EJSSEurasian Journal of Soil ScienceEurasian J Soil Sci2147 - 4249Federation of Eurasian Soil Science Societieshttp://ejss.fesss.org/10.18393/ejss.186184910.18393/ejss.1861849Localized subsurface placement of a polyacrylamide superabsorbent polymer improves soil moisture distribution and reduces irrigation requirement in wheat grown in Eastern KazakhstanAbdugani Azimov Gani Iztleuov Gani5@mail.ruRaikhan Omirova Aidar Bolysbek Dinara Sharipova Zhainagul Yertayeva Nazmi Mat Nawi 152149-1572025-06-212026-01-062026-01-122026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Water scarcity and increased drought frequency threaten irrigated cereal production across arid and semi-arid regions. Superabsorbent polymers (SAPs) can improve soil water retention and reduce non-productive losses, but field-scale effectiveness depends strongly on placement strategy and soil conditions [1–5]. This study evaluated a commercially available cross-linked polyacrylamide SAP applied locally using a slitter-based implement at two rates (30 and 60 kg ha⁻¹) and two placement depths (20 and 40 cm) under irrigated wheat (Triticum aestivum L., cultivar ‘Steklovidnaya-24’) in Eastern Kazakhstan (April–June 2025). A randomized complete block design with three replications was used (6 × 4 m plots). Soil moisture was measured by depth (0–5, 0–20, 20–40 cm) using the thermostat–weight (oven-drying) method; soil reaction (pH) was measured in a salt extract prepared by the TSINAO method using a calibrated pH meter; and grain yield was assessed by whole-plot harvest and converted to a hectare basis. Localized SAP placement redistributed water downward, with a 3.6–3.8 percentage-point reduction in the 0–20 cm layer and a 3.2–3.6 percentage-point increase in the 20–40 cm layer, resulting in an 8–11% increase in root-zone moisture reserves. The number of irrigations decreased from two to one, reducing seasonal irrigation from 1,800 to 900 m³ ha⁻¹, while crop growth indicators visibly improved relative to the control. Overall, 30 kg ha⁻¹ placed at 20 cm provided the most favorable balance between agronomic benefit and input intensity, consistent with broader evidence that targeted subsurface SAP placement can enhance irrigation water productivity.Superabsorbent polymer, polyacrylamide, localized placement, slitting, soil moisture, irrigation water productivity, wheat, Eastern Kazakhstan.http://ejss.fesss.org/10.18393/ejss.186193110.18393/ejss.1861931Short-term soil profile responses to controlled ozonation of irrigation groundwater in an arid irrigated agroecosystem of Kyzylorda, KazakhstanSholpan Umbetova Umirbek Umbetov Galimzhan Kurmanbayev gkurmanbayev@mail.ruNurlan Kulmurzayev Zeinegul Baimakhanova Zhanna Assanova Mukhtar Gani Aizere Khikmatullayeva 152158-1672025-09-292026-01-062026-01-132026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Soil salinization and alkalinity constrain irrigated agriculture in arid regions, particularly where shallow groundwater and limited drainage promote salt accumulation. Ozonation is increasingly applied for water treatment as a strong oxidant and disinfectant, yet its implications for soil chemical dynamics under field irrigation remain insufficiently documented. This pilot field study assessed short-term soil-profile responses to irrigation with ozonated groundwater under an arid production system in Tasboget, Kyzylorda (Kazakhstan). Groundwater (12–18 m boreholes) was conveyed through the same hydraulic line for all treatments, with ozone injection controlled at set-points of 0 (control), 0.5, 1.0 and 2.0 mg O₃ L⁻¹. Water was treated in a contact tank with an average hydraulic contact time of ~7 min. Baseline soil sampling was conducted in spring 2024 before fertilization, and post-treatment sampling was performed 21 days after initiation of water treatments (four irrigation events). Composite soil samples (five subsamples per depth) were collected from five depth intervals (0–20, 20–40, 40–60, 60–80 and 80–100 cm). Soil pH, salinity indicators (including ECe), humus, macronutrients and saturation extract ions were determined using relevant GOST/standard protocols. Across the 0–100 cm profile, soil pH decreased with increasing ozone set-point. In the 0–20 cm layer, pH declined from 8.30 under the control to 7.81 at 2.0 mg O₃ L⁻¹, while at 80–100 cm pH decreased from 7.52 to 7.31. Salinity indicators tended to improve under ozonated irrigation; for example, ECe at 80–100 cm decreased from 3.210 dS m⁻¹ (control) to 3.020 dS m⁻¹ at 2.0 mg O₃ L⁻¹. Mineral N increased under the highest ozone set-point (e.g., 28.6 to 39.7 mg kg⁻¹ at 0–20 cm), whereas available P₂O₅ and K₂O showed modest topsoil decreases at the highest dose. These findings suggest that controlled ozonation may influence soil chemical status indirectly (e.g., via redox/carbonate equilibria and leaching dynamics) rather than by changing conservative salt loads in irrigation water. Given the short duration and aggregated treatment means, longer fully replicated seasonal trials with residual ozone/ORP monitoring are required to confirm agronomic relevance.Ozonated irrigation water, Soil salinity (ECe), Soil pH dynamics, Saturation extract ions, Arid irrigated soils.http://ejss.fesss.org/10.18393/ejss.186340110.18393/ejss.1863401Exploring plant growth-promoting bacteria from peanut (Arachis hypogaea L.) rhizosphere in Morocco's sandy soils: Potential for soil fertility improvementOuissale Chaghouaoui Anass El Yemlahi Mariem Imziren Samia Hamane Ouiam El Galiou Amin Laglaoui Mounir Hassani Zerrouk Mohammed Bakkali Abdelhay Arakrak arakrak_abdelhay@yahoo.fr152168-1812025-05-122026-01-082026-01-142026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Peanut (Arachis hypogaea L.) cultivation in Morocco’s sandy soils is limited by poor soil fertility and high permeability, which restricts nutrient and water retention. This study aims to isolate, identify, and investigate native plant growth-promoting rhizobacteria to improve the growth and resilience of peanut. Fifteen bacterial isolates were recovered from the peanut rhizosphere collected from the surface layer of the sandy soils in northwestern Morocco, characterized by low phosphorus and organic matter contents. Two isolates, JR62 and JR86, exhibiting high phosphate-solubilizing activity (238.651 and 196.111 mg/L, respectively), were chosen and identified based on 16S rRNA gene sequencing analysis as being closely related to Microbacterium oxydans (PQ758594) and Enterobacter asburiae (OM101034), respectively. These strains were initially characterized for soil-related biochemical activities phosphate solubilization, siderophore production, and lytic enzyme activities given their pivotal roles in driving soil nutrient cycling and improving nutrient bioavailability. Subsequently, they were examined for additional plant growth-promoting attributes, including IAA production, ACC deaminase activity, HCN and ammonia synthesis, antifungal activity, and tolerance to multiple abiotic stresses (salinity, pH and temperature variability, and PEG-induced drought). Collectively, these functional traits underscore the strains’ potential to substantially influence soil nutrient dynamics while promoting plant health. Inoculation of peanut plants with E. asburiae JR86 and M. oxydans JR62 significantly enhanced growth parameters. The JR86 strain demonstrated the highest increases in shoot (42%) lengths and biomass (180%), whereas JR62 resulted in increases of 24% and 62%, respectively. Such results are attributed to soil-mediated processes, including phosphate solubilization and iron chelation, which together enhance nutrient availability, promote soil nutrient cycling, and improve the fertility of sandy soils.Arachis hypogaea L., Microbacterium oxydans, Enterobacter asburiae, PGPR, inoculation, sandy soil fertility. http://ejss.fesss.org/10.18393/ejss.188033610.18393/ejss.1880336Humus status of light chestnut soil in Southeastern Kazakhstan under long-term fertilizer applicationSerik Kenenbayev Vitaly Gusev agfaagro@mail.ruSamat Tanirbergenov 152182-1942025-09-192026-01-192026-02-022026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Humus is a central and relatively stable component of soil organic matter that regulates key fertility functions; therefore, robust evaluation of humus dynamics requires long-term stationary experiments. This study synthesizes results from long-term irrigated experiments on light chestnut soil in southeastern Kazakhstan (single-factor experiment, 1961–2005; multifactor experiment, 1991–2016) together with renewed environmental monitoring (2020–2023) to quantify the effects of mineral fertilization and cattle manure on humus status, plant-available nutrients, crop productivity, and environmental safety. Under continuous cropping without fertilizer input, humus in the 0–20 cm layer declined by 0.37 percentage points relative to the initial level. Mineral fertilization alone moderated humus loss but did not ensure a non-deficit humus balance, whereas combined organic–mineral fertilization (NPK + manure 60 t ha⁻¹ once per rotation) increased humus by 0.20 percentage points, reaching 2.80% by the end of the fifth rotation. Fertilization substantially improved nutrient status: under mineral fertilization, available