Soil Type Research Articles

Enhancing soil fertility, inorganic fertilizer efficiency, and oil palm productivity through bio-compost application in oxium biodegradable sacks on former mining land-podzols: Insights from a field study in Indonesia

Sandy podzolic soils, prevalent on former mining lands, present significant agricultural challenges due to their coarse texture, depth, acidity, and low fertility. This study evaluated the impact of bio-compost fertilizer, delivered in biodegradable oxium sacks, on soil quality and oil palm productivity in these soils. Conducted over 12 months in a 4-year-old oil palm plantation in East Belitung Regency, Indonesia, the research compared various combinations of bio-compost and inorganic fertilizers with a control group. The findings revealed that the integration of bio-compost with reduced doses of inorganic fertilizers markedly improved soil quality and decreased dependence on chemical inputs. Specifically, applying 50 kg or 75 kg of bio-compost per palm along with 50 % or 75 % of the standard inorganic fertilizer dose was particularly effective. This approach increased oil palm productivity to 14.50–15.87 tons per hectare per year. The method provides a sustainable solution for the palm oil industry and small farmers, improving soil fertility and productivity in degraded podzolic soils. The use of oxium biodegradable sacks allowed for a gradual release of nutrients. Future research should further explore the potential of bio-compost as a soil conditioner and its long-term environmental impacts across various soil types.

Study on the characteristics and scenario simulation of land use change in the Chaohu Lake Basin, China

Effectively evaluating the historical and future land use/cover change (LUCC) is significant for effective land use planning and management, ecological conservation, and restoration. Taking the Chaohu Lake Basin (CLB) as the study area, GIS technology and geographic detector were used to quantitatively analyze the change characteristics and driving factors of LUCC under the three periods in 2000, 2010, and 2020 of the CLB. This study aimed to comprehend the alterations that have transpired over the last two decades. In addition, the PLUS model was utilized to forecast LUCC trends under three scenarios: natural development, urban development, and ecological protection by 2030 in the CLB. The results suggest a significant decrease of the cultivated land area, while a considerable increase for the construction land area from 2000 to 2020 in the CLB. The expansion of the construction land area was mainly driven by the conversion of cultivated land area. Additionally, the slope was identified as the primary factor influencing LUCC, with q-values of 0.275, 0.266, and 0.258 in 2000, 2010, and 2020, respectively. The interaction between slope and soil type, distance to the trunk road and the secondary trunk road, and GDP was strong. The explanatory capacity of socioeconomic factors demonstrated a steady increase. The simulation results indicate that a decrease in cultivated land area and an increase in construction land area still occurred by 2030 in the CLB, particularly in the urban development scenario. Nonetheless, a notable deceleration of change was appeared in the ecological protection scenario. The alterations in forest and grassland areas were not significant. However, the water bodies area continued to enlarge, although the expansion was not substantial. The study results can provide policy references for the scientific management and long-term strategic planning of land resources in the CLB.

Development of growth-stage specific crop coefficient for drip irrigated wheat crop grown in climatic conditions of Jalandhar, Punjab

The crop coefficient (Kc) values given in FAO-56 report need to corrected for local conditions due to differences in climate, soil types, and water management practices. Therefore, present study was undertaken to develop growth-stage-specific Kc values of wheat grown under drip irrigated conditions for two years (2022-23 and 2023-24) at Jalandhar, Punjab. The developed Kc values are 0.36, 0.77, 1.05, 0.69, and 0.25 during initial, development, mid, late, and end growth stages, respectively. These average Kc values can be effectively utilized to schedule irrigation for drip-irrigated wheat crops in the Jalandhar region of Punjab. Irrigating wheat crop under drip irrigation with developed Kc values not only enhances grain yield by 36% but also improves IWUE by three times and saves 61% use of irrigation water as compared to conventional irrigation practices (flood irrigation).

