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Soil Science Society of America Journal Abstract -

Inorganic Nitrogen Determined by Laboratory and Field Extractions of Two Forest Soils


This article in SSSAJ

  1. Vol. 59 No. 2, p. 549-553
    Received: Jan 10, 1994

    * Corresponding author(s):
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  1. Helga Van Miegroet 
  1. Department of Forest Resources, Utah State Univ., Logan, UT 84322-5215



To assess the effect of a delay in soil processing on inorganic N levels in N-rich soils, field and laboratory extractions were compared at two forested sites with high N mineralization and nitrification potential. At eight sampling dates in 1989 and 1990, five mineral soil cores per site were taken between 0- and 10-cm depth and transported on ice to the laboratory for KCl extraction and NH4-N and NO3-N analysis. At three sampling dates in 1990, soil extractions were performed in the field immediately following sampling, and inorganic N concentrations were compared between extractions. Nitrate-N increased four- to sevenfold (net release of 2–7 mg NO3-N/kg dry soil) due to the transport and relatively short delay (<24 h) in the processing of the soil samples, either coinciding with increased net N mineralization or due to transformation of NH4-N into NO3-N. This study indicates that if possible, soil samples should be extracted in the field, especially at N-rich sites. The concerns raised by this study may not necessarily apply to N-poor soils characterized by slow N transformation rates.

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