Impacts of Soil Management Practices on the Organic Matter Structure ‐ Investigations by CPMAS <sup>13</sup>CNMR‐Spectroscopy

Fründ, R.; Haider, K.; Lödemann, H.‐D.

doi:10.1002/jpln.19941570106

Cited by 28 publications

(16 citation statements)

References 13 publications

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“…Solid-state 13 C NMR analysis revealed that land-use change imparts only subtle alteration of the chemical composition of SOM despite large changes in its amount (Tables 1, 3). This result is basically the same as the previous studies which not only originate from the temperate region (Skjemstad et al 1986;Hopkins et al 1993;Fründ et al 1994;Preston et al 1994;Kinchesh et al 1995;Mueller and Koegel-Knabner 2009) but also from the tropical areas (Diekow et al 2005a,b). On the other hand, there was a measurable disparity in soil organic C forms under different land use and even under different grass species in the rangeland (RG and RB).…”

Section: Discussionsupporting

confidence: 91%

Effects of land‐use change on chemical composition of soil organic matter in tropical lowland Bolivia

et al. 2009

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Land‐use change affects not only the amount of soil organic matter (SOM) but also its composition. We performed cross‐polarization magic angle spinning (CPMAS) 13C and 15N nuclear magnetic resonance (NMR) spectroscopy to investigate the chemical composition of bulk SOM in topsoils (0–15 cm) under different land use, namely native forest (NF), 27‐year cropland with wheat/soybean rotation (CL) and 27‐year rangelands with guineagrass (RG) and with bahiagrass (RB), in south‐east Bolivia. The findings of this study showed only a subtle alteration of composition of bulk SOM despite the large changes in carbon (C) content. Nevertheless, NF and RB showed a slightly lower abundance of aromatic C but a higher proportion of alkyl C compared to CL and RG where the loss of organic matter was substantial. This suggests that relatively stable components dominated by aromatic structures had relatively enriched during SOM decomposition under agricultural practices. A slight disparity of SOM composition observed between RG and RB (less O‐alkyl C but more aromatic C in RG than RB) suggests that grass species influenced SOM quality even under the same land use, namely the rangeland. On the other hand, organic N composition was less affected by land use or management practice than C forms.

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Section: Discussionsupporting

confidence: 91%

Effects of land‐use change on chemical composition of soil organic matter in tropical lowland Bolivia

et al. 2009

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“…Analyses of spectra of total soil and of soil fractions have shown strong signals due to plant and microbial residues particularly containing carbohydrates, aliphatic and aromatic structures (Wilson et al 1983;Fründ and Lüdemann 1991;Fründ et al 1993;Fox et al 1994;Schnitzer and Monreal 2011). Already 40 years ago, Martin and Haider proposed such molecular contributions by studies on the degradation of 14 C-labelled wheat straw (Martin et al 1974).…”

Section: Structure Of Humic Substancesmentioning

confidence: 97%

From humic substances to soil organic matter–microbial contributions. In honour of Konrad Haider and James P. Martin for their outstanding research contribution to soil science

et al. 2015

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Purpose Many decades of research have shown that humic compounds as part of the soil organic matter (SOM) are essential for the stability and ecosystem services of soils. James P. Martin and Konrad Haider based on several pioneers in humus research improved the basis for the current knowledge of key processes in the soil environment, in particular structure and formation of humus triggered mainly by soil fungi. Other major contributions are briefly described but not in the focus of this article, such as their innovative tracer experiments with isotopelabelled xenobiotic chemicals and natural litter to study their fate. Both scientists inspired generations of younger researchers to advance their approaches and laid the cornerstone of the current understanding of soil organic matter formation. Results and discussion This article values the key experiments of Martin and Haider in this field and the related follow-up research finally resulting in the current view on formation mechanisms of SOM and non-extractable residues (NER) of xenobiotics. The improved understanding of these processes considering necromass with tissue residues of plants, microbes and animals challenges the traditional views of humic matter as macromolecular organic matrix, which according to the research of the last years represents only a variable part of the total organic matter besides associates of low molecular weight molecules. We discuss views on soil organic matter and humic substances that are nowadays considered not to differ in molecular diversity. We will start by demonstrating the understanding of humus characteristics and humus formation three decades ago closely related to the findings of Martin and Haider. Methodological approaches to characterize relevant structural and mechanistic pictures of SOM such as the priming effect, clay mineral catalysed reactions and the various mechanisms by which natural and xenobiotic chemicals are protected in soil are briefly illustrated by examples. Fungal activities in producing secondary metabolites like polyketides and their probably minor contributions to SOM formation are presented. Conclusions and perspectives Open research questions stimulated by these two soil scientists are sketched which are nowadays possible to address by new sophisticated highresolution techniques.

