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Effect of pH on the Rate of Gaseous Products of Denitrification in a Silt Loam Soil
Author(s) -
Koskinen W. C.,
Keeney D. R.
Publication year - 1982
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/sssaj1982.03615995004600060009x
Subject(s) - denitrification , loam , chemistry , mineralization (soil science) , incubation , soil water , environmental chemistry , nitrous oxide , soil texture , soil ph , nitrogen , nitrate , agronomy , zoology , soil science , environmental science , biology , biochemistry , organic chemistry
To examine the effect of soil pH on the rate and products of denitrification, a silt loam soil (Typic Argiudoll) was used that had been collected from a field experiment maintained at various pH levels for 18 years. The soil pH ranged from 4.6 to 6.9 and was nearly uniform in organic C (1.15 ± 0.05%) and texture. Incubation was performed under He in all‐glass systems that were sealed throughout the incubation period. The soils were amended with 100 µg/g of NO ‐ 3 ‐N before incubation. Denitrification products (N 2 O, NO, and N 2 ) and CO 2 were determined by gas chromatography using an ultrasonic detector. It appears that the rate of organic C mineralization rather than pH controls the rate of denitrification in C‐limited systems. At 100 µg NO ‐ 3 ‐N added per gram of soil, the overall rates of denitrification correlated with the rates of C mineralization (CO 2 evolution) but were not consistently related to pH or to total organic C. Soil pH did affect the products of denitrification. Nitrous oxide comprised 83% of the gaseous‐N products for pH 4.6 and 5.4 when 90% of the NO ‐ 3 had been denitrified. The N 2 O was then rapidly reduced to N 2 . The highest amount of NO was observed at pH 4.6 and 5.4. At pH 6.0 the rate of production of N 2 O exceeded the rate of reduction only for the first 2 d of incubation. However, N 2 O was the dominant product until ∼83% of the NO ‐ 3 had been denitrified. At pH 6.9, N 2 was the dominant product after the 1st d of incubation.