| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
a Agriculture and Environment Div., IACR-Rothamsted, Harpenden, Herts, AL5 2JQ, UK
b Dep. of Chemistry, Queen Mary, University of London, London, E1 4NS, UK
c AAT Consultants, 15 Clerk Street, Edinburgh, EH8 9JH, UK
d Dep. of Soil Science and Agricultural Chemistry, Szent István University, 2103 Gödöll
, Hungary
* Corresponding author (saran.sohi{at}bbsrc.ac.uk)
Fractions of soil organic matter (SOM) were obtained from three soils using alternative physical fractionation procedures, and evaluated against the requirements of model pools. We compared two-stage density fractionation (isolating free and intra-aggregate fractions, before and after dispersion, respectively) with particle-size separation of dispersed soil. For full comparison, the organomineral fraction residual from density fractionation was also size separated. In standardizing the density-based method, we found recovery of intra-aggregate organic matter highly sensitive to separation density as compared with the free. Recovery of the intra-aggregate was also influenced by dispersion energy. The greatest amount was obtained using a combination of the highest density (1.80 g cm-3) and dispersion energy (1500 J g-1). Analysis by 13C nuclear magnetic resonance (NMR) showed O-alkyl/alkyl-C ratios 1.38 to 2.30 times greater in intra-aggregate organic matter than in the free. Diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) also indicated a greater proportion of aliphatic hydrocarbon, carboxylic anions, and aromatic C in intra-aggregate organic matter. The findings suggest this fraction comprises more decomposed and transformed organic matter relative to the free. Higher signal/noise ratios in NMR spectra of particle-size fractions (compared with their organomineral equivalents) were attributed to C in particulate SOM, not removed by prior density separation. Whilst particle-size fractions confuse particulate SOM with that attached to mineral surfaces, fractions isolated by two-stage density separation are small in number and display distinct chemical properties. We suggest they provide a sound basis for a model of SOM turnover based on measurable pools.
Abbreviations: CPMAS, cross-polarization magic angle spinning • DRIFT, diffuse reflectance Fourier transform infrared spectroscopy • NMR, nuclear magnetic resonance • SOM, soil organic matter • TOSS, total suppression of sidebands
This article has been cited by other articles:
|
|
 |
|
  E. W. Murage, P. R. Voroney, B. D. Kay, B. Deen, and R. P. Beyaert Dynamics and Turnover of Soil Organic Matter as Affected by Tillage Soil Sci. Soc. Am. J., June 29, 2007; 71(4): 1363 - 1370. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Veenstra, W. R. Horwath, and J. P. Mitchell Tillage and Cover Cropping Effects on Aggregate-Protected Carbon in Cotton and Tomato Soil Sci. Soc. Am. J., March 12, 2007; 71(2): 362 - 371. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Kinyangi, D. Solomon, B. Liang, M. Lerotic, S. Wirick, and J. Lehmann Nanoscale Biogeocomplexity of the Organomineral Assemblage in Soil: Application of STXM Microscopy and C 1s-NEXAFS Spectroscopy Soil Sci. Soc. Am. J., August 22, 2006; 70(5): 1708 - 1718. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. G. Gregorich, M. H. Beare, U. F. McKim, and J. O. Skjemstad Chemical and Biological Characteristics of Physically Uncomplexed Organic Matter Soil Sci. Soc. Am. J., April 19, 2006; 70(3): 975 - 985. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. F. Plante, R. T. Conant, C. E. Stewart, K. Paustian, and J. Six Impact of Soil Texture on the Distribution of Soil Organic Matter in Physical and Chemical Fractions Soil Sci. Soc. Am. J., January 6, 2006; 70(1): 287 - 296. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Rasmussen, M. S. Torn, and R. J. Southard Mineral Assemblage and Aggregates Control Carbon Dynamics in a California Conifer Forest Soil Sci. Soc. Am. J., September 29, 2005; 69(6): 1711 - 1721. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. C. Manning, E. Lopez-Capel, and S. Barker Seeing soil carbon: use of thermal analysis in the characterization of soil C reservoirs of differing stability Mineralogical Magazine, August 1, 2005; 69(4): 425 - 435. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. P. Sohi, N. Mahieu, D. S. Powlson, B. Madari, R. H. Smittenberg, and J. L. Gaunt Investigating the Chemical Characteristics of Soil Organic Matter Fractions Suitable for Modeling Soil Sci. Soc. Am. J., June 28, 2005; 69(4): 1248 - 1255. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Lopez-Capel, S. P. Sohi, J. L. Gaunt, and D. A. C. Manning USE OF THERMOGRAVIMETRY-DIFFERENTIAL SCANNING CALORIMETRY TO CHARACTERIZE MODELABLE SOIL ORGANIC MATTER FRACTIONS Soil Sci. Soc. Am. J., January 1, 2005; 69(1): 136 - 140. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. K. McLauchlan and S. E. Hobbie Comparison of Labile Soil Organic Matter Fractionation Techniques Soil Sci. Soc. Am. J., September 1, 2004; 68(5): 1616 - 1625. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Agronomy Journal | Crop Science | |||
| Journal of Natural Resources and Life Sciences Education |
Vadose Zone Journal | ||||
| Journal of Plant Registrations | Journal of Environmental Quality |
The Plant Genome | |||
