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This article in SSSAJ

  1. Vol. 61 No. 6, p. 1774-1780
    Received: July 15, 1996

    * Corresponding author(s):
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Moist- and Dry-Season Nitrogen Transport in Sierra Nevada Soils

  1. S. Burcar,
  2. W. W. Miller ,
  3. S. W. Tyler and
  4. R. R. Blank
  1. Dep. of Environmental and Resource Sciences, Univ. of Nevada, 1000 Valley Rd., Reno, NV 89512
    Desert Research Inst., Dandini Ln., Reno, NV
    USDA-ARS, Reno, NV



Characterization of ion mobility is a first step in the understanding of nutrient flux relationships in alpine forested watersheds. Our purpose was to: (i) investigate the transport dynamics of inorganic N in Sierra Nevada soils by applying unspiked source water as a control, and a 1 mmolc L-1 NH4NO3 spiked solution to two soil types (granitic and andesitic) under forest and meadow conditions via artificial rainfall during moist (spring) and dry (late summer-early fall) seasons; and (ii) evaluate the presence of macropore or preferential matrix flow from characteristic profile distributions of the two N forms. Peak concentrations in surface flow discharge (runoff) of both N forms from control treatments occurred early for both soil types and were highest from the meadow areas (1.6–0.4 mg NO-3-N L-1 meadow to forest for granitic soil and 0.3–0.1 mg L-1 meadow to forest for andesitic soil; 0.75–0.37 mg NH+4-N L-1 meadow to forest for granitic soil and 0.25–0.18 mg L-1 meadow to forest for andesitic soil). Both soils exhibited NH+4-N adsorption, but only the soil of andesitic origin appeared to sorb NO-3-N. Andesitic soils of the Sierra Nevada may thus serve as a temporary sink for NO-3-N deposition, whereas meadow areas of both soil types appear to serve as a source. Higher initial soil moisture for the spiked treatments generally resulted in the transport of NH+4-N to greater depths in both soils of forested cover (≈ 40 compared with 20 cm from spring to late summer-early fall), and for NO-3-N (≈ 50 compared with 40 cm) as well. Wet-season (spring) mobility must therefore be considered an important groundwater nutrient transport mechanism in Sierra Nevada watershed soils.

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