Selecting and Utilizing Populus and Salix for Landfill Covers: Implications for Leachate Irrigation

Abstract

The success of using Populus and Salix for phytoremediation has prompted further use of leachate as a combination of irrigation and fertilization for the trees. A common protocol for such efforts has been to utilize a limited number of readily-available genotypes with decades of deployment in other applications, such as fiber or windbreaks. However, it may be possible to increase phytoremediation success with proper genotypic screening and selection, followed by the field establishment of clones that exhibited favorable potential for clean-up of specific contaminants. There is an overwhelming need for testing and subsequent deployment of diverse Populus and Salix genotypes, given current availability of clonal material and the inherent genetic variation among and within these genera. Therefore, we detail phyto-recurrent selection, a method that consists of revising and combining crop and tree improvement protocols to meet the objective of utilizing superior Populus and Salix clones for remediation applications.

Although such information is lacking for environmental clean-up technologies, centuries of plant selection success in agronomy, horticulture, and forestry validate the need for similar approaches in phytoremediation. We bridge the gap between these disciplines by describing project development, clone selection, tree establishment, and evaluation of success metrics in the context of their importance to utilizing trees for phytoremediation.

KEY WORDS:

• phyto-recurrent selection
• phytoremediation
• poplar
• willow
• short rotation woody crops

ACKNOWLEDGMENTS

We are grateful to Steven Rock (US EPA) for the opportunity to provide our ideas to others interested in advancing phytoremediation technologies, along with his insightful technical reviews and suggestions. We thank the following plant breeders who contributed meaningful critiques of the manuscript: Dr. Richard B. Hall (Iowa State University—Populus spp., Alnus spp.), Dr. A. Assibi Mahama (Iowa State University—Glycine max, Populus spp., Sorghum bicolor, Zea mays), and Mr. Bernard McMahon (University of Minnesota National Resources Research Institute—Populus spp.). Also, we appreciate review of earlier versions of the manuscript from Robert Bridges, Deahn Donner, Neil Nelson, Adam Wiese, and Jill Zalesny.