Abstract: Gravitational fingering often occurs for water flow in the vadose zone and accurate modeling of this important flow process remains a significant scientific challenge. This paper presents the latest theoretical developments of the optimality-based Active Region Model (ARM), a macroscopic framework developed for describing gravitational fingering flow in the vadose zone. ARM divides the soil into active (fingering) and in-active regions, introducing a relationship between water flux and hydraulic gradient derived from the principle of optimality that the system self-organizes to maximize water flow conductivity. Unlike traditional models, ARM’s hydraulic conductivity de-pends on both capillary pressure or water saturation and water flux, reflecting the un-stable nature of fingering flow. The paper provides an updated mathematical derivation of ARM relationships using calculus of variations and extends ARM to account for small water flux in the non-fingering zone, resulting in a dual-flow field model. These new developments should make ARM more rigorous and realistic for field-scale applications.

Abstract: Carbon losses from decomposition and erosion threaten intensive crop production systems. While conservation tillage enhances soil organic carbon (SOC), soil tex-ture-dependent responses and time-scales of soil quality change remain poorly understood. We addressed this gap using a dual time-scale design: 11 years of minimum tillage (MT) versus conventional ploughing (CT), followed by 5-year transitions to no-till (NT) in contrasting textures (loamy vs. silty clay) in NE Slovenia. In loamy soils, reduced tillage significantly increased SOC, dissolved organic carbon (DOC), permanganate oxidizable carbon (POX-C), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC < 50 μm) in the 0-10 cm layer. In silty clay soils, high clay content provided baseline protection that masked tillage effects on bulk SOC, though POX-C and POC showed vertical stratification. MAOC in the fine fraction (< 20 μm) remained consistent (2.0-2.5%) across treatments and textures, except under CT in loamy soil (1.73%), indicating accelerated decomposition. Tillage intensity drove aggregate distribution: CT fragmented soil structure (fewer macroaggregates, higher Dm), while MT and NT promoted macroaggregate formation. Structural indices (MWD, GMD, Dm) correlated strongly with C fractions, confirming physical protection mechanisms. Our dual time-scale approach reveals labile C pools and aggregate recovery respond within 5 years of NT, while texture modulates response magnitude and detectability. Reducing tillage intensity consistently supports C preservation across textures, though lighter soils show faster, more pronounced responses.

Abstract:

Due to intensified use of fertilizers and inconsiderable organic matter return, the intensive cropping system is evidently changing soil properties. Even though the changes are hardly predictable spontaneously, it could appear with imbalanced soil mineral nitrogen transformation and decreased biological nitrogen immobilization. To address this uncertainty, we investigated the linkage of soil nitrogen transformation and soil microbial community distribution with the mineral nitrogen fertilization in long-term intensive cropping system during 2019-2022. In this study a three-factor (Factor A: rate of nitrogen (100, 150, 180 and 230 kg N ha⁻¹); Factor B: organic fertilizers (0 and 300 kg ha⁻¹); Factor C: liquid biological activator (0 and 0.1 L ha⁻¹)) experiment carried out on a loam soil (Calcaric Luvisol) in intensive cropping system (in rotation: winter wheat, winter wheat, winter rape and winter wheat). At the study site, soil organic carbon was significantly higher at higher rates of nitrogen application combined jointly with application of organic matter and biological activator. Although the rate of nitrogen fertilization was increasing, either in combination with organic matter or biological activator, induced no significant changes in the accumulation of total nitrogen. Thus, with higher rates of nitrogen fertilization, the content of biologically transformed nitrogen significantly increased. As nitrogen is released from organic matter, it was evident that organic matter inputs affected the biological nitrogen transformation. Organic matter inputs also affected the increase soil fungal community, however, with higher nitrogen inputs soil fungal and bacteria ratio was decreasing. This study highlights the significance of sustainably maintaining of nitrogen and organic matter inputs in intensive cropping systems.

