Sustainability

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GLBRC's Sustainability Research Area

Sustainability

Focusing on one attribute comes at a high price.

At the GLBRC, sustainability researchers are exploring complex issues in agricultural and industrial systems. Research focuses on understanding the attributes and mechanisms responsible for the environmental sustainability of biofuel production systems, such as environmental impacts — many of which may be positive — and socioeconomic factors including incentives and policy options

Learn about the Center's research approach

Sustainability Leadership

Sustainability Lead

A crop and soil scientist and ecosystem ecologist, Robertson focuses much of his research on the role that agriculture plays in greenhouse gas dynamics, and he is internationally known for his expertise in this area. Robertson has been the director...

Sustainability Lead

Jackson’s program focuses on structure and function of managed, semi-natural and natural grassland ecosystems. Research in Jackson’s grassland ecology lab spans many levels of ecological organization, from grass identification at the DNA level to landscape diversity effects on alternative biofuels...

Project Overview

A device used for measuring plant utilization of solar radiation sits in front of plots of switchgrass, corn and poplar growing in the Great Lake Bioenergy Research Center's fields at the Arlington Agricultural Research Station in Arlington, WI.GLBRC Sustainability research ranges from the microbial community level to regional modeling, and researchers conduct fieldwork at different project sites to reflect this diversity of scale. Small plots at Kellogg Biological Station in Michigan and the Arlington Agricultural Research Station in Wisconsin provide locations for measurement-intensive experiments, while investigators work in larger scale-up fields to collect data on carbon balances and biogeochemical processes. Finally, researchers pursue ecosystem-level biodiversity questions across landscapes, including marginal lands, in central Michigan and Wisconsin.

Specific sustainability projects include:

  • Novel biofuel production systems
  • Microbial-plant interactions for improved biofuel production
  • Biogeochemical responses
  • Biodiversity responses
  • Economic responses
  • Modeling, design and testing of drop-in fuels
  • Process synthesis and technoeconomic evaluation for biomass-to-fuels technologies.

 

Sustainability Publications

Cellulosic feedstock production on Conservation Reserve Program land: potential yields and environmental effects

Stephen D. LeDuc; Xuesong Zhang; Christopher M. Clark; César Izaurralde

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2016

Producing biofuel feedstocks on current agricultural land raises questions of a “food-vs-fuel” tradeoff. The use of current or former Conservation Reserve Program (CRP) land offers an alternative; yet the volumes of ethanol that could be produced and the potential environmental impacts of such a policy are unclear. Here, we applied the Environmental Policy Integrated Climate (EPIC) model to a U.S. Department of Agriculture database of over 200,000 CRP polygons in Iowa, USA, as a case study. We simulated yields and environmental impacts of growing three cellulosic biofuel feedstocks on CRP land: (i) an Alamo-variety switchgrass (Panicum virgatum L.); (ii) a generalized mixture of C4 and C3 grasses; (iii) and no-till corn (Zea mays L.) with residue removal. We simulated yields, soil erosion, and soil carbon (C) and nitrogen (N) stocks and fluxes. We found that although no-till corn with residue removal produced approximately 2.6-4.4 times more ethanol per area compared to switchgrass and the grass mixture, it also led to 3.9-4.5 times more erosion, 4.4-5.2 times more cumulative N loss, and a 10% reduction in total soil carbon as opposed to a 6-11% increase. Switchgrass resulted in the best environmental outcomes even when expressed on a per liter ethanol basis. Our results suggest planting no-till corn with residue removal should only be done on low slope soils to minimize environmental concerns. Overall, this analysis provides additional information to policy makers on the potential outcome and effects of producing biofuel feedstocks on current or former conservation lands. This article is protected by copyright. All rights reserved.

Comparative productivity of alternative cellulosic bioenergy croppingsystems in the North Central USA

Gregg R. Sanford; Lawrence G. Oates; Poonam Jasrotia; Kurt D. Thelen; Philip Robertson; Randall D. Jackson

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2016

Biofuels from lignocellulosic feedstocks have the potential to improve a wide range of ecosystem services while simultaneously reducing dependence on fossil fuels. Here, we report on the six-year production potential (above ground net primary production, ANPP), post-frost harvested biomass (yield), and gross harvest efficiency (GHE = yield/ANPP) of seven model bioenergy cropping systems in both southcentral Wisconsin (ARL) and southwest Michigan (KBS). The cropping systems studied were continuous corn (Zea mays L.), switchgrass (Panicum virgatum L.), giant miscanthus (Miscanthus × giganteus Greef & Deuter ex Hodkinson & Renvoize), hybrid poplar (Populus nigra × P. maximowiczii A. Henry ‘NM6’), a native grass mixture (5 sown species), an early successional community, and a restored prairie (18 sown species). Overall the most productive cropping systems were corn > giant miscanthus > and switchgrass, which were significantly more productive than native grasses ≈ restored prairie ≈ early successional ≈ and hybrid poplar, although some systems (e.g. hybrid poplar) differed significantly by location. Highest total ANPP was observed in giant miscanthus (35.2 ± 2.0 Mg ha−1 yr−1) at KBS during the sixth growing season. Six-year cumulative biomass yield from hybrid poplar at KBS (55.4 ± 1.3 Mg ha−1) was high but significantly lower than corn and giant miscanthus (65.5 ± 1.5, 65.2 ± 5.5 Mg ha−1, respectively). Hypothesized yield advantages of diversity in perennial cropping systems were not observed during this period. Harvested biomass yields were 60, 56, and 44% of ANPP for corn, perennial grass, and restored prairie, respectively, suggesting that relatively simple changes in agronomic management (e.g. harvest timing and harvest equipment modification) may provide significant gains in bioenergy crop yields. Species composition was an important determinant of GHE in more diverse systems. Results show that well-established, dedicated bioenergy crops are capable of producing as much biomass as corn stover, but with fewer inputs.

