scholarly journals Organo–organic and organo–mineral interfaces in soil at the nanometer scale

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Angela R. Possinger ◽  
Michael J. Zachman ◽  
Akio Enders ◽  
Barnaby D. A. Levin ◽  
David A. Muller ◽  
...  
Keyword(s):  
Organic Matter ◽  
C Sequestration ◽  
Nanometer Scale ◽  
Single Digit ◽  
Cryo Electron Microscopy ◽  
Organic Interfaces ◽  
N Enrichment ◽  
Mineral Interfaces ◽  
Micrometer Size ◽  
Electron Energy Loss

AbstractThe capacity of soil as a carbon (C) sink is mediated by interactions between organic matter and mineral phases. However, previously proposed layered accumulation of organic matter within aggregate organo–mineral microstructures has not yet been confirmed by direct visualization at the necessary nanometer-scale spatial resolution. Here, we identify disordered micrometer-size organic phases rather than previously reported ordered gradients in C functional groups. Using cryo-electron microscopy with electron energy loss spectroscopy (EELS), we show organo–organic interfaces in contrast to exclusively organo–mineral interfaces. Single-digit nanometer-size layers of C forms were detected at the organo–organic interface, showing alkyl C and nitrogen (N) enrichment (by 4 and 7%, respectively). At the organo–mineral interface, 88% (72–92%) and 33% (16–53%) enrichment of N and oxidized C, respectively, indicate different stabilization processes than at organo–organic interfaces. However, N enrichment at both interface types points towards the importance of N-rich residues for greater C sequestration.

scholarly journals A global comparison of grassland biomass responses to CO 2 and nitrogen enrichment

2010 ◽  
Vol 365 (1549) ◽  
pp. 2047-2056 ◽  
Author(s):  
Mark Lee ◽  
Pete Manning ◽  
Janna Rist ◽  
Sally A. Power ◽  
Charles Marsh
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
C Sequestration ◽  
Global Scale ◽  
Scale Model ◽  
Published Data ◽  
Climate Data ◽  
Forage Production ◽  
Global Comparison ◽  
N Enrichment

Grassland ecosystems cover vast areas of the Earth's surface and provide many ecosystem services including carbon (C) storage, biodiversity preservation and the production of livestock forage. Predicting the future delivery of these services is difficult, because widespread changes in atmospheric CO 2 concentration, climate and nitrogen (N) inputs are expected. We compiled published data from global change driver manipulation experiments and combined these with climate data to assess grassland biomass responses to CO 2 and N enrichment across a range of climates. CO 2 and N enrichment generally increased aboveground biomass (AGB) but effects of CO 2 enrichment were weaker than those of N. The response to N was also dependent on the amount of N added and rainfall, with a greater response in high precipitation regions. No relationship between response to CO 2 and climate was detected within our dataset, thus suggesting that other site characteristics, e.g. soils and plant community composition, are more important regulators of grassland responses to CO 2 . A statistical model of AGB response to N was used in conjunction with projected N deposition data to estimate changes to future biomass stocks. This highlighted several potential hotspots (e.g. in some regions of China and India) of grassland AGB gain. Possible benefits for C sequestration and forage production in these regions may be offset by declines in plant biodiversity caused by these biomass gains, thus necessitating careful management if ecosystem service delivery is to be maximized. An approach such as ours, in which meta-analysis is combined with global scale model outputs to make large-scale predictions, may complement the results of dynamic global vegetation models, thus allowing us to form better predictions of biosphere responses to environmental change.

Organic Matter Pore Characterization in Lacustrine Shales with Variable Maturity Using Nanometer-Scale Resolution X-ray Computed Tomography

2017 ◽  
Vol 31 (3) ◽  
pp. 2669-2680 ◽  
Author(s):  
Fujie Jiang ◽  
Jian Chen ◽  
Ziyang Xu ◽  
Zhifang Wang ◽  
Tao Hu ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Organic Matter ◽  
Nanometer Scale ◽  
X Ray ◽  
Pore Characterization ◽  
X Ray Computed

Functional complexity explains the depth-dependent response of organic matter to liming at the nanometer scale

Geoderma ◽  
2022 ◽  
Vol 408 ◽  
pp. 115560
Author(s):  
Yang Li ◽  
Marta Camps-Arbestain ◽  
Catherine P. Whitby ◽  
Tao Wang ◽  
Carsten W. Mueller ◽  
...  
Keyword(s):  
Organic Matter ◽  
Nanometer Scale ◽  
Functional Complexity

Analysis of Extended Energy-Loss Fine Structure of Nanometerscale Clusters

1999 ◽  
Vol 5 (S2) ◽  
pp. 708-709
Author(s):  
Y. Ito ◽  
H. Jain ◽  
D.B. Williams
Keyword(s):  
Fine Structure ◽  
Energy Loss ◽  
Atomic Clusters ◽  
Nanometer Scale ◽  
X Ray ◽  
Small Clusters ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Ionization Edge

Small atomic clusters are of great importance for applications such as catalysts whose activity depends on the surface of the cluster. Attempts to determine the atomic short-range order and size of clusters have been made by analyzing the extended X-ray absorption fine structure (EXAFS). However, the analysis was made on an average of many small clusters. Analysis of extended energy-loss fine structure (EXELFS) in an electron energy-loss spectrum (EELS) has developed to the point where in some cases, the quality of the results is comparable to its X-ray analogue, EXAFS. No other technique provides nanometer-scale spatial resolution of the analyzed area for determining the atomic structure. Most EXELFS analysis has been performed on the K-ionization edge of lighter elements. For heavier elements, a more complex ionization edge such as the L-edge has to be used, due to the inefficiency of collecting high quality EEL spectra at higher energy-losses (Z > 18).

