The use of stable carbon isotopes for estimating soil organic matter turnover rates

Bernoux, Martial; Cerri, Carlos Clemente; Neill, Christopher; Moraes, Jener Fernando Leite de

doi:10.1016/s0016-7061(97)00096-7

Cited by 241 publications

(187 citation statements)

References 29 publications

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“…The largest enrichment of 13 C was therefore associated with the SOC present in the H 2 O 2 resistant residue after LF removal. These results are in accord with other studies that documented enrichment of heavier 13 C compared to lighter 12 C with increasing degree of SOM decomposition (Nadelhoffer and Fry 1988;Balesdent et al 1993;Bernoux et al 1998). Such a trend in d 13 C signatures was not observed in soils from cultivated sites, where the d 13 C signatures of contemporary plant inputs are a mixture of both C 3 native species (average d 13 C of -27%) and C 4 corn (average d 13 C of -12%) ( Table 5).…”

Section: Isotopic Analyses Of Soc Before and After Oxidationsupporting

confidence: 92%

Evaluation of structural chemistry and isotopic signatures of refractory soil organic carbon fraction isolated by wet oxidation methods

et al. 2009

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Accurate quantification of different soil organic carbon (SOC) fractions is needed to understand their relative importance in the global C cycle. Among the chemical methods of SOC fractionation, oxidative degradation is considered more promising because of its ability to mimic the natural microbial oxidative processes in soil. This study focuses on detailed understanding of changes in structural chemistry and isotopic signatures of SOC upon different oxidative treatments for assessing the ability of these chemicals to selectively isolate a refractory fraction of SOC. Replicated sampling (to similar to 1 m depth) of pedons classified as Typic Fragiudalf was conducted under four land uses (woodlot, grassland, no-till and conventional-till continuous corn [Zea mays L.]) at Wooster, OH. Soil samples (< 2 mm) were treated with three oxidizing agents (hydrogen peroxide (H₂O₂), disodium peroxodisulfate (Na2S2O8) and sodium hypochlorite (NaOCl)). Oxidation resistant residues and the bulk soil from A1/Ap1 horizons of each land use were further analyzed by solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy and accelerator mass spectrometry to determine structural chemistry and C-14 activity, respectively. Results indicated that, oxidation with NaOCl removed significantly less SOC compared to Na2S2O8 and H₂O₂. The NMR spectra revealed that NaOCl oxidation preferentially removed lignin-derived compounds at 56 ppm and at 110-160 ppm. On the other hand, the SOC resistant to Na2S2O8 and H₂O₂ oxidation were enriched with alkyl C groups, which dominate in recalcitrant macromolecules. This finding was corroborated by the C-14 activity of residual material, which ranged from -542 to -259aEuro degrees for Na2S2O8 resistant SOC and -475 to -182aEuro degrees for H₂O₂ resistant SOC as compared to relatively greater C-14 activity of NaOCl resistant residues (-47 to 61aEuro degrees). Additionally, H₂O₂ treatment on soils after light fraction removal was more effective in isolating the oldest (C-14 activity of -725 to -469aEuro degrees) SOC fraction. The Delta C-14 signature of SOC removed by different oxidizing agents, calculated by mass balance, was more or less similar irrespective of the difference in labile SOC removal efficiency. This suggests that SOC isolated by many fractionation methods is still a mixture of much younger and older material and therefore it is very important that the labile SOC should be completely removed before measuring the turnover time of stable and refractory pools of SOC

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Section: Isotopic Analyses Of Soc Before and After Oxidationsupporting

confidence: 92%

Evaluation of structural chemistry and isotopic signatures of refractory soil organic carbon fraction isolated by wet oxidation methods

et al. 2009

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“…When trees and shrubs (dominantly C 3 species) are replaced by grasses (predominantly C 4 ) it is possible to determine the origin of the SOM from its isotopic composition (Balesdent et al, 1987;Chonè et al, 1991;Bonde et al, 1992;McDonagh et al, 2001;Roscoe et al, 2004;Desjardins et al, 2004;Schwendenmann & Pendall, 2006). Furtherover, the use of 13 C natural abundance technique together with simple mathematical approaches have further improved SOM turnover studies (Noordwijk et al, 1997;Bernoux et al, 1998;Wynn et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Changes in soil organic matter under different land management in misiones province (Argentina)

Píccolo

Andriulo

Mary³

2008

Sci. agric. (Piracicaba, Braz.)

