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The Effect of Acidity on Nitrate Reduction and Denitrification in Lower Coastal Plain Soils
Author(s) -
Waring S. A.,
Gilliam J. W.
Publication year - 1983
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/sssaj1983.03615995004700020014x
Subject(s) - soil water , chemistry , denitrification , nitrate , ultisol , soil ph , environmental chemistry , histosol , organic matter , nitrogen , soil organic matter , soil science , environmental science , organic chemistry , soil biodiversity
Denitrification and nitrate reduction to NH + 4 ‐N and organic N were investigated in the laboratory using surface samples of Histosols and Ultisols. A wide range of pH (3.4 to 7.3) was obtained by liming acidic virgin soils and by selecting a range of field‐limied soils. When incubated under waterlogged conditions in the presence of glucose for 2 d at 25°C, there was a very low loss of NO ‐ 3 ‐N below a pH of 4.0 and an increase in NO ‐ 3 ‐N loss with pH up to a pH of 6.0. After 12 d of incuhation, NO ‐ 3 ‐N loss (105‐115 mg L −1 ) was complete from soils at all pH values. Laboratory and field‐limed soils behaved as expected from their pHs. For soils incubated for 2 d without glucose, there was a moderate effect of soil pH upon NO ‐ 3 ‐N loss ( R 2 = 0.40). The correlation was even poorer at longer time periods becoming nonsignificant after 12 d. For incubations longer than 2 d soluble C appeared to be more important than pH in controlling loss of NO ‐ 3 ‐N. Soils with pH < 4.0 showed unexpectedly high NO ‐ 3 ‐N loss when incuhated for periods > 12 d without glucose. Experiments with 15 NO ‐ 3 ‐N showed that 16 to 20% of the NO ‐ 3 ‐N loss in soils with pH <4.0 was due to reduction to NH + 4 ‐N and organic N but only 1 to 2% for soils with pH > 4.0. Evidence indicates that the reduction was dissimilatory and unrelated to levels of soluble C. Denitrification was substantial in the soils with pH <4.0 and of a similar level to that for moderately acidic soils (pH 4.4‐5.4). In the neutral soils (pH 6.9‐7.3) denitrification was much higher but much of the increase appeared due to the higher level of soluble C.