The Nitrogen Filtering Capability of Carolina Poplar in an Artificial Riparian Zone
- G. J. O'Neill and
- A. M. Gordon *
The extensive use of inorganic N fertilizers in agricultural operations has been identified as an important source of nonpoint NO−3-N pollution, contaminating both ground and surface waters. The ability of trees planted in the riparian zone of streams draining agricultural areas, however, to filter NO−3-N in drainage water and reduce loadings to watercourses has not been proven conclusively. This study evaluated the ability of Carolina poplar (Populus × canadensis Moench) to remove NO−3-N from a saturated soil zone. An artificial riparian zone was designed to facilitate subsurface movement of NO−3-N through the rooting zone of trees. A Mariotte container was used to maintain a saturation zone and to deliver two NO−3-N concentrations (12.0 and 24.6 mg L−1) to the rooting zone. Planting densities of one and two poplar trees per compartment (0.48 m2) were compared with a control with no-trees. Four sampling locations were used to monitor the NO−3-N concentration of the soil solution as it moved through the tree rooting zone. The filtering of NO−3-N from the soil solution followed a quadratic function. The one and two poplar tree densities filtered 11 and 14%, respectively, more NO−3-N from the saturated soil zone than the control and over time, were able to lower the NO−3-N concentration in the saturated soil zone over time. Tree roots showed a significant increase in dry weight and TKN% with increasing NO−3-N concentration. These results indicate the N filtering capability of Carolina poplar with subsequent accumulation of the N in root biomass.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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