Soil Evolution Research Articles

Corn-cob Biochar Characterization and Application Effects to Carbon Dioxide (CO₂) Evolution in Acid Soil Added with Different Types of Fertilizers

Biochar, a carbon (C) rich material produced from biomass, is an inexpensive means of removing C from the atmosphere by incorporating it into the soil, where C sinks are formed for sequestration. The slow release of carbon dioxide (CO2) from the soil is related to C sequestration, long-term storage of CO2, or other forms of C that help lessen CO2 concentration. An incubation study was conducted in a laboratory to determine the effect of corn-cob biochar (CCB) application on Luisiana clay (Orthoxic Palehumults) acidic soil. The CO2 evolution from the incubation of various mixtures of organic materials, inorganic fertilizers added with CCB was measured using a titration of hydrochloric acid (HCl). The biochar application rate was 10 t/ha, and the organic fertilizers at 5 t/ha. Results show that CCB contained essential plant elements like C, K (potassium), Si (silicon), Cu (copper), Na (sodium), and Cl (chlorine). It also possesses a large surface area and high average pore size. The CO2 evolution increased in the first two weeks with a peak at Day 2, and the amount of cumulative CO2 decreased after that in all treatments during the incubation period. Treatments with CCB showed a constant reduction in the amount of CO2

Intra-Soil Milling for Stable Evolution and High Productivity of Kastanozem Soil

The long-term field experiment on the Kastanozem showed that the standard moldboard plowing to a depth of 22 cm (control), chiseling to a depth of 35 cm, and three-tier plowing (machine type PTN–40) to a depth of 45 cm was incapable of providing a stable soil structure and aggregate system. The transcendental Biogeosystem Technique (BGT*) methodology for intra-soil milling of the 20–45 cm layer and the intra-soil milling PMS–70 machine were developed. The PMS–70 soil processing provided the content of 1–3 mm sized aggregate particle fraction in the illuvial horizon of about 50 to 60%, which was 3-fold higher compared to standard plowing systems. Soil bulk density reduced in the layer 20–40 cm to 1.35 t m−3 compared to 1.51 t m−3 in the control option. In the control, the rhizosphere developed only in the soil upper layer. There were 1.3 roots per cm2 in 0–20 cm, and 0.2 roots per cm2 in 20–40 cm. The rhizosphere spreads only through the soil crevices after chilling. After three-tier plowing (PTN–40), the rhizosphere developed better in the local comfort zones of the soil profile between soil blocks impermeable for roots. After intra-soil milling PMS–70, the rhizosphere developed uniformly in the whole soil profile: 2.2 roots per cm2 in 0–20 cm; 1.7 roots per cm2 in 20–40 cm. Matric water potential was higher, soil salinization was lower, and the pH was close to neutral. Soil organic matter (SOM) content increased to 3.3% in 0–20 cm and 2.1% in 20–40 cm compared to the control (2.0% in the 0–20 cm soil layer and 1.3% in the 20–40 cm layer). The spring barley yield was 53% higher compared to the control. The technology life cycle profitability was moldboard 21.5%, chiseling 6.9%, three-tier 15.6%, and intra-soil milling 45.6%. The new design of the intra-soil milling machine provides five times less traction resistance and 80% increased reliability, halving energy costs.

Effect of calcium bentonite clay and fly ash on the stabilization of organic soil from Alberta, Canada

This paper presents findings of the effect of calcium bentonite (Ca-bentonite) and pulp mill fly ash (PFA) on the compressibility behavior, and microstructural evolution of organic soil. A natural soil consisting of 26% organic matter was collected from the wetlands in the Wabasca region, Northern Alberta, Canada. A various mix design was prepared for the laboratory tests with the addition of 5%, 8%, 10%, 12%, 15%, and 20% Ca-bentonite with constant 30% PFA. One-dimensional consolidation tests were carried out to evaluate compressibility behavior of the stabilized organic soil. In addition, fall cone tests were conducted to evaluate change in undrained shear streth of soil after stabilization. A series of scanning electron microscope (SEM) tests with energy dispersive X-ray (EDS) and X-ray diffraction (XRD) experiments were conducted to investigate the microstructural and chemical aspects of the organic soil treated with Ca-bentonite and PFA. The results showed that a mixture of 10% Ca-bentonite with 30% PFA was the optimum dosage for improving compressibility of organic soil regardless of the curing method. Microstructural and chemical analysis revealed that the mineralogical and morphological contents of the stabilized organic soil were affected due to the pozzolanic reaction. The results showed that Ca-bentonite and PFA were able to considerably improve the strength and compressibility of the selected organic soil.