Abstract: Land degradation (LD) is a dominant threat of the decade, which is deteriorating arable lands globally. Therefore, this intensification of LD has stimulated global governing bodies and researchers to take the initiative against this dilemma through sustainable and eco-friendly approaches. Geographical mapping is critical for analyzing land formation, its types, and uses; data-based maps provide a detailed overview of land use. In this study, we have created simplified SRTM-based maps for Saudi Arabia related to soil types, soil thickness, and soil uses either as vegetation or for agricultural aspects using GIS tools. Results of these GIS analyses showed that the maximum area of the country is sandy, followed by loam and sandy loam. Meanwhile, the maximum soil thickness is either under 0-4 meters or 43-50 meters. This geological display of the country could be instrumental in assessing the soil types and what sort of inputs or steps can be taken to make each type of soil fertile. Moreover, we also mentioned the land degradation pathways impacting the country’s arable lands and explained the pathways that can help assess such land losses. Besides land loss pathways, we explained the most suitable mitigation strategies, including mulching, cover cropping, agroforestry, riparian buffer strips, agroforestry, terracing, and nutrient use efficiency. In this article, we also focused on the aims of the Saudi Green Initiative and the steps that are being taken by international governing bodies like UNDP, UNEP, FAO, and the World Bank to mitigate land degradation in the region. However, further studies are required to assess the intensity of these solutions at each soil type and thickness.

Abstract: The ongoing environmental challenges posed by soil degradation and desertification are of particular concern. This situation is particularly alarming in agricultural and pastoral areas in communities in northern Senegal, as it compromises the food security of human communities. Considering this situation, composting is regarded as a pivotal instrument within agrosystems, facilitating the utilization of organic livestock and agricultural waste for the purpose of transforming it into fertilizer for crop cultivation. Development cooperation projects sometimes involve the transfer of scientific knowledge to develop products adapted to the conditions of the area targeted by the intervention. The study aims to examine the basic properties of the soils, analyse the composting process and the compost, and evaluate the effect of the compost obtained on the soil within the framework of a development cooperation project. Sampling has been carried out in several agro-livestock communities in Northern Senegal; physical and chemical parameter analyses were carried out on materials in the composting phase, compost, soils, and soils amended with compost and manure. The results indicate that the soil dedicated to cultivation in the areas studied are characterized by a predominantly sandy texture and exhibit significantly low levels of nitrogen and organic matter. The resulting compost has contributed significantly to improving the soils where it has been applied and therefore improve crop production, thereby highlighting the Kanel region.

Abstract:

Adapting agriculture to long-term accrual of organic carbon (С) is beneficial both for ensuring food security and for mitigating climate change. This study quantified the responses of total soil C content and its constituent pools to implementing no-tillage (NT) versus conventional tillage (CT) on farms with contrasting water regimes. The farms were chosen at two sites in the Russian steppe zone: Rostov with non-waterlogged Calcic Chernozem (CCH; sunflower-wheat rotation) and Krasnodar with periodic waterlogged Stagnic Chernozem (SCH; maize-wheat rotation). At each site, we surveyed the 0–10 cm and 10–30 cm soil layers in one continuous CT field and two short-term NT fields (8–14 years). The average C content in CCH was higher than in SCH (22.5 vs 17.7 g kg^–1). For both sites, NT showed the potential for an increase in C content (by 12–16%) relative to CT only in the 0–10 cm topsoil. Microbial-available C pool (mineralized for 180 days of soil incubation) was most sensitive to tillage systems, unlike unchanged particle-size pools. Specifically, it increased from CT to NT for CCH (by 7–16%), but it showed a decreased trend for SCH (by 11–29%), possibly due to the worsening of soil aeration in the periodically flooded regime. Gradient boosting machine models accurately predicted the spatial distribution of topsoil C content (R² = 0.99) and its microbial-available pool (R² = 0.78%) across the farmland area. The mutual drivers of both parameters were topography (elevation) and vegetation distribution (near-infrared surface reflectance). These outcomes are useful for developing site-specific management strategies to effectively restore C stocks in Chernozem soils.

