Depth In Soil Profile Research Articles

Accumulation of Cd and Pb in soils irrigated with sewage and non-sewage water in Prayagraj, India

Unmanaged agricultural fields and the extended usage of sewage irrigation water can raise the concentration of heavy metals (Cd and Pb) in the soil, turning it into barren soil. The study was conducted during 2022-23 at four sewage and non-sewage irrigated sites in Prayagraj namely Naini, Baxibandh, Rasulabad and Draupadi Ghat. The representative soil samples were taken at depths of 0-15, 15-30, 30-45 and 45-60 cm. Di-acid mixture method was used for the estimation of heavy metals (Cd and Pb) in the soil sample by AAS (Atomic Absorption Spectrophotometer) (AAnalyst600, Perkin Elmer Inc., MA, USA). Contamination factor (CF) and enrichment factor % (EF) of different sites showed various results which fulfill the basic criteria of present and future prospective of research. The highest concentration of Cd and Pb was found in the surface layer (0-15 cm) of sewage and non-sewage irrigated sites at Naini i.e., Cd (4.46±0.42 and 1.05±0.08 mg/kg) and Pb (6.53±0.62 and 1.18±0.12 mg/kg) respectively. The lowest concentration of Cd and Pb was found in the sub-surface layer (45-60 cm) of sewage and non-sewage irrigated sites at Draupadi Ghat i.e., Cd (1.02±0.09 and 0.16±0.01 mg/kg) and Pb (1.68±0.12 and 0.18±0.01 mg/kg) respectively. The concentration of heavy metals cadmium (Cd) and lead (Pb) declined with soil profile depth in both sewage and non-sewage irrigated soils. The long-term persistence of heavy metal contamination in soil can lead to severe issues; therefore, regular monitoring of sewage-irrigated soils is necessary to minimize heavy metal pollution.

Per- and polyfluoroalkyl substances (PFAS) in homegrown crops: Accumulation and human risk assessment

Homegrown crops can present a significant exposure source of per- and polyfluoroalkyl substances (PFAS) to humans. Field studies studying PFAS accumulation in multiple vegetable food categories and examining the potential influence of soil characteristics on vegetable bioavailability under realistic exposure conditions are very scarce. Crop PFAS accumulation depends on a complex combination of factors. The physicochemical differences among the numerous PFAS makes risk assessment very challenging. Thus, simplification of this complexity into key factors that govern crop PFAS accumulation is critical. This study analyzed 29 targeted legacy, precursor and emerging PFAS in the vertical soil profile (0–45 cm depth), rainwater and edible crop parts of 88 private gardens, at different distances from a major fluorochemical plant. Gardens closer to the plant site showed higher soil concentrations which could be linked with historical and recent industrial emissions. Most compounds showed little variation along the soil depth profile, regardless of the distance from the plant site, which could be due to gardening practices. Annual crops consistently accumulated higher sum PFAS concentrations than perennials. Highest concentrations were observed in vegetables, followed by fruits and walnuts. Single soil-crop relationships were weak, which indicated that other factors (e.g., porewater) may be better measures of bioavailability in homegrown crop accumulation. Regression models, which additionally considered soil characteristics showed limited predictive power (all R2 ≤ 35%), possibly due to low variability in crop concentrations. Human intake estimations revealed that the PFAS exposure risk via crop consumption was similar nearby and remotely from the plant site, although the contribution to the overall dietary exposure can be relatively large. The tolerable weekly intake was frequently exceeded with respect to fruit and vegetable consumption, thus potential health risks cannot be ruled out.

Nitrous oxide emissions and soil profile responses to manure substitution in the North China Plain drylands

