The impact of exotic forest plantations on the chemical composition of soil organic matter in Southern Brazil as assessed by Py–GC/MS and lipid extracts study

Soil organic matter (SOM) is composed of many pools with different properties (e.g. turnover times) which are generally used in biogeochemical models to predict carbon (C) dynamics. Physical fractionation methods are applied to isolate soil fractions that correspond to these pools. This allows the characterisation of chemical composition and C content of these fractions. There is still a lack of knowledge on how these individual fractions are affected by different climate change drivers, and therefore the fate of SOM remains elusive. We sampled soils from a multifactorial climate change experiment in a managed grassland in Austria four years after starting the experiment to investigate the response of SOM in physical soil fractions to temperature (eT: ambient and elevated by +3&#176;C), atmospheric CO2-concentration (eCO2: ambient and elevated by +300 ppm) and to a future climate treatment (eT x eCO2: +3&#176;C and + 300 ppm). A combination of slaking and wet sieving was used to obtain three size classes: macro-aggregates (maA, > 250 &#181;m), micro-aggregates (miA, 63 &#181;m &#8211; 250 &#181;m) and free silt & clay (sc, < 63 &#181;m). In both maA and miA, four different physical OM fractions were then isolated by density fractionation (using sodium polytungstate of &#961; = 1.6 g*cm-3, ultrasonication and sieving): Free POM (fPOM), intra-aggregate POM (iPOM), silt & clay associated OM (SCaOM) and sand-associated OM (SaOM). We measured C and N contents and isotopic composition by EA-IRMS in all fractions and size classes and used a Pyrolysis-GC/MS approach to assess their chemical composition. For eCO2 and eT x eCO2 plots, an isotope mixing-model was used to calculate the proportion of recent C derived from the elevated CO2 treatment. Total soil C and N did not significantly change with treatments.&#160; eCO2 decreased the relative proportion of maA-mineral-associated C and increased C in fPOM and iPOM. About 20% of bulk soil C was represented by the recent C derived from the CO2 fumigation treatment. This significantly differed between size classes and density fractions (p < 0.001), which indicates inherent differences in OM age and turnover. Warming reduced the amount of new C incorporated into size classes. We found that each size class and fraction possessed a unique chemical fingerprint, but this was not significantly changed by the treatments. Overall, our results show that while climate change effects on total soil C were not significant after 4 years, soil fractions showed specific effects. Chemical composition differed significantly between size classes and fractions but was unaffected by simulated climate change. This highlights the importance to separate SOM into differing pools, while including changes to the molecular composition might not be necessary for improving model predictions.&#160;&#160;&#160;&#160;

Download Full-text

Composition changes of eroded carbon at different spatial scales in a tropical watershed suggest enrichment of degraded material during transport

Biogeosciences ◽

10.5194/bg-11-3299-2014 ◽

2014 ◽

Vol 11 (12) ◽

pp. 3299-3305 ◽

Cited By ~ 3

Author(s):

C. Rumpel ◽

V. Chaplot ◽

P. Ciais ◽

A. Chabbi ◽

B. Bouahom ◽

...

Keyword(s):

Organic Matter ◽

Chemical Composition ◽

Soil Organic Matter ◽

Isotope Composition ◽

Spatial Scales ◽

Suspended Sediments ◽

Resonance Spectroscopy ◽

Vertical Decomposition ◽

Degraded Material ◽

Soil Units

Abstract. In order to assess whether eroded carbon is a net source or sink of atmospheric CO2, characterisation of the chemical composition and residence time of eroded organic matter (EOM) at the landscape level is needed. This information is crucial to evaluate (1) how fast EOM can be decomposed by soil microbes during its lateral transport and (2) its impact at deposition sites. This study considers a continuum of scales to measure the composition of EOM across a steep hillslope landscape of the Mekong basin with intense erosion. We sampled suspended sediments eroded during rainfall events from runoff plots (1 and 2.5 m2) and the outlets of four nested watersheds (0.6 × 104 to 1 × 107 m2). Here we show that changes in the chemical composition of EOM (measured by nuclear magnetic resonance spectroscopy) and in its 13C and 15N isotope composition from plot scale through to landscape scale provide consistent evidence for enrichment of more decomposed EOM across distances of 10 km. Between individual soil units (1 m2) to a small watershed (107 m2), the observed 28% decrease of the C/N ratio, the enrichment of 13C and 15N isotopes as well as O-alkyl C in EOM is of similar magnitude as changes recorded with depth in soil profiles due to soil organic matter "vertical" decomposition. Radiocarbon measurements indicated ageing of EOM from the plot to the watershed scale. Therefore transport of EOM may lead to enrichment of stabilised soil organic matter compounds, eventually being subject to export from the watershed.

