One example of biomimicry in action is found in the northern Sonoran
Desert countryside surrounding Tucson, Arizona. Here, agricultural
ecologist Dr. Greg Barron-Gafford and farmer, research scientist, and
MacArthur Fellow Dr. Gary Nabhan combine concepts from Mother Nature
with agrivoltaics, a system in which a single piece of land is used for
both solar photovoltaic power production and conventional agriculture.
More specifically, they took lessons learned from nurse plant ecology
and applied them to reduce water use and carbon footprints in food
production. In their plots at Biosphere 2, the world’s largest living research
center, and at Manzo Elementary School, which was awarded Best Green
School 2012 by the US Green Building Council’s Center for Green Schools,
Nabhan and Barron-Gafford are experimenting with using solar panels as
“host plants” and growing crops underneath them.
“Solar panels create a little heat island effect and, as they warm up,
they become less effective to the tune of about half a per cent efficiency
loss for every one degree Centigrade increase,” Barron-Gafford
explains. “Traditionally, panel installers have gotten rid of under-
vegetation before construction. But, plants take carbon out of the air
and in the process, moisture escapes and that transpiration, like human
perspiration, creates localized cooling. We theorized if we stuck some
plants under the panels, the in-ground and the above-ground efforts
would both benefit.”
“We took biomimicry and applied it to food production,” Nabhan says.
“Controlled environment settings (ergo, greenhouses) help, but semi-
controlled, climate-buffered shared environments adapted from 4,000 years
of field agriculture using what’s available—urban
heat islands that allow us to grow food under elevated
solar panels acting as nurse plants integrated into an
agrivoltaic agro-ecosystem—work well too.”
“ When we look at what is truly sustainable,
As they’re in the southwest US, the researchers started
with salsa gardens, growing jalapeños, tomatoes, and
the only real model that has worked over
chiltepin peppers, both under the panels and in open
long periods of time is found in the
plots for four months. The contrast was astounding and
led to further trials with chard, cabbage, carrots, basil,
and even some mango and avocado trees. After their
first year of experiments, the findings are promising.
“Plants under the panels receive less direct sunlight,
which leads to reduced evaporative loss of soil mois-
ture that allows for significant water savings,” says
Barron-Gafford. “Even if you irrigate every day, there’s still some savings. An
agrivoltaic system keeps things about four per cent wetter. You have to water
every day in an open system, but only every fourth day under cover.”
He also notes the microclimate under the panels “is cooler because of
the moisture release.” In open fields where summertime temperatures
soar into the triple digits for weeks on end, this is a boon to both crops
and the skin of workers.
“One of the things we’re excited about in our agrivoltaic gardens is they
allow us to really push the seasons. The planting calendar is not the same
anymore; it’s now a blended calendar,” says Moses Thompson at Manzo
Elementary School. “There’s so much flexibility. It’s all unknown and exciting.
We could be running all warm-season crops under cover during the winter
and they would be fine. I’m curious to see how long we can push the cool-
season stuff as the warmer weather arrives.”
natural world.”
grow cycle
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