Journal Article

PreJuSER-11859

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Organic-carbon fractions in an agricultural topsoil assessed by the determination of the soil mineral surface area

Séquaris, J.-M.FZJ* ; Guisado, G. ; Magarinos, M. ; Moreno, C. ; Burauel, P.FZJ* ; Narres, H.-D.FZJ* ; Vereecken, H.FZJ*

2010
Wiley-VCH Weinheim

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Please use a persistent id in citations: doi:10.1002/jpln.200800224

Abstract: According to recent conceptual models, the organic carbon (OC) of soils can be divided into OC fractions of increasing stability from labile free OC to resistant OC associated with the soil mineral phase. In this study, we present a method for quantifying two OC fractions based on soil aggregate-size fractionation and the N-2 gas-adsorption method. For this purpose, we analyzed soil material of the plow layer of a Haplic Chernozem subjected to different fertilizer treatments (no fertilizer, mineral fertilizer, mineral and organic fertilizer). The total organic-C concentration (TOO) and the clay content of the different size fractions were determined as well as the specific surface area (SSA(mineral)) and the sample pore volume after thermal oxidation (OC-free). The TOC of the different soil-aggregate fractions was linearly related to SSA(mineral). Clay-associated OC and nonassociated OC fractions of the different soil samples were quantified using two methods based on the OC surface loading at the clay fraction. The application of organic fertilizer increased the amount of nonassociated OC but hardly affected the concentration of clay-associated OC. This finding agrees with previous studies on C dynamics in soils and indicates a finite capacity of soil materials to sequester OC. Even without any addition of organic fertilizer, the mineral phase of the analyzed soil material appears to be C-saturated.

Keyword(s): J ; soil physical fractionation (auto) ; N-2 gas-adsorption method (auto) ; OC fractions (auto) ; mineral specific surface area (auto) ; clay-associated OC (auto) ; OC sequestration (auto)

Note: We thank three anonymous reviewers and the Associate Editor for their numerous valuable comments which helped to improve the manuscript. This work was performed as part of the HGF strategy fund project "Soil Functions" We thank C Walraf for her skilful laboratory assistance and J. Borchardt (Troposphere, ICG 2) for his help with the N<INF>2</INF> gas-adsorption technique We are grateful to Dr. M. Kehl (INRES, Bonn University) for the particle-size-distribution analysis The elemental chemical analyses performed at the Central Division of Analytical Chemistry (ZCH) are gratefully acknowledged G Guisado (gregorig@ucr.edu), M. R. Magarinos (rosario.magarinos-bernabe@basf.com), and C Moreno (clkcarlos2@mixmail.com) on leave from the University of Burgos (Spain) were supported by the European Community (Erasmus Grant)

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Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2010

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