About Us | Help Videos | Contact Us | Subscriptions



This article in SSSAJ

  1. Vol. 42 No. 6, p. 913-918
    Received: Aug 31, 1977
    Accepted: June 26, 1978

Request Permissions


Nitrate Reduction to Ammonium in Anaerobic Soil1

  1. R. J. Buresh and
  2. W. H. Patrick2



Knowledge regarding the pathway and soil conditions necessary for NO3- Conversion to NH4+ and organic N, a process which conserves soil N, is limited. The influence of rice straw (2.5 mg C/g soil), methanol (1.0 mg C/g soil), and glucose (1.0 mg C/g soil) on the fate of 100 µg/g 15N-labelled NO3--N was studied in Crowley silt loam. The fraction of the added NO3--N in the NO3-, N2, NH4+, and organic N forms was determined after 4-day incubations under an Ar atmosphere at 30°C. In glucose-amended soil 9 and 19% of the applied NO3--N was recovered as NH4+-N and organic N, respectively. A 1-day preincubation with glucose (0.5 mg C/g soil) before the 4-day incubation with added NO3- and glucose increased labelled NH4+-N and organic N recovery to 36 and 34% of the added NO3--N, respectively. The corresponding values for rice straw- and methanol-treated soil and soil containing no added energy source were each less than 5%.

Nitrate-N reduction to NH4+-N increased to 20.5% after a 4-day incubation when soil with no C amendment was incubated under Ar for 20 days before NO3- addition. The redox potential was −260 mV upon NO3- addition

Transformation of significant amounts of NO3- to NH4+ and organic N required intensely reduced soil conditions. The reaction was apparently not suppressed by NH4+. Evidence indicated that NO3- was reduced to NH4+ by a nonassimilatory pathway in which NO3- functioned as a terminal electron acceptor.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © . Soil Science Society of America