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Comparing Ecological Processes and External Inputs as Mechanisms for Increasing Prairie Productivity for Biomass ProductionEPA Grant Number: FP917160
Title: Comparing Ecological Processes and External Inputs as Mechanisms for Increasing Prairie Productivity for Biomass Production
Investigators: Jarchow, Meghann Elizabeth
Institution: Iowa State University
EPA Project Officer: Zambrana, Jose
Project Period: August 23, 2010 through August 22, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Science & Technology for Sustainability: Green Engineering/Building/Chemistry/Materials
My broad research objective is to compare prairie and corn cropping systems with regard to their suitability as biofuel feedstocks. I am comparing the growth, phenology, productivity, and estimated biofuel yield of prairie and corn systems. I also am determining the relationships among species and functional diversity, nitrogen fertilization, and productivity in prairie systems.
The developing lignocellulosic biofuel industry provides an opportunity to reincorporate perennial vegetation into the Corn Belt. Reincorporating native prairies could ameliorate many of the negative environmental impacts caused by annual row crops. The goals of this project are to compare the productivity and biofuel yields of prairie and corn cropping systems and to assess the relationships among diversity, nitrogen fertilization, and productivity of prairies managed for biofuel production.
My approach to understanding my research objectives is to conduct two field experiments in addition to laboratory analyses. Having two field experiments has allowed me to address my research objectives from multiple perspectives. In one field experiment, I am focusing specifically on the growth dynamics, phenology, and productivity of prairie, fertilized prairie, continuous corn, and continuous corn with rye cropping systems and on the effects of nitrogen fertilization on prairie species diversity. The second field experiment focuses on the effects of varying functional diversity and nitrogen fertilization on prairie phenology, productivity, and estimated biofuel yield and compares these characteristics to a continuous corn system. Laboratory analyses are used to determine carbon and nitrogen concentrations in the plant tissues throughout the growing season and are used to estimate the corn and prairie biofuel yields.
I am beginning my third field season with both experiments, so I now am able to comment on my observed results. I have found that prairie systems utilize more of the growing season than corn systems, but that corn systems produce more harvestable biomass than prairie systems. Nitrogen fertilization increases the productivity of the prairies, but reduces both species and functional diversity in terms of richness and evenness. Increasing functional diversity in the prairies does not increase prairie productivity beyond that of the most productive single functional group (i.e., transgressive overyielding) in the presence of nitrogen fertilization, but transgressive overyielding may occur in the most diverse unfertilized prairies. Both the functional groups present and whether nitrogen fertilization was applied affects the estimated biofuel yields of prairies, but the functional group affects the composition of the feedstock while fertilization affects the quantity of feedstock.
The trend in agriculture in the Midwestern United States for the last half century has been one of increasing simplification and intensification, which has resulted in cropping systems that are dominated by monocultures that require large inputs of fertilizers, herbicides, and other fossil-fuel derived inputs. Although these systems are incredibly productive with regard to saleable goods and are profitable with governmental subsidies, they cause a wide range of environmental degradation including increased nutrient pollution, increased soil erosion, and decreased biodiversity. Finding economically viable ways to reincorporate diverse, native prairies back into the landscape can ameliorate many of the environmental impairments caused by our current agricultural system while still benefiting farmers.