Download Full-text

Differences in soil organic matter and humus of sandy soil after application of biochar substrates and combination of biochar substrates with mineral fertilizers

Acta fytotechnica et zootechnica ◽

10.15414/afz.2020.23.03.117-124 ◽

2020 ◽

Vol 23 (3) ◽

pp. 117-124

Author(s):

Dušan Šrank ◽

Vladimír Šimanský

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Carbon Content ◽

Humic Substances ◽

Sandy Soil ◽

The Other ◽

Mineral Fertilizers ◽

Other Hand ◽

Sheep Manure ◽

The Impact

The effort to achieve the sustainable farming system in arable soil led to the intensive search for a new solution but an inspiration can also be found in the application of traditional methods of soil fertility improvement as it is shown in numerous examples in history. Recently many scientific teams have focused their attention on the evaluation of biochar effects on soil properties and crop yields. Since there are a lot of knowledge gaps, especially in explanations how biochar can affect soil organic matter (SOM) and humus substances, we aimed this study at the solution of these questions. Therefore, the objective of the experiment was to evaluate the impact of two biochar substrates (B1 – biochar blended with sheep manure, and B2 – biochar blended with sheep manure and the residue from the biogas station) at two rates (10 and 20 t ha-1) applied alone or in combination with mineral fertilizers (Urea was applied in 2018, at rate 100 kg ha-1, and Urea at rate 100 kg ha-1 + AMOFOS NP 12-52 at 100 kg ha-1 were applied in 2019) on the quantity and quality of SOM and humus of sandy soil (Arenosol, Dolná Streda, Slovakia). The results showed that application of the biochar substrates together with mineral fertilizers (MF) had more pronounced effect on the organic matter mineralization in the sandy soil which resulted in low accumulation of soil organic carbon (Corg) and labile carbon compared to biochar substrates treatments without MF. The share of humic substances in Corg significantly decreased by 16, 50, 16 and 24% in B1 at 10 t ha-1, B1 at 20 t ha-1, B2 at 10 t ha-1 and B2 at 20 t ha-1 treatments, respectively, compared to the control. A similar tendency was observed for biochar substrates treatments + MF, compared to MF control. The carbon content of humic substances (CHS) was equal to 4.40 – 5.80 g kg-1 and the biochar substrates had statistically significant influence on CHS content. On average, there was a smaller decrease of CHS in B1 at rate 10 t ha-1 than at rate 20 t ha-1 and no effect of B2 compared to control. The carbon content of fulvic acid (CFA) was 9% higher in B1 at 10 t ha-1, and 20 t ha-1, 47% higher in B2 at 10 t ha-1 and 17% higher in B2 at 20 t ha-1 compared to control. As a result of biochar substrates + MF application, the reduction in CFA was observed. The results showed a decrease of CHA : CFA ratio with association to biochar substrates alone application compared to control on one hand, and a wider of CHA : CFA ratio in biochar substrates + MF treatments in comparison to MF control on the other hand. Humus stability was increased in biochar substrates alone treatments compared to control, on the other hand, compared to MF control, the application of biochar substrates + MF resulted in a lower humus stability.

Download Full-text

Chemical composition of soil organic matter and potential enzyme activity in the topsoil along a moisture gradient in the High Arctic (Svalbard)

Geoderma ◽

10.1016/j.geoderma.2020.114304 ◽

2020 ◽

Vol 368 ◽

pp. 114304 ◽

Cited By ~ 1

Author(s):

Ekaterina Pushkareva ◽

Kai-Uwe Eckhardt ◽

Vivien Hotter ◽

Aline Frossard ◽

Peter Leinweber ◽

...

