fuel derived from plant materials), is now sold in filling stations throughout the country. But the rush to ramp up corn ethanol production comes at a cost—to the atmosphere, to marine and freshwater ecosystems, to wildlife habitat, and to the supply of land available for food production. Cellulosic feedstocks, an energy source derived from plant matter such as woodchips, corn stalks, and switchgrass, are an alternative biofuel that may avoid many of the environmental pitfalls of grain-based biofuel crops.
In this issue we will look at both types of “bioenergy landscapes”—one agricultural system based on grains and the other on cellulose—and review what is known about their biogeochemical impacts—the effects on biological, chemical, physical, and geological processes in the natural environment. However, evaluating the costs and benefits of particular cropping systems requires looking at more than just the type of plant that is grown. What are the tradeoffs to society and the environment? How will production affect the ability of the ecosystem to filter water, control runoff and drainage, and provide other “ecosystem services” such as pest protection and climate stabilization? What is the land currently being used for? Will only one type of crop be grown, or will different crops be rotated and how often? Does the production involve tilling the soil?
Because interactions within ecosystems are so complex and results from comprehensive experimental studies of many bioenergy cropping systems are not yet available, mathematical models of ecosystem performance are a useful way to compare alternative systems. Ecosystem models allow us to examine factors such as growing conditions and management practices and to project outcomes such as crop growth and nutrient loss over long time frames. We will examine the environmental outcomes of three alternative biofuel cropping systems to predict what the tradeoffs might be and how these outcomes might challenge our assumptions.
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