Theses and Dissertations Collection

Increasing bioenergy crop production may negatively affect soil and water quality through leaching of excess nutrients. We studied the effects of growing hybrid poplar in the Pacific Northwest on nutrient leaching of ammonium (NH4+), nitrate (NO3-) and orthophosphate (PO43-). This research will help to predict soil and water quality for the full scale planting from the regional agricultural land use shifts. Nutrient leaching was estimated as a product of soil water drainage using the water balance method and nutrient concentration in the effluent collected using suction lysimeters installed at 50 cm below the soil surface. Depending on site environmental condition, impact on nutrient leaching from hybrid poplar was either low or high compare to the agricultural system. Jefferson agriculture had highest NO3- leaching (2.5 kg ha-1) compared to all sites and management. However, among all the poplar plantation sites NO3- leaching was highest in Jefferson poplar (1 kg ha-1). Ammonium and PO43- were less than 0.005 kg ha-1 across all sites and management. It is expected that nutrient leaching will eventually drop down in hybrid poplar as root system gets well established compare to the agricultural system.