Novel Approach for Suppression of Ettringite Formation in Sulfate-Bearing Soil Using Blends of Nano-Magnesium Oxide, Ground Granulated Blast-Furnace Slag and Rice Husk Ash

The treatment of sulfate-bearing soil with calcium-based stabilizers such as cement or lime often results in ettringite formation, consequently leading to swelling and strength deterioration. Ettringite formation has negative environmental and economic effects on various civil engineering structures. This study was conducted to investigate the use of different materials (nano–magnesium oxide (M), ground granulated blast-furnace slag (GGBS), and rice husk ash (RHA)) for gypseous soil stabilization to prevent ettringite formation. Various tests were performed, including flexural strength, unconfined compression strength, linear expansion, and microstructure analysis (SEM/EDX), on lime (L)-, (M)-, (M-RHA)-, (M-GGBS)-, and (M-GGBS-RHA)-stabilized gypseous soil samples to determine their properties. The results indicated that the swelling rates of the soil samples mixed with 20% M-RHA, M-GGBS, and M-GGBS-RHA binders were much lower (less than 0.01% of volume change) than those of the soil samples mixed with 10% and 20% lime-stabilized binders after a curing period of 90 days. Meanwhile, the strengths of the soil samples mixed with 20% of M-RHA, M-GGBS, and M-GGBS-RHA soil specimens after soaking of 90 days were obviously higher (with a range from 2.7–12.8 MPa) than those of the soil samples mixed with 20% of lime-stabilized binder. The SEM and EDX results showed no ettringite formation in the M-RHA-, M-GGBS-, and M-GGBS-RHA-stabilized soils. Overall, the test results proved the potential of M-RHA, M-GGBS, and M-GGBS-RHA as effective soil stabilizers.

Does silica addition affect translocation and leaching of cadmium and copper in soil?

Soil and groundwater contamination with potentially toxic elements (PTEs) including cadmium (Cd) and copper (Cu) has become a serious problem for ecosystem functioning. Silicon (Si) may precipitate these metals as silicates, and may also form, at undersaturation of silicates, ‘Si-contaminant compounds’, i.e. particles of polymerized silica with PTEs incorporated or adsorbed by inner-sphere complexes. While the formation of these compounds in aqueous solution has been proven, their formation in soil remains unclear yet. Therefore, we conducted column experiments with a topsoil horizon artificially contaminated with Cd or Cu solutions (10 mM) in the presence (10 mM) and absence of monomeric Si, and monitored the elemental composition of the eluates during 12 irrigation steps with artificial rainwater by microwave-plasma atomic emission spectrometry, the size and charge of the particles eluted by dynamic light scattering and phase analysis light scattering, and determined the spatial distribution of total and exchangeable Cd and Cu in soil after the experiments. When Si was previously applied to soil, significantly larger particles (up to > 200 nm) in the eluates indicated Si polymerization and formation of Si-contaminant compounds. However, Cd and Cu concentrations were very low (<0.4 μM), pointing to efficient retardation in soil. In any variant, the particles formed were slightly negatively charged (−11 mV). The molar metal:Si ratios in the eluates and significant correlations between the amounts of Si and metals in soil extracted by NH4NO3 pointed to the formation of Si-contaminant compounds, too. More Cu than Cd was retained in soil, and significantly more in the presence of Si, but less Cu than Cd was in exchangeable form. While particularly Cu formed Si-contaminant compounds, which reduced the concentration of Cu ions, the Si-contaminant-compound particles in the eluates remained very small, thus potentially susceptible to particulate export from soil into the groundwater.

