Accrual of carbon (C) and nitrogen (N) in soil is a significant and realizable management option to mitigate climate change; thus, a clear understanding of the mechanisms controlling the persistence ...of C and N in soil organic matter (SOM) across different ecosystems has never been more needed. Here, we investigated SOM distribution between physically and chemically stabilized fractions in soils from a variety of ecosystems (i.e., coniferous and broadleaved forest soils, grassland soils, technosols, and agricultural soils). Using elemental and thermal analyses, we examined changes in the quantity and quality of physically fractionated SOM pools characterized by different mechanisms of protection from decomposition. Independently of the ecosystem type, most of the organic C and total N were found in the mineral-associated SOM pool, known to be protected mainly by chemical mechanisms. Indexes of thermal stability and C/N ratio of this heavy SOM fraction were lower (especially in agricultural soils) compared to light SOM fractions found free or occluded in aggregates, and suggested a marked presence of inherently labile compounds. Our results confirm that the association of labile organic molecules with soil minerals is a major stabilization mechanism of SOM, and demonstrate that this is a generalizable finding occurring across different mineral soils and ecosystems.
Soil poral architecture controls soil functioning and is submitted to temporal changes. The monitoring of soil structure dynamics is complicated by inherent technical constraints in its measurement ...that are either punctual or complex. In this study, four soils, from a natural one to incrementally anthropized (including three Technosols: Spolic Toxic, Terric Transportic, Spolic Garbic Hydric), have been studied. Seven 2-m3 lysimetric columns have been setup to compare planted and non-planted treatments over 3 to 6years. Data on the water balance and the hydrodynamics were continuously acquired. Differences were observed between the various soils as a function of their texture. The presence of vegetation also led to significant differences, especially in hot periods, between the vegetated and the bare soils treatments: the amount of water stored into the soil was up to 210Lm−2 higher for bare soil. Furthermore, the analysis of the “critical water storage capacity” highlighted differences in the hydrodynamics at two time scales. For vegetated soils, similar seasonal variations depending on the climatic conditions were observed for all soils, with higher SCRIT values in cold periods compared to hot periods (differences were up to 190Lm−2). These results were attributed to roots development over the climatic year that decreases water storage capacity and increases preferential flows. Besides, significant trend evolution was also observed but only for the youngest i.e. the most anthropized soils. Their total water storage capacity decreased down to 52%. It is possibly due to soil compaction, the increase of pore connectivity related to root development and the formation of organo-mineral associations. Our work promotes the association of monitored lysimeters as tool and the study of soils within a gradient of anthropization in order to describe a pedogenetic process like the dynamics of soil porosity.
•Lysimetric monitoring of the water budget of a range of soils, including Technosols•Different hydrodynamics were visible as a function of both soils and time.•Temporal dynamics of water budget followed the seasonal climatic variations.•The most anthropised soils exhibited a decrease of their total water storage capacity.
•Signs of anthropogenic soil transformation were found at all plots.•The soil cover on the plots is a combination of both natural and anthropogenic soils.•The anthropogenic sediments thickness varies ...from 10 to 135 cm.•The supplementary qualifier Waric introduction is suggested in the WRB new version.
In this paper, we studied the soils of recreational areas of Volgograd within three research areas. The survey found that in research area I the soils spatial distribution is mainly represented by the following soil group according to WRB: Urbic Technosols, Urbic Technosols (Mollic) and Gleyic Terric Phaeozem (Mollic, Prototechnic). Buried soils are represented by Gleic Cambisols (Protocalcic). In research area II, among natural soils, the largest areas are occupied by Calcaric Fluvisols (Loamic, Technic, Protovertic), Calcaric Fluvisols (Arenic, Salic), and Gleyic Calcisols (Sodic, Protocalcic, Technic, Salic). The anthropogenic-transformed soils include Urbic Technosols, and Ekranic Technosols are under buildings and road surfaces. In research area III, the natural soils spatial distribution is homogeneous and mainly represented by Gleyic Cambic Calcisols (Protocalcic), Gleyic Cambisols (Protocalcic, Prototechnic), and Calcaric Colluvic Regosols (Arenic, Prototechnic) in the bottoms of small flat-bottom valleys. In irrigation sites occur Urbic Technosols, and on hiking trails – Gleyic Cambisols (Prototechnic). Despite the presence of reclaimed horizons with a high content of phosphorus in the soils (average concentration of 82 mg kg−1), none of the profiles revealed Hortic horizon, but only some of its properties (colour, horizon thickness, zoogenic activity). The thickness of urbic-stratifying layer (Au) varies in a wide range from 10 to 135 cm, and the thickness of reclaimed horizons (A) also varies from 10 to 48 cm. The bulk density in Au horizons is 1.4 g cm−3, in the reclaimed horizons (A) – 1.39 g cm−3. The content of soil carbon in soil surface horizons varies from 0.85% to 4.58% in urbic horizons, and to 1.49% in reclaimed horizons. Chemical analysis of urbic (Au) and reclaimed (A) horizons revealed a low content of easily soluble salts (0.16%) and carbonates (1.5% and 1.7%, respectively).
