Premium
Contribution of nitrification and denitrification to the emission of N 2 O in a freeze‐thaw event in an agricultural soil
Author(s) -
Ludwig Bernard,
Wolf Inken,
Teepe Robert
Publication year - 2004
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.200421462
Subject(s) - denitrification , nitrification , chemistry , nitrogen , nitrate , simultaneous nitrification denitrification , nitrogen cycle , nitrous oxide , environmental chemistry , zoology , environmental science , biology , organic chemistry
The amounts of N 2 O released in freeze‐thaw events depend on site and freezing conditions and contribute considerably to the annual N 2 O emissions. However, quantitative information on the N transformation rates in freeze‐thaw events is scarce. Our objectives were (1) to quantify gross nitrification in a Luvisol during a freeze‐thaw event, (2) to analyze the dynamics of the emissions of N 2 O and N 2 , (3) to quantify the contribution of nitrification and denitrification to the emission of N 2 O, and (4) to determine whether the length of freezing and of thawing affects the C availability for the denitrification. 15 NO $ _3^- $ was added to undisturbed soil columns, and the columns were subjected to 7 d of freezing and 5 d of thawing. N 2 O emissions were determined in 3 h intervals, and the concentrations of 15 N 2 O and 15 N 2 were determined at different times during thawing. During the 12 d experiment, 5.67 mg NO $ _3^- $ ‐N (kg soil) –1 was produced, and 2.67 mg NO $ _3^- $ ‐N (kg soil) –1 was lost. By assuming as a first approximation that production and loss occurred exclusively during thawing, the average nitrate‐production rate, denitrification rate, and immobilization rate were 1.13, 0.05, and 0.48 mg NO $ _3^- $ ‐N (kg soil) –1 d –1 , respectively. Immediately after the beginning of the thawing, denitrification contributed by 83% to the N 2 O production. The ratios of 15 N 2 to 15 N 2 O during thawing were narrow and ranged from 1.5 to 0.6. For objective (4), homogenized soil samples were incubated under anaerobic conditions after different periods of freezing and thawing. The different periods did not affect the amounts of N 2 and N 2 O produced in the incubation experiments. Further, addition of labile substrates gave either increases in the amounts of N 2 O and N 2 produced or no changes which suggested that changes in nutrient availability due to freezing and thawing are only small.