Changes in profile distribution and chemical properties of natural nanoparticles in paddy soils as affected by long-term rice cultivation

Systematic studies on the genesis, properties, and distribution of natural nanoparticles (NNPs) in soil remain scarce. This study examined a soil chronosequence of continuous paddy field land use for periods ranging from 0 to 1 000 years to determine how NNPs in soil changed at the early stages of soil genesis in eastern China. Soil samples were collected from coastal reclaimed paddy fields that were cultivated for 0, 50, 100, 300, 700, and 1 000 years. Natural nanoparticles were isolated and characterized along with bulk soil samples (< 2-mm fraction) for selected physical and chemical properties. The NNP content increased with increasing soil cultivation age at 60 g m−2 year−1, which was related to decreasing soil electrical conductivity (172–1 297 µS cm−1) and NNP zeta potentials (from –22 to –36 mV) with increasing soil cultivation age. Changes in several NNP properties, such as pedogenic iron oxide and total organic carbon contents, were consistent with those of the bulk soils across the soil chronosequence. Notably, changes in NNP iron oxide content were obvious and illustrated active chemical weathering, pedogenesis, and potential impacts on the microbial community. Redundancy analysis demonstrated that the soil cultivation age was the most important factor affecting NNP properties, contributing 60.7% of the total variation. Cluster and principal component analysis (PCA) revealed splitting of NNP samples into age groups of 50–300 and 700–1 000 years, indicating rapid evolution of NNP properties, after an initial period of desalinization (approximately 50 years). Overall, this study provides new insights into NNP evolution in soil during pedogenesis and predicting their influences on agriculture and ecological risks over millennial-scale rice cultivation.

Evaluating a new landform evolution model: A case study using a proposed mine rehabilitation landform

AbstractLandform evolution models are powerful tools for determining long‐term erosional stability and denudation rates spanning geological timescales. SIBERIA, CAESAR and CHILD are examples of these model. The newly developed State Space Soil Production and Assessment Model (SSSPAM) coupled soilscape‐landform evolution model has the ability to assess overall erosion rates of catchment scale landforms either using short‐term precipitation events, variable precipitation or time‐averaged precipitation (annual average). In addition, SSSPAM has the capability of developing the subsurface soil profile through weathering and armouring. In SSSPAM, physical processes of pedogenesis such as erosion and armouring, diffusion, sediment deposition and weathering are modelled using a state space matrix approach. In this article we simulate the short‐term evolution (100 years) of a proposed post‐mining landform using both SIBERIA and SSSPAM and compare the erosion and sediment output results. For the short‐term simulations SSSPAM's armouring capability was disabled. The models were then used to simulate the evolution of the catchment for 10,000 years. Results demonstrate that the short‐term SSSPAM simulation results compare well with the results from the established landform evolution model SIBERIA. The long‐term armouring disabled SSSPAM simulations produces simulated erosion rates comparable with SIBERIA simulations both of which are similar to upper limit of field measured denudation rates. The SSSPAM simulation using armouring demonstrated that armouring reduced the erosion rate of the catchment by a factor of 4 which is comparable with the lower limit of field measured denudation rates. This observation emphasizes the importance of armouring in long‐term evolution of landforms. Soil profile cross‐sections developed from the same results show that SSSPAM can also reproduce subsurface soil evolution and stratification and spatial variability of soil profile characteristics typically observed in the field.

Evolution of scientific views at factors of chernozem soil formation and development

Based on the comparative-historical method, we considered scientific theories about factors of chernozem formation (soil-forming material, relief, climate, vegetation and animal life, time, human) in the paper, their interrelated impact on the formation and evolution of steppe soils reflected in works of F.I. Ruprecht, V.V. Dokuchaev, P.S. Kossovich, S.S. Nestruev, P.A. Kostychev, V.R. Williams, H. Jenny, S.A. Waksman, and other researchers. Taking into account ecosystem significance in the functioning of the steppe landscapes and the high degree of agricultural development of chernozem soils, intensification of degraded processes, a necessity of understanding of the real influence of natural and anthropogenic factors on chernozem evolution is urgent as it serves a basis for the design of ways of steppe soils restoration. Therefore, in the scientific community, an interest was arisen to solve Dokuchaev and Jenny’s equations identifying the functional relation between earth and soil formation factors. At the degree of accumulation of informational data on chernozem changeability in time and space, it has emerged conditions to develop approaches contradicting soil degradation processes.

