Soil Development Processes Research Articles

Underlying lithology controls trace metal mobilization during redox fluctuations

Redox state fluctuations are a primary mechanism controlling the mobilization of trace metals in soils. However, underlying lithology may modulate the effect that redox fluctuations have on trace metal mobility by influencing soil particle size and mineral composition. To investigate the relationships among trace metal behavior, lithology, and redox state, we subjected surface soils from two intensely weathered soil profiles formed on contrasting lithologies to consecutive, 8-day redox cycles. A suite of metals (Al, Mn, Fe, Ti, Rb, Zr, Nb, Mo, REEs, Pb, Th, U) were quantified in the aqueous phase (<10 nm) and solution (<415 nm, including colloids) from soil slurries. In soil formed on volcaniclastic bedrock with high clay content and a high abundance of short-range-ordered Fe-(oxyhydr)oxides phases (e.g. nano-goethite; quantified by Mössbauer spectroscopy), reducing events and colloidal dynamics drove trace metal mobilization. In contrast, in soil formed on granite bedrock with lower clay content and a low abundance of short-range-ordered Fe-(oxyhydr)oxides phases (nano-goethite and lepidocrocite), overall trace metal mobilization was lower, and mobilization was not predictable from redox state. Molybdenum isotopes were also measured through redox cycles but did not exhibit redox-dependent behavior. This study provides direct evidence that lithology remains an overarching factor governing the characteristics of metal mobility in soils, even after extended and intense chemical weathering and soil development processes.

Soil development processes under different tree species at afforested post-mining sites

The studied plantation is a post-mining sites of Kursk magnetic anomaly located in the northeastern part of Belgorod region in a iron-mining district of European part of Russia. The objects of this study are afforested external slope heaps produced by iron open-pit mine in Gubkin. Research work focused on 13-years old pure stands of birch (Betula pendula), sea buckthorn (Hippóphae rhamnoídes), locust tree (Robinia pseudoacacia), oleaster (Elaeágnus angustifólia) and grey alder (Alnus incana) growing on the different substrates. Soil physical and chemicals properties of substrates were analyzed and forest litter stocks were calculated in different slope parts. Substrate quality varied considerably. Forest litter stock depends on site characteristics, tree species and substrate. Study results show that vegetation is the important factor facilitating soil development, the impact of forest litter stock that the surface structure determined is higher with such N-fixing tree species as alder, locust tree and oleaster.

Some aspects of soil development in small sandy catchments of ancient river valleys (a case study of Ob-Tom interfluve)

Aeolian sands and ancient dune fields are widely widespread in the southern part of Western Siberia. Aeolian landscapes formed in the bottom part of large ancient valleys, on the surfaces of modern fluvial terraces and near large lake systems are characterized by the unique soil cover which is determent by the sedimentalogical, mineralogical and granulometric properties of sands and very slightly dependent from local vegetation and climate. Soils of ancient inland dune landscapes located within the ancient valleys of Ob-Tom interfluve were investigated. It was shown that local topography is the main factor controlling the diversity of soils. Soils developed in dune topographical sequences differ from each other in the thickness of eluvial-illuvial horizons, content of humus and oxalate-extractable iron. Humus accumulation and podsolization process are rather poor because of the low ash content in the litter, intensive natural and anthropogenic dynamics of aeolian landscapes and adjacent soils. The fact that processes of lateral podsolization determine the processes of soil development in such landscapes has been established. All soils are characterized by a small thickness of the modern profile − 50 cm and even less for the flat surfaces of dunes. Clayey lamellaes typical for aeolian sediments are present in the bottom parts of soils profiles, located in the lower part of the dune-interdune sequence. It is rather obvious that thick cemented lamellaes are a powerful soil-geochemical barriers that largely determines the conditions for lateral and radial migration.

РАЗРАБОТКА АГЕНТНОЙ ИМИТАЦИОННОЙ МОДЕЛИ ПРОЦЕССА, ОПИСЫВАЮЩЕГО ГИДРАВЛИЧЕСКУЮ РАЗРАБОТКУ ГРУНТА ПРИ ДНОУГЛУБЛЕНИИ

The article describes the process of hydraulic soil development when performing dredging operations in terms of a probabilistic process. To give the mathematical description of this process, the stochastic differential Langevin equation is used, which makes it possible to determine the velocity of the particle moving along the spatial axis in case of multiple collisions with other soil particles. In order to establish the adequacy of this approach with the experimental data obtained through the utility model there has been developed an agent simulation model. A population of agents containing a module of the system dynamics realizing the differential equation is integrated into the structure of the model.