Ecological Status Assessment of Permafrost-Affected Soils in the Nadym Region, Yamalo-Nenets Autonomous District, Russian Arctic

Permafrost-affected regions in the Russian Arctic are a critical study area for studying the sources of metal elements (MEs) in soils originating from geological/pedogenic processes or from anthropogenic sources via atmospheric transport. In the Nadym region of the Yamalo-Nenets Autonomous District, we investigated the contents of soil organic carbon (SOC), total nitrogen (TN), and MEs across different soil types and horizons, explored the source apportionment of MEs, and assessed local ecological risks of potentially toxic elements (PTEs). The results showed that (1) the contents of SOC and TN in Histic Cryosols (8.59% and 0.27%) were significantly higher than in Plaggic Podzols (Arenic, Gelic, and Turbic) (2.28% and 0.15%) and in Ekranic Technosols (Umbric) (1.32% and 0.09%); (2) the concentrations of MEs in the Nadym region were lower than in other Arctic regions; (3) the primary sources of MEs were identified as geological processes (36%), atmospheric transport (23%), agricultural activities (21%), and transportation (20%); and (4) the permafrost-affected soils in the Nadym region exhibited low ecological risks from PTEs. These results underscore the critical role of geological and anthropogenic factors in shaping soil conditions and highlight the relatively low ecological risk from PTEs, providing a valuable benchmark for future environmental assessments and policy development in Yamal permafrost regions.

Application of GIS-Based Multi-Criteria Decision Analysis of Hydro-Geomorphological Factors for Flash Flood Susceptibility Mapping in Bangladesh

Flash floods are one of the most prevalent natural disasters, triggering deadly damage to homesteads, crops, infrastructure, road networks, communications, and the natural environment in the Haor (Wetland) region of Bangladesh. The purpose of the study aims to identify eleven (11) hydro-geomorphological driving factors, namely elevation, slope, aspect, rainfall, land use and land cover (LULC), lithology, soil type, topographic wetness index (TWI), NDVI, distance from the river, and drainage density, which are being explored for mapping flood-prone areas. This research has produced a flash flood susceptibility map using the Analytical Hierarchy Process (AHP) and Analytical Network Process (ANP), which are interactive decision-making approaches under multi-criteria decision analysis (MCDA) in ArcGIS 10.8. The findings of this study showed that the susceptibility to flood hazards differs significantly among the seven Haor districts. As a result of the ANP and AHP, a more significant proportion of the Haor region is moderately susceptible to flooding (8685.09 to 9275.15 sq. km.), whereas 35.34% to 38.32% (7069.70 to 7668.67 sq. km.) accounts for high susceptible to flooding. Furthermore, 200 flood locations were identified in the northeast Haor region, where 140 (70%) randomly selected floods were used for training, and the remaining 60 (30%) were employed for validation purposes. The validation results showed that the AHP model had greater prediction accuracy (AUROC = 92.1%) than the ANP (AUROC = 88.5%) model. Therefore, the study findings can be helpful for researchers, academics, policymakers, and planners for sustainable flood mitigation strategies, particularly in Haor areas.

Data-enhanced design charts for efficient reliability-based design of geotechnical systems

This paper proposes a new design chart approach for reliability assessment, which enables clear visualization of the representative soil shear strength parameters under various reliability levels and effective stress levels. Utilizing the design charts, reliability assessment or reliability-based design can be performed with significantly reduced numbers of evaluations of the geotechnical system response. The design charts are established solely based on the probability distributions of soil parameters, and are applicable to a variety of geotechnical problems involving the same soil type. For practical illustration of the proposed approach, design charts are produced from the shear strength databases of saprolitic soils and colluvial soils in Hong Kong, and then applied to the reliability-based design of a slope with soil nail reinforcements. The ensuing design solutions require much fewer soil nails compared to the conventional design practice, while also achieving a better system reliability. The same charts are then applied to the reliability-based design of a retaining wall, where a series of design options are identified with equivalent reliability index against overturning failure and pullout failure. Through the proposed approach, the use of design charts promotes efficient reliability-based design of geotechnical systems with rational incorporation of reliability concepts.

Ecology of arbuscular mycorrhizal association in coconut (Cocos nucifera L.) palms: Analysis of factors influencing AMF in fields