Substituting synthetic fertilizers with manures in agriculture enhances soil properties and crop yield. However, the impact on nitrous oxide (N2O) emissions, especially from the soil profile, remains poorly understood. This study examined emissions from 2017 to 2019 on a well-established (>10-year) maize field site in the North China Plain. Three treatments were compared: 100 % synthetic nitrogen (NPK), 50 % synthetic fertilizer N + 50 % manure N substitution (50%MNS), and 100 % manure N substitution (100%MNS). N2O emissions were monitored for three years, and in 2019, N2O concentrations at 20 cm and 40 cm soil depths were analyzed in relation to surface N2O fluxes and environmental factors. The results showed manure substitution resulted in about 13.8 %–25.2 % (50%MNS) and 40.3 %–72.2 % (100%MNS) reduction in N2O emissions over the 3-year period compared with the NPK treatment. Throughout the maize growing season, the top-dressing accompanied by rainfall was responsible for the N2O emissions. The difference in N2O concentrations between all the treatments at 20 cm depth was insignificant, but at 40 cm depth the N2O concentrations were significantly higher for the 50%MNS treatment than the other treatments. The N2O fluxes and N2O concentration were not synchronized especially in NPK. The decoupled relationship between the N2O fluxes and the N2O concentration in the soil profile depth suggested the contribution of N2O produced in the soil profile to the surface N2O fluxes is limited. This study highlights that manure substitution is an efficient measure to reduce N2O emissions.

Profile-wise enrichment of metallic pollutants (Pb, Cr and Cd) in various sewage and non-sewage irrigated soils of Prayagraj

The study examined the profile-wise enrichment of metallic pollutants (Pb, Cr and Cd) at different sites, i.e., Naini, Draupadi Ghat, Phaphamau and Beligaon in Prayagraj (U.P.), India. The soil samples were collected from different soil profile depths: 0-15, 15-30, 30-45 and 45-60 cm. It was observed that maximum enrichment of Pb, Cr and Cd was found at the (0-15 cm) depth of sewage and non-sewage irrigated soil (5.12±0.42, 4.08±038 and 3.58±031 mg kg-1 ) and (1.58±0.09, 1.08±0.09 and 1.02±0.08 mg kg-1 ) and minimum enrichment was found at the (45-60 cm) depth (2.18, 0.56 and 0.48 mg kg-1 ) and (0.69±0.04, 0.56±0.04 and 0.47±0.03 mg kg-1 ) in Naini, respectively. Maximum enrichment of Pb, Cr and Cd was found at the (0-15 cm) depth of sewage and non-sewage irrigated soil (2.44±0.22, 2.19±0.14 and 2.08±0.16 mg kg-1 ) and (1.09±0.07, 0.97±0.06 and 0.84±0.07 mg kg-1 ) and minimum enrichment was found at the (45-60 cm) depth (1.01±0.06, 0.98±0.05 and 0.71±0.06 mg kg-1 ) and (0.19±0.02, 0.15±0.01 and 0.11±0.01 mg kg-1 ) in Beligaon, respectively. To find the maximum enrichment of heavy metals in Naini and the minimum enrichment in Beligaon. The enrichment of metallic pollution decreased with increasing soil profile depth in both sewage and non-sewage irrigated soils. Metallic contamination in soil can persist for a long time and create serious problems; therefore, proper monitoring of sewage irrigated soils is required to reduce metallic pollution

Measuring and modeling soil moisture and runoff at solar farms using a disconnected impervious surface approach

AbstractGround‐mounted photovoltaic sites are often treated as impervious surfaces in stormwater permits. This ignores the pervious soils beneath and between solar arrays and leads to an overestimation of runoff. Our objective was to improve solar farm stormwater hydrology models by explicitly considering the disconnected impervious nature of solar design and site characteristics. Experimental sites established on utility scale solar farms in Colorado, Georgia, Minnesota, New York, and Oregon had perennial vegetative plantings with mean precipitation ranging from 40.6 to 124.5 cm, and soil texture ranging from loamy sand to clay. Soil moisture measurements were collected beneath arrays, under drip edges, and in the vegetated area between arrays at each site. Hydrus‐3D models for soil moisture and stormwater hydrology were developed that accounted for precipitation falling on solar panels, drip edge redistribution of rainfall, infiltration, and runoff in the pervious areas between solar arrays and beneath panels. Drip edge runoff averaged 3‐ to 10‐times incident precipitation at the New York and Minnesota sites, respectively. Root mean square error values between measured sub‐hourly soil moisture and predicted moisture for large measured single storm events averaged 0.029 across all five sites. Predicted runoff depths were strongly affected by precipitation depth, soil texture, soil profile depth, and soil bulk density. Runoff depths across the five experimental sites averaged 13%, 25%, and 45% of the 2‐, 10‐, and 100‐year design storm depths, clearly showing that these solar farms do not behave like impervious surfaces, but rather as disconnected impervious surfaces with substantial infiltration of runoff in the vegetated areas between and beneath solar arrays.