Corn stover ethanol yield as affected by grain yield, Bt trait, and environment

Pavani Tumbalam; Kurt D. Thelen; Andrew Adkins; Bruce Dale; Venkatesh Balan; Christa Gunawan; Juan Gao

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2016

Literature values for glucose release from corn stover are highly variable which would likely result in tremendous variability in bio-refinery ethanol yield from corn stover feedstock. A relatively recent change in United States corn genetics is the inclusion of the Bacillus thuringiensis (Bt) trait, which now accounts for three-fourths of all US planted corn acreage. The objective of this study was to evaluate the effect of corn grain yield, inclusion of the Bt trait, and location environment on corn stover quality for subsequent ethanol conversion. Two hybrid pairs (each having a Bt and non-Bt near-isoline) were analyzed giving a total of 4 hybrids. In 2010 and 2011, field plots were located in Michigan at four lat- itudinal differing locations in four replicated plots at each location. Stover composition and enzymatic digestibility was analyzed and estimated ethanol yield (g g 1) was calculated based on hydrolyzable glucan and xylan levels. Analysis showed that there were no significant differences in total glucose or xylose levels nor in enzymatically hydrolyzable glucan and xylan concentrations between Bt corn stover and the non-Bt stover isolines. Regression analyses between corn grain yield (Mg ha 1) and corn stover ethanol yield (g g 1) showed an inverse relationship indicative of a photosynthate source-sink rela- tionship. Nevertheless, the quantity of stover produced was found to be more critical than the quality of stover produced in maximizing potential stover ethanol yield on a land area basis.

Detection of short-term cropping system-induced changes to soil bacterial communities differs among four molecular characterization methods

David S. Duncan; Kelsea A. Jewell; Garret Suen; Randall D. Jackson

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2016

Perennial grass-based agroecosystems are under consideration as sustainable sources of bioenergy feedstocks. Establishing these systems on land previously used for conventional agricultural production is expected to dramatically alter the composition and functional capacity of their associated soil bacterial communities, but the rate at which these changes will occur is unclear. Methods for characterizing bacterial communities are both varied and useful for documenting different aspects of the soil microbiota and their dynamics during this transition. Here, we studied the soil-associated bacterial communities of continuous corn and restored prairies systems within a cropping systems experiment 2–4 years after establishment using 1) phospholipid fatty acid (PLFA) profiling, 2) shotgun metagenomic sequencing, 3) amplicon sequencing of the 16S rRNA gene and 4) sequencing of the nitrogen-cycling gene nosZ. All characterization methods discriminated the bacterial communities between the two cropping systems, but the largest differences were observed with PLFA profiling. Differences between the two cropping systems did not significantly increase during the study period. The community compositions described by sequence-based methods were mutually correlated, but were only weakly correlated to the composition described by PLFA profiling. Shotgun metagenomics detected a much higher abundance of Actinobacteria than amplicon sequencing and revealed more consistent changes between cropping systems over time. Cropping system and interannual effects on the ratios of biomarkers associated with Gram-negative and Gram-positive bacteria were entirely different for PLFAs, rRNA amplicons, and shotgun-sequenced 16S rRNA. Our findings highlight how soil bacterial community characterization methods differ in their detection of microbial community composition as a result of recent land use change.

Does plant biomass manipulation in static chambers affect nitrous oxide emissions from soils?

Sarah M. Collier; Andrew P. Dean; Lawrence G. Oates; Matthew D. Ruark; Randall D. Jackson

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2016

One of the most widespread approaches for measurement of greenhouse gas emissions from soils involves the use of static chambers. This method is relatively inexpensive, is easily replicated, and is ideally suited to plot-based experimental systems. Among its limitations is the loss of detection sensitivity with increasing chamber height, which creates challenges for deployment in systems including tall vegetation. It is not always possible to avoid inclusion of plants within chambers or to extend chamber height to fully accommodate plant growth. Thus, in many systems, such as perennial forages and biomass crops, plants growing within static chambers must either be trimmed or folded during lid closure. Currently, data on how different types of biomass manipulation affect measured results is limited. Here, we compare the effects of cutting vs. folding of biomass on nitrous oxide measurements in switchgrass (Panicum virgatum L.) and alfalfa (Medicago sativa L.) systems. We report only limited evidence of treatment effects during discrete sampling events and little basis for concern that effects may intensify over time as biomass manipulation is repeatedly imposed. However, nonsignificant treatment effects that were consistently present amounted to significant overall trends in three out of the four systems studied. Such minor disparities in flux could amount to considerable quantities over time, suggesting that caution should be exercised when comparing cumulative emission values from studies using different biomass manipulation strategies.

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