College Park, MD 20740
“Dry Matter Partitioning, Seasonal Nutrient Cycling Dynamics, and Estimated Ethanol Production of Three Perennial Bioenergy Crops”
A presentation by Jennifer Burks, PhD candidate
Ecological Sciences and Engineering (ESE) Program
Department of Agronomy
Tuesday, Feb 12, 12:00-1:00pm.
Continuous, intensive seasonal data on biomass accumulation/partitioning and macronutrient cycling within perennial bioenergy crops grown in the US Midwest are sparse. Data from side-by-side studies are needed to assess and compare energy densities and potential ecosystem impacts of crops considered for commercial production to inform which, if any, are capable of meeting required targets outlined in government mandates. Results from this study assessing Miscanthus × giganteus, switchgrass (Panicum virgatum, ‘Shawnee’), and a big bluestem- (Andropogon girardii) dominated prairie indicate that Miscanthus annually accumulated more aboveground biomass, and thus higher ethanol production estimates (16 to 38 Mg ha-1; 5006 L ha-1) than switchgrass (9 to 13 Mg ha-1; 2430 L ha-1) and prairie (3 to 6 Mg ha-1; 1031 L ha-1); the higher biomass production resulting in higher amounts of nitrogen (N), phosphorus (P), and potassium (K) accumulation in Miscanthus than the other crops. Miscanthus increased rhizome mass three-fold by the end of the study, resulting in the highest rhizome N, P, and K accumulation of the candidate systems. This high amount of belowground tissue and nutrient accumulation translated to Miscanthus being unique among prairie and switchgrass in its ability to consistently remobilize positive amounts of N (38%), P (76%) and K (52%) from aboveground biomass belowground each year. The extent and consistency of annual nutrient remobilization in switchgrass and prairie were less pronounced. Carbon (C) concentrations were similar among crops and tissues, identifying belowground biomass accumulation as the main factor in system C sequestration potential. Results from this study identify Miscanthus as having the highest potential of meeting both energy density and environmental guidelines outlined in government mandates. Data from this research further our understanding of the plant and ecosystem physiology of these novel cropping systems; deeming them useful in informing large-scale models and in turn, informing government decisions on renewable energy projections.
Jennifer Burks is a PhD candidate at Purdue University where she is a member of the Ecological Sciences and Engineering (ESE) Program and conducts research within the Department of Agronomy under the guidance of Drs. Jeffrey Volenec and Sylvie Brouder. She originates from southern Indiana and completed her Bachelor’s degree from Earlham College where she earned a major in Biology and a minor in Chemistry. She has a deep appreciation for nature and conservation stemming from her early childhood days of morel mushroom hunting (has never once missed a season!) and fishing and extends that appreciation for nature and ecology into her career interests of utilizing her understanding of agro-ecology to inform policy-makers on Capitol Hill.