Soil Fertility Status of Major Coconut Growing Soils of Tumkur District, Karnataka, India

A study was conducted to assess the soil fertility status of major coconut growing soils of Tumkur district of Karnataka with soil pedon locations being Turuvekere and Gubbi. The results revealed that soils of the study area were slightly to strongly alkaline in reaction and non-saline in nature. The organic carbon content was varying from low to high and it followed decreasing trend with soil depth in both soil profiles (Turuvekere and Gubbi). The clay distribution, cation exchange capacity and base saturation of the soils varied from 17.83 to 60.37 per cent, 8.71 to 28.86 cmol (p+) kg-1 and 75.53 to 93.42 per cent, respectively. The macronutrient status of the soil samples indicated that the available nitrogen and phosphorus varied from low to medium, and available potassium content was varying from low to high. Analysis of secondary nutrients showed that exchangeable calcium and magnesium were found to be sufficient but available sulphur was varying from deficient to sufficient level in these soils. The DTPA extractable micronutrients viz., iron, manganese, zinc and boron were found to be deficient in entire study area where as copper was varying from deficient to adequate level with surface soil having relatively high copper content than subsurface soil.

SOC and TN fluctuations determine the variations in microbial enzymatic activities under diverse land use types in the Central Himalaya, India

Soil microbial enzymatic activities, often used as indicators of soil health and fertility, are vulnerable to changes in climate and anthropogenic activities. This study analyses the responses of specific soil enzymatic activities– dehydrogenase (DHA), acid phosphatase (APH), β-glucosidase (BG) and urease (URE)– in Nitosols/Luvisols of the subtropical zone of the Central Himalaya, India. We investigated how these enzymatic activities vary with different land uses: arable land (AL), kitchen garden (KG) and peach orchard (PO), across four villages– Niglat, Kainchidham, Majhera and Syalikhet. Considering associated management practices, we quantified cumulative average soil enzymatic activities for the rabi season (2017–2018). In general, catalytic activity of the selected enzymes was highest in Syalikhet and lowest in Majhera. However, for land use types, enzymatic activities were lower in AL and KG (75.56–90.17% and 39.41–61.72%, respectively) compared to PO values. MANOVA analysis evaluated significant spatial differences (P < 0.001) in enzymatic activities. Soil enzymatic mean values were highest in the surface layer (0–10 cm) and decreased gradually with increasing depth. Parameters such as soil moisture content (SMC) and pH, along with vegetation, management practices, and nutrients such as SOC, TN, K, AP, and N forms (NH4+–N and NO3––N) showed significant and strong correlations with all the soil enzyme activities (r = 0.40–0.97; P < 0.05). TN, SOC, K, SMC, pH, AP, NH4+- N, and clay content were key determining factors of soil enzymatic activities, explaining approximately 59% of the variation. These results suggest that using soil microbial enzymatic activities as soil quality indicators is a feasible approach to assess the impacts of vegetation, management practices, and soil profile depths in soils under different land use types/systems in selected impoverished villages of the fragile Central Himalaya, India.

Effect of crop rotation on nitrogen leaching with the lysimetric waters in vulnerable areas

Abstract. Climate change is known to subject the functioning of agroecosystems to high levels of biotic and abiotic stress and has a significant impact on agricultural production worldwide. Crop rotation is believed to be one way of adapting agriculture to climate change compared to monoculture This study aimed to examine the maize-wheat rotation impact on soil nitrogen dynamics and leaching losses. A study has been carried out on the experimental field of Tsalapitsa, Plovdiv region on Fluvisol. In this maize-wheat rotation experiment, we compared three fertilization treatments with increasing nitrogen and phosphorus rates to a control with no fertilization. In 2020, grain maize (Zea mays L.) FAO group 310, was grown with fertilizer rates (T0N0P0; T1N120P80; T2N160P120; T3N200P160). In the period 2020/2021, wheat, (Triticum aestivum L.), was grown with the following fertilizer variants – (Т0 N0P0; Т1N100P60; Т2 N140P100; Т3 N180P140). The field plots were equipped with modification of Ebermayer type of lysimeters, which collect water from 100 cm depth of soil profile. The volume of lysimetric waters was calculated, the nitrogen content and its leaching were analyzed. The study found that the lysimetric water volume after maize cultivation was 75.95 liters per square meter, approximately 2.5 to 3 times higher than that observed after wheat cultivation. Nitrogen content varied with fertilization rates, ranging from 10.8 to 37.5 mg/L for maize and 8.73 to 23.58 mg/L for wheat. The losses of the element with drainage runoff with the first crop were – 5.6-28.5 kg.ha-1, and with wheat – 1.2-6.3 kg.ha-1, respectively. It was established that when cereal crops were grown the losses of nitrate nitrogen out of the root zone were significantly reduced.