Charge - Ordered Manganeese Oxide Studied By Ω - Filter - Angular Resolved EELS

2001 ◽  
Vol 7 (S2) ◽  
pp. 1146-1147
Author(s):  
Y. Murooka ◽  
N. Tanaka ◽  
M. Hibino ◽  
K. Tsuda ◽  
M. Tanaka
Keyword(s):  
Electronic Structure ◽  
Colossal Magnetoresistance ◽  
Manganese Oxides ◽  
Charge Ordering ◽  
Nanometer Scale ◽  
Theoretical Studies ◽  
Optical Responses ◽  
Column Type ◽  
Valence Electrons ◽  
Electron Energy Loss

Despite of the intensive studies, Colossal Magnetoresistance (CMR) phenomena occurring in manganese oxides is still not fully understood. Theoretical studies based on an ordered crystal phase such as the charge-ordering (CO) phase have shown some successes in reproducing experimental evidences. Recently it was, however, shown that such a CO phase included giant clusters which were as large as 100 nm. This indicates the importance of the nanometer-scale information about the electronic structure to understand the CO. La0.5Sr1.5MnO4 is one of the oxides under intense investigations. in the CO phase, the eg valence electrons were found to be ordered at Mn sites. The optical responses of the CO clusters, however, has not been studied. in this study we have attempted to obtain such information from CO clusters in La0.5Sr1.5MnO4 by angular-resolved electron-energy-loss-spectroscopy (EELS) using an in-column type Ω-spectrometer.

Labile soil organic matter pools under a mixed grass/lucerne pasture and adjacent native bush in Western Australia

Soil Research ◽  
2007 ◽  
Vol 45 (5) ◽  
pp. 333 ◽  
Author(s):  
A. J. Macdonald ◽  
D. V. Murphy ◽  
N. Mahieu ◽  
I. R. P. Fillery
Keyword(s):  
Organic Matter ◽  
Plant Material ◽  
Surface Soil ◽  
Organic C ◽  
Soil Solutions ◽  
Mixed Grass ◽  
N Enrichment ◽  
Organic Matter Fractions ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr

Total C and N were measured in whole soils (0–0.15, 0.15–0.35, and 0.35–0.65 m), light organic matter fractions (<1 g/cm3 (LF 1.0) and 1.0–1.7 g/cm3 (LF 1.7)) in surface soils, and in leaf litter collected from a mixed grass/lucerne pasture and adjacent native bush at Moora, Western Australia. The C content of the plant material and light fractions was characterised by 13C cross-polarisation/magic angle spinning nuclear magnetic resonance (13C CP/MAS NMR) spectroscopy. Water-extractable organic C (WEOC) and N (WEON) were measured in soil, and dissolved organic C (DOC) and N (DON) were measured in soil solutions. In addition, both NO3-N and NH4-N (SMN) were measured in soil solutions and water extracts. Total soil C (0–0.65 m) did not differ significantly between land uses, but there was clear evidence of N enrichment under the pasture system, which contained significantly (P < 0.05) more total N in the surface soil (0–0.15 m) compared with that under native bush. The significantly (P < 0.05) smaller C/N ratios of the surface soil, plant litter, and light fractions (LF 1.0 and 1.7) under the pasture provided further evidence of N enrichment. The 13C CP/MAS NMR spectra for plant material and light fractions did not differ greatly between landuses, but in both cases the O-alkyl : alkyl carbon ratio declined with increasing density. The decomposition and subsequent mineralisation of the relatively N-rich organic matter fractions in the pasture system may have contributed to the significantly (P < 0.05) greater DOC, DON, and SMN concentration measured in soil solutions under pasture compared with those under native bush.

