Search Results (34)

Groundwater is the primary source of irrigation in many semi-arid hard-rock aquifer regions. Yet, its suitability assessment is often hindered by the nonlinear hydrochemical dynamics that traditional bivariate tools, such as the U.S. Salinity Laboratory (USSL) diagram, cannot adequately resolve. To overcome this limitation, we developed an explainable artificial intelligence (XAI) framework that predicts irrigation suitability categories directly from hydrochemical variables, without relying on calculated indices. Using 1872 post-monsoon groundwater samples from Telangana, India, we trained three ensemble tree-based classifiers (Random Forest, LightGBM, and XGBoost) on 11 hydrochemical variables (Na⁺, K⁺, Ca²⁺, Mg²⁺, HCO₃⁻, Cl⁻, F⁻, NO₃⁻, SO₄²⁻, pH, and total hardness). Class imbalance was addressed using the Synthetic Minority Over-sampling Technique (SMOTE), and model hyperparameters were optimized with Optuna. Among the tested models, LightGBM achieved the best performance (balanced accuracy = 0.938). Model interpretability was enabled using Shapley Additive Explanations (SHAP), supported by Piper and Gibbs diagrams, revealing a critical distinction between sodicity-driven salinity and hardness-driven mineralization, identifying calcium-saturated waters for which gypsum amendment can be chemically futile. To bridge the gap between algorithmic accuracy and operational simplicity, we distilled SHAP explanations into linear heuristics and quantified the trade-off between accuracy and simplicity. Accordingly, we proposed a tiered hydrochemical triage framework in which quantitative heuristics handled approximately 62.5% of the routine samples, while XAI resolved the complex and ambiguous cases. Overall, the proposed framework transforms classic suitability assessment tools into an adaptable, evidence-informed, proactive decision-support system for sustainable agricultural water management under increasing environmental stress. Full article

Secondary salinization in mulched drip-irrigated cotton fields of arid oasis–desert transition zones in Xinjiang imposes coupled root-zone constraints, including salt-induced aggregate structural degradation and ionic stress. However, field evidence remains limited on whether integrating a structure-oriented soil conditioner with humic acid can generate stable improvements across growing seasons. A two-year field experiment with a randomized block design (three replicates) was conducted to evaluate four treatments: control (CK), polyacrylamide (PAM, 30 kg ha⁻¹), humic acid (HA, 450 kg ha⁻¹), and PAM + HA. Soil physical and chemical properties and aggregate-size distribution were determined after harvest, while enzyme activities and root traits were assessed at the flowering–boll stage. Structural equation modeling (SEM) and random forest (RF) analysis were used to explore soil–root–yield linkages and identify key soil predictors associated with yield variation. Treatment effects were most evident in the 0–20 cm layer, with PAM + HA showing the greatest overall improvement. In the topsoil, PAM + HA lowered soil pH from 8.35 to 7.88 in 2024 (p < 0.05), increased soil organic carbon (SOC) to 4.29 g kg⁻¹ in 2025 (p < 0.01), and increased NO₃⁻–N to 25.51 and 30.27 mg kg⁻¹ in 2024 and 2025, respectively (both p < 0.05). PAM + HA also enhanced cellulase activity from 6.17 to 16.85 mg glucose g⁻¹ 72 h⁻¹ in 2024 and increased seed cotton yield to 6683.69 and 5996.89 kg ha⁻¹ in 2024 and 2025, with a 51.0% yield increase over CK in 2024. SEM showed that root development had the strongest direct positive effect on yield (β = 0.79, R² = 0.63; goodness of fit (GOF) = 0.74), while random forest identified alkaline phosphatase, cellulase, and NO₃⁻–N as the main yield predictors (out-of-bag R² (OOB R²) = 0.672, p = 0.01). This study elucidated the effects of the combined application of a structure-oriented soil conditioner and humic acid on the root-zone environment of mulched drip-irrigated cotton fields in arid regions, providing a theoretical basis for the coordinated regulation of soil structural improvement and nutrient activation in saline–sodic cotton fields. Full article