Sustainability of Forest Cover under Climate Change on the Temperate-Continental Xeric Limits

Climate change particularly threatens the xeric limits of temperate-continental forests. In Hungary, annual temperatures have increased by 1.2 °C–1.8 °C in the last 30 years and the frequency of extreme droughts has grown. With the aim to gain stand-level prospects of sustainability, we have used local forest site variables to identify and project effects of recent and expected changes of climate. We have used a climatic descriptor (FAI index) to compare trends estimated from forest datasets with climatological projections; this is likely for the first time such a comparison has been made. Four independent approaches confirmed the near-linear decline of growth and vitality with increasing hot droughts in summer, using sessile oak as model species. The correlation between droughts and the expansion of pest and disease damages was also found to be significant. Projections of expected changes of main site factors predict a dramatic rise of future drought frequency and, consequently, a substantial shift of forest climate classes, especially at low elevation. Excess water-dependent lowland forests may lose supply from groundwater, which may change vegetation cover and soil development processes. The overall change of site conditions not only causes economic losses, but also challenges long-term sustainability of forest cover at the xeric limits.

Long term carbon sequestration potential of biosolids-amended copper and molybdenum mine tailings following mine site reclamation

Management and reclamation of industrial mine sites for carbon (C) sequestration is an emerging technique for offsetting anthropogenic C emissions. Land application of municipal biosolids is an effective method for amending closed tailings storage facilities and providing the nutrients to establish a vegetative cover. Biosolids applications can influence the C sequestration potential of tailings and other mine wastes at the onset of reclamation by initiating soil development processes and enhancing primary productivity, thereby leading to increased accumulation of soil organic carbon (SOC) over time. The short term ecological benefits of biosolids applications are well understood, but the long-term (>10 years) effects of biosolids on reclaimed mine soils are under-researched. The objective of this long-term study was to determine the effects of biosolids applied in 1998 at increasing rates (0, 150 and 250 dry Mg ha−1) on the C sequestration potential of a copper and molybdenum mine tailings site in the southern interior of British Columbia, Canada that is currently undergoing reclamation to a pasture-based ecosystem. We assessed changes in C pools, plant productivity and select soil physiochemical parameters at an established research site at the Bethlehem Tailings Storage Facility over a 13-year period spanning from 1998 to 2011. Tailings total C and N concentrations increased with time and were highest when biosolids were applied at 250 Mg ha−1. Carbon pools increased with increasing biosolids application and ranged from 23 to 155 Mg C ha−1 after 13 years of reclamation. The net SOC sequestration rates (i.e. the C sequestration potential) ranged from 0.72 to 6.3 Mg C ha −1 yr −1 and were highest at the 250 Mg ha−1 application rate. The C storage efficiency was higher in the 150 Mg ha−1 treatment (0.74 Mg C stored per Mg of biosolids applied), indicating that lower application rates of biosolids are more efficient at storing C than higher application rates. Aboveground plant biomass was substantially higher on biosolid-amended tailings (6 and 6.7 Mg ha−1 for B150 and B250, respectively) compared to the unamended tailings (0.39 Mg ha−1), which suggests that the increase in C pools was a direct result of organic matter inputs from enhanced plant productivity. The tailings were naturally high in Cu and Mo, and when amended with biosolids at a rate of 250 Mg ha−1, elevated levels of Zn (as compared to federal soil quality guidelines) were detected. The unamended tailings increased in alkalinity with time, whereas the pH of the biosolid-amended tailings remained stable around neutral. This study demonstrated that a single application of biosolids can facilitate plant production and the accumulation of SOC on mine tailings for more than a decade, and supports the use of biosolids for promoting long-term C sequestration on reclaimed mine sites in similar environments.