Biocontrol Potential of Cinnamon Bark Extracts and Chitosan Against Meloidogyne incognita Inflicted Disease in Black Pepper Plants

In this study, we aimed to evaluate the nematicidal activity of cinnamon bark extracts (CE) and chitosan (Cs) against Meloidogyne incognita under in vitro, pot, and field conditions. In the pot experiments, CE mixed with Cs effectively inhibited M. incognita infection on black pepper plants. We applied the following formulations, which all significantly reduced the gall index and nematode number in 5 g of root and 100 g of soil: CE:Cs = 5 mg:20 mg, 10 mg:40 mg, and 15 mg:60 mg per pot. In addition, the application of CE:Cs = 32 mg:120 mg, 64 mg:240 mg, and 96 mg:360 mg per plant effectively reduced root gall formation and nematode density in black pepper roots and soil compared with that of the non-treated control under field conditions. Nematode density in the black pepper roots was positively correlated with the percentage of plants with yellow leaves. These results suggest that cinnamon mixed with chitosan may be used as an effective and eco-friendly pesticide against plant parasitic nematodes.

An integrated approach for tracking climate-driven changes in treeline environments on different time scales in the Valle d’Aosta, Italian Alps

Both biotic and abiotic components, characterizing the mountain treeline ecotone, respond differently to climate variations. This study aims at reconstructing climate-driven changes by analyzing soil evolution in the late Holocene and by assessing the climatic trends for the last centuries and years in a key high-altitude climatic treeline (2515 m a.s.l.) on the SW slope of the Becca di Viou mountain (Aosta Valley Region, Italy). This approach is based on soil science and dendrochronological techniques, together with daily air/soil temperature monitoring of four recent growing seasons. Direct measurements show that the ongoing soil temperatures during the growing season, at the treeline and above, are higher than the predicted reference values for the Alpine treeline. Thus, they do not represent a limiting factor for tree establishment and growth, including at the highest altitudes of the potential treeline (2625 m a.s.l.). Dendrochronological evidences show a marked sensitivity of tree-ring growth to early-summer temperatures. During the recent 10-year period 2006–2015, trees at around 2300 m a.s.l. have grown at a rate that is approximately 1.9 times higher than during the 10-year period 1810–1819, one of the coolest periods of the Little Ice Age. On the other hand, soils show only an incipient response to the ongoing climate warming, likely because of its resilience regarding the changeable environmental conditions and the different factors influencing the soil development. The rising air temperature, and the consequent treeline upward shift, could be the cause of a shift from Regosol to soil with more marked Umbric characteristics, but only for soil profiles located on the N facing slopes. Overall, the results of this integrated approach permitted a quantification of the different responses in abiotic and biotic components through time, emphasizing the influence of local station conditions in responding to the past and ongoing climate change.

Detection of Changes in Arable Chernozemic Soil Health Based on Landsat TM Archive Data

When soils are used for a long period of time as arable land, their properties change. This can lead to soil degradation and loss of fertility, as well as other important soil biosphere functions. Obtaining data on the trends in arable soil conditions over large areas using traditional field survey methods is expensive and time-consuming. Currently, there are large archives of satellite data that can be used to monitor the status of arable soils. The analysis of changes in the color of the surface of arable chernozem soils of the Belgorod region, for the period from 1985 to the present, has been carried out based on the analysis of Landsat TM5 satellite data and information about the spectral reflectance of the soils of the region. It is found that, on most parts of arable lands of the region, the color of the soil surface has not changed significantly since 1985. Color changes were revealed on 11% of the analyzed area. The greatest changes are connected with the humus content and moisture content of soils. The three most probable reasons for the change of humus content in an arable horizon of soils are as follows: the dehumidification of soils during plowing; the reduction of the humus content due to water erosion; and the increase in humus content due to changes in the land-use system of the region in recent years. The change in soil moisture regime has mainly been found in arable lands in river valleys, most likely conditioned by the natural evolution of soils. Trends of increasing soil moisture are prevalent. The revealed regularities testify to the high stability of arable soils in the region during the last few decades.

