Sustaining Soil and Water
AHB documented changes in soil and water quality in response to poplar bioenergy crop systems in comparison to agricultural fields. Temporal changes within the poplar fields and in comparison to equivalent agricultural fields provided reference points with which to determine relative impacts of woody energy crops on soil quality and off-site nutrient transport.
We observed greater soil respiration and microbial biomass in poplar sites than in agricultural fields regardless of location, which indicates vigorous cycling of carbon and nutrients. We have learned proportional changes in groups of soil microbes and their functions in soil organic matter cycling depends more on soil and site conditions than on cropping systems.
Overall, poplar bioenergy farms were not degrading the soil and water more intensely than the adjacent hay or wheat fields. However, the poplars in each of the AHB demonstration sites had different environmental impacts. For example, in Jefferson, OR, a location with nutrient-rich soil, the poplar fields were leaching significantly less nitrate into the groundwater than surrounding agricultural fields. In contrast, in Hayden, ID, a location with nutrient poor soil, the poplar fields were leaching slightly more than neighboring fields.
Air quality was studied at AHB’s demonstration sites to determine if isoprene (a volatile organic chemical (VOC) emitted by plants) had a negative impact on air quality. Isoprene can react with nitrous oxides (NOx) in the air to create ground level ozone and smog, negatively impacting air quality. Dr. Todd Rosenstiel’s team, from Portland State University, found the VOC emissions varied by poplar variety. They suggested that specialized breeding and/or genetic engineering of poplar can be used to reduce the amount of isoprene emitted from a poplar bioenergy farm. The research determined that unless poplar bioenergy farms are located near industrial areas or cities with high concentrations of NOx in the air, adverse air quality impacts are unlikely.
To Learn More
Read this AHB Newsletter Article on soil, water, genetic containment, and air.
Read this AHB Newsletter Article on soil and water.
Go here to watch a webinar on AHB’s soil and water research.
Go here to watch a webinar on AHB’s air quality research.