Saline irrigation water is increasingly used in arid and coastal regions, posing serious constraints to soil health and wheat yield, particularly in saline–sodic soils. A two-season field experiment was conducted to evaluate the effects of compost, biofertilizers (Azospirillum brasilense and Azotobacter chroococcum), and their combinations on soil physicochemical properties, microbial activity, wheat growth, yield, and physiological traits under two irrigation water salinity levels (3 and 6 dS m⁻¹). Two wheat varieties differing in salt tolerance (Miser 4 and Sakha 95) were tested. Salinity significantly increased soil EC and ESP and reduced plant growth, yield, and nutrient content, while integrated bio-organic treatments markedly alleviated these adverse effects. Compost combined with Azotobacter chroococcum markedly improved soil physical conditions, enhanced microbial biomass carbon, reduced sodicity indicators, and promoted wheat productivity across both seasons. Multivariate analyses including principal component analysis (PCA), redundancy analysis (RDA), and self-organizing maps (SOMs) revealed a strong positive association between yield traits, microbial activity, and soil fertility, and negative correlations with salinity stress indicators. The results demonstrate that combining compost with biofertilizers induces both immediate and residual improvements in saline–sodic soils, enhances wheat resilience to salinity stress, and offers a sustainable approach for improving cereal production under salt-affected environments. Full article

Phosphogypsum (PG), a calcium sulfate-rich byproduct of phosphate fertilizer production, is generated in vast quantities worldwide and represents a major environmental management challenge. At the same time, its chemical composition makes PG a potentially valuable soil amendment, particularly for the reclamation of saline, sodic, and acidic soils. This review critically synthesizes current knowledge on PG generation processes, physicochemical properties, agronomic performance, and associated environmental and health risks. Evidence from peer-reviewed studies demonstrates that appropriately managed PG applications can improve soil structure, enhance water infiltration, reduce sodium toxicity, alleviate aluminum stress, and increase crop productivity. However, PG contains variable levels of impurities, including heavy metals and naturally occurring radionuclides, which raise concerns regarding soil contamination, groundwater pollution, food safety, and human health, especially under high or repeated application rates. Regulatory frameworks governing PG use differ substantially between regions, reflecting inconsistencies in waste classification, radiological thresholds, and leaching criteria. This review highlights key knowledge gaps related to contaminant mobility, bioavailability, and long-term ecological impacts and discusses mitigation strategies such as purification, controlled application rates, and integrated regulatory oversight. By balancing agronomic benefits against environmental risks, this work provides a comprehensive framework for the safe valorization of phosphogypsum in agriculture, supporting sustainable land management and circular economy objectives. Full article

Salinity represents a major constraint on plant development and crop productivity in wheat, which represents one of the most critical sources of dietary calories worldwide. Its detrimental effects are particularly pronounced during the early stages of growth, including seed germination and seedling establishment. Salinity tolerance is a multifaceted trait governed by several interrelated mechanisms, notably ion homeostasis, osmotic adjustment, activation of enzymatic antioxidant systems, and transcriptional regulation of ion transporter genes. In the present study, contrasting wheat genotypes exhibiting differential salinity tolerance were selected from a panel of 172 accessions evaluated under salinity stress (175 mM NaCl) and control conditions (0 mM NaCl). The objectives of the current study are to confirm the underlying physiological and molecular mechanisms conferring salinity tolerance. Key physiological and molecular parameters including Na⁺, K⁺, and P homeostasis; activities of major antioxidant enzymes; and expression profiles of the salinity-responsive ion transporter genes TaAVP1 and NHX1 were quantified in six tolerant genotypes and one susceptible genotype. The tolerant genotypes exhibited higher concentrations of Na⁺ and K⁺ and elevated activities of all antioxidant enzymes, compared with the susceptible genotype. Furthermore, the tolerant genotypes showed differential expression of TaAVP1 and NHX1: both genes were upregulated in Javelin 48 and Kandahar, whereas they were downregulated in genotype 1018d. Notably, genotype Kule demonstrated the highest Na⁺ accumulation, accompanied by markedly elevated activities of all major antioxidant enzymes, with ascorbate peroxidase and glutathione reductase increasing by 9.20-fold and 2.32-fold, respectively, under salinity stress. Based on these findings, the tolerant genotypes can be categorized into two functional groups: Javelin 48, Ghati, and 1018d (characterized by high K⁺ and salinity tolerance) are better suited to soils affected by low Na⁺ salinity, whereas Kandahar, Kule, and 1049 (characterized by high Na⁺ and sodicity tolerance) are more adapted to soils with elevated Na⁺ levels. In conclusion, the tolerant genotypes exhibited distinct, coordinated mechanisms to mitigate salinity stress, underscoring the complexity and plasticity of adaptive responses in wheat. Full article

