Abstract Manager

Roadside areas can be especially difficult to get vegetation established. Pollutants associated with vehicle use can lead to contamination in the adjacent soil from road runoff containing leaked fluids, airborne deposition from emissions, or from the use and storage of road amendments. The contaminants, particularly salt, can be an ongoing and persistent problem which can significantly impact vegetation growth. Vegetation establishment can also be impacted by compaction of soil due to vehicle traffic.

Native plants are desirable species to use to vegetate roadsides. They are resilient to changing/extreme conditions (including the effects of climate change), require minimal maintenance, help to integrate roadsides into the surrounding ecosystems, and generally have a deeper rooting system which facilitates stabilization of the soil. However, establishment and long-term survival of native plants can be challenging, even in good conditions, as the seeds of native species are slow to germinate and the plants can be slow growing. When the soil is of poor quality or contains contaminants, establishment is even more challenging.

Plant growth promoting rhizobacteria (PGPR) will help plants to grow in stressful conditions, facilitating seed germination and plant growth in contaminated and/or poor-quality soil as well as compacted soil. This talk will review laboratory and field trial studies conducted by Earthmaster using a bacteria/plant phytotechnology consisting of PGPR added to seeds and plants (PEPSystems). Laboratory seed germination studies ±PGPR were conducted using 4 agronomic and 6 uncoated native grass species with different types of PGPR in salty conditions. In general, PGPR provided significant advantages for agronomic species in high salt but not low. Surprisingly, for most native grasses, PGPR provided significant advantages in high and low salt. However, there were some species where PGPR were detrimental in all conditions. Follow up field trials were conducted and, as with the germination studies, effects were variable and species dependent. These studies demonstrate the importance of testing PGPR/plant compatibility as well as optimum PGPR concentrations prior to site deployment. Case studies will also be discussed where PGPR/plant combinations have been used to remediate salt from contaminated soil and where salt hyperaccumulating plants have been used for in situ applications for site management.