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Post Windfarm Installation Impacts on Soil Properties and Crop Response in the Midwest
Throughout the United States, large windfarms, containing anywhere from 5 to 150 turbines, have been installed due to the increased demand for alternative energy. Since 2008, 1,264 turbines have been installed in Indiana, with the majority of installations occurring on agricultural fields. Despite the large number of turbine installations, impacts of these installations on soil and crop health is unknown. Turbine installation requires the traffic of heavy construction equipment within agriculture fields which may compact the soil altering its physical properties and negatively impact crop growth. To better understand the impact of turbine installation on soil and crop health, we developed a remote-sensing based method to quantify the areal extent of soil and crop impairment due to turbine installation. The method compares the normalized difference vegetation index (NDVI) from satellite images from areas of potential impairment to areas with no known impairment to determine statistical differences in NDVI between impaired and unimpaired areas and then calculates the area of potential impairment. We tested this methodology on two windfarms in Indiana. Our results showed that in the year following turbine installation, turbine installation was associated with an average impairment of 1.8 hectares per turbine and the area of impairment decreased approximately 15-30 percent in each subsequent year. Our results also suggest that soil texture and drainage have an effect on the magnitude and recovery rate of impairment. Coarse textured and/or well drained soils experienced very little to no impairment while fine textured and/or poorly drained soils experienced significant impairment and had not returned to pre-installation levels of impairment after three years. Our findings will allow landowners the opportunity to review current points of negotiation with windfarm developers as well as provide information regarding the potential loss of productivity in crops at these sites.