Distribution of soil nutrients and erodibility factor under different soil types in an erosion region of Southeast China.

BackgroundSoil erosion can affect the distribution of soil nutrients, which restricts soil productivity. However, it is still a challenge to understand the response of soil nutrients to erosion under different soil types.MethodsThe distribution of soil nutrients, including soil organic carbon (SOC), soil organic nitrogen (SON), and soil major elements (expressed as Al2O3, CaO, Fe2O3, K2O, Na2O, MgO, TiO2, and SiO2), were analyzed in the profiles from yellow soils, red soils, and lateritic red soils in an erosion region of Southeast China. Soil erodibility K factor calculated on the Erosion Productivity Impact Calculator (EPIC) model was used to indicate erosion risk of surface soils (0∼30 cm depth). The relationships between these soil properties were explored by Spearman’s rank correlation analysis, further to determine the factors that affected the distribution of SOC, SON, and soil major elements under different soil types.ResultsThe K factors in the red soils were significantly lower than those in the yellow soils and significantly higher than those in the lateritic red soils. The SON concentrations in the deep layer of the yellow soils were twice larger than those in the red soils and lateritic red soils, while the SOC concentrations between them were not significantly different. The concentrations of most major elements, except Al2O3 and SiO2, in the yellow soils, were significantly larger than those in the red soils and lateritic red soils. Moreover, the concentrations of major metal elements positively correlated with silt proportions and SiO2 concentrations positively correlated with sand proportions at the 0∼80 cm depth in the yellow soils. Soil major elements depended on both soil evolution and soil erosion in the surface layer of yellow soils. In the yellow soils below the 80 cm depth, soil pH positively correlated with K2O, Na2O, and CaO concentrations, while negatively correlated with Fe2O3 concentrations, which was controlled by the processes of soil evolution. The concentrations of soil major elements did not significantly correlate with soil pH or particle distribution in the red soils and lateritic red soils, likely associated with intricate factors.ConclusionsThese results suggest that soil nutrients and soil erodibility K factor in the yellow soils were higher than those in the lateritic red soils and red soils. The distribution of soil nutrients is controlled by soil erosion and soil evolution in the erosion region of Southeast China.

Carbon Availability and Nitrogen Mineralization Control Denitrification Rates and Product Stoichiometry during Initial Maize Litter Decomposition

Returning crop residues to agricultural fields can accelerate nutrient turnover and increase N2O and NO emissions. Increased microbial respiration may lead to formation of local hotspots with anoxic or microoxic conditions promoting denitrification. To investigate the effect of litter quality on CO2, NO, N2O, and N2 emissions, we conducted a laboratory incubation study in a controlled atmosphere (He/O2, or pure He) with different maize litter types (Zea mays L., young leaves and roots, straw). We applied the N2O isotopocule mapping approach to distinguish between N2O emitting processes and partitioned the CO2 efflux into litter- and soil organic matter (SOM)-derived CO2 based on the natural 13C isotope abundances. Maize litter increased total and SOM derived CO2 emissions leading to a positive priming effect. Although C turnover was high, NO and N2O fluxes were low under oxic conditions as high O2 diffusivity limited denitrification. In the first week, nitrification contributed to NO emissions, which increased with increasing net N mineralization. Isotopocule mapping indicated that bacterial processes dominated N2O formation in litter-amended soil in the beginning of the incubation experiment with a subsequent shift towards fungal denitrification. With onset of anoxic incubation conditions after 47 days, N fluxes strongly increased, and heterotrophic bacterial denitrification became the main source of N2O. The N2O/(N2O+N2) ratio decreased with increasing litter C:N ratio and Corg:NO3− ratio in soil, confirming that the ratio of available C:N is a major control of denitrification product stoichiometry.