Management effects on the dynamics and storage rates of organic matter in long-term crop rotations

2004 ◽  
Vol 84 (1) ◽  
pp. 49-61 ◽  
Author(s):  
E. A. Paul ◽  
H. P. Collins ◽  
K. Paustian ◽  
E. T. Elliott ◽  
S. Frey ◽  
...  
Keyword(s):  
Organic Matter ◽  
C Sequestration ◽  
Organic C ◽  
Soil C ◽  
Site Analysis ◽  
Laboratory Incubation ◽  
C And N ◽  
A Site ◽  
Management Effects

Factors controlling soil organic matter (SOM) dynamics in soil C sequestration and N fertility were determined from multi-site analysis of long-term, crop rotation experiments in Western Canada. Analyses included bulk density, organic and inorganic C and N, particulate organic C (POM-C) and N (POM -N), and CO2-C evolved during laboratory incubation. The POM-C and POM-N contents varied with soil type. Differences in POM-C contents between treatments at a site (δPOM-C) were related (r2= 0.68) to treatment differences in soil C (δSOC). The CO2-C, evolved during laboratory incubation, was the most sensitive indicator of management effects. The Gray Luvisol (Breton, AB) cultivated plots had a fivefold difference in CO2-C release relative to a twofold difference in soil organic carbon (SOC). Soils from cropped, Black Chernozems (Melfort and Indian Head, SK) and Dark Brown Chernozems (Lethbridge, AB) released 50 to 60% as much CO2-C as grassland soils. Differences in CO2 evolution from the treatment with the lowest SOM on a site and that of other treatments (δCO2-C) in the early stages of the incubation were correlated to δPOM-C and this pool reflects short-term SOC storage. Management for soil fertility, such as N release, may differ from management for C sequestration. Key words: Multi-site analysis, soil management, soil C and N, POM-C and N, CO2 evolution

Spatial organization of soil microaggregates

2020 ◽  
Author(s):  
Eva Lehndorff ◽  
Nele Meyer ◽  
Andrey Radionov ◽  
Lutz Plümmer ◽  
Peter Rottmann ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Spatial Organization ◽  
Inorganic Compounds ◽  
Spatial Relationship ◽  
Clay Content ◽  
Spatial Arrangement ◽  
C Sequestration ◽  
Spatial Correlations ◽  
Soil Minerals

&lt;p&gt;The physical arrangement of soil compounds in microaggregates is important in many ways, e.g. by controlling soil stability and C sequestration. However, little is known about the spatial arrangement of organic and inorganic compounds in soil microaggregates, due to the lack of in-situ analyses in undisturbed material. Here we hypothesize that microaggregates are spatially organized, resulting in deterministic, predictable spatial patterns of different organic matter and mineral phases and that this organization depends on the abundance of specific phases such as on clay mineral content. We separated the water stable, occluded large and small microaggregate fractions from Ap horizons of a sequence of sandy to loamy Luvisols (19 to 35% clay, Scheyern, Germany) and subjected in total 60 individual aggregates to elemental mapping by electron probe micro analysis (EPMA), which recorded C, N, P, Al, Fe, Ca, K, Cl, and Si contents at &amp;#181;m scale resolution. Spatial arrangements of soil organic matter and soil minerals were extracted using cluster analyses. We found a pronounced heterogeneity in aggregate structure and composition, which was not reproducible and largely independent from clay content in soil. However, neighborhood analyses revealed close spatial correlations between organic matter debris (C:N app. 100:10) and microbial organic matter (C:N app. 10:1) indicating a spatial relationship between source and consumer. There was no systematic relationship between soil minerals and organic matter, suggesting that well-established macroscale correlations between contents of pedogenic oxides and clay minerals with soil organic matter storage do not apply to soil microaggregates.&lt;/p&gt;

Humus, nitrogen and energy balances, and greenhouse gas emissions in a long-term field experiment with compost compared with mineral fertilisation

Soil Research ◽  
2016 ◽  
Vol 54 (2) ◽  
pp. 254 ◽  
Author(s):  
Eva Erhart ◽  
Harald Schmid ◽  
Wilfried Hartl ◽  
Kurt-Jürgen Hülsbergen
Keyword(s):  
Organic Matter ◽  
Field Experiment ◽  
Greenhouse Gas ◽  
Ghg Emissions ◽  
Organic Matter Content ◽  
C Sequestration ◽  
Organic C ◽  
Soil C ◽  
Positive Balance ◽  
Energy Balances

Compost fertilisation is one way to close material cycles for organic matter and plant nutrients and to increase soil organic matter content. In this study, humus, nitrogen (N) and energy balances, and greenhouse gas (GHG) emissions were calculated for a 14-year field experiment using the model software REPRO. Humus balances showed that compost fertilisation at a rate of 8 t/ha.year resulted in a positive balance of 115 kg carbon (C)/ha.year. With 14 and 20 t/ha.year of compost, respectively, humus accumulated at rates of 558 and 1021 kg C/ha.year. With mineral fertilisation at rates of 29–62 kg N/ha.year, balances were moderately negative (–169 to –227 kg C/ha.year), and a clear humus deficit of –457 kg C/ha.year showed in the unfertilised control. Compared with measured soil organic C (SOC) data, REPRO predicted SOC contents fairly well with the exception of the treatments with high compost rates, where SOC contents were overestimated by REPRO. GHG balances calculated with soil C sequestration on the basis of humus balances, and on the basis of soil analyses, indicated negative GHG emissions with medium and high compost rates. Mineral fertilisation yielded net GHG emissions of ~2000 kg CO2-eq/ha.year. The findings underline that compost fertilisation holds potential for C sequestration and for the reduction of GHG emissions, even though this potential is bound to level off with increasing soil C saturation.

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