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This article in SSSAJ

  1. Vol. 57 No. 1, p. 63-66
    Received: Jan 24, 1992

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Modeling the Flush of Nitrogen Mineralization Caused by Drying and Rewetting Soils

  1. M. L. Cabrera 
  1. Dep. of Agronomy and Institute of Ecology, 3111 Plant Sciences Building, Univ. of Georgia, Athens, GA 30602



The flush of N mineralization that follows rewetting a dry soil may release significant amounts of N where drying-rewetting cycles are common, so attempts to model N mineralized in the field should include this mechanism. Selecting a model for the N flush, however, is hampered by inadequate measurement frequency in existing data. My objective was to collect detailed data on the progress of the N flush to facilitate finding a model to describe the process. Samples of three soils were preincubated, dried, rewetted, and incubated at 30 °C for up to 20 d with periodic samplings for inorganic N determinations. Undried samples were also incubated and sampled periodically. Cumulative net N mineralized in undried samples was adequately described by zero-order kinetics. In contrast, describing cumulative net N mineralized in dried and rewetted samples required a model with two N pools, one following zero-order kinetics and the other following first-order kinetics. Apparently, the first-order N flush was superimposed on zero-order background mineralization. Drying and rewetting the soils also significantly increased the background mineralization rate, suggesting transfer of N from a passive pool to the zero-order pool.

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