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

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.

Investment risks in bioenergy crops

T. Skevas; S.M. Swinton; S. Tanner; G. Sanford; K.D. Thelen

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2016

A consistent positive association between landscape simplification and insecticide use across the Midwestern US from 1997 through 2012

Timothy D. Meehan; Claudio Gratton

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2015

During 2007, counties across the Midwestern US with relatively high levels of landscape simplification (i.e., widespread replacement of seminatural habitats with cultivated crops) had relatively high crop-pest abundances which, in turn, were associated with relatively high insecticide application. These results suggested a positive relationship between landscape simplification and insecticide use, mediated by landscape effects on crop pests or their natural enemies. A follow-up study, in the same region but using different statistical methods, explored the relationship between landscape simplification and insecticide use between 1987 and 2007, and concluded that the relationship varied substantially in sign and strength across years. Here, we explore this relationship from 1997 through 2012, using a single dataset and two different analytical approaches. We demonstrate that, when using ordinary least squares (OLS) regression, the relationship between landscape simplification and insecticide use is, indeed, quite variable over time. However, the residuals from OLS models show strong spatial autocorrelation, indicating spatial structure in the data not accounted for by explanatory variables, and violating a standard assumption of OLS. When modeled using spatial regression techniques, relationships between landscape simplification and insecticide use were consistently positive between 1997 and 2012, and model fits were dramatically improved. We argue that spatial regression methods are more appropriate for these data, and conclude that there remains compelling correlative support for a link between landscape simplification and insecticide use in the Midwestern US. We discuss the limitations of inference from this and related studies, and suggest improved data collection campaigns for better understanding links between landscape structure, crop-pest pressure, and pest-management practices.

A reassessment of the contribution of soybean biological nitrogen fixation to reactive N in the environment

Ilya Gelfand; Philip Robertson

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2015

The expansion of soybean (Glycine max (L.) Merr) acreage, increasing yields, and recent nitrogen (N) fertilization recommendations could have a major effect on the contribution of biological N fixation (BNF) in soybeans to reactive nitrogen (Nr) in the environment. We used 15N natural abundance to separate fixed N into grain, aboveground vegetative biomass, and roots along a 9-point N-fertilizer gradient to ask: 1) is the belowground BNF contribution sufficiently different from aboveground to affect regional estimates of soybean Nr production based on harvested biomass, and 2) how does N fertilizer affect soybean yield and BNF’s contribution to different tissues? The contribution of root and vegetative biomass to overall plant BNF was five times lower than that for grain. Including this difference in BNF extrapolations translates to 3.5 ± 0.5 Tg Nr yr-1 for total US soybean production, *37 % lower than earlier estimates that did not differentiate tissue source. Production of Nr ranged between 35 ± 11 and 73 ± 5 g Nr kg-1 grain and was affected by both fertilization and irrigation. In all cases N credits to the next rotational crop were minor. N-fertilization at even very low levels (17–50 kg N ha-1) did not affect yield, but grain N content increased with fertilizer level. The percent BNF contributed to plant N decreased linearly with increasing fertilization, in grain from 49 ± 8 % in unfertilized plots to a plateau of 16 ± 6 % at fertilization C85 kg N ha-1; in aboveground vegetative biomass from 77 ± 4 % to aplateauof11 ± 11 %at146 kg Nha-1;andinroots from 88±12% to a plateau of 41±6% at 146 kg N ha-1. The average whole-plant BNF con- tribution decreased from *84 % in unfertilized plots to a plateau of *34 % at fertilization rates greater than 84 kg ha-1. Results underscore the unnecessary expense and environmental burden of adding N fertilizer to modern soybean varieties, and provide a refined lower estimate for the contribution of soybean N fixation to the US and global Nr budgets of 3.5 and 10.4 Tg Nr yr-1, respectively.

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