Characteristics Analysis of Land Use Spatial Distribution on Terrain Gradient in Henan Province

Terrain is the most basic natural geographical elements, restricting the redistribution of surface material and energy, affecting the soil and vegetation formation and development process. Land use structure is the inevitable result of the interaction between nature and mankind. Based on the digital elevation model and land use classification grid data, the paper utilizes geostatistical analysis method to quantitatively analyze the spatial distribution characteristics of terrain gradient, and the spatial relations between land use structure and terrain gradient in Henan province. The results show that: In Henan province, the terrain gradient is dominated by low value, with the increase of terrain gradient, the area of unit gradient decreases gradually; With the increase of the longitude, the terrain gradient decreases gradually, showing the spatial pattern of the west high east low, the variety on the same latitude belt is significantly larger than that on the corresponding longitude belt. Farmland, water area, construction land and unused land are mainly distributed in the low gradient regions, and the grassland distributes in the middle gradient regions, and the gradient of forest land distribution is relatively high. The total area of construction land is increasing over time, occupying lots of farmland and forest land, the growth rate in middle low gradient region is higher than that in the low gradient region, and there is a trend of expanding to higher gradient region at the same time. The total area of farmland is decreasing over time, it tries to expand to higher gradient region to make up for the lost area, the area of middle gradient in its advantage region decreases mostly. In order to make up for the occupied area, the forest grassland is expanding toward higher gradient region. The area of water land has been increasing continuously, but the area of agricultural water in low gradient region is decreasing, and the advantage position is reducing.

Soil and vegetal shifts in meadows under conditions of alluvial lithogenic matrix on islands in the delta of the Northern Dvina River

In this paper we represent the results of our research: a scheme of plant and soil succession changes on the alluvial lithogenic matrix in the zone of river and marine accumulation in the delta of the Northern Dvina river. We used more than 1000 geobotanical and 200 soil descriptions. The succession scheme of the transformation of meadow communities in the river accumulation zone is represented in this work. This scheme occurs both in the natural processes of phytocenosis and soil development, as well as in agrogenic influence, as well as a number of successional changes during formation of meadows in the zone of marine accumulation.

A conceptual model of the controlling factors of soil organic carbon and nitrogen densities in a permafrost-affected region on the eastern Qinghai-Tibetan Plateau

Many investigations of the preservation of soil organic carbon (SOC) in permafrost regions have examined roles of geomorphology, pedogenesis, vegetation cover, and permafrost within particular regions. However, it is difficult to disentangle the effects of multiple factors on the SOC in permafrost regions due to the heterogeneity in environmental conditions. Based on data from 73 soil study sites in permafrost regions of the eastern Qinghai-Tibetan Plateau, we developed a simple conceptual model, which relates SOC to topography, vegetation, and pedogenesis. We summarized the dominant factors and their controls on SOC using 31 measured soil physiochemical variables. Soil texture explains approximately 60% of the variations in the SOC stocks for the upper 0–2 m soil. Soil particle size closely correlates to soil moisture, which is an important determinant of SOC. Soil salinity and cations are important factors as well and can explain about 10% of the variations in SOC. The SOC and total nitrogen (TN) stocks for the 1–2 m depths have larger uncertainties than those of upper 1 m soil layer. The vegetation, pH, and bulk density mainly affects SOC and TN stocks for the upper 1 m soil layers, while the active layer thickness and soil particle size have greater influence on SOC and TN stocks for the 1–2 m soils. Our results suggest that the soil particle size is the most important controller of SOC pools, and the stocks of SOC and TN are strongly effected by soil development processes in the permafrost regions of the eastern Qinghai-Tibetan Plateau.

Валовий хімічний склад темно-сірих опідзолених ґрунтів Малого Полісся і його трансформація в процесі антропогенези

