Isotopic Composition of Nitrogen and Transformation of Nitrogen Compounds in Meadow-Alpine Soils
- Authors: Makarov M.I.1, Malysheva T.I.1, Menyailo O.V.2
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Affiliations:
- Lomonosov Moscow State University
- Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences, Akademgorodok
- Issue: Vol 52, No 9 (2019)
- Pages: 1028-1037
- Section: Soil Chemistry
- URL: https://journals.rcsi.science/1064-2293/article/view/225167
- DOI: https://doi.org/10.1134/S1064229319090059
- ID: 225167
Cite item
Abstract
Isotopic composition of nitrogen in soils can be an informative indicator of N transformation processes and sources of N nutrition of plants, but data on δ15N of labile N compounds are scarce. It is shown that N transformation in meadow-alpine soils (Leptic Umbrisols) of the northwestern Caucasus (Teberda Reserve, Karachay-Cherkess Republic) leads to well-expressed differences in isotopic signatures of different N compounds: δ15N of extractable organic matter > δ15Ntotal > δ15N–\({\text{NH}}_{{\text{4}}}^{ + }\) > δ15N–\({\text{NO}}_{{\text{3}}}^{ - }.\) The range of δ15N in this sequence reaches 25‰. Differences in δ15N within the same pool of N in soils of different alpine ecosystems, as well as seasonal dynamics of δ15N–\({\text{NH}}_{{\text{4}}}^{ + },\) are much less pronounced (the range of δ15N is 2–4‰). The values of δ15Ntotal and δ15N–\({\text{NH}}_{{\text{4}}}^{ + }\) positively correlate with N mineralization and nitrification and demonstrate the accumulation of heavy N isotope in soils of the alpine ecosystems with more active N transformation processes. Obviously, nitrification is the key process controlling the isotopic signature of N–\({\text{NH}}_{{\text{4}}}^{ + }.\) The role of N mineralization in the fractionation of N isotopes is less obvious, and 15N accumulation in the extractable organic matter can be related to the significant content of “heavy” microbial N in extractable organic N pool.
About the authors
M. I. Makarov
Lomonosov Moscow State University
Author for correspondence.
Email: mmakarov@soil.msu.ru
Russian Federation, Moscow, 119991
T. I. Malysheva
Lomonosov Moscow State University
Email: mmakarov@soil.msu.ru
Russian Federation, Moscow, 119991
O. V. Menyailo
Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences,Akademgorodok
Email: mmakarov@soil.msu.ru
Russian Federation, Krasnoyarsk, 660036