The quantity and quality of soil organic matter and humic substances following dry-farming and subsequent restoration in an upland pasture

Mobile and potentially mobile forms of heavy metals are probably one of the most important toxic hazards in the environment. Besides pH, which is a factor influencing the mobility/availability of heavy metals to the greatest extent, the content and mainly the quality of soil organic matter play a very important role in the evaluation of heavy metal behaviour in the environment. The fraction of metals bound to organic compounds is exclusively associated with humic substances and particularly with humic acids (HA). A relationship between the parameters reflecting the actual structure of humic acids and mobile or potentially mobile fractions of heavy metals was studied in 12 soil localities representing different soil types. It can be stated on the basis of the acquired data that heavy metals tend to form complexes with soil organic matter that are different for each metal. The results suggest that copper is bound mainly in an unavailable form (significant correlations of fraction IV with HA parameters) and cadmium prefers exchangeable forms (significant correlations of fraction I with HA parameters) and is more available. It can be assumed on the basis Spearman’s correlations that mobile fractions of cadmium are predominantly bound to the aliphatic part of humic substances, and copper prefers strong bonds to humic acids with a high degree of humification.

Download Full-text

Characterization of Soil Organic Matter Individual Fractions (Fulvic Acids, Humic Acids, and Humins) by Spectroscopic and Electrochemical Techniques in Agricultural Soils

Agronomy ◽

10.3390/agronomy11061067 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1067

Author(s):

Aleksandra Ukalska-Jaruga ◽

Romualda Bejger ◽

Guillaume Debaene ◽

Bożena Smreczak

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Soil Organic Matter ◽

Humic Substances ◽

Humic Acids ◽

Agricultural Soils ◽

Fulvic Acids ◽

Sorption Properties ◽

Aliphatic Chains

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.

Download Full-text

Conversion of Brazilian savannah to agricultural land affects quantity and quality of labile soil organic matter

Geoderma ◽

10.1016/j.geoderma.2021.115509 ◽

2022 ◽

Vol 406 ◽

pp. 115509

Author(s):

Rafael S. Santos ◽

Martin Wiesmeier ◽

Dener M.S. Oliveira ◽

Jorge L. Locatelli ◽

Matheus S.C. Barreto ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Agricultural Land ◽

Brazilian Savannah ◽

Labile Soil Organic Matter

Download Full-text

Biomass of Coarse Woody Debris Following Fire and Clearcutting in Lodgepole Pine Forests

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.1997.3317 ◽

1997 ◽

Vol 21 ◽

pp. 33-35

Author(s):

Dennis Knight ◽

Daniel Tinker

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Coarse Woody Debris ◽

Significant Contribution ◽

Woody Debris ◽

Mineral Soil ◽

Primary Source ◽

Timber Harvesting ◽

Micro Organisms

In forest ecosystems, the decomposition of coarse woody debris, woody roots, twigs, leaves and micro-organisms is a primary source of mineral soil organic matter. Primary productivity, the accumulation of nutrients, and other important ecosystem processes are largely dependent on the mineral soil organic matter that has developed during hundreds or thousands of years. Large quantities of coarse woody debris are typically produced following natural disturbances such as fires, pest/pathogen outbreaks, and windstorms, and make a significant contribution to the formation of soil organic matter (SOM). In contrast, timber harvesting often removes much of the coarse woody debris (CWD), which could result in a decrease in the quantity and a change in the quality of mineral soil organic matter.

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

CO2-C losses and carbon quality of selected Maritime Antarctic soils

Antarctic Science ◽

10.1017/s0954102012000648 ◽

2012 ◽

Vol 25 (1) ◽

pp. 11-18 ◽

Cited By ~ 9

Author(s):

Juliana Vanir De Souza Carvalho ◽

Eduardo De Sá Mendonça ◽

Newton La Scala ◽

César Reis ◽

Efrain Lázaro Reis ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Temperature ◽

Soil Carbon ◽

Humic Substances ◽

Microbial Activity ◽

Chemical Characteristics ◽

Maritime Antarctic ◽

Antarctic Soils ◽

Humification Degree

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.