Abstract: The Overseer model is widely used in New Zealand for estimating nitrate (NO₃⁻) leaching losses in agricultural systems. This study evaluated the accuracy of the Over-seer model in simulating nitrate (NO₃⁻) leaching through a two-year lysimeter experi-ment conducted at Woodhaven Gardens, New Zealand, under beetroot and pak choi cultivation. Seven distinct nitrogen (N) fertiliser treatments were applied to assess model performance. In Year 1, Overseer overestimated NO₃⁻ leaching by an average of 45.2 kg N/ha (15.7%), due to underestimated crop uptake. Similarly, overestimations were observed in Year 2, with overprediction rates reaching up to 63.5%. Sensitivity analysis highlighted soil texture, impeded layer depth and crop residue incorporation as key drivers of leaching variability, underscoring the need for improved model cali-bration. Overseer performed reasonably well under lysimeter conditions, with a strong linear relationship (Pearson’s correlation coefficient r = 0.89, P < 0.0001) between measured and predicted values and explaining 77% of the variance (R²=0.77) in the observed data. The model predicted a baseline leaching loss of 39.4 kg N/ha/year even when measured losses were zero. Overseer demonstrates moderate reliability in simulating NO₃⁻ leaching under vegetable cropping systems but exhibits notable limi-tations in handling crop-specific N dynamics, soil hydrology, and fertiliser timing.

Abstract: Climate change driven by the accumulation of greenhouse gases (GHG) in the atmosphere is projected toincrease average global surface temperatures, influencing agricultural production and nutrient cycling. Phosphorus (P), a key nutrient for plant growth, can both contribute to and reduce the effects of climate change. Climate change and P management are interrelated, as climate change will influence optimal P management while P fertilizer can both help in ameliorating and adapting to climate change effects on agriculture and the environment and contribute to direct and indirect GHG emissions. Greenhouse gases are emitted during phosphate rock extraction, as well as during the production transport and application of P fertilizer. Emissions during production could be reduced by improving energy efficiency, using alternative, non-fossil energy sources, or possibly using emerging technologies for synthesis of the ammonia used in production. To reduce the amount of indirect greenhouse gas emissions linked to P manufacture, it is important to optimize the efficiency of P fertilizer as the less P that is mined, processed, transported and applied to the field per unit of agricultural production, the less risk there is of both GHG emissions and off-site transport. While production and transport of P fertilizer can contribute to climate change, efficient P management can reduce negative effects of climate change and may contribute to reductions in GHG emissions and to climate change adaptation. Optimal P management is needed to support carbon sequestration in soil, to allow plants to benefit from increasing CO2 concentrations, to reduce risk of indirect GHG emissions, to reduce P movement to water bodies and to enhance resiliency of crops to climate stress. Proper nutrient management, including P management, plays a key role in Climate Smart Agriculture, Low-Carbon Agriculture and Sustainable Intensification, that are different approaches to encouraging optimal crop productivity while minimizing the contribution of agriculture to climate change. Managing P fertilizer in a changing environment requires use of the 4R principles to select the rate, source, timing and placement combination best suited to the site-specific agronomic and environmental conditions.

Abstract: Soil, with 30,000 Gt SOC (Gigatonnes of Soil Organic Carbon), is the greatest global store of active carbon as well as being source and sink of most atmospheric CO2. Soil respiration/decay (~220 Gt C/yr) is twenty times Fossil Fuel (FF) emissions (~10 Gt C/yr). Soil supports >99.9% of species biodiversity (mainly microbes), provides ~99% of human food, and filters100% of our drinkable freshwater (via earthworm burrows). Soil is yet the most neglected biome as are its main monitors and mediators, the resident earthworms. These are silently dying, just as soil is being eroded and degraded at irreplaceable rates, to our, and all other species’, detriment. Land use changes (LUC) release carbon from deforestation and soil erosion/poisoning at rates about twice that of FF emissions, themselves twice the CO2 increase (5 Gt C/yr). Knowing all this provides a ready solution to Climate, to Food Security as well as the most pressing of issues: The rapid and irreversible species extinction. Based upon proper scientific context and urgent triage priority, the imperative is to redirect all our efforts and funding to restore topsoil. The simplest remedies, available to anyone, are to vermi-compost, to demand or support 100% organic food (thus protecting earthworms), and to reduce excess red-meat. In this way rich soil humus is revived, deforestation is reduced and toxic poisoning of our air, water, soil and food is resolved. Organic husbandry within broader Permaculture design principles allows practical and proven solutions to the ecologically interlinked problems.

