Enhanced Nitrogen and Phosphorus Removal by Woody Plants with Deep-Planting Technique for the Potential Environmental Management of Carcass Burial Sites

Phytoremediation is a promising technology to remediate carcass burial sites where deep soil layers are contaminated with nitrogen (N), phosphorus (P) and other potential contaminants by leachate. The current study was conducted to examine the remedial efficiency of two different woody plants, poplar (Populus euramericana) and willow (Salix alba), by employing the deep-planting technique for the enhanced removal of N and P for the soil affected by leachate. For this, pot trials to assess N and P removal efficiency of poplar and willow in liquid manure-applied soil, and pilot-scale column experiments to evaluate the suitability of the deep-planting technique for the enhanced phytoremediation of deep soil layer were conducted. The results of this study showed that poplar and willow removed N and P from soils effectively while surviving under deep-planting conditions. Notably, compared to the surface planted roots, the roots of the deep-planted poplar and willow could transfer significant amounts of N and P leachate from the deep soil layer to the rhizosphere, from where it can be absorbed by the plants. For the first time, the use of poplar or willow plants are recommended by employing the deep-planting technique for the successful remediation of carcass burial sites.