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This article in SSSAJ

  1. Vol. 65 No. 1, p. 244-246
    Received: Jan 5, 2000

    * Corresponding author(s): shigeru@agri.pref.toyama.jp


Comparison of Gross Nitrogen Mineralization Rates by Zero-Order Models

  1. Shigeru Takahashi *
  1. Toyama Agricultural Research Center, Soils and Fertilizer Section, 1124-1 Yoshioka, Toyama, 939-8153, Japan


Several zero-order models for estimating gross N mineralization rate (M) using 15N have been proposed. In a comparison of the Ms estimated with some experimentally determined values, different models sometimes gave substantially different results. Although the Ms are estimated by using changes in NH4–N (NH414N + NH415N) and NH415N, a comprehensive comparison based on model equations is lacking. I compared four zero-order models to clarify the extent of the difference in estimated Ms between models under different conditions of changes in NH4–N and NH415N. The ratio of M by one model equation to M by another is expressed by R = ( AT 2 AT 1) and r = ( AL 2 AL 1), where AT is NH4–N, AL is NH415N, and the subscripts 1 and 2 denote the initial and final values, respectively. Ranges of R and r are R > 0 and 0 < r < 1, respectively, and R > r The farther r is from 1, the more different the estimated Ms are. Estimation of M must be done with caution when r ≤ 0.2 since model differences increase uncertainties in estimates.

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Copyright © 2001. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.65:244–246.