•Use of South African fine coal waste as basis of a Technosol was demonstrated.•Validation was conducted by the growth of grass species Eragrotis tef.•Technosols from mine waste and poor soil reduce ...topsoil needed in mine restoration.•FabSoil production reduces the amount of fine coal disposed in dump deposits.•FabSoils reduce land-use footprint and add to circular economy and zero-waste.
Appropriate handling and disposal of coal waste is key to maximizing a sustainable approach towards coal processing activities. This paper investigates the feasibility of using the desulfurised fraction of coal processing slurry (<500 µm) streams from a colliery in the eMalahleni coalfields of South Africa as the main component for the manufacture of ‘FabSoil’, a fabricated soil or technosol, for use as topsoil in the rehabilitation of mine sites. Compost and anaerobic digester sludge were added as organic matter and nutrient source, whilst malt residue was used as physical ameliorant. Native soil from the study area was used as control. Validation of the potential of the fabricated soils was conducted through germination and growth experiments using the grass species Teff (Eragrotis tef), an indigenous grass from the Mpumalanga region of South Africa commonly cultivated on degraded mine land. Results showed that soils produced with coal waste and native soil in a 3:1 ratio amended with compost or anaerobic digester sludge and malt residue had the highest biomass production after 90 days. According to this study, the use of these soil substitutes can reduce the amount of topsoil used in coal mine restoration, while also reducing the amount of fine coal disposed in dump deposits significantly. This minimises the land-use footprint and the social and environmental impact of mining activities as part of circular economy and zero-waste strategies.
Purpose Constructed soils are Technosols resulting from the deliberate combination of various artefacts. Similarly to natural soils, technogenic parent materials are transformed by pedogenic factors ...contributing to their evolution. This work was conducted to study the first stages of the pedogenesis of constructed soils. Materials and methods Two soils were constructed in lysimetric plots (10 × 10 m) using an engineering process by the combination of paper-mill sludge, thermally treated soil material and green waste compost. Evolution of the soil profiles, composition of soils and leachates were studied for 3 years. Results and discussion A strong evolution of the profiles was observed over the 3 years with rapid changes in the number and characteristics of the horizons. Significant changes in chemical weathering (decarbonatisation) and physical status (aggregation), i.e. processes similar to those occurring in natural soils were observed. Other processes specific to the technogenic materials were recorded, e.g. massive dissolution of gypsum or drainage of constitutive water. Apart from constructed Technosols classification, prediction was made on their future pedogenic evolution. Conclusions Constructed Technosols made of finely divided reactive organic and mineral compounds were observed to evolve quickly. Evidences of original pedogenic processes have been highlighted that could be considered as a general diagnostic characteristic of Technosols. Finally, some considerations about the application of the World Reference Base for Soil Resources to the classification of Technosols are proposed, taking into account some aspects of their pedogenesis that have been highlighted by our work.
Understanding the processes in soils after disturbances could be helpful in better designing restoration practices. The labile fraction of soil organic carbon (LSOC) plays a vital role in recovering ...soil properties and quality. This study compared labile C and N fractions, including microbial biomass C (MBC), cold-water-soluble C (WSC), water-soluble N (WSN), hot-water-extractable C (HWC), hot-water-extractable N (HWN), particulate organic carbon (POC), and particulate organic nitrogen (PON) in post-mining, post-fire, and undisturbed soils under different tree cover (Scots pine, common birch, and black alder). Nearly 30 years after the disturbance, post-mining soils were characterized by lower soil organic carbon (SOC) and total nitrogen (TN) as well as their labile fractions compared to those of post-fire and undisturbed soils. Disturbed soils had less stable SOC than undisturbed soils. Compared to the post-fire site, the higher proportion of WSC in SOC in post-mining soils suggests higher SOC turnover and leaching potential during primary succession compared to secondary succession. The post-fire soils had a similar SOC stock to undisturbed soils but differed in the C and N labile fractions stock. Post-fire soils were characterized by higher POC stocks due to charcoal admixture and lower WSN, HWC, and HWN fractions than undisturbed soils. The studied tree species differently affected the recovery of SOM properties after disturbances. Post-mining soils under alder had higher SOC, TN, and labile fractions (except MBC) than soils under birch and pine cover. However, this was not true for the post-fire site, where only WSN was higher under the alder. The soils under birch stands had the highest MBC stocks across all sites. The soils under pine had less stable SOM than those under birch and alder, which may accelerate podzolization processes. Results indicate a longer time for the recovery of C and N pools during primary succession than in secondary succession on sandy soils. Alder, as phytomelioration species that increases the C and N pools in post-fire sites, has limited usefulness.
•Disturbed soils had less stable SOC than undisturbed soils.•Post-mining soil was characterized by the lowest labile C and N stocks.•Soils under pine characterized by less stable SOM than under birch and alder.•Alder increase labile C and N stock only in post-mining soils.
