TY - JOUR T1 - Contribution of streambanks to phosphorus export from Iowa JF - Journal of Soil and Water Conservation SP - 103 LP - 112 DO - 10.2489/jswc.2022.00036 VL - 77 IS - 2 AU - K.E. Schilling AU - T.M. Isenhart AU - C.F. Wolter AU - M.T. Streeter AU - J.L. Kovar Y1 - 2022/03/01 UR - http://www.jswconline.org/content/77/2/103.abstract N2 - 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 unaccounted for 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 using a multistep process and relate this to overall statewide P export. Using GIS mapping and field monitoring, we estimate that 35,200 m of 3.2 m high streambanks are actively eroding in Iowa rivers at a rate of 12.4 cm y–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 is annually eroded from streambanks and delivered to Iowa rivers. Over 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. Our study is believed to be among the first to address the issue of streambank P at a scale that has confounded many state and regional nutrient assessments. ER -