Evaluating stacked conservation practice effects at the field-scale in the Lake Champlain Basin of Vermont

Excess phosphorus (P) contributes to the eutrophication of freshwater bodies and subsequent Harmful Algal Blooms (HAB). This is an increasingly urgent problem in freshwater systems globally, including the Lake Champlain Basin (LCB). Agriculture, including dairy farming, is a prominent part of the landscape within the LCB and contributes a significant portion of the P load entering Lake Champlain. There are promising edge-of-field practices that may reduce dissolved and total P loads from agricultural surface and subsurface runoff. A Conservation Effects Assessment Project (CEAP) Stacked Practices and Innovative Phosphorus Removal project was initiated as a field-scale study in 2021. The field study takes place in Bridport, Vermont. The study evaluates the ‘stacking’ of multiple conservation practices at the field-scale including manure injection, no-till, cover cropping, and edge-of-field phosphorus removal technologies (subsurface tile drain filters) to determine their effects on the water quality of agricultural runoff. The tile drain filters contain iron oxide material mixed with pea gravel with the goal of reducing dissolved and total P loads from subsurface runoff. Results of surface and subsurface flow monitoring and water quality sampling from study fields will be presented, as well as performance data for the phosphorus removal structures.