Pitfalls of distinguishing anthropogenic and geogenic reasons for risk elements in soils around coal-fired power plants: from a case study in the Northwestern Czech Republic to general recommendations

PurposeMany historical industrial activities, including coal mining and burning, have started near geogenic anomalies. It resulted in spatial overlap of anthropogenic and natural causes of elevated soil risk element contents. Here, distinguishing between anthropogenic and geogenic contributions cannot be achieved by conventional geochemical soil mapping, in particular, when only pseudo-total contents of risk elements were obtained, soil depth profiles were not acquired, and geological maps were not implemented.MethodsThe local geology, topography and anthropogenic activities were taken into account when planning the soil sampling. Soil profiles were obtained using an auger sampler. Total contents of risk and lithogenic elements were obtained by X-ray fluorescence. Aqua regia extraction and inductively coupled plasma mass spectrometry (ICP-MS) were also used for analyses.ResultsCoal use in the study area increased the soil contents of Cd, Hg, and Zn in 7 km circle east of the major power plant, typically to 2 × local background in topsoils. In the profiles closest to that plant, Cd emissions have already been translocated to soils below ploughed horizons that weaken the contamination signal in topsoils. The highest As and Pb contents in the Most Basin soils originated from a local geogenic anomaly and not coal burning.ConclusionCommon soil mapping projects and data mining routines cannot decipher anthropogenic contribution to the soil risk elements unequivocally, as it is demonstrated in this paper. When working in geogenically anomalous areas, a fundamental knowledge of the mechanisms controlling the content of risk elements in soils is required.

Расчет поливной нормы при капельном орошении древесно-плодовых культур в садовых насаждениях

Purpose: to develop the methodology for calculating irrigation rate for drip irrigation of tree-fruit crops, ensuring the formation of moistened soil contours in soil space with the required geometric and moisture parameters. Materials and methods. The empirical basis for the methodology development was the materials of the author's research devoted to determining the geometric dimensions (parameters) of soil moisture contours. The working hypothesis of the study involved determining the water supply rate for one emitter, one tree-fruit plant and a number of crops in the plantation, with further determining drip irrigation rate per unit area of drip-irrigated agricultural land, taking into account the number of drip micro-water outlets located on it. Results and discussion. When determining the geometric parameters of moisture contours and water supply rate, the main soil and technological parameters of drip irrigation and contour formation (physical clay content in soil, its lowest moisture capacity and bulk density, levels of pre-irrigation and after-irrigation soil moisture, specified depth soil profile moistening and dripper consumption) were considered as influence factors. The dependencies obtained by the author make it possible to determine the linear, areal and volumetric dimensions of local moisture contours and water supply rate, which, under appropriate conditions of drip irrigation, ensures the formation of a local, initially formed moisture contour with the required soil wetting depth in the soil layer. A study of the proposed methodology showed a deviation of the predicted parameters from the experimental soil moisture contours within ±10.0 %. Conclusions. A methodology allowing determining the irrigation rate for drip irrigation of agricultural land as the sum of the water supply rates of all drip water outlets irrigating 1 hectare of agricultural land with practical accuracy has been developed.