Natural attenuation along subsurface flow paths based on modeling and monitoring of a pesticide metabolite from three case studies

BackgroundGroundwater—especially for the use as drinking water—is a strictly protected resource in the existing guidelines for pesticide registration and drinking water protection in the EU. One aspect that has hardly played a role in this context so far is the attenuation of pesticide concentrations along the flow path from the regulatory leaching concentration at a depth of 1 m below the applied field to raw water abstraction systems. The soil metabolite N,N-dimethylsulfamide (DMS) is formed from two fungicidal substances: tolylfluanid and dichlofluanid. According to the EU guidance document on relevant metabolites in groundwater, DMS is a “non-relevant” metabolite. However, long-term application of the two active substances on permanent crops has resulted in elevated and quantifiable amounts of DMS in groundwater catchment areas of water supplying plants. Therefore, in the case of DMS, substantial monitoring data is available. This enables in combination with groundwater modeling, a quantitative analysis of the natural attenuation of DMS concentrations over time and distance. To this end, extensive real-world data from three case studies of drinking water catchment areas in Germany were analyzed.ResultsThe environmental fate of DMS in soil and groundwater was evaluated according to the respective data determined at the study sites. Analyses using monitoring data and combined modeling approaches as well, were performed to obtain comparable results. These merged outcomes from monitoring and modeling show total attenuation factors of 12–93 from leachate at 1 m depth down to monitoring wells—close to raw water collection. If concentration attenuation further downwards to collected raw water is considered, the overall attenuation factor is even higher (40–246).ConclusionsThe conditions at the catchment areas of the three case studies are very diverse, thus providing a wide range of attenuating conditions. When following the path of DMS from its formation in soil below a treated field, to its leaching into the aquifer, and within the aquifer down to the raw water collection site, its concentration in water is continuously and consistently decreasing. The results from DMS represent conservative estimations due to non-sorptive, quick transport processes. Extended to other sorptive solutes, it represents the lower end of expected attenuation. Therefore, natural pesticide concentration attenuation processes are suggested for the consideration in regulatory pesticide risk assessments for a more realistic yet still protective evaluation of expected concentrations in raw water.

Micro-structural Evolution of Granite Residual Soil under External Loading Based on X-ray Micro-computed Tomography

As a completed decomposed product of granite rock, the granite residual soil widely distributes in South China with a special soil structure that can be easily damaged under external disturbance. Therefore, studying the evolution of soil cracks during the loading process is important for engineering practice that needs to evaluate the soil shear strength, such as slope stability analysis. The purpose of this study is to investigate the micro-structure for the intact granite residual soil under external loading base on X-ray computed tomography (CT) through global and local scanning (with resolutions of 180 µm and 26.7 µm, respectively). The micro-structural evolution of the cross-sections of soil column extracted from a granite residual soil layer under axial loading was investigated by CT scanning with a 0.5 mm slice thickness. The number of cracks (including macro-cracks and meso-cracks), area ratios and porosity corresponding to varying loading stages (initial, peak-stress and failure) were analyzed based on the cross-sectional CT images. Test results shows that the structure strength of the soil was mainly subject to macro-cracks. In addition, the increase of the porosity is mainly attributed to the generation and expansion of the cracks along sandy particle under external loading. This study can provide theoretical support and data support for understanding the micro-structural evolution of granite residual soil that is commonly encountered in civil engineering.

