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Journal of Environmental Quality Abstract - Landscape and Watershed Processes

Riverine Response of Sulfate to Declining Atmospheric Sulfur Deposition in Agricultural Watersheds

 

This article in JEQ

  1. Vol. 45 No. 4, p. 1313-1319
    unlockOPEN ACCESS
     
    Received: Dec 21, 2015
    Accepted: Mar 14, 2016
    Published: July 7, 2016


    * Corresponding author(s): mbdavid@illinois.edu
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doi:10.2134/jeq2015.12.0613
  1. Mark B. David *a,
  2. Lowell E. Gentrya and
  3. Corey A. Mitchella
  1. a Univ. of Illinois, Dep. of Natural Resources and Environmental Sciences, W503 Turner Hall, 1102 S. Goodwin Ave., Urbana, IL 61801
Core Ideas:
  • Riverine sulfate in agricultural watersheds responds to atmospheric deposition inputs.
  • Agricultural sulfur budgets suggest annual depletion of organic S pools.
  • Tile drains respond quickly to agricultural sulfate inputs.

Abstract

Sulfur received extensive study as an input to terrestrial ecosystems from acidic deposition during the 1980s. With declining S deposition inputs across the eastern United States, there have been many studies evaluating ecosystem response, with the exception of agricultural watersheds. We used long-term (22 and 18 yr) sulfate concentration data from two rivers and recent (6 yr) data from a third river to better understand cycling and transport of S in agricultural, tile-drained watersheds. Sulfate concentrations and yields steadily declined in the Embarras (from ∼10 to 6 mg S L−1) and Kaskaskia rivers (from 7 to 3.5 mg S L−1) during the sampling period, with an overall −23.1 and −12.8 kg S ha−1 yr−1 balance for the two watersheds. There was evidence of deep groundwater inputs of sulfate in the Salt Fork watershed, with a much smaller input to the Embarras and none to the Kaskaskia. Tiles in the watersheds had low sulfate concentrations (<10 mg S L−1), similar to the Kaskaskia River, unless the field had received some form of S fertilizer. A multiple regression model of runoff (cm) and S deposition explained much of the variation in Embarras River sulfate (R2 = 0.86 and 0.80 for concentrations and yields; n = 46). Although atmospheric deposition was much less than outputs (grain harvest + stream export of sulfate), riverine transport of sulfate reflected the decline in inputs. Watershed S balances suggest a small annual depletion of soil organic S pools, and S fertilization will likely be needed at some future date to maintain crop yields.

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Copyright © 2016. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.