Measuring and Modeling the Source, Transport and Bioavailability of Phosphorus in Agricultural Watersheds

EPA Grant Number: R830669
Title: Measuring and Modeling the Source, Transport and Bioavailability of Phosphorus in Agricultural Watersheds
Investigators: Lathrop, Richard C. , Armstrong, D. E. , Hoopes, John A. , Karthikeyan, K. G. , MacKay, David Scott , Nowak, Peter , Panuska, John C. , Penn, Michael R. , Potter, Kenneth W. , Wu, Chin H.
Institution: University of Wisconsin Madison , University of Wisconsin - Platteville , Wisconsin Department of Natural Resources
Current Institution: Wisconsin Department of Natural Resources , The State University of New York at Buffalo , University of Wisconsin Madison , University of Wisconsin - Platteville
EPA Project Officer: Hiscock, Michael
Project Period: December 17, 2002 through December 16, 2005 (Extended to December 16, 2006)
Project Amount: $749,307
RFA: Nutrient Science for Improved Watershed Management (2002) RFA Text |  Recipients Lists
Research Category: Water , Water and Watersheds


The linkage between watershed characteristics and the transport of bioavailable phosphorus (BAP) to surface waters is complex as processes that link agricultural P inputs to net BAP losses span a range of scales. Agricultural inputs of P in individual fields represent the primary initial source of BAP in runoff, but the spatially distributed transport pathways, in conjunction with the distribution of initial sources and storage reservoirs (e.g., stream pools), determine the quantity and rate of net BAP exported from a watershed. As a result, a substantial knowledge gap exists between the conservation practices at the field-scale and regulatory needs at the watershed-scale. By necessity, water regulation authorities often look specifically at water quality at selected points in a stream when assessing impacts on a watershed scale. However, authorities working more closely with agricultural producers involved in crop and animal production have focused at the field scale where decisions made by landowners significantly impact source contributions. Decisions at either scale are often made without consideration of the linkages between P sources and transport pathways.

1. Quantify effects of manure management and crop production systems on runoff P losses.
2. Determine spatial patterns of sediment and associated P in streams.
3. Determine in-stream fate and transport processes of P.
4. Evaluate and improve modeling tools used to assess P transport in agricultural watersheds over a wide range of spatial scales.
5. Determine relation of P losses with the scale of animal operation.
6. Integrate outreach into on-going research efforts.


The sources, transport, and fate of P, especially bioavailable phosphorus (BAP), will be measured and modeled in the mostly agricultural 604-km2 watershed of Lake Mendota near Madison, Wisconsin. This well-known eutrophic lake is impacted by phosphorus (P) loading from agricultural sources, including row crops, dairy operations, and land applications of manure and commercial fertilizers, and is the site of an on-going nonpoint pollution abatement program in its watershed. Research focus is on the scale-dependent processes that link agricultural P sources to watershed export of BAP.

Expected Results:

Modeling tools (e.g., APEX and SWAT) will be improved for assessing P transport over a wide range of spatial scales. Results will be integrated with stakeholders, agency partners and other researchers through farmer-feedback procedures, agency assessments and model refinement. Knowledge gained will be crucial for effective state and national TMDL development and implementation.

Publications and Presentations:

Publications have been submitted on this project: View all 50 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 9 journal articles for this project

Supplemental Keywords:

agricultural nonpoint pollution, bioavailable phosphorus, sediment transport, stream hydrodynamic processes, APEX model, SWAT model, TMDL, Lake Mendota watershed., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, ECOSYSTEMS, Water, Waste, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, Bioavailability, Aquatic Ecosystem, Water Quality Monitoring, Terrestrial Ecosystems, Environmental Monitoring, Watersheds, anthropogenic stress, bioassessment, anthropogenic processes, watershed classification, nutrient transport, fate and transport, model, ecosystem monitoring, watershed management, biodiversity, nutrient flux, conservation, nitrogen inputs, diagnostic indicators, ecosystem indicators, aquatic ecosystems, bioindicators, watershed sustainablility, water quality, biological indicators, ecosystem stress, watershed assessment, conservation planning, nitrogen uptake, bioavailable phosphorus, transport modeling, ecosystem response, aquatic biota, land use, restoration planning, watershed restoration, biological impairment

Progress and Final Reports:

  • 2003 Progress Report
  • 2004 Progress Report
  • 2005 Progress Report
  • Final Report