Расчет поливной нормы при капельном орошении древесно-плодовых культур в садовых насаждениях

Purpose: to develop the methodology for calculating irrigation rate for drip irrigation of tree-fruit crops, ensuring the formation of moistened soil contours in soil space with the required geometric and moisture parameters. Materials and methods. The empirical basis for the methodology development was the materials of the author's research devoted to determining the geometric dimensions (parameters) of soil moisture contours. The working hypothesis of the study involved determining the water supply rate for one emitter, one tree-fruit plant and a number of crops in the plantation, with further determining drip irrigation rate per unit area of drip-irrigated agricultural land, taking into account the number of drip micro-water outlets located on it. Results and discussion. When determining the geometric parameters of moisture contours and water supply rate, the main soil and technological parameters of drip irrigation and contour formation (physical clay content in soil, its lowest moisture capacity and bulk density, levels of pre-irrigation and after-irrigation soil moisture, specified depth soil profile moistening and dripper consumption) were considered as influence factors. The dependencies obtained by the author make it possible to determine the linear, areal and volumetric dimensions of local moisture contours and water supply rate, which, under appropriate conditions of drip irrigation, ensures the formation of a local, initially formed moisture contour with the required soil wetting depth in the soil layer. A study of the proposed methodology showed a deviation of the predicted parameters from the experimental soil moisture contours within ±10.0 %. Conclusions. A methodology allowing determining the irrigation rate for drip irrigation of agricultural land as the sum of the water supply rates of all drip water outlets irrigating 1 hectare of agricultural land with practical accuracy has been developed.

Estimation of Carbon and Nitrogen Contents in Forest Ecosystems in the Background Areas of the Russian Arctic (Murmansk Region)

In this study, carbon and nitrogen contents in the undisturbed terrestrial ecosystems in the northern taiga zone of Russia’s Murmansk region were estimated. The goal of this study was to examine the carbon and nitrogen dynamics in atmospheric precipitation, assimilating organs of coniferous trees (Picea obovata and Pinus sylvestris), needle litter, soils, and soil water. The objects of our research were the most common dwarf shrub-green moss spruce forests and lichen-dwarf shrub pine forests of the boreal zone. The study was carried out on permanent plots between 1999 and 2020. The long-term dynamics of carbon concentrations in snow demonstrated a trend towards increasing carbon concentrations in forested and treeless areas of the Murmansk region. It was shown that in representative spruce and pine forests, the concentrations and atmospheric precipitation of carbon compounds and carbon leaching with soil water were higher below the tree crowns, compared to between the crowns. In soil water, a decrease was found in carbon concentration with the soil profile depth. For soils, the highest carbon concentrations were found in the organic and illuvial soil horizons. The main soil sinks of carbon and nitrogen in northern taiga forests were found to be located in the organic soil horizon below the crowns. In northern taiga forests, the carbon content of living Picea obovata and Pinus sylvestris needles and Pinus sylvestris needle litter had minor variability; no significant interbiogeocoenotic and age differences were found. We found that the nitrogen content in brown needles and needle litter was significantly lower compared to photosynthetically active needles, probably due to retranslocation processes (withdrawal before needle abscission), corroborating the literature in the results session. The largest stocks of carbon and nitrogen in northern taiga forests are concentrated in the soil organic horizon, and the removal of these elements with soil water is insignificant. Carbon and nitrogen stocks in living and fallen needles are lower than in soil. The least amount of carbon and nitrogen is contained in atmospheric precipitation.

Applying thallium isotopic compositions as novel and sensitive proxy for Tl(I)/Tl(III) transformation and source apportionment

Thallium is a rare metal known for its highly toxic nature. Recent research has indicated that the precise determination of Tl isotopic compositions using Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP MS) provides new opportunities for understanding Tl geochemical behavior. While isotopic fractionation of Tl derived from anthropogenic activities (e.g., mining, smelting) have been reported, there is limited information regarding Tl influenced by both natural weathering processes and anthropogenic origins. Herein, we investigated, for the first time, the Tl isotopic compositions in soils across a representative Tl-rich depth profile from the Lanmuchang (LMC) quicksilver mine (southwest China) in the low-temperature metallogenesis zone. The results showed significant variations in Tl isotope signatures (ε205Tl) among different soil layers, ranging from −0.23 to 3.79, with heavier isotope-205Tl enrichment observed in the bottom layers of the profile (ε205Tl = 2.18–3.79). This enrichment of 205Tl was not solely correlated with the degree of soil weathering but was also partially associated with oxidation of Tl(I) by Fe (hydr)oxide minerals. Quantitative calculation using ε205Tl vs. 1/Tl data further indicated that the Tl enrichment across the soil depth profile was predominantly derived from anthropogenic origins. All these findings highlight that the robustness and reliability of Tl isotopes as a proxy for identifying both anthropogenic and geogenic sources, as well as tracing chemical alterations and redox-controlled mineralogical processes of Tl in soils. The nascent application of Tl isotopes herein not only offers valuable insights into the behavior of Tl in surface environments, but also establishes a framework for source apportionment in soils under similar circumstances.

