The effect of inorganic nitrogen on the added nitrogen interaction of soils in incubation experiments

F. Azam, F. W. Simmons, Richard L Mulvaney

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A laboratory incubation experiment was conducted to study the effect of indigenous inorganic N on the immobilization of applied N and on the occurrence of an added N interaction (ANI). Samples of six Mollisols from Illinois were incubated with 15N-labelled (NH4)2SO4 (100 or 200 mg N kg-1 soil), with or without the use of 0.01 M CaCl2 to extract inorganic N (mainly NOinf3sup-) before incubation. From 6 to 49% of the N applied was immobilized, higher percentages being obtained with unextracted soils than with the extracted soils and with the higher rate of N addition. Net mineralization of native N occurred in both the unextracted and extracted soils, but was more extensive in the unextracted soil and increased with the addition of N. The increases were accompanied by a positive ANI, which usually exceeded the amount of applied N immobilized and increased with the rate of addition. The ANI values observed with extracted soils were attributed to increased mineralization of native organic N.

Original languageEnglish (US)
Pages (from-to)103-108
Number of pages6
JournalBiology and Fertility of Soils
Issue number2
StatePublished - Jul 1 1994



  • Added N interaction
  • Mollisols
  • N immobilization
  • N mineralization
  • Priming effect

ASJC Scopus subject areas

  • Microbiology
  • Agronomy and Crop Science
  • Soil Science

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