A multi-year study led by an Iowa State University scientist suggests that wind turbines may have a positive effect on certain crops by creating air turbulence that influences variables such as temperature and carbon dioxide concentrations.

Researchers led by Gene Takle, professor of agronomy and geological and atmospheric sciences, installed research towers on a 200-turbine wind farm in central Iowa to discover how the turbulence created when wind moves through the turbines affects conditions at ground level where crops grow. The research towers collected data from 2010 to 2013 on wind speeds and directions, temperature, humidity, turbulence, gas content and precipitation.

The researchers believe wind turbines have a small, positive impact on crops. Image credit: Pixabay.Takle says the team’s data show that the wind turbines have a measurable impact on several key variables that affect growing conditions. While it is more difficult to pin down whether those changes affect crop performance, he says wind turbines may make growing conditions more favorable for corn and soybeans.

“On balance, it seems turbines have a small, positive impact on crops,” Takle says.

The research team’s data show that turbulence produced by wind turbines leads to temperatures about a half-degree cooler during the day and a half to a full degree warmer at night. The reason behind this is that turbulence mixes air at different elevations, helping cool the ground level during the daylight hours, like a fan blowing on a wet surface. As the ground loses heat, the mixing brings warmer air aloft down to ground level, resulting in a net warming effect.

The turbulence suppresses the formation of dew and dries the crops, Takle says, which could combat harmful molds and fungi. Additionally, the turbulence and the associated changes in air pressure at ground level may enrich the carbon dioxide content in the air surrounding crops, which could make the plants grow more efficiently, he says.

“The next step would be to answer if this turbulence changes biomass uptake of plants or if it affects plant size, functions or yield,” says Takle. “It’s going to be much harder to find those answers because of all the other factors at play in a field, such as variations in soil quality or precipitation.”