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The Isotope Composition of Residual Fertilizer Nitrogen in Soil Columns
Author(s) -
Karamanos R. E.,
Rennie D. A.
Publication year - 1981
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/sssaj1981.03615995004500020018x
Subject(s) - nitrification , fertilizer , fractionation , leachate , nitrogen , dilution , isotope fractionation , isotope dilution , chemistry , stable isotope ratio , isotope , environmental chemistry , isotopes of nitrogen , soil water , environmental science , zoology , soil science , mass spectrometry , physics , organic chemistry , chromatography , quantum mechanics , biology , thermodynamics
A growth chamber experiment was carried out in which soil coumns that had received none or 200 kg N/ha were subjected to two differing water regimes. The δ a 15 N (per mill 15 N excess) of the NO 3 ‐N present in the leachate of all treatments decreased initially, with maximum depletion occurring between 4 and 6 weeks. In general, during the 14‐ to 16‐week period, large increases in the δ a 15 N of the leachate occurred. The magnitude of the decreases and subsequent increases were least for the drier water regimes receiving no fertilizer N (δ a 15 N ranging from −2 to +7) and greatest for the high water fertilized treatment (δ a 15 N ranging from −12 to +40). This very extensive fractionation was attributed to the preferential nitrification of 14 NH 4 + . Isotope balance calculations based on the isotope dilution principle are included to illustrate the serious errors that can be made in estimating the fertilizer N content of selected N compartments if the NO 3 ‐ ‐N is leached before the NH 4 + oxidation is completed.