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Soil Science Society of America Journal Abstract -

Capacity of Desert Algal Crusts to Fix Atmospheric Nitrogen1


This article in SSSAJ

  1. Vol. 35 No. 5, p. 843-844
    Received: Feb 19, 1971
    Accepted: Apr 16, 1971

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  1. A. N. Macgregor and
  2. D. E. Johnson2



Approximately 4% of the soil surface of an area of desert grassland in the Sonoran Desert of southern Arizona possessed algal-crust formations. Samples of dry intact algal crusts were examined for nitrogen fixation by the acetylene-ethylene method. Three hours after being moistened, algal crusts produced detectable levels of ethylene. Premoistened algal crusts were capable of producing ethylene equivalent to 0.7 µg of N/cm2 of algal crust per hour. On the basis of these findings, 1 ha of desert grassland may receive a nitrogen input of 3 to 4 g of N/hour (0.3 mg to 0.4 mg N/m2 per hr) following a rainfall.

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