P₂O₅ and exchangeable K₂O reached 39.5 mg kg⁻¹ and 601 mg kg⁻¹, respectively, while under the combined system they reached 52.3 mg kg⁻¹ and 765 mg kg⁻¹. Regression models from the multifactor experiment quantified dose–response relationships between fertilizer/manure inputs and soil indicators. In the fifth rotation, yields of winter wheat, maize, and alfalfa increased by 1.4–2.0 times relative to the unfertilized control, while sugar beet yield increased more than threefold. Soil heavy metal concentrations remained below sanitary–hygienic thresholds across treatments; however, lead (Pb) in maize grain exceeded the maximum permissible concentration across all fertilization systems, indicating the need for continued product monitoring and source/pathway evaluation.Humus, soil organic matter, available phosphorus, exchangeable potassium, long-term experiment, heavy metals, crop yield, irrigated steppe.http://ejss.fesss.org/10.18393/ejss.188040810.18393/ejss.1880408Effects of biochar and poultry manure on soil properties, growth and yield of yam in degraded tropical Alfisol in Southwestern Nigeria (2023-2024)Taiwo Michael Agbede taiwo.agbede@aaua.edu.ng152195-2082025-10-151970-01-012026-02-022026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Soil degradation poses a major challenge to sustainable yam (Dioscorea rotundata) production in tropical regions due to continuous cultivation and declining soil fertility. This study presents the first field-based two-year factorial evaluation of cocoa pod husk biochar (CPHB) combined with poultry manure (PM) on yam performance in a degraded tropical Alfisol at Owo, southwestern Nigeria. The experiment was arranged in a factorial design with three CPHB rates (0, 15.0, and 30.0 t ha-1) and three PM rates (0, 10.0, and 20.0 t ha-1), replicated three times over two consecutive years (2023 and 2024). Results showed that CPHB and PM, applied singly or in combination, significantly (p < 0.05) improved soil physical and chemical properties compared with the control. The combination of 30 t ha-1 CPHB + 20 t ha-1 PM produced the most favorable soil conditions—lower bulk density, higher porosity and moisture content, and enhanced nutrient status—and significantly increased leaf N, P, K, Ca, and Mg, as well as growth and tuber yield. Averaged over the two years, the highest tuber yield (46.1 t ha-1) was obtained from the combined application of 30 t ha-1 CPHB + 20 t ha-1 PM, representing substantial yield gains over individual or the control. These findings demonstrate the synergistic potential of biochar and poultry manure in improving soil fertility and promoting yam productivity. However, given the high amendment rates, practical adoption will depend on local availability, transport logistics, and labor, and further economic evaluation is recommended to assess economic/on-farm feasibility on degraded tropical Alfisols.Cocoa pod husk biochar, Degraded Alfisol, Poultry manure, Soil physical properties, Soil chemical properties, Yam.http://ejss.fesss.org/10.18393/ejss.188163610.18393/ejss.1881636Estimating carbon sequestration potential of dryland enclosures: A comparative assessment assisted by Sentinel 2 time-series and machine learning frameworkTumuzghi Tesfay tumuzghitesfay7@gmail.comTesfalem W. Ghebretnsae Elsayed S. Mohamed 152209-2272025-10-312026-01-232026-02-042026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies In Eritrea, in response to widespread land degradation, rehabilitation works are underway. However, the impacts of such works on soil carbon remain unknown. This study assessed the impacts of enclosures by comparing four land uses: permanent enclosure, oxen enclosure, communal grazing, and rainfed farming. Seasonal Sentinel-2 time-series data were extracted using Google Earth Engine and soil organic carbon (SOC) concentration and stock (SOCs) predictive models were developed using soil, topographic, and Sentinel 2 data using machine learning. We compared Random Forest versus Ridge Regression models across four seasons with correlation-based versus Boruta algorithm-based selected features. Kruskal-Wallis H and Dunn post-hoc tests showed that conservation enclosures significantly enhanced soil carbon compared to grazing and rainfed cropping lands. The highest median SOC (1.28%) and SOCs (37.66 Mg ha-1, up to 30 cm soil layer) were found in the permanent enclosure followed by the oxen enclosure, while rainfed farming had the lowest values (0.45% and 14.85 Mg ha-1). These improvements correspond to potential carbon sequestration gains of up to 153.6% when converting degraded land to permanent enclosure. Modelling