Abstract: Urban and peri-urban agriculture (UA) plays an increasingly important role in pro-moting sustainable urban development, delivering socioeconomic, environmental, and educational benefits. However, UA is often associated with nutrient accumulation in soils, as vegetable-growing areas typically receive substantial inputs of organic and inorganic fertilizers. This study examines soil variability in two sections of an urban allotment garden subjected to long-term manure fertilisation for 12 or 16 years at ap-plication rates up to 10–12 kg m⁻² yr⁻¹. Surface soils were analysed for organic and in-organic carbon, total N, available P and K, pH, and elemental composition using port-able X-ray fluorescence (pXRF). Prolonged manure incorporation substantially in-creased soil fertility, evidenced by elevated soil organic carbon, total N, available K, and both total and available P. Marked shifts in mineral composition were also ob-served, including significant increases in total Ca, inorganic C (as calcium carbonate), Sr, and S. Despite the high manure inputs, no accumulation of potentially toxic ele-ments (PTEs) was detected. Nevertheless, pronounced heterogeneity was found among individual plots, reflecting differences in fertilisation intensity and management prac-tices. pXRF proved highly effective for identifying soil compositional changes and pre-dicting nutrient availability, highlighting its potential as a rapid diagnostic tool for precision agriculture management.

Abstract:

Modeling the water cycle requires a proper understanding of interactions within the critical zone compartments - soil, vegetation, and atmosphere. Among the key processes involved, soil water flow modeling using a mechanistic approach relies on accurately determining the hydrodynamic parameters that define the soil hydraulic conductivity and water retention curves. Various estimation methods exist, including pedotransfer functions (PTFs) based on soil properties derived from field samples, and inverse modeling approaches that adjust hydrodynamic parameters to minimize discrepancies between simulations and observations. While the PTF approach is widely used due to its simplicity and limited technical requirements, inverse modeling demands specific instrumentation and advanced numerical tools. This study, conducted on the experimental site of the Hydro-Geochemical Environmental Observatory - the Strengbach forested catchment - aimed to determine the optimal hydrodynamic parameters for two contrasting forest plots, one dominated by spruce and the other by beech. The results highlight the importance of accounting for soil stoniness to improve the efficiency of flow modelling, as well as the need to assess the robustness of the derived parameter set, given that selecting an optimal calibration period remains challenging and that the model should be able to represent hydrological variability.

Abstract: For the numerical simulation of rainwater infiltration in forest slope, information on the water retention curve (WRC), which shows spatial variability due to forest ecosystem and weathered granite in natural forest soils, is required. A scaling approach using three parameters of the LN model has been developed to simplify the spatial variability in the WRCs of forest slope of the soil under geomorphological process. This approach showed that we required spatial data set in scaling parameter, effective porosity, e, and each average value of remaining two parameters (the matric pressure head corresponding to the median pore radius, m, and the width of the pore-size distribution, ) which were defined as reference parameters. In this study, we estimated the minimum number of WRCs required to determine the reference parameters effectively. For this purpose, 77 WRCs of core samples were collected from whole 25 m forest slope, and we randomly sampled WRCs using a Monte Carlo simulation. The effect of scaling (EOS) increased with the sample size, and the increase became small at a sample size of approximately 20. We could explain 78% (EOS = 0.78) of spatial variability in the WRCs at the 95% confidence level by using the reference parameters derived from 8 samples. In addition, we performed stratified sampling to reduce the number of WRCs required. As a result, the sampling scheme, which considers the variability in only slope direction, was the most advantageous. This result indicated that the geomorphological process, which produces spatial variability in the reference parameters of forested slopes, is an important factor to effectively determine reference parameters. This paper concluded that scaling approach enables us to reduce the required number of samples for WRCs.

