Bio

Degree

M.S. Agroecology (2009); Ph.D. Agronomy (2016)

Education

M.Sc. Agroecology, University of Wisconsin, Madison, 2009

B.S. Biological Sciences, Stanford University, 2006

Current Position

Statistical Marketing Analyst – American Family Insurance, Madison, WI

Research and Professional Interests

I study the link between soil microbial communities and nitrous oxide (N₂O) production in bioenergy cropping systems. N₂O is a potent greenhouse gas that in the U.S. primarily stems from agricultural activities. N₂O is produced by soil microbes through processes that include nitrification (ammonia oxidation) and denitrification (nitrate reduction). Modeling and predicting N₂O production is a major challenge, particularly for ecologically complex systems like perennial grasslands. I am working with the giant trace gas dataset generated by the Great Lakes Bioenergy Research Center and with a large collection of shotgun metagenomes to correlate the microbial community to N₂O generation patterns.

Another aspect of my research considers the effects of nitrogen fertilization on nitrogen cycling in switchgrass fields. This is a collaborative project where my focus is on comparing denitrification and N₂O production under field conditions to potential denitrification under idealized conditions. By studying denitrification under conditions where it is limited only by the capabilities of the soil microbial community, I hope to improve our understanding of how much these capabilities vary and how they might influence the N₂O we actually observe in the field.

I also work with Zip-Lignin, a variety of lignin genetically engineered to be easier to break apart chemically. I am incubating tissues from Zip-Lignin poplars in soil microcosms to test whether these materials decompose more quickly in soil, which might impact soil carbon accumulation in systems with this trait.

My overarching interests entail understanding and modeling complex systems to improve our capacity to predict their future behavior. This makes me a voracious consumer of statistical methods, as I look for new ways to quantify and interpret variability in the systems I study. Mixed effects models (linear and nonlinear) and ordination are my workhorses, but I have been expanding into elastic net models, Bayesian models and model averaging. As shiny and enticing as they are, statistical methods alone are insufficient to fully understand a system. I make an effort to understand the biology and mechanisms that govern systems I study so that I will be able to contextualize and critically interpret my analyses. I also relish the opportunities, when they arise, to design experiments to explicitly test and further our understandings of these systems.

Publications

Oates LG, Duncan DS, Sanford GR, Liang C and Jackson RD. 2016.  Bioenergy cropping systems that incorporate native grasses stimulate growth of plant-associated soil microbes in the absence of nitrogen fertilization. Agriculture, Ecosystems and Environment. 233, 396-403.  doi: 10.1016/j.agee.2016.09.008

Duran BEL, Duncan DS, Oates LG, Kucharik CJ, Jackson RD. 2016. Nitrogen fertilization effects on productivity and nitrogen loss in three grass-based perennial bioenergy cropping systems. PLOS ONE.
doi: 10.1371/journal.pone.0151919
Data

Duncan DS, Jewell KA, Suen G, Jackson. 2016. Detection of short-term cropping system-induced changes to soil bacterial communities differs among four molecular characterization methods. Soil Biology and Biochemistry. 96: 160-168.
doi: 10.1016/j.soilbio.2016.02.002

Liang C, Jesus EC, Duncan DS, Quinsen JF, Jackson RD, Balser TC, Tiedje JM. 2016. Switchgrass rhizospheres stimulate microbial biomass but deplete microbial necromass in agricultural soils in the U.S. upper Midwest. Soil Biology and Biochemistry. 94:173-180.
doi: 10.1016/j.soilbio.2015.11.020

Oates LG, Duncan DS, Gelfand I, Millar N, Robertson GP, Jackson RD. 2015. Nitrous oxide emissions during establishment of eight alternative cellulosic bioenergy cropping systems in the North Central United States. GCB – Bioenergy
doi: 10.1111/gcbb.12268
Data

Duncan DS, Krohn AL, Jackson RD, and Casler MD. 2015. Conservation implications of the introduction history of meadow fescue (Festuca pratensis Huds.) to the Driftless Area of the Upper Mississippi Valley, USA. Plant Ecology & Diversity 8:91-99.
doi: 10.1080/17550874.2013.851294

Herzberger AJ, Duncan DS, Jackson RD. 2014. Bouncing back: plant-associated soil microbes respond rapidly to prairie establishment. PLOS ONE.
doi: 10.1371/journal.pone.0115775
Data

Zou LQ, Chen FS, Duncan DS, Fang XM, Wang H. 2014.Reforestation and slope-position effects on nitrogen, phosphorus pools, and carbon stability of various soil aggregates in a red soil hilly land of subtropical China. Canadian Journal of Forest Research. 45: 26-35.
doi: 10.1139/cjfr-2014-0275

Chen FS, Duncan DS, Hu XF, Liang C. 2014. Exogenous nutrient manipulations alter endogenous extractability of carbohydrates in decomposing foliar litters under a typical mixed forest of subtropics. Geoderma. 214-215: 19-24.
doi: 10.1016/j.geoderma.2013.10.009

Liang C, Duncan DS, Balser TE, Tiejde JM, Jackson RD. 2013. Soil microbial residue storage linked to soil legacy under biofuel cropping systems in southern Wisconsin, USA. Soil Biology & Biochemistry 57:939-942.
doi: 10.1016/j.soilbio.2012.09.006