This study is the first thorough ecological analysis of arbuscular mycorrhizal fungal (AMF) diversity in randomly selected traditional coconut fields across Kerala, South India. We conducted a critical analysis of AMF diversity, percentage root length colonization (PRLC), and mean spore density (MSD) across 248 sites, taking into account variations in plant, environmental, and soil factors like coconut varieties, palm health conditions, agroclimatic zones, soil types, and seasons in the region. A total of 23 AMF species from seven genera (Acaulospora, Archaeospora, Funneliformis, Glomus, Sclerocystis, Septoglomus, and Scutellospora) were identified, with Acaulospora scrobiculata being the dominant species in all studied fields. A critical analysis of diversity indices, including the Shannon-Weiner Index, Simpson's diversity index, and Gini-Simpson index, concerning variables indicated that soil series influences AMF diversity in specific fields. Correlational and principal component analyses highlighted the interrelationships between specific soil types and quality parameters affecting AMF characteristics, underscoring their crucial role in coconut palm growth. The study also revealed the ecological amplitudes of indigenous AMF species related to specific soil fertility parameters. Overall, this research serves as a model for identifying root- and soil-specific AMF in agricultural fields and provides valuable ecological insights for utilizing indigenous AMF species as ecotechnological tools for sustainable coconut cultivation.

Risk hotspots and influencing factors identification of heavy metal(loid)s in agricultural soils using spatial bivariate analysis and random forest

Heavy metal(loid)s (HMs) in agricultural soils not only affect soil function and crop security, but also pose health risks to residents. However, previous concerns have typically focused on only one aspect, neglecting the other. This lack of a comprehensive approach challenges the identification of hotspots and the prioritization of factors for effective management. To address this gap, a novel method incorporating spatial bivariate analysis with random forest was proposed to identify high-risk hotspots and the key influencing factors. A large-scale dataset containing 2995 soil samples and soil HMs (As, Cd, Cr, Cu, Mn, Ni, Pb, Sb, and Zn) was obtained from across Henan province, central China. Spatial bivariate analysis of both health risk and ecological risks revealed risk hotspots. Positive matrix factorization model was initially used to investigate potential sources. Twenty-two environmental variables were selected and input into random forest to further identify the key influencing factors impacting soil accumulation. Results of local Moran's I index indicated high-high HM clusters at the western and northern margins of the province. Hotspots of high ecological and health risk were primarily observed in Xuchang and Nanyang due to the widespread township enterprises with outdated pollution control measures. As concentration and exposure frequency dominated the non-carcinogenic and carcinogenic risks. Anthropogenic activities, particularly vehicular traffic (contributing ~37.8 % of the total heavy metals accumulation), were the dominant sources of HMs in agricultural soils. Random forest modeling indicated that soil type and PM2.5 concentrations were the most influencing natural and anthropogenic variables, respectively. Based on the above findings, control measures on traffic source should be formulated and implemented provincially; in Xuchang and Nanyang, scattered township enterprises with outdated pollution control measures should be integrated and upgraded to avoid further pollution from these sources.

Integrated spatial priority assessment in Central Asia: Bridging biodiversity, ecosystem services, and human activities

Central Asia (CA) faces escalating threats from increasing temperatures, glacier retreat, biodiversity loss, unsustainable water use, terminal lake shrinkage, and soil salinization, all of which challenge the balance between ecological integrity and socio-economic development essential for achieving sustainable development goals. However, a comprehensive understanding of priority areas from a multi-dimensional perspective is lacking, hindering effective conservation and development strategies. To address this, we developed a comprehensive assessment framework with a tailored indicator system, enabling a spatial evaluation of CA's priority areas by integrating biodiversity, ecosystem services (ESs), and human activities. Combining zonation and geographical detectors, this approach facilitates spatial prioritization and examines ecological and socio-economic heterogeneity. Our findings reveal a heterogeneous distribution of priority areas across CA, with significant concentrations in eastern mountainous regions, river valleys, and oasis agricultural lands. We identified 184 key districts crucial for ecological and societal sustainability. Attribution analysis shows that natural factors like soil types, precipitation, and evapotranspiration significantly shape these areas, influencing human activities and the distribution of biodiversity and ESs. Multi-dimensional analysis indicates existing protected areas cover only 15% of the top 30% priority areas, revealing substantial conservation gaps. Additionally, a 38% overlap between ESs and human activities, along with 63.25% congruence in integrated areas, underscores significant human impacts on ecological systems and their dependency on ESs. Given CA's limited resources, it is crucial to implement measures that strengthen conservation efforts, align ecological preservation with socio-economic demands, and enhance resource efficiency through sustainable integrated land and water resource management.