Abstract:

Biochar surface chemistry strongly influences the adsorption and partitioning of organic matter in soils, yet the sorption-mediated stabilization mechanisms of biochars derived from invasive plant biomass remain poorly constrained. In this study, Solanum rostratum biomass was pyrolyzed at 300–700 °C to generate biochars with distinct surface functionalities and structural characteristics. Multi-analytical characterization (FTIR, Raman, XPS, SEM) was used to quantify temperature-induced changes in aromaticity, oxygen-containing groups, and pore morphology, while soil incubation experiments assessed impacts on organic carbon fractions. High-temperature biochars showed reduced O-containing groups and enhanced aromatic condensation, indicating a shift from hydrogen bonding and electrostatic interactions to hydrophobic and π–π sorption mechanisms. These surface transformations were associated with increased stable carbon pools and reduced labile carbon in soil, consistent with stronger adsorption and protection of organic matter. Sequencing analysis revealed that biochar amendments significantly altered bacterial community composition and enhanced deterministic assembly processes, suggesting that microbial reorganization further reinforces sorption-driven carbon stabilization. These findings demonstrate that S. rostratum biochars possess strong sorptive properties that promote long-term carbon retention and modulate microbial ecological processes, supporting their potential use as sustainable adsorbents in soil carbon management.

Abstract: Cowpea production potential often falls short, despite the crop's efficiency as a legume. This underperformance is primarily attributed to widespread deficiencies of phosphorus (P), cobalt (Co), and molybdenum (Mo) in Brazilian soils, especially in the Cerrado region. This study aimed to determine the optimal doses of P, Co, and Mo to enhance cowpea nodulation, biological nitrogen fixation, and overall plant growth. Two greenhouse exper-iments were conducted using a randomized complete block design in a 2 × 5 factorial scheme (two soils and five doses of each nutrient, inoculated with strain BR 3262), with four replicates. In Trial I, P₂O₅ doses of 0, 100, 200, 300, and 400 mg pot⁻¹ were tested, while in Trial II, Co:Mo ratios (w:w) were evaluated: 0:0, 2:8, 3:16, 4:32, and 6:64 (mg pot⁻¹). The variables analyzed included phytotechnical parameters. The application of 200 mg pot⁻¹ of P₂O₅ (200 kg ha⁻¹) resulted in the highest nodulation, nitrogen accumulation, and increased cowpea biomass. Furthermore, medium-high micronutrient levels (Mo at 32 g ha-1 and Co at 4 g ha-1) provided superior nodulation, biomass, and nitrogen accumu-lation. Adequate P and micronutrient fertilization is essential for plant development, rein-forcing its pivotal role in maximizing cowpea productivity under Cerrado soil conditions.

Abstract: Drought stress profoundly impacts citrus growth and soil health, yet the role of rhizosphere microbial communities in plant drought tolerance remains poorly understood. This study investigated the rhizosphere microbial structure, soil enzymatic activities, and physicochemical properties of drought-tolerant (DR) and drought-sensitive (DS) citrus varieties under drought stress condition. High-throughput sequencing revealed that drought significantly altered microbial community composition, enriching for gram-negative, stress-tolerant, and potentially pathogenic bacteria, as well as plant pathogenic fungi, while reducing undefined saprotrophs. Notably, the DR variety exhibited more stable and complex bacterial network, higher enrichment of beneficial fungi like Penicillium and Trichoderma, and unique recruitment of mycorrhizal fungi, which were absent in DS. Furthermore, soil catalase and urease activities downregulated under drought, whereas acid phosphatase activity upregulated, particularly in drought tolerant cultivar. Correlation analyses indicated that these microbial shifts were closely linked to changes in soil nutrient availability. Our findings demonstrate that the drought-tolerant citrus variety modulates its rhizosphere microbiome towards a more cooperative and resilient state, highlighting the critical role of host-specific microbial recruitment enhances plant adaptation to drought stress for sustainable agriculture.

