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 Google Scholar Google Scholar Articles by Johns, M. M. Articles by Skogley, E. O. Search for Related Content PubMed Articles by Johns, M. M. Articles by Skogley, E. O. Agricola Articles by Johns, M. M. Articles by Skogley, E. O.

Soil Organic Matter Testing and Labile Carbon Identification by Carbonaceous Resin Capsules

Department of Plant, Soil, and Environmental Science, Montana State Univ., Bozeman, MT 59717-0312

*Corresponding author.

ABSTRACT

An alternative test for soil organic matter that does not produce toxic dichromate waste, as does the Walkley-Black test, and that also allows identification of labile soil C components is currently desired. The objectives of this study were to apply carbonaceous resin capsules for measurement of soil organic C (SOC) and for identification of soluble SOC constituents. Seven carbonaceous resins, selective for nonpolar organic adsorbates, were evaluated. The resins were tightly packed as spherical capsules and placed in saturated soil pastes of 19 Montana soils. Resin capsules were desorbed with NaOH, CH₃OH, CHCl₃, and C₆H₁₄. Capsules extracted with the organic solvents were used in identification by nuclear magnetic resonance and infrared spectroscopy. Ultrafiltration and atomic absorption spectrophotometry of trace metals were also used. All resin capsules sorbed measurable levels of soil labile C (LC). All the resin types provided statistically significant prediction of SOC. The Ambersorb 564 resin showed the highest prediction, with a linear relationship between capsule-extracted LC (NaOH) and SOC of r² = 0.09 (P < 0.0001). Prediction results from these soils suggested a linear relationship between soluble SOC and solid-phase SOC, describable as constant partitioning. Labile C was composed of mostly aliphatics and some aromatics. Carbohydrates, OH, COOH groups, and metal-organic complexes were present. Most of the LC was composed of low molecular weight humics (<1000 daltons). The ability of LC to be desorbed by the more nonpolar solvents indicated an amphipathic character for some LC constituents. The resin capsule methodology showed good testing potential for these SOC investigations.

Contribution of the Montana Agric. Exp. Stn. Journal no. J2808.

Received for publication October 20, 1992.