Study of Soil Heterotrophic Respiration as a Function of Soil Moisture under Different Land Covers

The relationship between soil heterotrophic respiration (Rh) and soil moisture conditions has been often studied using disturbed soil samples and simple gravimetric and volumetric soil moisture indicators. The objective of this study was to investigate the relationship between Rh and soil moisture in terms of water-filled porosity (WFP), matric potential (), and relative soil gas diffusivity () using undisturbed soil cores obtained under different land covers. Soil CO2 efflux, WFP, and were simultaneously measured in undisturbed soil samples (250 cm3) without collected in the 0-5 cm soil layer without any vegetation or living roots under laboratory conditions by combining a CO2 gas analyzer, a precision scale, and precision mini-tensiometers. For each sample we also measured soil chemical properties, soil physical properties, and soil microbial composition using phospholipid fatty acid analysis. Grasslands had the largest total microbial biomass (6,275 ng g-1), followed by soils from riparian (5,327 ng g-1), and cropland (2,745 ng g-1) sites. Bacteria were the dominant group representing 46% (SD = 5%) of the total biomass across all sites and land covers. Maximum Rh was 1.88 (SD = 0.40) μmol CO2 m-2 s-1 in grassland, 1.64 (SD = 0.82) μmol CO2 m-2 s-1 in riparian, and 0.94 (SD = 0.56) μmol CO2 m-2 s-1 in cropland soils. Using WFP as the predictor variable resulted in the most consistent moisture response function. Considering all land cover and soil types, our observations revealed that peak Rh occurred at mean WFP = 0.81 = -6 kPa, and = 0.003. The simpler WFP soil moisture indicator was a better predictor of Rh than or from air-dry to near saturation across soils with contrasting soil texture and soil structure.

Corn yield response to phosphorus fertilizer in Michigan: a metamodeling approach for phosphorus management policies

Phosphorus (P) pollution from nonpoint sources is a persistent agricultural externality. P fertilizer use in excess of crop removal leads to soil P accumulation and increases chance of P runoff from agricultural fields. For fertilizer-intensive crops such as corn, effective nutrient management can partly mitigate the externality associated with fertilizer use. In states such as Michigan with abundant freshwater resources that are vulnerable to P pollution and where corn is grown intensively, understanding yield response is instrumental for P management policies. We analyze corn yield response to P fertilizer and control for soil P. We use farmer survey data from 1650 corn farmers in Michigan and a crop-simulation model to obtain data in a metamodeling approach to estimate yield function. Using the estimated function in profit maximization set up, we calculate agronomically and economically optimal profit-maximizing P application rates for Michigan, across agricultural regions, and across different soil types. We find that corn yield responds to P only in low soil P (0–5 ppm or mg kg−1) fields and the economically optimal P rate for Michigan is [63, 68] kg ha−1 or [53, 61] lbs acre−1 for low soil P fields and would be zero for fields with adequate soil P. For existing soil P levels in Michigan, the self-reported P application of Michigan corn farmers exceeds the profit-maximizing P application rate. We compare our analysis results with self-reported survey data to demonstrate excess P applications. Since many fields in Michigan have high soil P, additional P application in excess of crop removal increases risks of eutrophication. We also find that 10 % increase in P prices faced by farmers would lead to 3.1 % reduction in the economically optimal P application rate. Based on these results, we discuss suitable policy options such as fertilizer “usage fee” and tailored fertilizer recommendations.

Does soil type influence the occurrence of fire outbreaks in Cerrado, Brazil?

Forest fires associated with anthropic activities in Cerrado, Brazil, have been the main cause of the degradation of the biome. Thus, this study aims to understand the dynamics of fire foci and Gross Primary Production as a function of soil classes in an Environmental Preservation Area. This study combined soil types with meteorological variables of rainfall, soil moisture and air temperature to relate to fire occurrences and Gross Primary Production (GPP) for the years 2001 to 2020. For the evaluated period, there was an increase in temperature (±0.5 ºC) and a reduction in rainfall (±50% in the driest years). The highest numbers of fire outbreaks were recorded in the areas corresponding to the Neossolos (Arenosols), followed by Latossolos (Ferralsols) between August and October. The future projection of the occurrence of foci for the next 10 years indicated that there would be an increase in the number of fire foci in all soil classes (700%), especially for Neossolos. The future projection of GPP for the next 10 years indicates that there would be a reduction in coverage, especially for Gleissolo (Gleysol, 40 to 80%). As a prevention strategy, attention should be doubled between August and October, as these months are the most conducive to fire outbreaks in the Cerrado.

