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Soil nitrogen availability and in situ nitrogen uptake by Acer rubrum L. and Pinus palustris Mill. in the southeastern U. S. Coastal Plain1

Permanent URL:
http://handle.nal.usda.gov/10113/48753
File:
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Abstract:
Plant uptake of soil organic N in addition to inorganic N could play an important role in ecosystem N cycling as well as plant nutrition. We measured in situ plant uptake of organic and inorganic N by the dominant canopy species in two contrasting temperate forest ecosystems (bottomland floodplain forest, subxeric sandhills long-leaf pine forest). Seedlings of Acer rubrum L. and Pinus palustris Mill. in floodplain and sandhills forests, respectively, were treated with isotopically-enriched organic N (¹⁵N-[[2]]-¹³C-glycine) or inorganic N (¹⁵NH₄⁺⁺) to examine in situ uptake. We also measured soil organic and inorganic N concentrations to assess the availability of N for plant uptake. Neither species took up organic N as intact ¹⁵N-[[2]]-¹³C-glycine, but significant root ¹⁵N enrichment in both species indicated that N mineralized from labeled glycine was taken up. Free amino-N dominated the total 2 M KCl-extractable N in floodplain (57 ±± 3%%) and sandhills soils (75 ±± 3%%), followed by NH₄⁺⁺ then NO₃⁻⁻ in both soils. Up to 13%% of glycine label was mineralized to NH₄⁺⁺ at both sites, suggesting that the majority of label was immobilized or adsorbed in the soil. Recovery of NH₄⁺⁺ label also indicated strong soil immobilization, particularly in sandhills soils after 24 hours. Although uptake of intact organic N did not occur in either species, N mineralized from glycine was taken up by plants in these two contrasting temperate forested ecosystems.
Author(s):
Jin Virginia L. , Romanek Christopher S. , Donovan Lisa A. , Sharitz Rebecca R.
Note:
Journal title changed from 'The Journal of the Torrey Botanical Society'
Source:
The journal of the Torrey Botanical Society 2010 10 v.137 no.4
Language:
English
Publisher:
Torrey Botanical Society
Year:
2010
Collection:
Journal Articles, USDA Authors, Peer-Reviewed