Soda saline–alkaline soils have seriously restricted the sustainable development of agriculture in the Songnen Plain, China. Applying soil amendments has proven to be an effective remediation strategy for these sodic soils; however, conventional amendments face limitations, including prolonged remediation periods and the potential to cause secondary pollution upon misapplication. In this study, we combined three different amendments and applied them as four distinct treatments—citric acid + nano-silica (CS), citric acid + nano-silica + humic acid (CSH), nano-silica + humic acid (SH), and citric acid + humic acid (CH)—with no amendment used as the control (CK). The effects of these treatments on improving the soda saline–alkali soil was evaluated using a field positioning experiment. The results indicate that, compared to the CK treatment, applying the amendments significantly increased the concentrations of available phosphorus (AP) (9.19% to 44.43%) and organic matter (SOM) (3.53% to 16.48%) while decreasing alkalinity and salinity indicators (pH, EC (electrical conductivity), ESP (exchangeable sodium percentage), SAR (sodium adsorption ratio), and TA (total alkalinity)) and soil alkali stress ions (water-soluble and exchangeable Na⁺, CO₃²⁻, and HCO₃⁻). The partial least squares path modeling analysis (PLS-PM) demonstrated that the application of the amendments improved soil quality by changing its alkalinity and ion composition, thereby increasing the maize yield (from 3.01% to 9.80%). Full article

In arid regions, the soil degradation from salinization, low organic matter content, and compaction severely limits agricultural productivity. Leguminous perennials such as alfalfa (Medicago sativa L.) have the potential to restore soil quality, but their long-term effects remain underexplored in North African drylands. This study aimed to evaluate the impacts of long-term (7–8 years) alfalfa cultivation on soil fertility and salinity in the Ziban region of Algeria. Ninety topsoil samples (0–30 cm) from cultivated and adjacent uncultivated plots were collected and analyzed, determining organic matter (OM), soil organic carbon (SOC), soil nitrogen stock (SNS), electrical conductivity (EC), sodium adsorption ratio (SAR), pH, major cations (Ca²⁺, Mg²⁺, Na⁺), sulfate (SO₄²⁻), bulk density (BD), and texture. Compared with uncultivated soils, alfalfa cultivation increased OM by 82.26%, SOC by 78.38%, and SNS by 102.99%, while reducing EC by 40.36%, SAR by 28.94% and BD by 6.16% (p < 0.05), indicating significant improvements in fertility, structure and reductions in sodicity. PCA revealed distinct gradients separating fertility–salinity parameters from compaction–sodicity in cultivated and uncultivated soils. These results confirm that alfalfa systems enhance nutrient cycling, reduce salt stress, and improve structural stability in arid agroecosystems through reduced bulk density and increased organic matter in arid agroecosystems. Integrating alfalfa into land management strategies could promote sustainable restoration of degraded soils in drylands. Further research should optimize irrigation and organic inputs to maximize these benefits under climate-stress conditions. Full article

