In agricultural areas there is often excess nutrient and sediment loss to nearby waterways. In recent decades, the implementation of best management practices (BMPs) has served to facilitate nutrient capture and processing, benefiting downstream water quality. While proven effective at nitrogen and sediment removal, recent research has brought into question the effectiveness of BMPs to manage dissolved phosphorus, with some at times found to contribute dissolved phosphorus. In addition, farmland settings often have high levels of residual, or ‘legacy’ soil phosphorus from decades of past management, leading to poor practice phosphorus performance or observed performance lag-time. Excess dissolved phosphorus contributes to harmful algal bloom development, the occurrence of which has increased in recent years.
Through field and desktop data collection, this work proposes to characterize and quantify agricultural dissolved phosphorus losses, the level of contribution or control from individual BMPs, and the role of site-specific factors and legacy phosphorus. Research will comprise of work conducted at sites within three agricultural watersheds one containing cover crops, bioreactors and a treatment wetland within the Blue Earth River watershed one containing a saturated buffer within the Cannon River watershed and one containing numerous wetland restoration sites within the Sauk River watershed. Field data collection, dating back to 2013 consists of hydrologic and nutrient loading at practice inlets and outlets, and site-specific soil, landscape, management and climate characteristics.
Preliminary results suggest practice contributions of dissolved phosphorus in many cases, the findings of which will be complete in the summer of 2021 as part of a doctoral dissertation with the UMN Bioproduct and Biosystems Engineering Department. Findings will inform management recommendations, BMP design and model development to more readily account for dissolved phosphorus losses.
Speaker(s)
Laura Bender, University of Minnesota