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Nitrate Reduction to Ammonium in Anaerobic Soil
Author(s) -
Buresh R. J.,
Patrick W. H.
Publication year - 1978
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1978.03615995004200060017x
Subject(s) - chemistry , loam , incubation , straw , nitrate , ammonium , amendment , environmental chemistry , nitrogen , methanol , zoology , denitrification , ammonia , agronomy , soil water , inorganic chemistry , biochemistry , ecology , organic chemistry , biology , political science , law
Knowledge regarding the pathway and soil conditions necessary for NO 3 ‐ Conversion to NH 4 + 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 µ g/g 15 N‐labelled NO 3 ‐ ‐N was studied in Crowley silt loam. The fraction of the added NO 3 ‐ ‐N in the NO 3 ‐ , N 2 , NH 4 + , 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 NO 3 ‐ ‐N was recovered as NH 4 + ‐N and organic N, respectively. A 1‐day preincubation with glucose (0.5 mg C/g soil) before the 4‐day incubation with added NO 3 ‐ and glucose increased labelled NH 4 + ‐N and organic N recovery to 36 and 34% of the added NO 3 ‐ ‐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 NH 4 + ‐N increased to 20.5% after a 4‐day incubation when soil with no C amendment was incubated under Ar for 20 days before NO 3 ‐ addition. The redox potential was −260 mV upon NO 3 ‐ addition Transformation of significant amounts of NO 3 ‐ to NH 4 + and organic N required intensely reduced soil conditions. The reaction was apparently not suppressed by NH 4 + . Evidence indicated that NO 3 ‐ was reduced to NH 4 + by a nonassimilatory pathway in which NO 3 ‐ functioned as a terminal electron acceptor.