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| Photo by Irene Miles |
On its millions of acres of farmland, Illinois grows enough corn and soybeans to produce more ethanol than any other state in the US. If Illinois farmers decided to grow perennial grasses for biofuel rather than corn and soybeans, though, how might the way Illinois uses water and fertilizer change? That’s what Andy VanLoocke and Carl Bernacchi wanted to know, and they won an IWRC Annual Small Grant to fund their search for an answer. At the end of their project, Andy and Carl told us about their findings, what the research could mean for Illinois water resources, and what Andy is doing with his new PhD.
A cellulosic biofuel
feedstock is a crop that is grown primarily to convert the cellulose, most of a
plant’s structural material, into a fuel like ethanol. This is in contrast to
the “grain or oil” being used to produce ethanol or biodiesel, because with
cellulosic feedstocks the energy source isn’t limited to the seed of the crop,
like with corn or soybean.
Would you please give
us a quick overview of the whole project, not just the IWRC-funded piece?
The overall goal of
this project was to come up with a quantitative way to assess large-scale land
use shifts across the Midwest that are associated with biofuel production. We
also looked at the impacts this could have on the critical aspects of our
agro-ecosystems, such as the cycling of carbon, water, and nutrients. Within
the context of the IWRC funding, we were particularly focused on ecosystem water
use, such as determining how producing cellulosic bioenergy crops would alter stream
flows and water quality of our rivers.
Would you talk about
the models you used a little bit: what is IBIS, how do you determine model
inputs, and how accurate are the results?
Because we are asking
questions on such a large scale, and with numerous hypothetical scenarios, we
had to use computer models to answer our research questions. To model the
production of the crops we chose an ecosystem model called Agro-IBIS, which
stands for the Integrated BIoSphere model – Agricultural version. We ran this
model in conjunction with a stream flow and nutrient transport model called
Terrestrial Hydrology Model with Biogeochemistry (THMB).
To conduct this
research, we fed the ecosystem model (Agro-IBIS) climate data including temperature
and precipitation. The model then simulated the uptake of carbon through
photosynthesis, the loss of water through transpiration and evaporation, and a
range of other outputs. We also input management information into Agro-IBIS,
such as crop type and fertilization rates that are used with the climate data
to determine how much carbon, nitrogen, and water are entering and leaving a
given location (typically the size of a county). The results of Agro-IBIS are
then given as inputs into THMB, which simulates the movement of water and
nitrogen runoff from each location, through the various rivers and streams of
the Mississippi River Basin, and eventually out to the Gulf of Mexico.
We compare the model
results to any available observations we can find to insure the model is
accurate. For the new cellulosic biofuel crops, information is limited, but we
have been able to compare the model predictions for key components of the
carbon, water, and nitrogen cycles for a few locations in Central Illinois. So
far the models do a pretty good job simulating what we have seen in the field. Given
the limited data, there are uncertainties when scaling from the well-measured
areas to the whole region. We can increase the confidence in the model over larger
spatial scales by modeling existing crops (corn, soy, and wheat), which we have
much more information on, and determine how well the modeled data and measured
data agree.
What were your major
findings?
The primary question
we were trying to address is: What impact would large-scale production of
cellulosic feedstock in the Midwest have on water quality and quantity in the
Mississippi River Basin? We know from observations that Miscanthus and
Switchgrass, the two major leading candidate cellulosic feedstocks and our
study focus, use more water than corn and soybean, but require less fertilizer
to achieve high yields. When we expanded the study with the computer models we
found that, as long as we kept production less than the current fraction levels
(i.e. ~40% of corn grain goes to ethanol each year), there was a minimal impact
on streamflow for most of the Mississippi River Basin. At the same time we saw
that we could significantly improve water quality if we followed these
production scenarios.
Did any of those
findings surprise you?
We had a pretty good
idea of what to expect, given that we knew the model was based on measurements,
so we were not totally surprised by our findings. The extent that the
cellulosic feedstock production has a small effect on stream flow yet a large
effect on improving water quality, however, was unexpected.
What kind of
implications do you see for agriculture in the Midwest based on your work?
We are aware that
economics truly drive this, and any other, industry. Cellulosic feedstock production
is not increasing rapidly, as was initially predicted, but our research will
provide evidence for ecosystem services should this industry begin to
expand.
What about
implications for Illinois water resources? Considering the number of droughts
Illinois has experienced recently, what kind of changes do you think would
happen to water usage in Illinois agriculture if every farmer switched from
corn to miscanthus or switchgrass?
We never really
considered a scenario where all farmers make this transition, as this would not
be practical. There is tremendous uncertainty on how land-cover changes could
affect the climate, so there are very interesting questions that can be
addressed with coupled ecosystem-climate models. Observational data from a
variety of sites are currently being analyzed over the recent drought years by
the Bernacchi Lab, and we will soon have a pretty good estimate of how these
specific species responded to the drought, but the interactions with the
climate would require much more research and improved model coupling.
What kind of response
have you received as you’ve shared the results of your research? And where have
you shared your results? Does being at a Land Grant school change your outreach
strategy at all?
These results have
been presented at a wide range of meetings, including the Tropical Maize/Energy
Crop Field Day, the Illinois State Water Survey, the Illinois Water 2012 Conference,
the Pan American Congress on Plants and
Bioenergy, and at the American Geophysical Union annual meeting. The
data has been published in a peer-reviewed journal Agricultural and Forest Meteorology
and another manuscript is in preparation to be submitted to the Proceedings of
the National Academies of Science. The research is generally well received, and
most people are excited to see a study conducted at such a large scale and with
direct implications to national policy. Being at a land grant university has
made outreach a bit easier, given the excellent resource of U of I Extension.
Andy, how did you
become interested in the role of biofuel crops in the hydrologic cycle?
This one is pretty
simple, I was visiting a field site when I was an intern at the Illinois State
Water Survey, during a tour of the SoyFACE research site at the University of
Illinois. I had recently learned about techniques to measure plant water use in
a course I took as an undergrad at Ohio State University, and when I saw how
large Miscanthus grew in Illinois, my very first question to Carl (my future
PhD supervisor) was “Wow, that’s big, but how much water does it use?” The rest
is history.
We know you’ve
defended your PhD and moved on to a post-doc over the last 13 months. Could you
tell us a little about your plans for the future and how the IWRC-fellowship
has helped you?
In the year or so
since I graduated, I’ve been working as a postdoctoral research associate in
the USDA Agricultural Research Service – Global Change and Photosynthesis Unit.
On January 1st, 2014 I started as an Assistant Professor in
the Department of Agronomy at Iowa State University. The experience of writing
the proposal for the IWRC fellowship and the opportunities to present my
research that the fellowship facilitated were really vital to advancing as a
scientist. In addition, securing the fellowship illustrated my ability to get
external funding, and I’m sure this was a key factor in the decision for the
hiring committee at Iowa State.
