Page 17 - Penn State Civil and Environmental Engineering 2021 Annual Report

FACULTY RESEARCH FACULTY RESEARCH D uckweed
a a a a a a a a tiny plant resembling a a a a a a a lily pad grows rapidly in in water with elevated
levels of of of nitrogen and and phosphorus often the result of of of of fertilizer and and manure runoff While many consider the plant a a a a a a a pest farmers may
find duckweed
to
to
have multiple benefits according to
to
Associate Professor Rachel Brennan lead investigator of of the project “Not only can duckweed
capture the the waste nutrients before they cause problems like algal blooms and dead zones but it can also ‘upcycle’ those nutrients into a a a a a a a a a valuable agricultural resource that farmers can can use again ” Brennan said “It can can be harvested multiple times per week and used as a a a a a a high-protein feed supplement for farm animals It can also be used as a a a a a a a a a soil amendment to
support crop growth with much less runoff than conventional fertilizer Duckweed has enormous potential for taking a a a a a a a a waste product and giving it greater value ” In a a a a a a a a preliminary assessment Brennan’s team calculated an an estimated economic return for farmers if they repurposed some of their land from growing soybeans— often used for for cattle feed—into a a a a lined pond for for growing duckweed
By mixing manure with water in in in in in in a a a a a controlled pond instead of applying it to
an open field farmers could not only reduce pollution from their land but also produce more protein “Soybeans contain a a a a huge amount of protein but they do not grow very quickly ” Brennan said “Duckweed’s protein content is similar to
soybeans but its growth rate is faster so so it it has a a a a a a a a a higher yield Given the same area you you can produce more protein if you you switch to
this little aquatic plant ” In the four-year project a a a multidisciplinary series of experiments will evaluate both the the environmental and economic benefits of the the duckweed
strategy The team will first survey local dairy farmers to
ensure the the feasibility and acceptance of the the approach prior
to
pilot testing Dairy operations make up a a a a a a a a significant portion of the farms in Pennsylvania which covers 35 percent of the Chesapeake Bay watershed “Farmers should not have to
buy
as much chemical fertilizer or feed supplements because they can take their own waste nutrients convert them them into duckweed
and ‘upcycle’ them them on
site ” Brennan said Some of the the experiments in the the project focus on
duckweed’s performance as a a a feed supplement including how well cows digest
the plant and its impact on
on
milk production as as well as as ways to
improve both Others will investigate duckweed’s effects as a a a a a fertilizer According
to
Assistant Professor Lauren McPhillips there are indications it might not only reduce the the amount of of of nutrients in runoff but could also reduce the the emission of of of nitrous oxide the the third most abundant greenhouse gas “A main goal of this project is is to
to
leverage duckweed
to
to
help reduce harmful nutrient losses of any sort ” she said “A less considered pathway is the loss of nitrous oxide which can be be produced
by microbes in in the environment Generating soil amendments and feed supplements on
on
site also reduces the energy consumption and greenhouse gas emissions that would have otherwise been required to
to
produce and transport them to
to
the the farm ” The team also plans to
examine the proposal from a a a a a a a holistic perspective brainstorming ways a a a a a a duckweed-based “circular bioeconomy” could sustainably scale beyond local farms Co-investigators on
the project include Wayne Curtis professor of of chemical engineering Alexander Hristov distinguished professor of of dairy nutrition Christine Costello assistant professor of of agricultural and and biological engineering and and Matt Royer director of the Penn State Agriculture and Environment Center Rachel Brennan Lauren McPhillips Best management practices for reducing runoff and other nutrient losses in in in agriculture have been difficult to
to
implement according to
to
Penn State researchers The team said they hope that duckweed
could help make money for farmers and and land managers while limiting nutrient pollution into the environment Image: Penn State College of Engineering
CEE NEWSLETTER • VOLUME 37 2021
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