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Source: Mark Floyd, Oregon State University

Oregon State University (OSU) scientists have discovered that solar arrays could be used as resource to increase agricultural production on dry, unirrigated farmland.

In a study published earlier this month in the journal PLOS One, a research team in OSU’s College of Agricultural Sciences found that grasses favored by sheep and cattle thrive in the shade of a solar array installed in a pasture on the OSU campus.

The results of the OSU study indicate that locating solar panels on pasture or agricultural fields could increase crop yields, according to corresponding author Chad Higgins, an associate professor in the Department of Biological and Ecological Engineering.

“There are some plants that are happier in shaded environments,” he says. “The amount of water that went into the making those plants is tremendously smaller than in the open field. You get double the yield, less water and all the solar energy.”

Higgins notes that the idea of developing solar PV projects on agricultural land is not new. However, he says, “The difference here is that this solar array was installed without the intent to influence plant production. It was by accident. Nobody engineered this system. Now we’re trying to develop a deeper understanding of how we can engineer the system to be technically feasible, environmentally sound and economically viable.”

OSU’s solar sites in Corvallis cover 10 acres and have the capacity to generate 2.6 million kWh of power per year. This study focused on the 35th Street Solar Array, installed in 2013 on the west side of the OSU campus.

Walking past the array one day, Higgins and his colleagues noticed green grass growing in the shade of the panels. In May 2015, they installed microclimate research stations that recorded mean air temperature, relative humidity, wind speed, wind direction and soil moisture. By August, the instrumentation revealed that the areas under the solar panels maintained higher soil moisture throughout the three-month period, says OSU.

The researchers also found that the areas under the array produced double the amount of plant material than the unshaded areas and increased the nutritional value of the plants. The researchers also noted a significant increase in late-season plant growth.

“It’s like a tortoise and a hare race,” Higgins says. “The plants that experience the full brunt of the sun use their water resources as quickly as possible. They grow to the extent they can, and then they die. On the other hand, the plants in the shade take sips of water because they are less stressed, and they keep chugging along.”

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