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 Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (88) Citing Articles via Google Scholar Google Scholar Articles by Skjemstad, J. O. Articles by Barron, P. F. Search for Related Content PubMed Articles by Skjemstad, J. O. Articles by Barron, P. F. Agricola Articles by Skjemstad, J. O. Articles by Barron, P. F.

Spectroscopic Investigations of Cultivation Effects on Organic Matter of Vertisols¹

ABSTRACT

Solid state carbon-13 nuclear magnetic resonance (¹³C NMR) spectroscopy with cross polarization and magic angle spinning (CP/MAS) was used to study the effect of cultivation on the nature of organic matter in a Vertisol (mesic, mixed, clayey, Typic Chromusterts). Continuous cultivation for 20, 35, and 45 yr resulted in 50, 61, and 66% loss in organic matter, respectively, from the 0- to 0.1m layer. However, ¹³C NMR spectroscopy performed directly on samples from these cultivated soils (0–0.1 m depth) and on adjoining virgin soil under native, virgin brigalow (Acacia harpophylla) scrub showed only minor differences in the in situ organic matter. Resonance bands representing long-chained alkyl groups were the dominant feature of all four spectra and represented >50% of the organic C. Fractions obtained from density separations (<1.6, 1.6–2.0, 2.0–2.4, >2.4 Mg m^–3) made on the soil under native scrub and the soil that had been cultivated for 35 yr showed that the organic C content of the light fractions (<2.0 Mg m^–3) was greatly reduced after cultivation, while the heaviest fraction remained unchanged. Carbon-13 NMR spectra determined on the fractions with a density <2.4 Mg m^–3 showed that the organic matter with the highest alkyl content occurred in the 2.0- to 2.4-Mg m^–3 fraction. Also, the relative amount of humic acid decreased after cultivation, while the relative amount of clay-bound organic matter increased. Ultraviolet/visible and infrared spectroscopic analyses of the humic acid and humin fractions agreed well with the NMR data. It is concluded that the major mechanism responsible for the relative stability of the persistent soil organic matter is a physical association with the inorganic components of the soil, rather than an inherent chemical or biochemical inertness of the organic matter itself.

¹ Contribution from CSIRO, Div. of Soils, Brisbane, Queensland Wheat Research Institute, Toowoomba, and NMR Centre, Griffith Univ., Brisbane. This research was supported in part by the Queensland Wheat Industry Research Committee.

² Experimental Scientist, Div. of Soils, CSIRO, St. Lucia, 4067; Soil Scientist, Queensland Wheat Research Institute, Toowoomba 4350; and Research Fellow, Brisbane NMR Centre, Griffith Univ., Nathan 4111, Australia, respectively.

Received for publication May 24, 1985.

This article has been cited by other articles:

				S. Haile-Mariam, H. P. Collins, S. Wright, and E. A. Paul Fractionation and Long-Term Laboratory Incubation to Measure Soil Organic Matter Dynamics Soil Sci. Soc. Am. J., January 25, 2008; 72(2): 370 - 378. [Abstract] [Full Text] [PDF]

				D. Solomon, J. Lehmann, J. Kinyangi, B. Liang, and T. Schafer Carbon K-Edge NEXAFS and FTIR-ATR Spectroscopic Investigation of Organic Carbon Speciation in Soils Soil Sci. Soc. Am. J., January 1, 2005; 69(1): 107 - 119. [Abstract] [Full Text] [PDF]

				D. Solomon, F. Fritzsche, M. Tekalign, J. Lehmann, and W. Zech Soil Organic Matter Composition in the Subhumid Ethiopian Highlands as Influenced by Deforestation and Agricultural Management Soil Sci. Soc. Am. J., January 1, 2002; 66(1): 68 - 82. [Abstract] [Full Text] [PDF]

				W. Amelung, K.W. Flach, and W. Zech Neutral and Acidic Sugars in Particle-Size Fractions as Influenced by Climate Soil Sci. Soc. Am. J., July 1, 1999; 63(4): 865 - 873. [Abstract] [Full Text]