RT Journal Article
SR Electronic
T1 Contribution of streambanks to phosphorus export from Iowa
JF Journal of Soil and Water Conservation
FD Soil and Water Conservation Society
SP 00036
DO 10.2489/jswc.2022.00036
A1 K.E. Schilling
A1 T.M. Isenhart
A1 C.F. Wolter
A1 A. Nouri
A1 M.T. Streeter
A1 J.K. Kovar
YR 2021
UL http://www.jswconline.org/content/early/2021/12/08/jswc.2022.00036.abstract
AB 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.