revealed that SOC was predicted with excellent accuracy (R2 = 0.85, RPD = 2.57) using Ridge Regression and with very good accuracy (R2 = 0.80, RPD = 2.22) with Random Forest with Boruta selected winter season features. For SOCs, the best models of both models achieved similar fair accuracy (R2 = 0.60, RPD = 1.58). Key predictors for SOC were bulk density, Sentinel 2 bands B5 and B8A, while for SOCs B5, Soil Organic Carbon Index (SOCI), B11, and soil pH. Winter (Jan-Mar) was the optimal window season and Boruta-selected features gave the best results for SOC and SOCs prediction. The study demonstrates that enclosure systems are effective for soil carbon restoration in dryland landscapes. This framework highlights the potential for cost effective satellite based monitoring of restoration outcomes. These findings provide evidence based support for scaling up enclosure based restoration in Eritrea and similar dryland regions, contributing to both land degradation neutrality and climate change mitigation goals.SOC stock, Random Forest, Ridge Regression, Carbon sequestration, enclosure, Sentinel-2 time-series data.http://ejss.fesss.org/10.18393/ejss.188172910.18393/ejss.1881729Formaldehyde-crosslinked GIPANA–polyacrylamide hydrogel improves root-zone soil moisture, infiltration, and crop yield under arid irrigation in the Turkistan RegionAbdugani Azimov Gani Iztleuov Gani5@mail.ruRaikhan Omirova Aidarbek Bolysbek Zhainagul Yertayeva Nazmi Mat Nawi Tursunali Eshburiev 152228-2412025-07-132026-01-252026-02-062026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies This study evaluated a superabsorbent polymer (SAP) hydrogel synthesized from hydrolyzed polyacrylonitrile (GIPANA) and an anionic polyacrylamide component cross-linked with formaldehyde for improving soil water status and crop performance under arid field conditions in the Turkistan Region (Saryagash District, Kazakhstan) during the 2024 growing season. A randomized complete block design with three replicates tested three crops (rice, wheat, saffron) under three hydrogel treatments: control (T0), 0.2% (w/w) hydrogel (T1), and 0.4% (w/w) hydrogel (T2), with identical crop-specific irrigation inputs across treatments. Soil moisture was monitored using TDR at 0–10, 10–20, and 20–40 cm depths over time; field infiltration, wetting depth, and a retention coefficient were determined using double-ring infiltrometry; and laboratory swelling capacity was measured for unmodified and Ca–P modified hydrogels. The experimental soil remained non-saline and chemically stable across the season, enabling attribution of observed responses primarily to hydrogel amendment. Hydrogel application increased volumetric soil water content in a consistent dose-responsive manner acrss crops and depths, with the largest and most persistent gains under T2, particularly in the 20–40 cm layer in rice later in the season. In parallel, infiltration rate, wetting depth, and retention coefficient increased substantially with hydrogel dose. Laboratory tests confirmed rapid swelling and high absorption capacity, which further increased with Ca–P modification. Improved soil water availability translated into enhanced vegetative growth (plant height and leaf number) and higher yields in all crops, with T2 providing the most consistent agronomic benefits. Overall, the results demonstrate that GIPANA–polyacrylamide hydrogel amendment can improve root-zone moisture dynamics, soil water transmission, and crop productivity in arid irrigated systems, supporting its use within integrated water-saving soil management strategies.Superabsorbent polymer, Hydrogel, Soil moisture, Infiltration, Arid irrigated agriculturehttp://ejss.fesss.org/10.18393/ejss.188587910.18393/ejss.1885879Integrated physicochemical and structural characterization of date palm pit–derived biochar produced by slow pyrolysisAmjed Salata amjed9015@gmail.comGalina Borisova Maria Maleva 152242-2522025-11-282026-02-042026-02-102026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Biochar, a carbon-rich material produced via biomass pyrolysis, has attracted growing attention due to its diverse physicochemical properties and potential relevance in soil-related and environmental applications. In this study, biochar was produced from date palm (Phoenix dactylifera L.) pit residues, an abundant agro-industrial by-product, through slow pyrolysis at temperatures of 350 °C. The resulting material was systematically characterized to evaluate its physicochemical and structural attributes using proximate analysis, pH and cation exchange capacity (CEC) measurements, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analysis. The