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Soil Science Society of America Journal Abstract -

Factors Controlling Denitrification in a Chihuahuan Desert Ecosystem


This article in SSSAJ

  1. Vol. 55 No. 6, p. 1694-1701
    Received: July 23, 1990

    * Corresponding author(s):
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  1. William T. Peterjohn  and
  2. William H. Schlesinger
  1. The Ecosystems Center, Marine Biological Lab., Woods Hole, MA 02543
    Dep. of Botany and Geology, Duke Univ., Durham, NC 27706



Denitrification may be an important pathway for N loss from desert ecosystems. Few studies, however, have investigated the factors limiting this process in a desert environment. A factorial experiment was conducted to determine the factors controlling denitrification in the northern Chihuahuan Desert. Specifically, we measured the response of denitrification to additions of water, C, N, and C + N. Soil cores were collected from four vegetation zones along an alluvial piedmont. Dry cores were subjected to five treatments: (i) water; (ii) water + NO3; (iii) water + C; (iv) water + NO3 + C; and (v) a control (no additions). When denitrification rates were averaged across vegetation zones and patch types (between or under vegetation), the following treatment effects were significantly different: water + NO3 + C > > > water + NO3 = water » water + C > control. These results indicate that denitrification at this site is limited by the availability of water. In wet soil cores, C additions immobilized available NO3 and suppressed denitrification. When water + NO3 + C was added (C/N = 22), however, denitrification was significantly greater than when water + NO3 were added. This result indicates that C and N interact to control denitrification in wet desert soils. No evidence for an overall NO3 limitation in moist cores was found. Surprisingly, denitrification rates in wet cores of nutrient-poor desert soils (≈32.9 ng N cm−2 h−1) were similar to those measured in the nutrient-rich soils of temperate and tropical forests. When extrapolated to an annual rate, denitrification for this site is 7.22 kg N ha−1 yr−1. Extreme drying-wetting cycles common in desert ecosystems may account for the high rates observed.

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