Ecosystems

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The Influence of Legacy P on Lake Water Quality in a Midwestern Agricultural Watershed

  • Melissa Motew
  • Xi Chen
  • Eric G. Booth
  • Stephen R. Carpenter
  • Pavel Pinkas
  • Samuel C. Zipper
  • Steven P. LoheideII
  • Simon D. Donner
  • Kai Tsuruta
  • Peter A. Vadas
  • Christopher J. Kucharik
Article

Abstract

Decades of fertilizer and manure applications have led to a buildup of phosphorus (P) in agricultural soils and sediments, commonly referred to as legacy P. Legacy P can provide a long-term source of P to surface waters where it causes eutrophication. Using a suite of numerical models, we investigated the influence of legacy P on water quality in the Yahara Watershed of southern Wisconsin, USA. The suite included Agro-IBIS, a terrestrial ecosystem model; THMB, a hydrologic and nutrient routing model; and the Yahara Water Quality Model which estimates water quality indicators in the Yahara chain of lakes. Using five alternative scenarios of antecedent P storage (legacy P) in soils and channels under historical climate conditions, we simulated outcomes of P yield from the landscape, lake P loading, and three lake water quality indicators. Legacy P had a significant effect on lake loads and water quality. Across the five scenarios for Lake Mendota, the largest and most upstream lake, average P yield (kg ha−1) varied by −41 to +22%, P load (kg y−1) by −35 to +14%, summer total P (TP) concentration (mg l−1) by −25 to +12%, Secchi depth (m) by −7 to +3%, and the probability of hypereutrophy by −67 to +34%, relative to baseline conditions. The minimum storage scenario showed that a 35% reduction in present-day loads to Lake Mendota corresponded with a 25% reduction in summer TP and smaller reductions in the downstream lakes. Water quality was more vulnerable to heavy rainfall events at higher amounts of P storage and less so at lower amounts. Increases in heavy precipitation are expected with climate change; therefore, water quality could be protected by decreasing P reserves.

Keywords

legacy phosphorus eutrophication nonpoint source pollution watershed modeling agricultural runoff manure 

Supplementary material

10021_2017_125_MOESM1_ESM.docx (2.9 mb)
Supplementary material 1 (DOCX 2936 kb)

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Copyright information

© Springer Science+Business Media New York 2017

Authors and Affiliations

  • Melissa Motew
    • 1
  • Xi Chen
    • 1
    • 2
  • Eric G. Booth
    • 3
    • 4
  • Stephen R. Carpenter
    • 5
  • Pavel Pinkas
    • 1
  • Samuel C. Zipper
    • 4
  • Steven P. LoheideII
    • 4
  • Simon D. Donner
    • 6
  • Kai Tsuruta
    • 7
  • Peter A. Vadas
    • 8
  • Christopher J. Kucharik
    • 1
    • 3
  1. 1.Nelson Institute Center for Sustainability and the Global EnvironmentUniversity of Wisconsin-MadisonMadisonUSA
  2. 2.Department of GeographyUniversity of CincinnatiCincinnatiUSA
  3. 3.Department of AgronomyUniversity of Wisconsin-MadisonMadisonUSA
  4. 4.Department of Civil and Environmental EngineeringUniversity of Wisconsin-MadisonMadisonUSA
  5. 5.Center for LimnologyUniversity of Wisconsin-MadisonMadisonUSA
  6. 6.Department of GeographyUniversity of British ColumbiaVancouverCanada
  7. 7.Department of ForestryUniversity of British ColumbiaVancouverCanada
  8. 8.USDA-ARS Dairy Forage Research CenterMadisonUSA

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