Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2011
Publication Date: 11/1/2011
Citation: Zeri, M., Anderson-Teixeira, K., Hickman, G., Masters, M., DeLucia, E., Bernacchi, C.J. 2011. Carbon exchange by establishing biofuel crops in Central Illinois. Agriculture, Ecosystems and Environment. 144:319-329. Interpretive Summary: Increasing focus on finding alternatives to the burning of fossil fuels is resulting in more efforts toward integrating perennial biofuel crops into cropping systems. Perennial grass species, such as miscanthus and switchgrass as well as mixed prairie ecosystems, are currently identified as ideal candidates to meet the demand for renewable fuels. However, the environmental impacts of these crops are uncertain. One possible impact of large-scale planting of these perennial cropping systems is the potential for increased carbon sequestration in the soil. This benefit helps to remove carbon dioxide from the atmosphere, improve soils, and reduce the emission of greenhouse gases from agricultural system. To investigate whether these benefits exist, we measured the exchange carbon between the atmosphere and each of these three perennial crop systems during the initial establishment phase (two years) and compared the measurements with corn. We found that the perennial grasses and the prairie had much more carbon entering the ecosystem than corn. These perennials systems also released less carbon dioxide into the atmosphere. These results suggest that these ecosystems can improve the carbon dynamics of the landscape if they replace annual crops.
Technical Abstract: Perennial grass biofuels may contribute to long-term carbon sequestration in soils, thereby providing a broad range of environmental benefits at multiple scales. To quantify those benefits, the carbon balance was investigated over three perennial grass biofuel crops miscanthus (Miscanthus giganteus), switchgrass (Panicum virgatum) and a mixture of native prairie plants and a row crop control (maizemaize-soy) in Central Illinois, USA, during the establishment phase of the perennial grasses (2008 and 2009). Whereas maize attained the highest maximal carbon uptake rates, the perennial grasses had significantly extended growing seasons, and both switchgrass and prairie sequestered more carbon than maize during the second growing season. When net ecosystem carbon balance (NECB) from fall 2008 to fall 2009 was computed by subtracting the carbon in harvested (maize) or harvestable (perennial grasses) biomass, the maize agroecosystem was a net carbon source (NECB of -153 g C m-2), miscanthus and prairie were approximately carbon neutral (NECB of 33.6 ±229 g C m-2 and 32.2 ±151 g C m-2, respectively), and switchgrass was a small sink (106.0 ±112 g C m-2). This study supports previous suggestions that perennial grass bioenergy crops would provide environmental benefits through their potential to sequester carbon in roots and soil.