characterization results revealed that the produced biochar had a high yield of 75%, a low ash content (1.22%), and an acidic pH of 4.46. The biochar also exhibited a carbon-rich composition with a fixed carbon content of 27.3%, a measurable BET surface area of 18.22 m² g⁻¹, and a cation exchange capacity of 20.45 (cmol(+) kg⁻¹) These properties reflect the structural and chemical features of the biochar generated under the applied pyrolysis conditions. While no soil or biological performance was evaluated in this study, the measured physicochemical characteristics suggest potential relevance for future soil-based or environmental assessments. Overall, this work demonstrates the valorization of date palm pit residues into biochar with well-defined physicochemical and structural properties, contributing to waste management strategies and circular bioeconomy approaches. Further studies are recommended to assess the performance of this material under specific application conditions.Date palm pit biochar, slow pyrolysis, physicochemical properties, porous structure, cation exchange capacity, agro-industrial residue.http://ejss.fesss.org/10.18393/ejss.189136210.18393/ejss.1891362Bacterial population and several soil properties across different vegetation stands in Andisols profiles at Mount Merbabu National Park, IndonesiaJaka Suyana jokosuyonouns@staff.uns.ac.idHayu Wisesa Tuada Dhany Eko Prasetyo Endang Setia Muliawati Komariah 152253-2662025-10-072026-02-032026-02-172026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies A fundamental understanding of the forest stands and upland farming practices is imperative for effective land management, as it impacts the several soil properties. This research was to evaluate the relationship of bacterial population and several soil properties across different vegetation stands in Andisols soil profiles. Soil sampling was conducted on Mount Merbabu National Park (puspa (Schima noronhae Theaceae) and pine (Pinus merkusii Pinaceae)) and upland farming. For each vegetation observation plot unit, a pedon was created and 3 replications were carried out; and each pedon was sampled at soil profile depths 0-100 cm (0-10, 10-20, 20-30, 30-50, 50-70, and 70-100 cm) so 54 soil samples were obtained. The soil samples were then analyzed: bacterial population by the Spread Plate Count method, soil pH by pH meter, soil organic matter (SOM) by Walkley and Black method, and soil moisture by gravimetric method. The results showed that puspa had the highest means bacterial population (19.9 ± 2.67 ×10⁷ CFU g⁻¹), SOM (8.24 ± 1.06 %) and soil moisture (29.71 ± 1.93 %) which were significantly different from pine and upland farming; the highest bacterial population and SOM content in each stands was produced in the top layer (0-10 cm) and decreases with increasing soil depth; the lowest soil moisture was obtained in the top layer and increases with increasing soil depth; and bacterial population had a very significant relationship and are positively correlated with SOM and negatively correlated with soil moisture.Bacterial population, forest stands, soil properties, upland farming.http://ejss.fesss.org/10.18393/ejss.189388910.18393/ejss.1893889Sequential foliar NPK nutrition and amino acid supplementation mitigate plant-available water deficit effects on growth, yield, and tuber carbohydrates of potato under greenhouse conditionsBakhytkul Kenzhaliyeva Gulnur Daldabayeva daldabaevag@gmail.comGulzhanat Shamshina Naziya Suleimenova Zhazira Zhumataуeva Rauza Abdukerim Nurgul Amangeldi Khansulu Kuspangaliyeva Bakhyt Seitmuratov 152267-2782025-10-072026-02-132026-02-202026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Water deficit is a major constraint for potato (Solanum tuberosum L.) production, reducing canopy development, tuber filling, and quality-related carbohydrate accumulation. Foliar nutrition and amino-acid-based biostimulants may partially offset drought-induced limitations in root nutrient uptake and plant metabolic activity. This greenhouse pot experiment evaluated whether a phenology-based, sequential foliar nutrition program and amino acid supplementation can alleviate the effects of progressive reductions in plant-available water (PAW) on potato growth, yield, and tuber carbohydrate composition. Certified seed tubers of cv. Agria were grown in clay loam soil under a completely randomized design with three replications. Pots were maintained at four PAW regimes (100%, 75%, 50%, and 25%), with three foliar regimes within each PAW level: (i) non-sprayed control, (ii) sequential foliar fertilization, and (iii) sequential foliar fertilization plus amino acids. Foliar applications were conducted four times from early vegetative growth to tuber bulking, using stage-specific water-soluble NPK formulations supplemented with micronutrients; the amino acid product was applied concomitantly in the combined treatment. Decreasing PAW reduced stem number, stem diameter, plant length, total leaf number, tuber yield, and tuber carbohydrate concentrations. Across irrigation regimes, sequential foliar fertilization improved vegetative growth and increased tuber yield relative to the control, and amino acids provided a further benefit. Yield responses exceeded changes in tuber number, indicating effects mainly on tuber growth rather than tuber set. Foliar treatments—particularly with amino acids—also increased tuber glucose, fructose, sucrose, and starch within each PAW level, suggesting improved carbon assimilation and/or sink activity under water limitation. Overall, a stage-targeted foliar NPK program integrated with amino acids is a practical strategy to reduce yield penalties and sustain tuber carbohydrate accumulation under deficit irrigation. Field validation across cultivars and mechanistic measurements are warranted to refine dose–timing recommendations.Potato, deficit irrigation, foliar fertilization, amino acids, tuber carbohydrates.http://ejss.fesss.org/10.18393/ejss.189467310.18393/ejss.1894673Dose- and source-dependent effects of foliar potassium on growth, tuber yield, and leaf nutrient status of potato (Solanum tuberosum L.) cv. ÇanlıbelZarbayim Babacanov Nazrin Rahmanova Sanubar Alakbarova Müjgan Masimli Ulkar Qanbarzade Shaban Maxsudov Rahila İslamzade rehile.islamzade@asoiu.edu.az152279-2902025-10-142026-02-142026-02-232026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Potassium (K) plays a central role in potato physiology and tuber bulking, yet foliar K programs may differ markedly depending on application rate and fertilizer source. This study evaluated the effects of foliar K source and dose on vegetative growth, tuber yield, and leaf nutrient status of potato (Solanum tuberosum L.) under controlled conditions. The experiment was conducted in a growth chamber from 2 February to 2 May 2025 using certified seed tubers of cv. Çanlıbel (Azerbaijan), obtained via the apical meristem technique and pre-sprouted for 20 days at 25 ± 2°C. A clay soil was used as the growing medium, and pots were maintained at 100% plant-available water throughout the experiment. Treatments were arranged in a completely randomized design with three replications (n = 3) and included a control (no foliar K) and foliar applications supplying 500, 1000, or 2000 mg kg⁻¹ K₂O from four K sources: KCl, K₂SO₄, KNO₃, and potassium silicate (K₂O₃Si). Foliar sprays were applied twice during the tuber bulking period using Tween-20 (0.1%) as a wetting agent. Foliar K significantly improved canopy development, increasing stem number, stem diameter, plant length, and total leaf number relative to the control, with responses generally strengthening as K₂O dose increased. Tuber yield per plant increased from 531 ± 25 g in the control to 663 ± 41 g under 2000 mg kg⁻¹ K₂O as KNO₃, while tuber number varied within a comparatively narrow range, indicating that yield gains were driven primarily by improved tuber bulking rather than tuber set. Leaf macronutrient concentrations (especially N and K) and micronutrients (Fe, Cu, Zn, and Mn) were enhanced by foliar K, with the greatest and most consistent improvements observed for KNO₃, followed by potassium silicate and K₂SO₄. Overall, foliar K application during tuber bulking-particularly KNO₃ at ≥1000 mg kg⁻¹ K₂O—was effective for improving potato growth, yield, and nutritional status under non-limiting water conditions.Potato, foliar fertilization, potassium sources, tuber bulking, nutrient status, yield components.http://ejss.fesss.org/10.18393/ejss.190180010.18393/ejss.1901800Evaluation of soil quality in a cornell-based polye ecosystem in a Karstic Area: Integration of geostatistics and machine learningHüseyin Alper Aktop Sevda Altunbaş Beritanli saltunbas@akdeniz.edu.trBayram Çağdaş Demirel 152291-3012025-10-212026-02-232026-03-032026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies Assessing soil quality and establishing processes to control quality is critically important in environmentally sensitive karst systems. This study aimed to analyze the spatial behavior of soil quality and the dominant soil properties controlling it in the karstic polje system of Gembos Plain (Southern Turkey) using the Cornell Soil Quality Index (SQI). SQI values were