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This article in JEQ

  1. Vol. 21 No. 1, p. 1-12
    Received: Feb 18, 1991

    * Corresponding author(s):
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Nitrogen Retention in Forest Soils

  1. Dale W. Johnson 
  1. Biological Sciences Center, Desert Research Institute, Reno, NV 89506, and Dep. of Range, Wildlife, and Forestry, Univ. of Nevada Reno, NV 89557-6611



Factors affecting N retention in both fertilized and natural forest ecosystems are reviewed. Collectively, the literature suggests that current conceptual models describing N competition among heterotrophs, plants, and nitrifiers in the soil may need some modification. Nitrifiers seem to be better competitors for N than previously recognized, especially in situations where N inputs are continuously elevated (such as in polluted sites or with repeated fertilization). The assumption that heterotrophs are the most effective competitors for N may be valid for the short term with relatively low N inputs, but may not hold true over the long term or with high N inputs. The apparent “mining” of N from soils by trees in N-poor sites suggests that they, rather than heterotrophs, are the most effective long-term competitors for N in such cases. Nonbiological reactions of N with soil organic matter are known to be a major cause of N immobilization following fertilization and may represent significant competition for N during decomposition in unfertilized sites as well.

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