Download Full-text

A molecular dynamic study of Soil Organic Matter stabilization mechanisms

10.5194/egusphere-egu21-2486 ◽

2021 ◽

Author(s):

Edgar Galicia-Andrés ◽

Yerko Escalona ◽

Peter Grančič ◽

Chris Oostenbrink ◽

Daniel Tunega ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Humic Substances ◽

Clay Mineralogy ◽

Metal Cations ◽

Dense Matter ◽

Chemical Degradation ◽

Molecular Graphics ◽

Organic Matter Stabilization ◽

Reactive Surfaces

It is well known that some fractions of soil organic matter (SOM) can resist to physical and (bio)chemical degradation which can be attributed to factors ranging from molecular properties to the preference for digesting other molecular species by microorganisms. Some mechanisms, by which organic matter is protected, are often referred to as: physical stabilization through microaggregation, chemical stabilization by formation of SOM-mineral aggregates, and biochemical stabilization through the formation of recalcitrant SOM.Protection mechanisms are responsible for the accumulation process of organic carbon, reducing the exposure of organic matter and making it less vulnerable to microbial, enzymatic or chemical attacks. In these mechanisms, water molecular bridges and metal cation bridges play a key role. Cation bridges serve as aggregation sites on humic substances, forming dense matter, in comparison to systems where bridges are missing. This effect is enhanced in systems with cations at higher oxidation states.By using the modeler tool developed in our group (Vienna Soil&#8211;Organic&#8211;Matter Modeler, VSOMM2) (Escalona et al., 2021), we generated aggregate models of humic substances at atomistic scale reflecting the diversity in composition, size and conformations of the constituting molecules. Further, we built models of organo-clay aggregates using kaolinite and montmorillonite as typical soil minerals. This allowed a systematic study to understand the effect of the surrounding environment at microscopic scale, not fully accessible experimentally.Molecular simulations of the adsorption process of SOM aggregates on the reactive surfaces of led to two observations: 1) the humic substances aggregates were able to interact with the reactive surfaces mainly via hydrogen bonds forming stable organic matter-clay complexes and 2) the aggregates subsequently lost rigidity and stability after metal cations removing, consequently leading to a gradual loss of humic substance molecules, evidencing the role of metal cations in the protection mechanism of soil organic matter aggregates and possibly explaining its recalcitrance (Galicia-Andr&#233;s et al., 2021).References<ul><li>Escalona, Y., Petrov, D., & Oostenbrink, C. (2021). Vienna soil organic matter modeler 2 (VSOMM2). Journal of Molecular Graphics and Modelling, 103, 107817. https://doi.org/10.1016/j.jmgm.2020.107817</li> <li>Galicia-Andr&#233;s, E., Gran&#269;i&#269;, P., Gerzabek, M. H., Oostenbrink, C., & Tunega, D. (2021). Modeling of interactions in natural and synthetic organoclays. In I. C. Sainz Diaz (Ed.), Computational modeling in clay mineralogy.</li> </ul>

Download Full-text

Quality of Soil Organic Matter Under Crop Rotations and Continuous Cultures

Soil as World Heritage ◽

10.1007/978-94-007-6187-2_23 ◽

2013 ◽

pp. 251-259

Author(s):

B. P. Boincean ◽

L. I. Bulat ◽

M. A. Bugaciuc ◽

M. Cebotari ◽

V. V. Cuzeac

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Crop Rotations ◽

Continuous Cultures

Download Full-text

Effect of Different Doses of Nutrients on Changes of Soil Organic Matter in Rendzic Leptosol

Agriculture (Pol nohospodárstvo) ◽

10.2478/v10207-012-0014-7 ◽

2012 ◽

Vol 58 (4) ◽

pp. 131-137

Author(s):

Vladimír Šimanský ◽

Erika Tobiašová

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Samples ◽

Water Soluble ◽

Hot Water ◽

Fertilizer Treatment ◽

Content Increase ◽

Npk Fertilizer ◽

Different Doses

Abstract The effect of different doses of NPK fertilizer on the changes in quantity and quality of soil organic matter (SOM) in Rendzic Leptosol was evaluated. Soil samples were taken from three treatments of different fertilization: (1) control - without fertilization, (2) NPK 1 - doses of NPK fertilizer in 1st degree intensity for vine, and (3) NPK 3 - doses of NPK fertilizer in 3rd degree intensity for vine in the vineyard. Soil samples were collected in years 2008-2011 during the spring. The higher dose of NPK fertilizer (3rd degree intensity of vineyards fertilization) was responsible for the higher content of labile carbon (by 21% in 0-0.3 m and by 11% as average of the two depths 0-0.3 m and 0.3-0.6 m). However, by application of a higher dose of NPK (1.39%) in comparison to no fertilizer treatment (1.35%) or NPK 1 (1.35%) the tendency of total organic carbon content increase and hot-water soluble carbon decrease were determined. Fertilization had a negative effect on SOM stability. Intensity of fertilization affected the changes in quantity and quality of SOM; therefore it is very important to pay attention to the quantity and quality of organic matter in productive vineyards.

Download Full-text