Constructed wetlands can be effective in removing nitrate from agricultural tile drainage. However, there is little research that identifies or quantifies removal mechanisms (primarily denitrification and uptake). We are conducting an investigation on the Gully wetland at the Franklin Demonstration Farm in Lexington, IL that is operated by The Nature Conservancy. The Gully wetlands consists of 3 sequential cells, with the area of each cell representing 3% of the tile drainage area. The natural N isotopic composition of nitrate, macrophytes, and sediments was analyzed in order to calculate nitrification, denitrification, and uptake rates using a N isotopic mass balance equation. The N isotopic composition was shown to be higher in the [...]