Earth Observation Capacity of the National Geoinformation Center of Bulgaria as Part of the Tools for Geo- and Anthropogenic-Hazard Management in EPOS

Exploring the nature of the Earth system and its multi-scale architecture requires an integrated symbiotic approach not only to understand our planet but also to reveal the hazards and footprints of their events on human life. Following the conceptual model of the European Plate Observing System (EPOS) we integrate a variety of research to obtain a multilateral use of geoinformation for scientific and practical purposes. In 2018, we started building a Bulgarian distributed scientific infrastructure called the National Geoinformation Center, aiming to provide data, products, and expertise to predict and prevent natural and anthropogenic risks and disasters, as well as environmental changes. The present paper demonstrates the capabilities of seismological, Global Navigation Satellite System (GNSS), geomagnetic and multi-scale laboratories (MSL) in Bulgaria that participate to the respective thematic core services of EPOS. More than 40 seismological stations register and transmit data in real time through the operational center of the Bulgarian Seismological Network. Data from 18 GNSS stations, part of the National GNSS network, are officially registered in the EPOS GNSS Data Gateway. Data and products are available via the EPOS GNSS Product Portal for interested users. Panagjurishte geomagnetic observatory (PAG) provides real time variations and long-period data series for the Earth’s magnetic field. The Palaeomagnetic Laboratory at the National Institute of Geophysics, Geodesy and Geography (NIGGG) participates in MSL with its unique facilities for paleo-, archeo- and environmental magnetism studies. Four case studies are presented to illustrate best practices for utilizing the data collected. The analysis of seismicity in a region of a long-time exploited salt deposit is upgraded with GNSS data to reveal the reason for crustal movements in the region. The results show that the majority of the seismic events took place in the upper part of the Earth’s crust at a depth of up to 5 km, where the salt body is buried. The observed significant local deformations of the Earth’s surface are very likely related to the technological process of deposit exploitation. A recent model of the geomagnetic declination over the Bulgarian territory is also presented. It tracks the variation of the regional magnetic field from 2015 to 2020 and adds short-wavelength signals from the secular network observations. Last but not least, the application of a mineral magnetic laboratory analysis along the depth of a Holocene soil profile is demonstrated. Results reveal the soil evolution in response to environmental changes adding a new magnetic proxy parameter for more precise identification and characterization of the soil formation processes.

Viral metagenomics reveals diverse virus-host interactions throughout the soil depth profile.

Soil viruses can moderate the roles that their host microbes play in global carbon cycling. However, given that most studies investigate the surface layer (i.e., top 20 cm) of soil, the extent to which this occurs in subsurface soil (i.e., below 20 cm) is unknown. Here, we leveraged public sequencing data to investigate the interactions between viruses and their hosts at soil depth intervals, down to 115 cm. While most viruses were detected throughout the soil depth profile, their adaptation to host microbes varied. Nonetheless, we uncovered evidence for the potential of soil viruses to encourage their hosts to recycle plant-derived carbon in both surface and subsurface soils. This work reasons that our understanding of soil viral functions requires us to continue to dig deeper and compare viruses existing throughout soil ecosystems.

Impacts of long-term organic manure inputs on cultivated soils with various degradation degrees