calculated using physical and chemical data obtained from 72 soil samples (0–30 cm). According to analysis results SQI values ranged from 53 to 59, with an average value of approximately 56. Semivariogram analysis showed that SQI exhibited moderate spatial dependence; the Gaussian variogram model was selected as the most appropriate model due to lowest error values and RMSSE close to 1. The spatial distribution obtained by ordinary kriging revealed that low-to-medium quality classes were dominant across the area and that geochemical micro-scale patterns prevailed over distinct morphological zoning. In addition, Random Forest and XGBoost models showed the highest performance in machine learning analyses (R² = 0.74 and 0.71). Variable importance analysis has shown that soil reaction (pH) is the primary control factor determining SQI variability, while P, Fe, and K are effective at a secondary level. Also soil organic matter plays a secondary role in explaining SQI variability due to its narrow range of variation. The results reveal that soil quality in karstic polje conditions is controlled by chemical constraints rather than physical properties, and that the combined use of geostatistical modeling and machine learning significantly improves the interpretability of soil quality analyses.Soil quality, Karstic polje, Cornell Soil Quality Index, Geostatistical modeling, Machine learning.http://ejss.fesss.org/10.18393/ejss.190923810.18393/ejss.1909238Stage-sensitive conjunctive use of river and collector–drainage water sustains rice production under saline soil conditions in the Kazakh Aral Sea Region: A three-year field studyAkbope Aibekkyzy Bakhytzhan Shayanbekova shbakhyt_67@list.ruAdylkhan Balmakhanov Bakyt Kenbayev Olga Ashirova Almasbek Berdibek Zhanylkhan Bukabayeva 152302-3242025-10-112026-03-102026-03-132026-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies The sustainability of rice cultivation in the lower Syr Darya irrigated lowlands of Kazakhstan's Aral Sea region is increasingly threatened by freshwater scarcity and secondary salinization. Over three consecutive seasons (2023–2025), field experiments were conducted to evaluate rice plant responses in terms of agronomic performance and soil salinity under saline soil conditions using a conjunctive irrigation strategy involving river water, collector–drainage water, and their mixtures. It was carried out as a randomized complete block design with five irrigation variants and four replicates: V1, river water for the whole season; V2, collector–drainage water for all seasons; V3, mixed water throughout; V4, river water until full emergence then mixed water; and V5, irrigation with river water until full seedling emergence, after which collector–drainage water was applied. These consisted of irrigation-water quality, early establishment and stand survival, plant yield components, grain yield, indicators of irrigation efficiency, soil salinity profiles and ionic composition as well as shallow groundwater conditions. Irrigation-water quality consistently differed between sources: river water showed the lowest indicators for salinity and sodicity, collector–drainage water the highest, and mixed water intermediate values. Crop and soil responses showed pronounced differences consistent with these hydrochemical disparities. V1 and V4 produced the highest three-year mean grain yields of 6.56 and 6.45 t ha⁻¹, respectively, whereas V2 yielded only 0.59 t ha⁻¹. The V1 and the V4 showed minimum specific irrigation water use; whereas, it was maximum in the case of V2, but that trend reversed for water productivity. Repetitive application of collector–drainage water also caused less favorable soil salinity environments, higher ionic load and groundwater EC. In contrast, the stepwise regime in V4 preserved soil and groundwater conditions that were reminiscent of river-water irrigation conditions. The results show that continuous irrigating with collector–drainage water substantially limits rice productivity under saline field conditions. But it is not a requirement to use only water of the highest quality. Cultivation with good-quality river water in the crop establishment phase followed by mixed-water irrigation thereafter maintained grain yield equivalent to that of river-water irrigation only. These results suggest that stage-sensitive conjunctive use of river and drainage-discharge water provide a high leverage option for sustaining rice production along with reducing adverse load on already scarce freshwater resources in salt-affected irrigation systems.Rice, collector–drainage water, conjunctive irrigation, soil salinity.