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This article in JEQ

  1. Vol. 36 No. 2, p. 498-507
     
    Received: Dec 19, 2005
    Published: Mar, 2007


    * Corresponding author(s): wilymalr@cabnr.unr.edu
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doi:10.2134/jeq2005.0465

Inorganic Nitrogen and Phosphorus in Sierran Forest O Horizon Leachate

  1. T. M. Loupea,
  2. W. W. Miller *c,
  3. D. W. Johnsonc,
  4. E. M. Carrollb,
  5. D. Hansederb,
  6. D. Glassa and
  7. R. F. Walkerc
  1. a Hydrologic Sciences Program, College of Agriculture, Biotechnology, and Natural Resources, Univ. of Nevada, Reno, NV 89512
    c Dep. of Natural Resources and Environmental Science, College of Agriculture, Biotechnology, and Natural Resources, Univ. of Nevada, Reno, NV 89512
    b Dep. of Natural Resources and Environmental Science, College of Agriculture, Biotechnology, and Natural Resources, Univ. of Nevada, Reno, NV 89512

Abstract

High in situ concentrations of inorganic N and P have been reported in overland/litter interflow from Sierran forests, indicating that these nutrients are derived from the forest floor O horizons. To test this hypothesis, forest floor monoliths consisting of the combined Oe and Oi horizons were collected near the South Shore of Lake Tahoe, Nevada, for leaching experiments. Three monoliths were left intact, and three were hand-separated according to horizon for a total of three treatments (combined Oe+Oi, Oe only, and Oi only) by three replications. Samples were randomized and placed into lined leaching bins. Initial leaching consisted of misting to simulate typical early fall precipitation. This was followed by daily snow applications and a final misting to simulate spring precipitation. Leachate was collected, analyzed for NH4 +–N, NO3 –N, and PO4 3−–P, and a nutrient balance was computed. There was a net retention of NH4 +–N, but a net release of both NO3 –N and PO4 3−–P, and a net release of inorganic N and P overall. Total contributions (mg) of N and P were highest from the Oe and Oe+Oi combined treatments, but when expressed as per unit mass, significantly (p < 0.05) higher amounts of NO3 –N and PO4 3−–P were derived from the Oi materials. The nutrients in forest floor leachate are a potential source of biologically available N and P to adjacent surface waters. Transport of these nutrients from the terrestrial to the aquatic system in the Lake Tahoe basin may therefore play a part in the already deteriorating clarity of the lake.

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Copyright © 2007. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA

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