Assessment, identifying, and presenting a plan for the stabilization of loessic soils exposed to scouring in the path of gas pipelines, case study: Maraveh-Tappeh city

Dealing with collapsible soils consistently presents a crucial challenge for geological and geotechnical engineers. Loess soil is among the most widely recognized types of collapsible soils, covering approximately 10 % of the Earth's land surface. Loessic soil is a sedimentary deposit primarily composed of silt-size grains, loosely bound together by calcium carbonate. In Iran, approximately 17 % of Golestan province is covered by silty, clayey, and sandy loesses, primarily composed of loessic soil. Additionally, several energy transmission lines in this province traverse these loess-covered areas. Based on the reports from Golestan Gas Company experts, the scouring of gas pipeline channels in various regions, such as Dashli-Alum in Maraveh-Tappeh city, causes significant risks in the traffic roads and is one of the most critical issues facing this company. This research assessed the dispersion and collapse potentials of loess soil using a range of field exploration and laboratory testing methods. These methods included atomic absorption spectroscopy, the double hydrometer, scanning electron microscope photography, wavelength-dispersive X-ray fluorescence spectrometry, and consolidation tests. The results indicate that soil collapsibility was acquired as one of the components of the scouring phenomenon occurrences. To achieve an optimal solution, the effectiveness of the chemical stabilization method involving cement, bentonite, micro-silica, and synthesized nano‑titanium additives was evaluated through an oedometer, Atterberg limits, uniaxial compression, and direct shear tests. Additives dry mixing of cement and nano‑titanium were obtained as the optimal stabilization solutions against scouring compared to other additives. However, considering the environmental impacts of cement production and use, nano‑titanium presents a more environmentally sustainable option due to CO2 absorption and reduced damage potential to vegetation.

Fate of chlordecone in soil food webs in a banana agroecosystem in Martinique

Large quantities of chlordecone-based insecticides were produced and used throughout the world. One of its most important uses was to control the damage caused by Cosmopolites sordidus in banana-growing regions. In the islands of Martinique and Guadeloupe, 18,000 ha of farmland are potentially contaminated. Despite the key role played by soil macrofauna in agroecosystems, there are currently no data on their contamination. The aim of this study was to explore the fate of chlordecone (CLD) and its transfer to different organisms of the soil food web.Seven species of invertebrates representing different taxonomic groups and trophic levels of the soil communities of Martinique were targeted and collected in six experimental banana fields, with a level of contamination within a range of values classically observed. Soil samples and macrofauna from the study sites were analysed for CLD and chlordecol (CLDOH) its main transformation product. The contamination of the soil fauna were related to δ15N (trophic level), proportion of soil ingestion (diet) and types of epidermis (mucus or exoskeleton) in order to study the different mechanisms of macrofauna contamination.Presence of CLD and CLDOH could be quantified in all the soil organisms from contaminated fields. Results showed a significant relationship between the CLD contamination of detritivorous and the ash content of their faeces, suggesting that soil ingestion was the main contamination pathway. In contrast, the exoskeleton-bearing diplopod Trigoniulus coralinus and the soft-bodied earthworm Eudrilus eugeniae, both detritivores with a comparable diet, had similar contamination levels, suggesting that the type of tegument has little influence on bioaccumulation. At the scale of the entire trophic network, a significant relationship was uncovered between δ15N values and CLD contamination of the fauna, therefore providing some in situ evidence for a bioamplification process along the soil food chain.

Enhancing Maize Yield and Nutrient Utilization through Improved Soil Quality under Reduced Fertilizer Use: The Efficacy of Organic–Inorganic Compound Fertilizer