Soil salinity and sodicity are escalating global threats to agricultural productivity, severely limiting crop yield and quality. In the Igdir Plain of Türkiye, high summer temperatures, minimal precipitation, and a shallow groundwater table have intensified salinity-related challenges, currently affecting one-third of the arable land. Despite the substantial impact of salinity stress on eggplant (Solanum melongena L.) production, studies addressing plant tolerance mechanisms under real field conditions remain limited. In this study, eggplant was cultivated in eight distinct soil classes under open-field conditions to evaluate the effects of soil salinity and saline-alkalinity on morphological, physiological, and biochemical traits. Increasing soil exchangeable sodium percentage (ESP) and electrical conductivity (ECe) levels significantly suppressed plant height, root length, stem diameter, and leaf area, along with over 90% reductions in shoot and root biomass. Salinity impaired the uptake of essential nutrients (Ca, K, P, and Fe), while promoting toxic Na⁺ accumulation in leaves. This ionic imbalance induced oxidative stress, as indicated by elevated malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and antioxidant enzyme activities (SOD, CAT, APX), all of which were strongly correlated with proline accumulation. The results highlight a coordinated plant response under salinity stress but also reveal the insufficiency of natural defense mechanisms under high salinity levels. Unless supported by external interventions to improve stress resilience and ensure productivity, growing eggplant in saline–alkaline soils should be avoided. Full article

Rice serves as the staple food for half of the world’s population. Given the expanding global population, the urgency to allocate land for rice cultivation is paramount. In Northeast China, saline–sodic and black soils represent two distinct soil types used in rice production. During rice growth, soil microorganisms, including arbuscular mycorrhizal fungi (AMF), play pivotal roles in nutrient uptake and resistance to biotic and abiotic stressors. While numerous studies have elucidated the role of AMF in enhancing rice growth and its adaptation to stress, the differences in AMF communities within paddy fields between different soil types have been largely overlooked. In this study, high-throughput sequencing technology was employed to analyze the diversity and community structure of AMF, and metagenomic sequencing was employed to analyze AMF functional gene differences between the two soil types (black and saline–sodic soils). At the same time, the commonalities and differences of the soil characteristics (nitrogen, phosphorus, potassium, pH, etc.) were verified in influencing AMF communities. The results indicated that Glomus was the predominant genus in both soil types, followed by Paraglomus. The overall abundance of AMF was higher at the heading stage than at the harvest stage, with Paraglomus showing greater adaptation to the saline–sodic soil environment. Total phosphorus (TP) was identified as the primary factor influencing AMF diversity at the heading stage. In the harvest stage, AMF community diversity was greater in saline–sodic paddy soil compared to black soil, a reversal from the heading stage. Further analysis of the functional genes of Rhizophagus intraradices revealed that gene activity in the heading stage of saline soils significantly surpassed that in black soils, suggesting that R. intraradices plays a more crucial role in saline environments. Additionally, spore density and the content of easily extractable glomalin-related soil protein were relatively higher in saline–sodic soil than in black soil. Thus, it may be inferred that AMFs are more vital in saline–sodic soils than in black soils of the paddy fields in Northeast China. This study may offer valuable insights into the utilization of AMF in paddy fields in Northeast China. Full article

