PTraM Wins $750K to Study P Dynamics in Tile Drained Landscapes

By Matt Scholz of the Sustainable Phosphorus Alliance

Matt Scholz

Members of the Alliance’s P transport modeling (PTraM) group recently won a $750,000 applied research grant through the USDA-NIFA-AFRI foundational funding program. The project entitled “Advancing knowledge and prediction of phosphorus dynamics in tile drained landscapes” will involve interdisciplinary collaborations among soil scientists and watershed modelers. The four-year project aims to improve our understanding of phosphorus (P) loss in tile drainage systems and to improve tile P simulation in the Soil Water Assessment Tool (SWAT), a watershed scale hydrology and nutrient transport model.

“Our long-term goal is to provide science-based information to farmers and other stakeholder groups to support sustainable agricultural production while promoting water quality.”, said Dr. Vinayak Shedekar, who is leading the research project. “Watershed models like SWAT are often used for identifying critical source areas of these nutrients and to evaluate the efficacy of conservation practices in improving water quality. The stakeholder group plays a critical role in our work by informing our models with more realistic (on-the-ground) information. They also help us identify opportunities for improvement of these models. This project is perfect example of stakeholder-driven research and outreach,” said Shedekar.

The main focus area of the project will be the Western Lake Erie Basin (WLEB), where P transported via surface and subsurface flows from agricultural systems plays a major role in water quality impairments downstream, including harmful algal blooms (HABs). In heavily tile-drained agricultural landscapes of the WLEB, understanding and quantifying dynamics of dissolved P (DP) transport through tile drainage is critical. Dr. Chad Penn, a soil scientist at the USDA-ARS National Soil Erosion Laboratory explains, “While the transport of total P (TP) and DP have been extensively studied, knowledge and modeling gaps exist in relating soil properties with sorption dynamics and P transport through matrix and preferential flow pathways. Poor representation of P sorption and transport processes impact the usefulness of watershed models in guiding environmental policy.”

Dr. Penn has developed novel laboratory methods that help characterize the process of P desorption from topsoils and sorption by subsoils under different flow regimes. The knowledge from laboratory studies will then help improve the theoretical framework in the SWAT model, by adopting mathematical models of P dynamics and improving the representation of preferential and matrix flow to tile drains.

Dr. Margaret Kalcic will lead the watershed modeling research for the project with the help of field-scale monitoring data from within the watershed. “These possible source code modifications in SWAT will be an important improvement, especially for the WLEB, said Kalcic. Dr. Kevin King leads an extensive edge-of-field monitoring network in Ohio and plans to contribute monitoring data that would eventually help validate the proposed SWAT model improvements. The Alliance, including Dr. Rebecca Muenich, will play an advisory role on the model improvements and help with the dissemination of the information.