Topographic Effects On Denitrifcation in Drained Agricultural Fields.

Denitrification is affected by soil moisture, while soil moisture can be affected by topography.  Therefore, denitrification can be spatially correlated to topographic gradients. Three prior converted fields on the Delmarva Peninsula were sampled spatially for denitrification enzyme activity (DEA). The upper six inches of soil were sampled from twenty points in each field. The spatial sites were selected randomly using Arc-GIS. Denitrification enzyme activity was performed in the lab using the acetylene inhibition method. The average pH, EC, and SOC were similar for each field, but average DEA was greater in field H (11.59 µg N kg soil^-1 hr^-1) versus field B (4.95 µg N kg soil^-1 hr^-1) and field C (6.56 µg N kg soil^-1 hr^-1). Further spatial analysis of DEA within each field will be performed using the topographic wetness index.