Green Horizons

The use and management of vegetation to benefit farming activities has come a long way, and as our knowledge increases so does our ability to apply vegetation to meet diverse goals associated with today's farming practices. These are exciting times in the field of agroforestry.

Until approximately 10 years ago the term Vegetative Environmental Buffer (VEB) did not exist. Up to that point, the science of integrating trees with farming to impact air movement was purely considered windbreak technology (farmstead windbreaks, field windbreaks, shelterbelts). However, with specific considerations to issues of our time, new and unique design efforts have built living biofilters that are today focused on enhancing air quality. In the future, the move from classic windbreak technologies, which primarily employ trees and shrubs, to the VEB design technology, which incorporates fan deflectors, grasses, trees and shrubs, will be seen as a breakthrough which improves air quality, removes atmospheric carbon, filters water from the site, and alleviates social stigmas that are, at times, issues associated with animal agriculture. The MU Center for Agroforestry is working with intensive livestock agriculture in Missouri to enhance the application of VEB technologies so that farms and communities may exist in harmony.

With many of the intensive livestock farms odor is often a concern. Odor often originates from animal barns and the air used to ventilate and cool those barns. As with many water quality issues, the traditions of the past are not applicable today. Past sayings, such as "dilution is the solution to pollution," are unacceptable, whether referring to water quality or air quality issues. It is not appropriate to export a problem, or try to cover it. However, with appropriate design, VEB technologies are made to capture and process odor-causing elements on the site where they originate.

Many odors are transported by very small dust particles which air currents carry. When we pass air through vegetation, the air slows. This, in turn, causes dust particulates to drop from the air currents. So, beyond filtering odor fromthe air, how does the VEB work as a living biofilter? There are two important components of the leaf surface area useful in breaking down odor-causing VOCs (volatile organic compounds): the waxy surface cuticle and the stomatal openings. Stomatal openings allow chemicals to enter the leaf in their gaseous form, or, when wetted, in a soluble/ dissolved form. The waxy leaf surface area (cuticle) has shown an affinity for nitrogen-based chemicals. The leaf surface area is where odor-causing VOCs are removed and digested by microbial populations. There is a whole world of microbial communities, including bacteria, living on leaf surfaces. As we design VEBs, this is a good reason to always include conifers whose leaf surface area remains intact throughout the year. In the future, scientists will measure and publish on both above ground (phyllosphere) and below ground (rhizosphere) components of the VEB. Their workings, both above ground and below ground, will be viewed as significant contributors to the stewardship of air, water, and soil resources exercised by producers.

Through the combined effect of filtering, slowing air movement and breaking down VOC components on-site, VEB technologies have been shown to reduce odor from livestock operations. The effectiveness of VEBs also can be enhanced by using air deflectors to direct air into the vegetation. Air carrying the odor must pass through the vegetation. VEBs also offer the potential for energy savings and the long-term storage of carbon in plant tissues. While applying and promoting VEB adoption, the MU Center for Agroforestry continues to participate in research that will further help farms achieve and maintain high environmental integrity. From small to large producers, we support Missouri agriculture and environmental stewardship.