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Injection of Nitrogen‐15 into Trees to Study Nitrogen Cycling in Soil
Author(s) -
Horwath William R.,
Paul Eldor A.,
Pregitzer Kurt S.
Publication year - 1992
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/sssaj1992.03615995005600010051x
Subject(s) - nitrogen , cycling , nitrogen cycle , litter , biomass (ecology) , growing season , agronomy , canopy , plant litter , environmental science , organic matter , chemistry , dilution , botany , nutrient , biology , forestry , physics , organic chemistry , geography , thermodynamics
Most 15 N dilution techniques disturb either the soil or N‐pool size. The objective of this study was to develop a method of labeling the roots of Populus trees with 15 N without physically disturbing the soil. Such a method would enable the direct measurement of the flux of 15 N from dead roots into the soil organic matter. Leaf and root biomass were labeled by injection of 15 N directly into the vessel elements of hybrid Populus trees during their second growing season. The 15 N was uniformly distributed throughout the canopy and root system. The rate and amount of 15 N turnover from plant tissue can be determined by pool transfer or through differences in plant 15 N concentrations. The 15 N was detected in the dead‐root pool 8 wk after injection, indicating root turnover. Results demonstrate the ability to measure the contribution of fine‐root litter to N‐cycling processes without disturbing the soil environment.