Keyword(s):

Organic Matter ◽

Enzyme Activity ◽

Chemical Composition ◽

Soil Organic Matter ◽

High Arctic ◽

Moisture Gradient ◽

Potential Enzyme Activity

Download Full-text

Investigating the impact of in situ soil organic matter degradation through porewater spectroscopic analyses on marsh edge erosion

Chemosphere ◽

10.1016/j.chemosphere.2020.129266 ◽

2021 ◽

Vol 268 ◽

pp. 129266

Author(s):

Michael P. Hayes ◽

Yadav Sapkota ◽

John R. White ◽

Robert L. Cook

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Organic Matter Degradation ◽

Marsh Edge ◽

Spectroscopic Analyses ◽

The Impact

Download Full-text

Evaluation of Noah-MP Land-Model Uncertainties over Sparsely Vegetated Sites on the Tibet Plateau

Atmosphere ◽

10.3390/atmos11050458 ◽

2020 ◽

Vol 11 (5) ◽

pp. 458

Author(s):

Guo Zhang ◽

Fei Chen ◽

Yueli Chen ◽

Jianduo Li ◽

Xindong Peng

Keyword(s):

Heat Flux ◽

Organic Matter ◽

Soil Organic Matter ◽

Tibetan Plateau ◽

Sensible Heat Flux ◽

Limiting Factors ◽

Tibet Plateau ◽

The Tibetan Plateau ◽

Annual Total ◽

The Impact

The water budget and energy exchange over the Tibetan Plateau (TP) region play an important role on the Asian monsoon. However, it is not well presented in the current land surface models (LSMs). In this study, uncertainties in the Noah with multiparameterization (Noah-MP) LSM are assessed through physics ensemble simulations in three sparsely vegetated sites located in the central TP. The impact of soil organic matter on energy flux and water cycles, along with the influence of uncertainties in precipitation are explored using observations at those sites during the third Tibetan Plateau Experiment from 1August2014 to31July2015. The greatest uncertainties are in the subprocesses of the canopy resistance, soil moisture limiting factors for evaporation, runoff (RNF) and ground water, and surface-layer parameterization. These uncertain subprocesses do not change across the different precipitation datasets. More precipitation can increase the annual total net radiation (Rn), latent heat flux (LH) and RNF, but decrease sensible heat flux (SH). Soil organic matter enlarges the annual total LH by ~26% but lessens the annual total Rn, SH, and RNF by ~7%, 7%, and 39%, respectively. Its effect on the LH and RNF at the Nagqu site, which has a sand soil texture type, is greater than that at the other two sites with sandy loam. This study highlights the importance of precipitation uncertainties and the effect of soil organic matter on the Noah-MP land-model simulations. It provides a guidance to improve the Noah-MP LSM further and hence the land-atmosphere interactions simulated by weather and climate models over the TP region.

Download Full-text

Temperature response of litter and soil organic matter decomposition is determined by chemical composition of organic material

Global Change Biology ◽

10.1111/gcb.12342 ◽

2013 ◽

Vol 19 (12) ◽

pp. 3858-3871 ◽

Cited By ~ 47

Author(s):

Björn Erhagen ◽

Mats Öquist ◽

Tobias Sparrman ◽

Mahsa Haei ◽

Ulrik Ilstedt ◽

...

Keyword(s):

Organic Matter ◽

Chemical Composition ◽

Soil Organic Matter ◽

Organic Material ◽

Temperature Response ◽

Organic Matter Decomposition ◽

Soil Organic Matter Decomposition

Download Full-text

Characteristics of bottom sediments of Lake Widryńskie

Limnological Review ◽

10.2478/v10194-012-0061-5 ◽

2012 ◽

Vol 12 (4) ◽

pp. 207-212 ◽

Cited By ~ 1

Author(s):

Daniel Szymański ◽

Julita Dunalska ◽

Michał Łopata ◽

Izabela Bigaj ◽

Rafał Zieliński

Keyword(s):

Organic Matter ◽

Chemical Composition ◽

Bottom Sediments ◽

Dry Weight ◽

Calcium Carbonates ◽

Dominant Component ◽

Littoral Sediments ◽

The Impact ◽

Made In ◽

Profundal Zone

AbstractThe aim of this study was to determine the chemical composition of Lake Widryńskie bottom sediments (max. depth. 27.0 m, area 123.9 ha). The sampling of bottom sediments was conducted once, on 16 August 2010. Sampling was made in 10 specific areas. Among the 10 samples, 4 samples were taken from the littoral and sublittoral zones, while the rest were taken from the profundal zone. The dominant component of the sediments was silica and calcium carbonates were subdominant. Based on the survey, it was determined that silica occurred in greater numbers in littoral sediments, while in sublittoral sediments there was increased participation in the chemical composition of organic matter. The elements that build a capacity complex were a small percentage of the dry weight of sediment. Sediment from the vicinity of inflows contains higher amounts of silica, which confirmed the impact of the catchment on the chemical composition of sediments.

Download Full-text