Compressive strength and microstructure evolution of lime-treated silty soil subjected to kneading action

Long-term improvement in behaviour of soil subjected to lime treatment depends on the mechanism of its implementation. In-situ lime-treated fine-grained soil is often subjected to ‘kneading action’ developed by Pad-foot roller. The mechanism underlying the effect of kneading on lime-treated soil remains less investigated. Unconfined Compressive Strength (UCS) and microstructural modification of the lime-treated soil subjected to kneading compaction are evaluated. Kneading action undergoes better lime-dispersion during compaction. This feature accompanied with available water favours the long-term pozzolanic-reactions and hence enhanced the UCS evolution, particularly in the kneaded soil compacted at Wet Moisture Content (WMC). Lime-treated kneaded soil compacted at WMC, which is slightly higher than the Optimum Moisture Content (OMC) is beneficial for enhanced UCS evolution in specimens subjected to longer and accelerated curing. The UCS evolution in the laboratory accelerated-cured kneaded soil is of a similar level as the average UCS measured in the in-situ 7 years atmospherically cured kneaded soil.

Soil catenas in a pilot sub-basin in the region of Itajubá, Minas Gerais state, Brazil, for environmental planning

Systemic studies that allow the environmental characterization of pilot sub-basins are essential to guide their management, which are the basis for adequate environmental planning. The José Pereira sub-basin has an area of approximately 40 km² and is located in the municipality of Itajubá, south of the state of Minas Gerais, Brazil. This area was chosen as a pilot sub-basin for this study because it holds an important forest remnant, the Serra dos Toledos Biological Reserve, and part of the urban area of the municipality in the process of expansion, as well as a rural area where inappropriate and intensive agricultural activities are practiced. In this scenario, this atudy examined the soil catenas of this sub-basin to serve as an important instrument of planning for this unit. Eight soil catenas distributed into three topo-morphological compartments were studied. According to the generated soil map, Haplic Cambisols occupy 26% of the sub-basin, in mountainous relief; Red and Red-Yellow Latosols, 6% of the area, predominating in the flat-to-undulating relief; Haplic Gleysols, 7% of the area, in the lowlands, in flat relief and at the footslope. Finally, Red and Red-Yellow Argisols were the predominant classes, occurring in almost 50% of the sub-basin, under undulating and strongly undulating reliefs. Based on the combined results, a model of local evolution of the sub-basin soils was proposed: the younger soils, Haplic Cambisol and Haplic Gleysol, occupy the positions of convex top and floodplain, respectively. In the upper and lower thirds of the landscape, the predominance of Red Argisol is related to constant renewal of soil material, preventing it from reaching the latosolic stage. In addition, part of these Argisols has a Bw horizon below Bt horizon in rugged relief. Moreover, in the landscape lower third, Latosols are present, even in areas with steep slope.

Middle Pleistocene to Holocene palaeoenvironmental evolution of the south-eastern Alpine foreland basin from multi-proxy analysis

The multidisciplinary analysis of two long sedimentary successions of continental and shallow marine deposits from the Venetian plain (NE Italy) provides new data on the stratigraphic architecture and the landscape evolution of the south-eastern Alpine foreland basin during the last 210–220 ka, with further evidences of a warm temperate phase older than MIS 8.We present and discuss a detailed multi-proxy data set from these successions (GER1 and CB cores). The results of stratigraphic, palynological and micropalaeontological analyses are cross-interpreted, showing the potentiality of building a composite section of two close continental successions within the same alluvial system, the Brenta megafan, with 15 km distance between cores along a downstream direction. The chronology of the upper part of the cores is supported by radiocarbon dating, showing the presence of Last Glacial Maximum (LGM) and post-LGM fluvial deposits. Lower down, the estimated chronology relies on the tight integration between palynostratigraphy and lithostratigraphy, on the recognition of main unconformities, as well as on the correlation with other regional biostratigraphic records and the Northern Hemisphere/global isotopic record.The only marine transgression recorded in the studied successions is attributed to the MIS 7.3 and represents the basal tiepoint for the correlation between the two cores. Below the MIS 7.3 transgressive marine surface there is a fluvial succession with weakly-developed palaeosoils and a poor pollen content suggesting cold climate (possibly MIS 8), that lies on top of a thick peat layer showing palynological evidence of a warm temperate climate. The occurrence of well-preserved Pterocarya and Carya pollen in the basal peat level (GER1 core) is compared to that of other pollen sequences in Europe, providing new insights for the chronological framing of the problematic last occurrence of these taxa in the southern alpine area.Whilst mixed temperate forest persisted throughout MIS 7c-7a, conifers spread during MIS 6. By this time, a glaciofluvial aggradation phase is recorded, highlighting the strong relationship between glacial maxima and alluvial aggradation in the Venetian plain. None of the drilling sites were reached by the Last Interglacial sea transgression. However, the Eemian forest signature is well recorded in CB core, and the following Early to Middle Würm stadial-interstadial sequence is clearly outlined thanks to the joint analysis of the two successions. Broad-leaved thermophilous forests disappeared at the end of the Early Würm and only Pinus and Betula persisted throughout the LGM, during which a chronologically well-constrained glaciofluvial aggradation occurred. The last depositional event corresponds to the post-LGM cut-and-fill of fluvial incised valleys in GER1 core, and to soil evolution and very thin burial by Brenta River fluvial deposits in CB core. The comparison between the results of this study with data of previous deep cores in the distal alluvial plain remarks an increasing long-term subsidence towards Venice area.