With an increasing concern of soil health and sustainable development, organic manure application has been readdressed in recent years. In Northeast China, the agricultural industry is highly developed and organic manure resources are abundant, but soil degradation is serious due to extensive expansion of cultivation. Currently, limited information is available on how soils with various degradation degrees respond to long-term manure fertilization. Given that, a comparative study was conducted based on soil functional assessment of croplands with over 35 years of manure fertilization (maize straw compost, SA; cattle manure, CA) and various degradation degrees (none, light, moderate, and heavy). Soils in these croplands were loess-derived Mollisols and concentrated on a gentle to flat slope. Except for the difference in manure fertilization (SA and CA), similar field managements were adopted for these croplands during the past 35 years. Results showed that the impacts of erosion degradation and manure fertilization on soil physical structure lasted across the whole profile (0 ∼ 120 cm), while their impacts on soil nutrient properties were concentrated in shallow layers (<50 cm). Meanwhile, erosion degradation dominated 17.9% of the variance of soil physical structure, and soil profile depth contributed to 15.9% of soil nutrient variation. According to field validation regarding soil erosion modulus and crop yield, principal component analysis (PCA) with a nonlinear scoring method showed a good performance on the integrated soil functional index (ISI) assessment in this study area. The ISI of these croplands was found to be minimally characterized by BD, SOC, TN, AK, sand content, and CEC (R2 >0.64, p < 0.001). In addition, manure fertilization could significantly improve the ISI and maize yield for degraded soils, but had a slight impact on these two indicators for non-degraded soils. In terms of contribution to ISI improvement, SA (1.79% ∼ 283.73%) generally outperformed CA (4.53% ∼ 212.83%), while the latter was more effective in altering soil structure in deep layers (>70 cm). Generally, the ISI and maize yield were more susceptible to erosion degradation than manure fertilization. The obtained results provide useful information for a better cropland management in Northeast China.

Seismic Fragility Curves of Combined Multiple Tunnel Complexes in Soft Soils

Seismic fragility assessment is the probability of damage exceeding a certain design limit. The dynamic performance of a combined multiple tunnel complex is less explored and requires thorough study. This research is based on the numerical approach to evaluate the damage caused to the two new types of tunnel complexes, i.e. twin and triple tunnel complexes in a soft soil profile. A two-dimensional (2D) finite element analysis is performed to determine the induced bending moments for each of the tunnel complexes and develop the seismic fragility curves. A set of full acceleration-time histories are applied to the soil–tunnel complex system by varying embedment depths in different soft soil profiles. From the results, it is concluded that increasing the embedment ratio results in an increased probability of tunnel damage. The developed fragility curves are also inter-compared for both the tunnel complexes to evaluate the better performer during a seismic event. This study serves as an initial step toward the guidelines to determine the percentage of incurred damage and design the combined multiple tunnel complex in a seismic-prone area.

Plant species and soil depth differentially affect microbial diversity and function in grasslands

AbstractIntroductionGrassland ecosystems are a major store of terrestrial carbon (C), yet little is known about their capacity to cycle and store C in deeper soil horizons. Further, it is unclear how plant community composition within agricultural grasslands mediates this capacity and influences microbial community composition. We investigated whether the aboveground community composition in intensively managed agricultural grasslands influenced belowground microbial community composition, abundance, respiration and enzyme activities with depth.Materials and MethodsSoil was sampled in four soil layers: A (0–15 cm), B (15–30 cm), C (30–60 cm) and D (60–90 cm) in monocultures of six grassland species and a mixture of all six. Functional capacity was measured through enzymatic and substrate‐induced respiration assays, and microbial abundance and diversity were assessed via quantitative polymerase chain reaction and sequencing (16S, Internal transcribed spacer), respectively.ResultsMicrobial abundance and C cycling enzyme activity decreased and community composition changed, along the soil depth gradient, regardless of the plant community. Microbial abundance was not significantly influenced by plant community type across the entire soil depth profile. However, prokaryotic community composition was significantly influenced by plant community in the top 15 cm of soil, and fungal community composition was significantly influenced between 15 and 30 cm in depth. Plant community types mediated the rate at which C cycling enzyme activity decreased along the soil depth gradient, and selected C cycling enzymes were significantly more active at 15–60 cm depth when Cichorium intybus (a deep rooting species) was present.ConclusionThis study provides an improved understanding of how agricultural grassland communities affect the soil microbiome with depth; this has potential implications for the management of these systems for enhanced soil health. Our work indicates the potential for multispecies mixtures with deep rooting species to be a practical strategy to increase C cycling capacity in deeper soil layers within grasslands, which may have implications for policy goals related to C storage.