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Highly weathered tropical soils rapidly loose soil organic matter (SOM) and may be affected by water erosion and soil compaction after deforestation and intensive cultivation. With the main objective to estimate the SOM balances in a subtropical soil we determined the dynamics of SOM in a degraded yerba mate (Ilex paraguaiensis Saint Hil.) plantation introduced after deforestation and with elephant grass (Pennisetum purpureum L.) as a cover crop. The study site was in Misiones, Argentina, and we use the natural 13 C abundance methodology and a descriptive model. The study was conducted on three contiguous 50 × 100 m plots of a typic Kandihumult soil with: (i) native forest, (ii) 50 years of continuous yerba mate monoculture with intensive tillage, and (iii) yerba mate associated with elephant grass as a cover crop and no tillage. We determined bulk density, carbon (C), nitrogen (N) and 13 C content of the soil (0 -0.05, 0.05 -0.15 m layers) and the grass biomass. Yerba mate monoculture reduced soil C and N content as well as porosity at 0 -0.15 m depth by 43 and 23%, respectively, as compared to the native forest. After ten years of yerba mate -elephant grass association soil C and N contents at the same depth increased by 19 and 12%, respectively, compared to the yerba mate monoculture, while soil porosity remained similar. Total C input, 13 C, and soil organic C were incorporated into a three compartment model to evaluate elephant grass C dynamics. Through the natural 13 C abundance methodology we tracked the elephant grass C incorporation and the "old" soil C loss, and determined the model parameters -humification (k 1 ) and mineralization (k) coefficients and stable C (C s )-unambiguously. The high k 1 and k predicted by the model are probably explained by elephant grass root system incorporation under no tillage and humid subtropical climate, respectively. In soil under yerba mate monoculture, C s was counted as 91% of the total soil organic C. Key words: Ilex paraguaiensis, Pennisetum purpureum, natural 13 C abundance, soil carbon, modelling MUDANÇAS NA MATÉRIA ORGÂNICA EDAFICA SOB DIFERENTES MANEJOS DE SOLO NA PROVÍNCIA DE MISIONES (ARGENTINA)RESUMO: Os solos altamente intemperizados dos trópicos perdem rapidamente matéria orgânica do solo (SOM) e podem ser afetados pela erosão hídrica e compactação depois de seu deflorestamento e agricultura contínua. O objetivo foi determinar a dinâmica da matéria orgânica do solo com capimelefante (Pennisetum purpureum L.) em um Kandihumult da província de Misiones (Argentina) após desmatamento e cultivo contínuo de erva-mate (Ilex paraguaiensis Saint Hil.), utilizando a metodologia da abundância natural em carbono 13 ( 13 C) e um modelo descritivo. O estudo foi conduzido em três parcelas contíguas de 50 × 100 m. As situações comparadas foram: (a) floresta nativa, e (b) local com 50 anos de monocultivo intensivo de erva-mate, e (c) erva-mate associada com capim-elefante como cultivo de cobertura sob plantio direto. Determinaram-se os conteúdos de carbono (C),...

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“…Em agroecossistemas, a origem do C orgânico do solo pode ser proveniente da vegetação nativa previamente existente ou do remanescente da cultura e do processo de decomposição dos resíduos culturais (BERNOUX et al, 1998).…”

Section: Haynes; Meyer 2002a)unclassified

“…Os estoque de C e N microbiano foram calculados a partir dos teores de C e N da biomassa microbiana, densidade do solo e espessura da camada (BERNOUX et al, 1998), os resultados finais foram expressos em kg ha -1 , de acordo com a Equação 4:…”

Section: Nbm = (Nf-nnf)/kn (3)unclassified

Efeito da remoção de quantidades de palha de cana-de-açúcar na biomassa e na comunidade microbiana do solo

Morais¹

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The use of stable carbon isotopes for estimating soil organic matter turnover rates

Cited by 241 publications

References 29 publications

Evaluation of structural chemistry and isotopic signatures of refractory soil organic carbon fraction isolated by wet oxidation methods

Evaluation of structural chemistry and isotopic signatures of refractory soil organic carbon fraction isolated by wet oxidation methods

Changes in soil organic matter under different land management in misiones province (Argentina)

Efeito da remoção de quantidades de palha de cana-de-açúcar na biomassa e na comunidade microbiana do solo

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