Technosols are soils dominant in technical artifacts, formed from anthropogenic deposits or transported materials. While anthropogenic in origin, it is clear that pedogenic processes are active ...within Technosols, i.e. transformation and translocation of elements, minerals and particles within these materials. Three different Technosols were assessed as part of this study, comprising gold, platinum and kimberlite Technosols. The objective of this paper was to discuss the pedogenic processes observed within the three Technosols. The discussion is based on observations of different pedogenic processes within the Technosols as well as analytical data and published data from the literature. Irrespective of the time since deposition or rehabilitation, well-defined pedochemical transformation processes, such as changes in pH and cation exchange capacity and base saturation, have been observed within these Technosols and are referenced within this article. Additional pedogenic processes, including leaching, eluviation-illuviation and oxidation, as well as normal weathering are also present. Finally, field observations revealed processes such as salinisation, neo-mineralisation, surface crusting and horizon differentiation in terms of structural differences have been observed within the Technosols studied. Structural differences resulted in horizon differentiation due to the addition of compost and the establishment of vegetation in a portion of the Technosols.
ABSTRACT Physical properties of the Technosols formed by the tailings deposition may constitute a physical barrier that limits water movement and plant development due to the properties received from ...those sediments. This study aimed to evaluate the physical quality of the Technosols formed by the deposition of sediments displaced by the Fundão Dam failure, Mariana, Minas Gerais State, Brazil, based on the evaluation of physical properties and Load Bearing Capacity Models (LBCM). For that, three areas under different vegetation types were selected: eucalyptus (Euc), forest with human-assisted revegetation (RF), and forest with native vegetation (NF). Three sampling subareas were demarcated in each area: non-impacted areas (Ni), and Technosols formed in directly impacted areas (Di), and partially impacted areas (Pi). Undisturbed samples were collected in two layers and subjected to the uniaxial compression test after equilibration at five matric potentials. Soil compression curves and LBCM were determined. Soil bulk density (BD), total porosity (TP), organic matter (OM), granulometry, and particle density (PD) were also determined. Clay content was less significant, and the silt and very fine sand content was significantly higher in the Technosols, generating an increase in BD and reduction in TP. Technosols generally exhibited greater load-bearing capacity due to higher pre-consolidation pressure values attained by these soils due to the lower clay and OM contents. High resistance of these soils is one limitation for revegetation of the areas evaluated, being necessary management practices to improve physical properties of the Technosols.
Core Ideas
Charcoal hearth remains are a widespread legacy of historic iron production.
Soils on charcoal hearth remains are a carbon sink.
Soils on charcoal hearths are classified as Anthropic ...Udorthents.
Historic charcoal hearth remains provide a unique archive of the long‐term interaction between biochar, soil development, and plant growth. Charcoal as raw material was crucial for production of iron in iron works, and hence numerous charcoal hearths can be found in the forests near historic iron works in Europe and in the eastern United States. Charcoal hearths are round to elliptical forms often around 10 m in diameter and consist of several‐decimeter‐thick layers that contain charcoal fragments, ash, and burnt soil. We studied the soil chemistry of 24 charcoal hearths and compared them with the surrounding “natural” soils in the northern Appalachians of northwestern Connecticut. The thickness of the topsoils on the charcoal hearths and their carbon content are remarkably higher than in the surrounding topsoils. The presence of residual products from charcoal production classifies the soils as Anthropic Udorthents (US Soil Taxonomy) or Spolic Technosols (Humic) according to the World Reference Base for Soil Resources. The widespread occurrence of charcoal hearth remains, and their high spatial density in different ecosystems underlines their importance for further pedological research.
It is becoming increasingly popular to use phytoremediation methods for the reclamation of mine sites containing metal(loid)s. This study aims to assess the phytostabilization ability of two willow ...species (Salix viminalis and Salix purpurea) on technosols from a former gold mining site presenting polymetallic contamination (As, Sb and Pb). Different reconstituted soils using a mixture of the litter and the technosol collected on this previously mined site and a non-contaminated control garden soil were investigated in a laboratory mesocosm. The physico-chemical soil parameters and the total metal(loid)s content in pore water were determined. After 45days of growth, roots, leaves and stems from the two willow species were harvested. The biomass, metal(loid) concentrations and the mineral mass were determined for the different plant organs. Both Salix species were able to develop root systems on the different reconstituted soils and a variable aboveground biomass according to the soil composition. As, Sb and Pb accumulated mainly in the Salix rhizosphere. S. purpurea was more efficient in accumulating As in the plant's upper parts than S. viminalis. S. viminalis showed an ability to transfer Pb and Sb to its shoots whereas S. purpurea did not translocate these elements.
•Phytoremediation of contaminated technosols from a former mine were studied.•Stabilization potential of wo Salix genotypes was evaluated for As, Sb and Pb.•Their concentrations in soils, soil pore water and plant organs were determined.•As, Sb and Pb accumulated mainly in the Salix rhizosphere.•S. viminalis transfers As, Pb and Sb in shoots and S. purpurea only As.
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