Abstract: Greenhouse gas (GHG) emissions from agricultural crops remain a critical challenge for climate change mitigation. This review synthesizes evidence on cropland management interventions and global N₂O mitigation potential. Agricultural practices such as cover cropping, agroforestry, reduced tillage, and diversification show promise in reducing CO₂, CH₄, and N₂O emissions, yet uncertainties in measurement, verification, and socio-economic adoption persist. Complementing this, global-scale analysis underscores the dominant role of optimized nitrogen fertilization in curbing N₂O emissions while sustaining yields. To bridge gaps between practice-level interventions and global emission dynamics, this paper introduces the ICEMF, a novel approach combining field-based management strategies with spatially explicit emission modelling. Only peer-reviewed articles published in English between 2014 and 2025 were selected to ensure recent and reliable findings. The review highlights knowledge gaps, evaluates policy and technical trade-offs, and proposes ICEMF as a pathway toward scalable and adaptive mitigation strategies in agriculture.

Abstract: Humic substances (HSs) are naturally occurring macromolecular organic acids derived from plant residues, with structural properties that vary depending on their origin and environmental conditions. These substances influence the solubility and toxicity of environmental pollutants, making their chemical characterization essential. Charge-transfer-type fluorochromes, which exhibit shifts in fluorescence intensity and emission wavelength in response to solvent polarity changes, have been widely employed to investigate solute–solvent interactions. In this study, we developed a rapid and straightforward method to characterize HS polarity using fluorescent solvatochromism. The fluorescence peak shifts of four dyes—8-anilino-1-naphthalenesulfonic acid (ANS), acridine orange (AO), methylene blue (MB), and Rhodamine B (RhB)—were evaluated in the presence of humic acids (HAs), a major component of HSs. To assess environmental variability, HAs from seven different sources were tested. Among these, AO and MB exhibited distinct spectral shifts without overlapping with the intrinsic fluorescence of HAs. Notably, MB displayed a consistent blue shift dependent on HA concentration, with the most stable response observed at 5 mg/L. The magnitude of this shift was significantly correlated with HA aromaticity, molecular weight, and polarity index. Additionally, the peak shifts were positively correlated with log KOM (anthracene) and negatively correlated with log KML (mercury), suggesting that the method reflects HA–pollutant interaction characteristics. Overall, this study demonstrates that fluorescent solvatochromic dyes can serve as polarity-sensitive probes for HS characterization, offering a practical tool for environmental monitoring and risk assessment.

Abstract: Accumulation of salts in irrigated soils can be detrimental not only to growing crops but also to groundwater quality. Soil salinity should be monitored reg-ularly and appropriate irrigation with the required leaching rate should be applied to avoid excessive salt accumulation in the root zone, thereby im-proving soil fertility and crop production. We combined two frequency domain electromagnetic induction (FD-EMI) mono-channel sensors (EM31 and EM38) and operated them at different heights and with different coil orientations to monitor the vertical distribution of soil salinity in a salt-affected irrigated area in Kairouan (central Tunisia). Multiple measurement heights and coil orientations were used to enhance depth sensitivity and thereby improve salinity predictions from this type of proximal sensors. The resulting mul-ti-configuration FD-EMI datasets were used to derive soil salinity information using inverse modeling based on a recently developed in-house laterally constrained inversion (LCI) approach. The collected apparent electrical con-ductivity (ECa) data were inverted to predict the spatial and temporal distri-bution of soil salinity. The results highlight several findings about the distri-bution of salinity in relation to different irrigation systems using brackish water, both in the short and long term. The expected transfer of salinity from the surface to deeper layers was systematically observed by our FD-EMI surveys. However, the intensity and spatial distribution of soil salinity varied between different crops, depending on the frequency and amount of drip or sprinkler irrigation. Furthermore, our results show that the vertical transfer of salinity is also influenced by the wet or dry season. The study provides in-sights into the effectiveness of combining two different FD-EMI sensors EM31 and EM38 for the monitoring of soil salinity in agricultural areas, contributing to the sustainability of irrigated agricultural production. The inversion ap-proach provides a more detailed representation of the of soil salinity distri-bution over spatial and temporal scales across different depths and irrigation systems compared to the classical method based on soil samples and labora-tory analysis which is a point-scale measurement. It provides a more extensive assessment of soil conditions at depths up to 4 m with different irrigation systems. For example, the influence of local drip irrigation was imaged and the history of a non-irrigated plot was evaluated, confirming the potential of this method.