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“…Line-broadening and Fourier transformation are followed by phasing and possibly baseline correction, both of which can have significant effects on the appearance, and thus the intensity distribution of the spectra (Fründ et al 1994a). Ideally, the start of the FID acquisition period coincides with alignment of the magnetization exactly along the detection axis, resulting in a perfect absorption-mode spectrum.…”

Section: Techniques For 13 C Cpmas Nmr Of Sommentioning

confidence: 99%

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Preston¹

2001

Can. J. Soil. Sci.

112

104

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).Preston, C. M. 2001. Carbon-13 solid-state NMR of soil organic matter -using the technique effectively. Can. J. Soil Sci. 81: 255-270. Solid-state 13 C CPMAS NMR offers many options for characterizing carbon in soil organic matter (SOM). Its effectiveness, however, is often limited by a poor understanding of the techniques, and lack of hands-on access and training opportunities for students. Of nearly 250 modern NMR systems in Canada, approximately one is genuinely available for SOM studies, and there is poor communication between NMR operators and SOM users. While quantitative reliability can be addressed to some extent by multiple contact-time experiments or single-pulse (Bloch decay) spectra, it is also important to consider the effects of spectrometer background, spinning sidebands (especially with higher magnetic fields) and processing operations such as linebroadening, phasing and baseline correction. In many studies, more consideration needs to be given to instrument specifications, the type of information needed, and whether sample fractionation or pretreatment should be used. Structural information can be greatly enhanced by dipolar-dephasing and sideband suppression sequences. Sequences based on relaxation differences can reveal pools of carbon with different structures. Data analysis can be enhanced by principal component analysis, spectrum deconvolution and difference spectra. Studies of xenobiotics and C metabolism can be greatly aided by 13 C-labeling. However, a key limitation to SOM applications remains the gap in culture and expectations of the users.Key words: Soil organic matter, 13 C CPMAS NMR, Bloch decay, dipolar dephasing, spinning sidebands Preston, C. M. 2001. Analyse de la matière organique du sol par RMN au 13 C électronique -de l'importance de bien utiliser la technique. Can. J. Soil Sci. 81: 255-270. La RMN CPMAS 13 C électronique permet de caractériser le carbone présent dans la matière organique du sol (MOS) de diverses manières. Il arrive souvent cependant que cette technique perde de son efficacité parce qu'on la connaît mal et parce que les étudiants n'ont pas eu la chance de l'examiner ou de l'expérimenter. Sur les 250 systèmes modernes de RMN existant au Canada, un seul, à peu près, est vraiment réservé à l'étude de la MOS; de plus, la communication passe mal entre les opérateurs de systèmes RMN et les utilisateurs de MOS. Bien qu'on puisse remédier dans une certaine mesure au problème de la fiabilité quantitative en multipliant les expériences sur la durée de contact ou en recourant au spectre obtenu après une seule impulsion (décroissance de Bloch), il ne faut pas négliger les effets de l'arrière-plan du spectromètre, de la rotation des bandes latérales (surtout quand le champ magnétique est puissant) et des opérations de traitement comme l'élargissement des lignes, la mise en phase et la correction de la ligne de base. Dans de nombreux cas, on devrait accorder plus d'attention aux paramètres de l'instrument, au genre de données requises et à la nécessité de fractionner et...

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Impacts of Soil Management Practices on the Organic Matter Structure ‐ Investigations by CPMAS ¹³CNMR‐Spectroscopy

Cited by 28 publications

References 13 publications

Effects of land‐use change on chemical composition of soil organic matter in tropical lowland Bolivia

Effects of land‐use change on chemical composition of soil organic matter in tropical lowland Bolivia

From humic substances to soil organic matter–microbial contributions. In honour of Konrad Haider and James P. Martin for their outstanding research contribution to soil science

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

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Impacts of Soil Management Practices on the Organic Matter Structure ‐ Investigations by CPMAS 13CNMR‐Spectroscopy

Cited by 28 publications

References 13 publications

Effects of land‐use change on chemical composition of soil organic matter in tropical lowland Bolivia

Effects of land‐use change on chemical composition of soil organic matter in tropical lowland Bolivia

From humic substances to soil organic matter–microbial contributions. In honour of Konrad Haider and James P. Martin for their outstanding research contribution to soil science

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

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Impacts of Soil Management Practices on the Organic Matter Structure ‐ Investigations by CPMAS ¹³CNMR‐Spectroscopy