Dark gray podzolized soils (Phaeozems Albic (PHad), WRB, 1998) are typical for the natural area of Pasmove Pobuzhia physiographic oblast of the Small Polissya. The investigation of the transformation of the gross chemical composition of dark gray podzolized soils of Small Polissya due to erosion processes conducted for the first time, confirming the relevance of the research. Standard methods of research were used in the investigation of the gross chemical composition of dark gray podzolized soils. The research results have been worked out according to the methodology of Y. Arynushkina and N. Myakina. According to the research, SiO2 dominated in all genetic soil horizons. Its content in the humus-accumulative horizon is 82.06 % by weight of calcined soil, decreasing to 74.45 % in soil rock. Different distribution of silica in the soil profile indicates the poor process of podzolic soil development. Among oxides in the soil profile dominates Al2O3, it contents in the humus-accumulative horizon is 8,10 %. A slight accumulation of Aluminium oxides was found in horizon confirming weak profile differentiation by eluvial-alluvial type. Content of Fe2O3 oxides in the soil profile is low variadic in the arable layer and the content is 2.30 %. Oxides of CaO content ranges from 0,75 % in the horizon He to 6,17 % in soil rock, and the content of oxides MgO, respectively, from 0.65 % to 1.06 %. Gross content of iron oxides, titanium, manganese, sodium, potassium, phosphorus and sulfur in the soil genetic horizons ranges from 0,04 % to 2,39 %. The estimated ratio between the major oxides and their profile distribution also confirm weak profile differentiation of dark gray podzolized soils. The content of the constitutional water of humus He horizon of dark gray podzolized soils is 1.57 %. Increase of constitutional water in the middle of the profile may be caused by increasing of internally soil deflation processes. This is also confirmed by the growth of silica coefficient changes of the soil at the same depth. In eroded dark gray podzolized soils of the arable layer the content of SiO2 is decreasing, reaching values of 79,63–80,84 % in strongly eroded. The content of other oxides tends to increase as well as decrease comparing to non-eroded soil. The correlation between wash out level and molar magnitude ratios The correlation between wash out level and molar magnitude ratios is being observed in eroded soils. With erodation increase the ratio of SiO2: Al2O3 and SiO2: R2O3 is being narrowed, which indicates accumulation in arable horizons of aluminium, including oxides in general, compared with non-eroded types. The content of the constitutional water increases and expands the coefficient of the silica changes, indicating the strengthening of internally soil deflation processes in the arable layer of erosion-degraded dark gray podzolized soils compared to non-eroded types. Key words: dark gray podzolized soils, gross chemical composition, oxides, degradation.

Late Glacial erosion and pedogenesis dynamics: Evidence from high-resolution lacustrine archives and paleosols in south Bohemia (Czech Republic)

Sediments from three paleolakes and two paleosol horizons in south Bohemia, Czech Republic, provide evidence of climate change and landscape evolution in central-eastern Europe on millennial to centennial timescales over the Late Glacial (~16–11.5ky). Based on a combination of geochemical, sedimentological and geophysical proxy indicators, along with the pollen record and soil micromorphology, we propose a relationship between vegetation cover, soil development, and erosional processes. Four major and two minor environmental stages, identified in all investigated paleo-lakes, were broadly correlated with the Late Glacial climatostratigraphy. Short-term (decadal to centennial) climatic deteriorations between the Bølling and Allerød, and within the Allerød, have been correlated with the Older Dryas and the Intra-Allerød Cold Period (IACP) respectively. B horizons of two (gleyic) podzols discovered under aeolian sand dunes in the lake catchments were dated to the Allerød interstadial and were parallelized with Usselo soils – pedostratigraphical marker horizons of west- and northern-central Europe. The upper parts of these soils have signs of colluvial processes. According to the radiocarbon dating, the erosion occurred at 13,155±150cal. yr BP and can be associated with the IACP event, which is marked by a significant input of allogenic material into the lake basins. We attribute the significant increase in the iron and consequent phosphorus content in the lake sediments during the Allerød to the podzolization that occurred with the humid interstadial conditions.

Biogeochemistry on the Range: Editor's Note

Editor's Note: In this issue of The Paper Trail, an up-and-coming ecologist and an established biogeochemist take aim at understanding deserts; those “other” places where many would say are too dry and barren for anything interesting to be happening. As the French would say, “au contraire mon frère” and these two can prove it. Eventually ending up at the Jornada Experimental Range (JER), the two researchers made a connection through the established's “islands of fertility” framework that describes the soil development process specifically in desert grasslands and shrubland habitats. The details of his approach and research he conducted are part of what has inspired the up-and-comer to further his research at the JER where not only soils, but fundamental understanding is being built along the way.

Effects of binding materials on microaggregate size distribution in bauxite residues.