Radiometric and magnetic susceptibility characterization of soil profiles: Geophysical data and their relationship with Antarctic periglacial processes, pedogenesis, and lithology

Maritime Antarctica is still pedologically unexplored by proximal geophysical sensors. In-depth soil geophysical characterizations in depth can provide comprehensive information regarding how weathering, pedogenesis, and periglacial processes operate in periglacial environments, with advantages like non-invasive methodology, fast and precise data acquisition, practical equipment operation, and cost-effectiveness. This research aimed to carry out the first proximal gamma-spectrometric and magnetic geophysical characterization of soil profiles in maritime Antarctica and to relate the geophysical variables analyzed with periglacial processes, weathering, pedogenesis, geology, and landscape dynamics. The study was carried out in the Keller Peninsula (King George Island, Maritime Antarctica) with the pedological characterization of soil profiles, using two proximal geophysical sensors (gamma spectrometer and susceptibility meter) that quantify, respectively, soil radionuclides uranium, thorium and potassium as well as soil magnetic susceptibility. For that, twenty soil profiles were described and characterized, and soil samples were collected for physico-chemical analysis. In addition, readings were carried out with the two geophysical sensors in each soil profile, through soil horizons up to the lithic contact and/or permafrost top. We performed exploratory statistical analyses in R software as follows: visualizing the geophysical variables in soil depth for each profile and soil class, obtaining descriptive statistics among soil classes, analyzing geophysical variables by geology and soil classes, performing Spearman correlation between geophysical variables and soil physico-chemical attributes, and applying principal component analysis to pedological classes, geophysical variables, and soil physico-chemical attributes. The results showed that radionuclide contents increased with soil profile depth in all profiles and soil classes analyzed, except for Cryosols where permafrost is present, and cryoturbation was more pronounced. The potassium content was high in all soil profiles, evidencing the low degree of chemical weathering and leaching. The soil magnetic susceptibility values tended to decrease in depth, mainly where permafrost was present. The gravel content contributed more to the levels of radionuclide content. The clay content in some soil classes present contributed secondarily to uranium and thorium contents. Soil profiles located on marine terraces were influenced by periglacial reworking and deposition of different materials, showing increases in magnetic susceptibility values with soil depth by the absolute accumulation of ferrimagnetic minerals. Principal component analyses efficiently separated Regosols from other soil classes by soil κ related to lithology, whereas Cambisols and other soil classes were separated by radionuclide contents related to incipient pedogenesis. These findings may give new insights into understand this inhospitable continent.

Enrichment of Cd, Cr, Pb and Biological Detoxification Strategies in Sewage Irrigated Soils

Aim: Long-term use of sewage-sludge and improper management of agricultural lands can lead to an elevated heavy metal concentration in the soil resulting in barren soil. The present investigation was carried out to study the influence of different soil characteristics on the enrichment of Cd, Cr and Pb and their detoxification strategies in sewage irrigated soil profiles of Prayagraj region, India. Methodology: Di-acid mixture method used for soil analysis. The clean filtrate was used for the estimation of the heavy metals (Cd, Cr and Pb) by Atomic Absorption Spectrophotometer (AAS) (AAnalyst600, Perkin Elmer Inc., MA, USA). Isolation and identification of Cd, Cr and Pb Detoxifying microorganisms were isolated from the sewage-irrigated soils by nutrient agar medium. Results: It was observed that surface soils contained higher amount of DTPA- extractable heavy metals (Cd 3.00-3.20 mg kg-1,Cr 5.20-6.40 mg kg-1 and Pb 6.80-7.20 mg kg-1) and these amounts along with CEC (26.10 Cmol (p+) kg-1) and organic carbon (OC) Content (0.58%) decreased with the depth of soil profiles. Among the tested microorganisms, the highest accumulation of heavy metals in the sewage irrigated soils was observed in Citrobacter spp. to the extent of Cd 13.2%, Cr 36%, and Pb 42%. However, the lowest accumulation was observed in Escherichia coli to the extent of Cd 1.2%, Cr 8.4%, and Pb 10.2%. Conclusion: The horizons A of the studied soil profiles contain almost 12% more Cd, 9.11% more Cr, and 52% more Pb as compared to the contents of horizons B. Biological detoxification system metal uptake is largely influenced by the availability of metals. The highest accumulation of heavy metals was observed in the order of Pb &gt; Cr &gt; Cd by the selected microorganisms in the order of Citrobacter spp. &gt;Bacillus spp. &gt; Pseudomonas aerugia &gt; Rhizopus arrhizus &gt; Escherichia coli, resulting in the detoxification of the metals in the sewage irrigated soils. GRAPHICAL ABSTRACT