Fertilization effects on microbial community composition and aggregate formation in saline‐alkaline soil

Soil was sampled (0–20 cm) from a 5-year Yellow River Delta paddy field experiment: no fertilizers (Control), mineral fertilizers (NPK), and NPK plus organic fertilizer (soybean and bean litter) applied at rates of 450 and 900 kg C ha− 1 (NPKC1 and NPKC2). The aggregate size, labile carbon fractions and root growth were investigated in combination with microbial community structure by high-throughput sequencing. NPKC1 and NPKC2 fertilization decreased Na+ content, but increased available nitrogen, phosphorus and Ca2+ contents. Macroaggregate formation was increased under NPKC1 (by 28 %) and NPKC2 (by 62 %) fertilization through increase of labile carbon fractions (particularly microbial biomass carbon), as well as better root growth. NPKC1 and NPKC2 fertilization increased microbial diversity and enriched the microbial community towards taxa responsible for aggregate stability (e.g., Actinobacteria and Ascomycota). RDA revealed that dissolved organic carbon content was the main factor affecting microbial community composition. Combined mineral and organic fertilizers decreased Na+ content, increased macroaggregates due to broader microbial diversity, increased contents of labile organic carbon and Ca2+. Consequently, combined organic and mineral fertilization were the best practice to increase microbial biomass and labile carbon fractions that strongly contribute to aggregate formation in saline-alkaline soil. Soil structure is a key factor in sustainable agriculture, especially for saline-alkaline soils, because Na+ destroys clay minearls and colloids, and thus, prevents the aggregate formation. We assessed the effects of organic amendments in combination with mineral fertilizers on chemical properties, microbial community composition and aggregate formation in a typical saline-alkaline soil.

К вопросу об эволюции почв археологических памятников эпохи раннего железного века (Республика Башкортостан)

The study examined the physico-chemical parameters on the example of soils of archaeological sites Akberdinsky-II, Shipovsky and Okhlebininsky-II settlements (Kara-abyss culture of the early iron age IV century BC to the turn of the II-I centuries BC). Archaeological sites and the background area of the Park named after M. I. Kalinin (Ufa) are located within the forest-steppe zone on the territory of right-Bank Pribelsky district of the Ufa-Simsky region of the Republic of Bashkortostan. The soil cover of the monuments is represented by dark gray forest loamy soils. Humus reserves and the uniformity coefficient Cu of elementary soil particles are calculated based on physico-chemical parameters. The humus reserves and the uniformity coefficient showed that the modern soils on the surface of archaeological sites are close to the soils of the background undisturbed territory. For buried soils and urbanized horizons on the territory of archaeological sites over the past 2200 – 2400 years, there is no approximation to the background soil in the main parameters. In general, the soil cover of archaeological sites of different ages is a valuable source of information not only about natural phenomena and events of ancient historical epochs, but also about the features of the evolution and genesis of soils. Keywords: SOIL COVER, SOIL EVOLUTION, HUMUS RESERVES, GRANULOMETRIC COMPOSITION, ARCHAEOLOGICAL SITE