Tall wheatgrass, a perennial forage grass renowned for its salt–alkali tolerance, has recently been proposed as a key species for planting in coastal saline–alkaline lands to establish a “Coastal Grass Belt”. Highly salt-tolerant and high-yielding varieties are essential to achieve this objective. To enhance breeding efficiency, a method integrating seed germination, seedling emergence, and seedling growth was established to evaluate salt tolerance in tall wheatgrass. Germination tests revealed that under 250 mM NaCl, 150 mM Na₂SO₄, 150 mM NaHCO₃, or 100 mM Na₂CO₃, the relative seed germination rates were 31.5%, 65.4%, 68.2%, and 32.6%, respectively, compared to the non-stress condition. Germination tests can use 250 mM NaCl and 100 mM Na₂CO₃ to assess tall wheatgrass tolerance to neutral and sodic salt stress, respectively. In addition, 250 mM NaCl or saline water with EC_w = 6.6 dS m⁻¹ resulted in relative seedling emergence rates of 52% and 59.8%, respectively, compared to the non-stress condition. Seedling hydroponic culture demonstrated that exposure to 300 mM NaCl resulted in relative total dry weight, shoot dry weight, and root dry weight of 38.2%, 35.7% and 50%, respectively, compared to the non-stress condition. Salt-response genes exhibited differential expression in tall wheatgrass under long-term and short-term salt stress. Interestingly, the expression levels of NHX7.1 and NCL1 were significantly higher in salt-tolerant lines compared to salt-sensitive lines. Based on an integrated evaluation of seed germination, seedling emergence, and seedling growth, five out of the 28 tall wheatgrass lines were identified as salt-tolerant. Additionally, two Tritipyrum lines, derived from the cross of Triticum aestivum cv. Xinong 6028 and Thinopyrum ponticum line Zhongyan 1, were found to inherit salt tolerance from tall wheatgrass. Collectively, this work provided an integrated method for salt tolerance testing in a tall wheatgrass breeding program. Full article

Soil salinization, which is second only to soil erosion in terms of soil degradation, significantly hinders crop growth and development, leading to reduced yields. This study investigated the enzymatic and non-enzymatic antioxidant defense mechanisms of four ancient hulled wheat species under salt stress, with and without exogenous glycine betaine (0.5 mM). We aimed to assess the salt tolerance of these species and their potential for cultivation in saline/sodic soils. Our findings indicate that sodium and potassium chloride concentrations exceeding 100 mM induce significant stress in hulled wheat. However, combined salt stress (sodium and potassium chloride) reduced this stress by approximately 20–30%. Furthermore, exogenous glycine betaine supplementation almost completely alleviated the negative effects of salt stress, particularly in Triticum boeoticum. This species exhibited a remarkable ability to restore normal growth functions under these conditions. Our results suggest that ancient hulled wheat, especially T. boeoticum, may be a promising candidate for cultivation in sodium-saline soils. By supplementing with potassium fertilizers in addition to nitrogen, plants can effectively control salt influx into their cells and maintain intracellular K⁺/Na⁺ balance, thereby mitigating the adverse effects of salinity stress. This approach has the potential to increase crop yields and enhance food security in saline environments. Full article

Soil salinization is a severe environmental problem that restricts crop productivity. Straw amendment could increase the fertility of saline–sodic soils by improving soil physical properties and carbon sequestration; however, the chemical mechanism of saline soil improvement via straw reclamation is not clear. This study aimed to investigate the effects of straw return with nitrogen fertilizer on soil leaching characteristics, rice organ ion concentrations, and yield. Therefore, a soil column leaching experiment was conducted in 2021 in Baicheng, Jilin Province, using two straw application rate treatments (0 and 8 t hm⁻²) and three nitrogen application rate treatments (0, 180, and 360 kg hm⁻²). The results revealed the following: 1. The combination of straw return and nitrogen fertilizer significantly increased the soil leachate volume, leachate pH, Na⁺ concentration, and Na⁺/K⁺ ratio, thereby reducing Na⁺ stress on rice; 2. The application of nitrogen fertilizer during straw return effectively minimized soil nitrogen loss by lowering the ammonium and nitrate nitrogen concentrations in the soil leachate; 3. This combination also reduced plant Na⁺ concentrations while increasing plant K⁺ concentrations, thus improving the Na⁺/K⁺ ratio in the plants; 4. Straw return with nitrogen fertilizer significantly enhanced rice yield, which increased with higher nitrogen application rates. In summary, the integration of straw return with nitrogen fertilizer not only regulates rice salinity tolerance but also boosts rice yield, presenting a novel approach for improving saline–sodic soils. Full article

