HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Khan, S. A. Articles by Brooks, P. D. Search for Related Content PubMed Articles by Khan, S. A. Articles by Brooks, P. D. GeoRef GeoRef Citation Agricola Articles by Khan, S. A. Articles by Brooks, P. D.

Diffusion Methods for Automated Nitrogen-15 Analysis using Acidified Disks

Dep. of Natural Resources and Environmental Sciences, 1102 S. Goodwin Ave., Univ. of Illinois, Urbana, IL 61801

P. D. Brooks

Dep. of Environmental Science, Policy, and Managemnet, Univ. of California, Berkeley, CA 94720

* Cooresponding author (mulvaney{at}uiuc.edu).

ABSTRACT

Diffusion methods are often employed to speciate inorganic N in soil extracts or water for N-isotope analysis with automated mass spectrometers. Diffusion is usually carried out in a plastic specimen container with an acidified filter disk to collect the diffused NH₃. Owing to the small size of the container and the limited surface area of the acidified disk, a diffusion period of 6 to 14 d is generally required, and even then recovery may be incomplete. Simple diffusion methods were developed that use two acidified disks in a 473-mL (1-pint) wide-mouth Mason jar. Diffusions with MgO to recover NH₄-N, or with MgO plus Devarda's alloy to recover (NH₄ + NO₃)-N or (NH₄ + NO₃ + NO₂)-N, were performed from 5 to 100 mL of either 2 or 4 M KCl. Quantitative recovery of 150 µg of N was achieved in 1 to 7 d at 20 to 25°C, and in 2 to 14 h by heating on a hot plate at 45 to 50°C. Isotopic analyses of labeled soil extracts were accurate to within 5%, as determined by isotope-dilution calculations. Incomplete diffusion led to <2% error in analysis of NH₄-N, whereas serious error occurred in analysis of (NH₄ + ¹⁵NO₃)-N.

This study was a part of Project ILLU-15-0392, Illinois Agric. Exp. Stn.

Received for publication April 14, 1997.

This article has been cited by other articles:

				D. S. Ross and H. C. Hales Sampling-Induced Increases in Net Nitrification in the Brush Brook (Vermont) Watershed Soil Sci. Soc. Am. J., January 1, 2003; 67(1): 318 - 326. [Abstract] [Full Text] [PDF]

				K. K. Moran, R. L. Mulvaney, and S. A. Khan A technique to facilitate diffusions for nitrogen-isotope analysis by direct combustion Soil Sci. Soc. Am. J., May 1, 2002; 66(3): 1008 - 1011. [Abstract] [Full Text] [PDF]

				J. P. Kaye, D. Binkley, X. Zou, and J. A. Parrotta Non-labile Soil 15Nitrogen Retention beneath Three Tree Species in a Tropical Plantation Soil Sci. Soc. Am. J., March 1, 2002; 66(2): 612 - 619. [Abstract] [Full Text] [PDF]

				G. D. Eudoxie and G. A. Gouveia Microdiffusion of Strongly Fixed Ammonium in Soil-Acid Digests Prior to Automated Nitrogen-15 Analysis Soil Sci. Soc. Am. J., November 1, 2001; 65(6): 1846 - 1852. [Abstract] [Full Text] [PDF]

				O. C. Devevre and W. R. Horwath Stabilization of Fertilizer Nitrogen-15 into Humic Substances in Aerobic vs. Waterlogged Soil Following Straw Incorporation Soil Sci. Soc. Am. J., March 1, 2001; 65(2): 499 - 510. [Abstract] [Full Text] [PDF]

				S.A. Khan, R.L. Mulvaney, and R.G. Hoeft Direct-Diffusion Methods for Inorganic-Nitrogen Analysis of Soil Soil Sci. Soc. Am. J., May 1, 2000; 64(3): 1083 - 1089. [Abstract] [Full Text]