It is recognized that for successful establishment of a vegetation cover on bauxite residue disposal areas, soil formation and a greater understanding of the processes of soil development are crucial. The stability of microaggregates is a very important physical property that prevents erosion in bauxite residues. Samples were collected from a disposal area in Central China to determine not only the mechanism of aggregation but also clay dispersion. Colloidal stability was assessed by determining organic matter, carbonate, electrolyte, clay mineral, and iron-aluminum oxide forms, as these would contribute to their stability. Organic matter improved microaggregate stability by combining with clay particles and polyvalent cations to form macroaggregates. Polyvalent cations such as calcium had a positive effect on particle flocculation, while organic molecules were more effective at stabilizing microaggregates. Removal of salinity dispersed silt-size aggregates into clay-size aggregates and reduced microaggregate stability. Calcium improved particle aggregation, while sodium had the reverse effect. Quartz powder was added to the residues but did not show any cementing effect, while free and amorphous iron-aluminum oxides were effective binding agents for microaggregate formation. We propose that the presence of organic matter and polyvalent cations, together with incorporation of organic carbon and calcium minerals, may enhance the stability of this material and prove beneficial toward improving its physical condition.

Paenibacillus sp. Strain SB-6 Induces Weathering of Ca-montmorillonite: Illitization and Formation of Calcite

ABSTRACTInvestigation of the weathering of silicate minerals is helpful to understand the process of soil development, cycling of nutrient elements, and potential applications in fixation of carbon dioxide from the atmosphere through carbonate precipitation. In this study, weathering experiments of calcium-montmorillonite were conducted using Paenibacillus sp. strain SB-6 for 70 days. The results indicated that the Si4+, Al3+, Ca2+ and Na+ concentrations in the medium of the biotic experiments were evidently higher than those of the abiotic experiments, and that Paenibacillus sp. could help the transformation of partial montmorillonite into an illite–montmorillonite mixed-layer. In the process of illitization, K+ went into the interlayer of montmorillonite and hydrated Ca2+ and Na+ released from it. In the late stage of the experiments, the Ca2+ released from montmorillonite combined with carbonate ions generated by the bacterial metabolism, forming calcite.

Scheffer/Schachtschabel Soil Science

The soils are fundamental to our existence, delivering water and nutrients to plants, that feed us. But they are in many ways in danger and their conservation is therefore a most important focus for science, governments and society as a whole. A team of world recognised researchers have prepared this first English edition based on the 16th European edition. • The precusors and the processes of soil development • The physical, biological and chemical properties of soils • Nutrients and Polluntants • The various soil classifications with the main focus on the World Reference Base for Soil Resources (WRB) • The most important soils and soil landscapes of the world • Soil Evaluation Techniques • Basic Principles of Soil Conservation Whoever works with soils needs this book.

Soil fungal community development in a high Arctic glacier foreland follows a directional replacement model, with a mid-successional diversity maximum.

Directional replacement and directional non-replacement models are two alternative paradigms for community development in primary successional environments. The first model emphasizes turnover in species between early and late successional niches. The second emphasizes accumulation of additional diversity over time. To test whether the development of soil fungal communities in the foreland of an Arctic glacier conforms to either of these models, we collected samples from the Midtre Lovénbreen Glacier, Svalbard, along a soil successional series spanning >80 years. Soil DNA was extracted, and fungal ITS1 region was amplified and sequenced on an Illumina Miseq. There was a progressive change in community composition in the soil fungal community, with greatest fungal OTU richness in the Mid Stage (50–80 years). A nestedness analysis showed that the Early Stage (20–50 years) and the Late Stage (>80 years) fungal communities were nested within the Mid Stage communities. These results imply that fungal community development in this glacier succession follows a directional replacement model. Soil development processes may initially be important in facilitating arrival of additional fungal species, to give a mid-successional diversity maximum that contains both early- and late-successional fungi. Competition may then decrease the overall diversity due to the loss of early successional species.

