Phosphorus Concentrations Have Been Declining In The Illinois River: Was It Point Sources, Farm-Level Nutrient Management, Or What?

Animal Manure Management November 06, 2013 Print Friendly and PDF

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Abstract

Elevated phosphorus concentrations in the Illinois River Watershed (IRW) have long been an environmental issue between the states of Arkansas and Oklahoma, which has led to the development of a watershed-reservoir model and future TMDL by the U.S. Environmental Protection Agency.  Here, we examine phosphorus concentrations from multiple sources, including the Arkansas Water Resources Center and the U.S. Geological Survey, to evaluate trends in flow-adjusted concentrations.   Flow-adjusted phosphorus concentrations have been decreasing in the Illinois River at Arkansas Highway 59, and this translates into decreases further downstream to Tahlequah, Oklahoma.  However, flow-adjusted concentrations in Flint Creek have been increasing over time until the last few years.  These decreases are tied to the reductions in effluent phosphorus, which have occurred over the last couple decades.  But, the application of poultry litter has also likely decreased within the IRW.  A nutrient mass balance of the Watershed Research and Education Center in Fayetteville, Arkansas showed that reduced litter applications and increased forage export (i.e., hay being removed from fields) can result in phosphorus export at the farm-scale.  The missing piece of this study would be understanding legacy phosphorus, and how this influences source apportionment and changes over time.

Authors

Brian Haggard, Arkansas Water Resources Center, haggard@uark.edu

Thad Scott, Crop, Soil and Environmental Sciences Department, Division of Agriculture, University of Arkansas System

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

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USDA / NIFA

This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.