Objectives: The substitution of chemical fertilizers with organic alternatives presents a viable strategy for enhancing soil quality and boosting agricultural productivity. However, the question remains whether organic–inorganic compound fertilizers (COIFs) can sustain improved soil quality and crop yields while reducing chemical fertilizer use. The underlying mechanisms of COIF’s impact still warrant further exploration. Methods: In this study, a long-term fertilization trial was conducted from 2020 to 2023 at two sites with different soil textures and types in the Huang-Huai-Hai Plain, China. The experiment involved three fertilization treatments, each replicated three times: (1) LCF (conventional fertilizer treatment); (2) COIF1 (COIF applied at 90% of the recommended rate); and (3) COIF2 (COIF applied at 80% of the recommended rate). The objective was to assess the effects of COIF on summer maize growth, grain yield, nutrient uptake and utilization, and soil quality. Results: Compared to LCF, COIF1 in Yantai and Dezhou increased biomass by 6.4% and 8.1%, grain yield by 5.9% and 4.12%, PFP (N, P, and K) by 17.6% and 15.7%, and soil quality by 563.6% and 462.5%, respectively. No significant differences in biomass and grain yield were observed between COIF2 and LCF, yet COIF1 in Yantai and Dezhou enhanced PFP (N, P, and K) by 19.7% and 18.6%, and soil quality by 109.1% and 175.0%, respectively. In conclusion, COIF improved soil quality by enhancing soil organic matter (SOM), available nutrients, pH, and other soil indices. It promoted summer maize growth, increased grain yield, and improved nutrient utilization. COIF was a practical and effective measure to reduce chemical fertilizer use, enhance field soil quality, and ultimately increase maize yield and nutrient utilization.

Five decades' experience of long‐term soil monitoring, and key design principles, to assist the EU soil health mission

AbstractThe European Union has a long‐term objective to achieve healthy soils by 2050. The European Commission has proposed a Directive of the European Parliament and of the Council on Soil Monitoring and Resilience (Soil Monitoring Law, SML), the first stage of which is to focus on setting up a soil monitoring framework and assessing soils throughout the EU. Situated in NW Europe, the UK has substantial experience in soil monitoring over the last half century which may usefully contribute to this wider EU effort. A set of overarching principles have and continue to guide design of national soil monitoring and may prove helpful as other European countries embark on similar monitoring programmes. Therefore, we present the principles of design from five decades of national soil monitoring. The monitoring discussed is based on a stratified‐random design, has matured in support of policy questions, and operates over space and time scales relevant to the SML. The UK Centre for Ecology & Hydrology (UKCEH) Countryside Surveys (CS) of Great Britain and Northern Ireland, Welsh Government, Environment and Rural Affairs Monitoring and Modelling Programme (ERAMMP) and the England Ecosystem Survey (EES) monitoring programme are national programmes currently operating in the UK. Some important lessons learnt include: adopting a question‐based approach; having a clear robust statistical design for the purpose; selecting indicators that address policy and underlying scientific questions; and selecting indicators that can detect change and use robust and well‐tested methodologies across a wide range of soil and land use types, remaining valid over long time scales, supporting thinking long‐term. Technical lessons learned include the proven cost effectiveness of a stratified‐random design including replication, while adopting a common stratification layer of stable environmental attributes aids comparability between monitoring programmes. Common protocols are vital for future intercomparisons, but a full ecosystem approach that includes co‐located soil and vegetation samples for interpreting a co‐evolving system has proved hugely advantageous. UK monitoring programmes offer a range of experience that may prove valuable to future soil monitoring design to address the major societal challenges of our time, such as maintaining food production and addressing climate change and biodiversity loss.

Miniaturized device to measure urease activity in the soil interstitial fluid using wenner method

This paper presents a microdevice developed to measure the electrical conductivity of a liquid or a saturated porous medium using Wenner method. It is developed in the context of biocementation as soil improvement technique, which is used in Civil Engineering applications to produce calcium carbonate through bacterial or enzymatic activity, replacing the use of other binder materials such as cement or resins, and therefore reducing carbon footprint. The microdevice was used to measure urease activity in the soil interstitial fluid, to investigate if bacterial activity could be affected by the presence of the particles and tortuosity from pore geometry. Such analysis is important to understand biocementation mechanism inside the soil and helps to improve the design of such treatment solutions. The device is basically a squared reservoir printed in polypropylene using a 3D printing machine, incorporating stainless steel electrodes in its base. The electrical resistivity was computed adopting Wenner method, by connecting 4 PCB electrodes to a signal generator and an oscilloscope for measuring the voltage when a AC current of 1 mA was applied. Both square and sinusoidal waves with 5 kHz frequency were selected among other frequencies. The measurements were adjusted during the calibration of the microdevice, done using standard salt solutions with known electrical conductivity measured using an electrical conductivity probe. For the bacterial activity measurements, the bacterial and urea solutions were added to a uniform-graded size quarzitic sand (average diameter 0.3 mm) placed inside the microdevice and covering completely the electrodes. Bacterial activity was not affected by the presence of the sand, which confirms that this treatment is effective for this type of soils.