Assessment of Technosol formation and in situ remediation in capped alkaline tailings

Technosols formed from mineral processing wastes such as tailings are of growing importance worldwide due to the increasing demand for mineral and energy resources. The construction and nature of tailings and capping materials in tailing storage facilities are likely to influence soil formation rates; however, these have not been evaluated to date. This study used bauxite residue (alumina refining tailings) as a model material to compare soil development and in situ remediation with reference to initial residue composition, landscape position, and cap type. Soil development in the capped tailings deposits was limited to accumulation of organic matter in the upper 0–2cm of capping materials, and shallow (<10cm deep) decreases in pH and salinity within the underlying tailing layers. Landscape position had little effect on soil development due to the formation of technic hard material through calcite cementation in sintered bauxite residues, which inhibited weathering. Weak structure development, likely due to volume shrinkage through desiccation, was observed in unsintered bauxite residue. Leaching of acidic pore waters from pyritic mine spoil caps aided in pH neutralization in unsintered bauxite residues.The current Technosol classification was adequate for description of the soil materials within the study site; however, the introduction of a novel prefix qualifier, Ordic, would enable more accurate description of multilayered Technosols. Unsintered bauxite residue under a pyritic mine spoil cap was predicted to move from a Spolic Technosol to a Haplic Cambisol based on variations in structure and colour within the capping. The lack of observable weathering precluded identification of a likely pedogenic trajectory in sintered bauxite residue. Accelerating natural processes of soil development and in situ remediation may be achieved by application of chemically reactive caps; however, these should not preclude atmospheric gas exchange, leaching, or interaction with biota as pedogenesis will be retarded.

Ecological benefit of different revegetated covers in the middle of Hexi corridor, northwestern China

Desertification is one of the major obstacles to the development and utilization of oases in arid and semi-arid regions of China. Revegetation of oases is an effective means of protecting oases from sand invasion (the main cause of desertification) and enhancing the ecological stability of oasis. In order to assess the effects of revegetated plant communities, 21-year-old Haloxylon ammodendron shrubland (Shrubland), 28-year-old Populus simonii Carr. land (Poplar land) and 33-year-old Pinus sylvestris var. mongolica Litv land (Pine land) were selected as study objects. The topsoil properties and material changes were monitored, taking the native desert shrubland (Desert land) as a basis. The results show that different revegetated covers can lead to significant changes in soil organic carbon (SOC), as well as soil inorganic carbon (SIC) and total nitrogen (TN). SOC, SIC and TN content can be significantly increased from 0.56, 0.06, and 4.93 g kg−1 in Desert land to 5.85, 0.47, and 7.26 g kg−1 in revegetated covers, respectively. Different revegetated covers can also change plant species richness, productivity, and plant C and N content. It is also found that Poplar land and Pine land were more effective than Shrubland in improving soil fertility and plant productivity. In addition, this study confirmed that the establishment of revegetated covers can reduce the rates of wind erosion on soil surface up to 74.83–94.15 % compared to natural desert shrubland. The atmospheric dust fall was also affected significantly by the different covers. The results show that there are significant advantageous changes in soil characteristics and vegetation parameters, as well as the reduction of soil erosion and retention of atmospheric dust fall in the revegetated covers and habitat conditions. The results suggested the appreciable ecological effects of the different revegetation covers on soil development and restoration process of plant communities. Additionally, some rational management practices could also cause positive influence on the quality of soil, e.g. irrigation. Understanding these ecological effects may be helpful for designing and establishing protective forest systems in desert–oasis areas.

Soil development and soil movement process in the glacier foreland of the Western Glacier of Cerro Charquini, Bolivian Andes

Soil development and soil movement process in the glacier foreland of the Western Glacier of Cerro Charquini, Bolivian Andes

Ecosystem CO2 flux rates in relation to vegetation type and age of Leymus arenarius dunes on Surtsey

The primary succession on the 50 year old volcanic island of Surtsey, Iceland, has been intensively studied. Initial soil development and other belowground processes are important drivers of primary succession but frequently overseen. A Leymus arenarius and Honckenya peploides dominated plant community has formed a relatively stable successional sere on the island, where external inputs of nutrients remain low. These plants have had a stable &lt;10% aboveground surface cover during the past 20 years, but less is known about their belowground development. We investigated the organic matter (carbon) output and input processes (soil respiration, ecosystem respiration and photosynthesis) of the community and how they were affected by soil temperature, soil water content, vegetation and age of L. arenarius dunes. We found that both soil respiration and root stocks have increased substantially from 1987, when an earlier study was conducted. The same pattern was found when different aged L. arenarius dunes were studied. L. arenarius had a stronger effect on the soil respiration fluxes than its surface cover might indicate, through its much higher photosynthesis rates than H. peploides. The study furthermore illustrated how water stress may temporally limit belowground processes in this coastal community.