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Evolution of Dinitrogen and Nitrous Oxide from Nitrogen‐15 Fertilized Soil Cores Subjected to Wetting and Drying Cycles
Author(s) -
Mulvaney R. L.,
Kurtz L. T.
Publication year - 1984
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/sssaj1984.03615995004800030026x
Subject(s) - nitrous oxide , nitrification , soil water , denitrification , wetting , water content , nitrogen , chemistry , fertilizer , moisture , environmental chemistry , zoology , soil science , environmental science , materials science , geology , biology , geotechnical engineering , organic chemistry , composite material
A laboratory study was conducted to establish trends in evolution of dinitrogen (N 2 ) and nitrous oxide (N 2 O) associated with the wetting and drying of soils and to assess the relative significance of nitrification and denitrification as sources of the N 2 O evolved from NH + 4 ‐fertilized soils. Mass spectrometric procedures were used to analyze atmospheric samples collected each day during a 6‐week period from intact soil cores treated with 15 N‐labeled KNO 3 (65.5 atom % 15 N) or (NH 4 ) 2 SO 4 (81.4 atom % 15 N) at a rate equivalent to 100 kg N ha −1 and periodically treated with water to simulate rainfall. Data reported show that N 2 and N 2 O were evolved only if enough water was applied to increase the soil moisture content to a level above the 0.03‐MPa moisture percentage, that these gases were evolved concurrently, that maximal evolution occurred 2 to 9 d after the water had been applied, and that more N 2 was usually evolved than N 2 O. Calculations to determine the origin of the N 2 and N 2 O evolved from the soil cores showed that most (usually 60–80%) of this N 2 and N 2 O was derived from the fertilizer applied, that the percentage of fertilizer‐derived N 2 and N 2 O was greater for the NO ‐ 3 ‐treated cores than for the NH + 4 ‐treated cores, and that the 15 N enrichment of the N 2 O often exceeded that of the N 2 . The work reported provides support for the usual assumption that N 2 and N 2 O evolved from NH + 4 ‐, as well as NO ‐ 3 , fertilized soils originate largely, if not entirely, through denitrification of NO ‐ 3 under anaerobic conditions, and it suggests that evolution of these gases follows an over‐all cycle associated with wetting and drying of the soil. Very little, if any, N 2 and N 2 O appears to be evolved when the soil moisture content is well below field capacity. Evolution virtually ceases when the soil is saturated by rainfall, and it subsequently increases as the soil dries, with maximal evolution occurring several days after the rainfall. Evolution then decreases and eventually ceases.