Abstract: In flooded soils, the concentrations of exchangeable Mn2+ and, mainly, Fe2+ can be high and need to be considered in determining the cation exchange capacity (CEC) of the soil under flooded conditions. However, these reduced forms of Mn and Fe are oxidized and precipitated during the extraction process used by traditional methods for determining CEC. This procedure underestimates the exchangeable portion of these cations and, consequently, the CEC value of the flooded soil. The objective of this study is to propose an alternative to estimate the exchangeable Fe2+ and the effective CEC (ECEC) of flooded soils. To achieve this goal, 21 surface samples (0-20 cm) of soils from rice fields were collected, distributed in the cultivation regions of Southern Brazil. The soils were flooded for 50 days. The soil solution was collected on the first day and after 50 days of flooding. and, pH, Na, K, Ca, Mg, Fe and Mn were determined. In these samples, exchangeable cations (K, Na, Ca, Mg, Mn, Al and H+Al) were determined to calculate ECEC and CEC at pH 7 of unflooded soil and after 50 days of flooding. The results were used to develop models to predict ECEC and exchangeable Fe content after 50 days of flooding. The estimation of the ECEC after flooding by the gradient of pH increase before and after flooding generated values closer to CEC pH 7.0, correcting the possible underdetermination of the ECEC during flooding. The amount of exchangeable Fe estimated was higher than the exchangeable Fe determined, correcting the possible underestimation of these quantities determined during flooding. It is concluded that the estimatives of ECEC after flooding through the equation ECECafter=ECEC+pHsol.after- pHsol.before . (CECpH7- ECEC)(7- pHsol.before) and the exchangeable Fe2+ after flooding through the equation Feexc.after.estimated=ECECafter- Ca+Mg+K+Na+Mn corrected the problem of underestimating the values of these variables by analythical methods, demonstrating its viability for the use in flood prone soils.

Abstract: Coal mining leaves behind extensive tailings dumps that pose long-term ecological and soil degradation challenges. This study investigates the restoration potential of vegetation on coal mine tailings in the Jiu Valley, Romania, focusing on soil nutrient dynamics and heavy metal distribution. Field sampling was conducted across three vegetation types—unvegetated (UV), herbaceous (HV), and arboreal (AV, Robinia pseudoacacia)—at two intervals: three- and six-years post-plantation. Soil samples were analyzed for pH, organic carbon, macronutrients, micronutrients, and heavy metals using standardized spectrometric and titrimetric methods. Results showed that vegetated plots, particularly AV, exhibited significant improvements in total nitrogen, organic carbon, and base cation availability, alongside reductions in pH and certain heavy metals. HV plots demonstrated enhanced manganese and copper mobilization, while UV soils retained higher levels of total potassium and zinc, likely due to limited biological uptake. Heavy metal concentrations remained below European safety thresholds for lead and chromium, though nickel levels exceeded recommended limits across all variants. Vegetation type influenced nutrient cycling and metal stabilization, with arboreal cover showing the most consistent ameliorative effects. These findings underscore the role of targeted revegetation in improving soil quality and mitigating ecological risks in post-mining landscapes.