The Fate of 15NO− 2 Tracer in Soils under Different Tree Species of the Catskill Mountains, New York
- Ross D. Fitzhugh *a,
- Lynn M. Christensonb and
- Gary M. Lovettb
The incorporation of nitrite (NO− 2) into soil organic matter (SOM) has received little attention as a mechanism contributing to the retention of atmospherically deposited N in forest ecosystems, despite previous studies in agricultural systems showing that NO− 2 fixation by SOM is enhanced in soils with high acidity and organic matter content, characteristics commonly found in forest soils. Given previous studies showing that nitrification and nitrate (NO− 3) leaching may vary significantly in soils under different tree species, the primary objectives of this study were to determine if the incorporation of NO− 2 into SOM was quantitatively significant and if the incorporation varied among soils under different tree species from the Catskill Mountains in New York State. A pulse-chase laboratory experiment was performed, where 15NO− 2 was added to organic soils from three tree species (American beech [Fagus grandifolia], northern red oak [Quercus rubra], sugar maple [Acer saccharum]), and 15N recoveries were determined in total soil, extractable inorganic, readily mineralizable, microbial biomass, dinitrogen (N2), and nitrous oxide (N2O) pools. Results from our experiment demonstrate that the incorporation of NO− 2 into SOM can occur rapidly, at time scales of 1 d or shorter, and that NO− 2 incorporation into SOM is the dominant fate of the 15NO− 2 tracer, suggesting that the incorporation of NO− 2 into SOM is a potentially important N sink in forest soils. The incorporation of NO− 2 into SOM did not vary significantly among tree species. Our results suggest that models of the N cycle in forest ecosystems should include considerations of NO− 2 incorporation into SOM.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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