Enhancement of Shear Strength Properties of Soft Clay Using Coir Fiber-Coconut Husk Ash-Wood Ash Mixture

Soft clay is a problematic type of soil because it has high water content, low shear strength, low bearing capacity, and high compressibility. This study explores the effectiveness of stabilizing soft clay using a combination of coir fiber, coconut husk ash, and wood ash. This research investigated the impact of incorporating 0.75% coir fiber and varying levels of a coconut husk ash-wood ash mixture (ranging from 0% to 10%) on the shear strength properties of soft clay. The study applied two different curing times: seven and 21 days. An unconsolidated-undrained triaxial test was conducted following ASTM D2850-03. The results demonstrated that combining coir fiber reinforcement with chemical stabilization through the ash mixture significantly enhanced the deviatoric stress, cohesion, internal friction angle, shear strength, and elastic modulus of soft soil. Specifically, an 8% ash content with a 21-day curing time achieved the highest deviatoric stress and shear strength. This highest shear strength value was 210% greater than soil solely reinforced with coir fiber.

Soil type data provide new methods and insights for heavy metal pollution assessment and driving factors analysis

Assessing heavy metal pollution and understanding the driving factors are crucial for monitoring and managing soil pollution. This study developed two modified assessment methods (NIPIt and NECI) based on soil type-specific background values and pollution indices, and combined them with the receptor model to evaluate pollution status. Additionally, a structural equation model was used to analyze the driving factors of soil heavy metal pollution. Results showed that the average NIPIt and NECI were 1.48 and 0.92, respectively, indicating a low pollution risk level. In some areas, Cd and Hg were the primary heavy metals contributing to pollution risk, with their highest average concentrations exceeding soil type-specific background values by 2.06 and 2.04 times, respectively. Additionally, in black soils, meadow soils, and chernozems, heavy metals primarily originated from natural sources, accounting for 48.92%, 45.98%, and 45.58%, respectively. In aeolian soils, agricultural sources were predominant, contributing 43.38%. Soil pH and organic matter were key soil properties affecting NECI and NIPIt, with direct effects of 0.36 and -0.19, respectively. This study aims to provide new methods and insights for the comprehensive assessment and driving factors analysis of soil heavy metal pollution, with the goal of enhancing pollution monitoring and reducing risk.

Comparing LUCAS Soil and national systems: Towards a harmonized European Soil monitoring network

A recent assessment states that 60–70% of soils in Europe are considered degraded. Protecting such valuable resource require knowledge on soil status through monitoring systems. In Europe, different types of monitoring networks currently exist in parallel. Many EU Member states (MS) developed their own national soil information monitoring system (N-SIMS), some being in place for decades. In parallel in 2009, the European Commission extended the periodic Land Use/Land Cover Area Frame Survey (LUCAS) led by EUROSTAT to sample and analyse the main properties of topsoil in EU in order to develop a homogeneous dataset for EU.Both sources of information are needed to support European policies on soil health evaluation. However, a question remains whether the assessment obtained by using soil properties from both monitoring programs (N-SIMS and LUCAS Soil) are comparable, and what could be the limitations of using either one dataset or the other.Conducted in the context of European Joint Programme (EJP) SOIL, this study shows the results of a comparison between N-SIMS and LUCAS Soil programs among 12 different EU member states including BE, DE, DK, EE, ES, FR, DE, HU, IT, NL, PL, SE and SK. The comparison was done on: (i) the sampling strategies including site densities, land cover and soil type distribution; (ii) the statistical distribution of three soil properties (organic carbon, pH and clay content); (iii) two potential indicators of soil quality (i.e. OC/Clay ratio and pH classes). The results underlined substantial differences in soil properties statistical distributions between N-SIMS and LUCAS Soil in many member states, particularly for woodland and grassland soils, affecting the evaluation of soil health using indicators. Such differences might be explained by both the monitoring strategy and sampling or analytical protocols exposing the potential effect of data source on European and national policies. The results demonstrate the need to work towards data harmonization and in the light of the Soil Monitoring Law, to carefully design the future of soil monitoring in Europe taking into account both LUCAS Soil and N-SIMS considering the significant impact of the monitoring strategies and protocols on soil health indicators.