Biophysical Limits to Adoption of Denitrification Management Systems.

Constructed wetlands and denitrifying bioreactors (wood chip-filled trenches) designed to intercept and treat tile drainage and other agricultural runoff are promising technologies for removing nitrate. These technologies have been shown to remove a significant percentage of the nitrate load from agricultural runoff before entering streams and ditches; however, the adoption of these systems is limited by their capacity and landscape suitability. Ideally, wetlands and bioreactors should be placed such that influx matches system capacity. In this presentation, we will discuss biophysical limits to adoption of these systems including land availability, landscape suitability, adequacy and estimation uncertainty of hydrologic inputs and nitrate concentrations, and uncertainty regarding system capacity. Examples will be drawn from the Upper Mississippi and Chesapeake Bay watersheds. We will also discuss the applications and limitations of geospatial data to improve regional siting of these systems and provide input to design decisions. Geospatial data covered will include soil survey, climate, artificial drainage, landscape geomorphology, topography, and hydrology. As rapid installation of pattern tile drainage systems occur in the Upper Mississippi River Basin and population growth continues in the Chesapeake Bay Watershed, innovative technologies are needed to remediate nutrient inputs into aquatic systems.