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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #413608
Research Project: Managing Nutrient, Carbon, and Water Fluxes to Provide Sustainable and Resilient Cropping Systems for Midwestern Landscapes

Location: Agroecosystems Management Research

Title: Contribution of eroding streambanks to phosphorus export from Iowa, USA

Author
item Kovar, John
item SCHILLING, KEITH - University Of Iowa
item ISENHART, THOMAS - Iowa State University
item WOLTER, CALVIN - Iowa Department Of Natural Resources
item STREETER, MATTHEW - University Of Iowa

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/23/2024
Publication Date: 8/18/2024
Citation: Kovar, J.L., Schilling, K.E., Isenhart, T.M., Wolter, C.F., Streeter, M.T. 2024. Contribution of eroding streambanks to phosphorus export from Iowa, USA. [abstract]. 10th International Phosphorus Workshop. August 26-30, 2024. Dundee, Scotland.

Interpretive Summary:

Technical Abstract: Phosphorus (P) from nonpoint upland and channel sources contributes to development of hypoxic conditions in receiving waters around the world. Streambanks are thought to be a potentially large contributor to sediment P loads in agricultural watersheds but are often not taken into account in P loss reduction strategies. In this analysis, we estimate the contribution of streambank sources to total P (TP) export from the state of Iowa, USA, using a multi-step process and relate this to overall statewide P export. Results from GIS mapping and field monitoring indicated that 35,200 km of streambanks along third- through sixth-order streams with a mean bank height of 3.2 m are actively eroding in Iowa streams and rivers at a rate of 12.4 cm yr-1. With an average streambank soil TP concentration of 470 mg kg-1 and bulk density of 1.17 g cm-3, approximately 7,681 Mg of TP are annually eroded from streambanks and delivered to Iowa rivers. During an 18-year period, we estimate that streambanks contributed approximately 31% of the riverine TP export from Iowa. Despite limitations in our analysis, an improved understanding of streambank P contributions will help natural resource managers make appropriate recommendations for effective soil and water conservation practices that best reduce P loading to rivers. This study is thought to be among the first to address the issue of streambank P losses at a scale that has confounded many state and regional nutrient assessments.