Soil salinization is considered a major global environmental problem due to its adverse effects on agricultural sustainability and production. Compost is an environmentally friendly and sustainable measure used for reclaiming saline–sodic soil. However, the responses of the physiological characteristics of alfalfa and the structure and function of rhizosphere fungal communities after compost application in saline–sodic soil remain elusive. Here, a pot experiment was conducted to explore the effect of different compost application rates on soil properties, plant physiological traits, and rhizosphere fungal community characteristics. The results showed that compost significantly increased soil nutrients and corresponding soil enzyme activities, enhanced leaf photosynthesis traits, and ion homeostasis compared with the control treatment. We further found that the rhizosphere fungal communities were dominated by Sodiomyces at the genus level, and the relative abundance of pathogenic fungi, such as Botryotrichum, Plectosphaerella, Pseudogymnoascus, and Fusarium, declined after compost application. Moreover, the α-diversity indexes of the fungal community under compost application rates of 15% and 25% significantly decreased in comparison to the control treatment. The soil SOC, pH, TP, and TN were the main environmental factors affecting fungal community composition. The leaf photosynthetic traits and metal ion contents showed significantly positive correlations with Sodiomyces and Aspergillus. The fungal trophic mode was dominated by Pathotroph–Saprotroph–Symbiotroph and Saprotroph. Overall, our findings provide an important basis for the future application of microbial-based strategies to improve plant tolerance to saline-alkali stress. Full article

An experiment was conducted to investigate the optimal use of high-salt water for alfalfa fodder growth and quality in Aridisol. The experiment included five treatments and was performed using a completely randomized design (CRD) as factorial design with three replications. We used a leaching fraction technique (LF), which is a mitigating technique (MT). The five treatments were T1 = MT1 as normal irrigation (control), T2 = MT2 as a leaching fraction (LF) of 15% with the same quality of water, T3 = MT3 as a LF of 30% with the same quality of water, T4 = MT4 as a LF of 15% with good-quality water (as percentage of total water), in the form of 2–3 irrigations every 3 months, and T5 = MT5 as a LF of 30% with good-quality water (as percentage of total water), in the form of 2–3 irrigations every 3 months. The duration of the experiment was three years and normal soil (non-saline, non-sodic) was used in the current study. Results showed that saline water irrigation negatively affected the growth traits, but the application of the LF technique with same-quality or good-quality water mitigated such negative effects. The fodder quality traits such as crude protein (CP), crude fiber (CF) and ashes were also affected in a negative way with the use of saline irrigation water. This negative impact was more intensified in the third year as the concentration of salts increased in saline water during the three years of the current investigation. A LF with canal water at 15 or 30% reduced the negative effects of salt stress and improved fodder biomass production and quality traits. For examples, using a LF with canal water at 30% increased the biomass production to 33.30 g and 15.87 g when plants were irrigated with W1 and W5, respectively. In addition, it improved quality traits such as crude protein content (5.54% and 3.73%) and crude fiber content (14.55% and 12.75%) when plants were irrigated with W1 and W5, respectively. It was concluded that the LF technique can be recommended for practice in the case of saline water irrigation for the optimized growth and quality of alfalfa fodder. Full article

Saline-sodic stress induces iron deficiency in rice, reduces leaf photosynthetic performance, and inhibits yield enhancement. In this study, we investigated the effects of exogenous Fe on the photosynthetic performance and transcriptomics of two different tolerant rice cultivars CB9 (Changbai9: saline tolerant cultivar) and TH899 (Tonghe899: saline sensitive cultivar) with 4-week-old Fe-deficient rice seedlings under saline stress, Fe deficiency stress, and both co-stresses. The results showed that under saline and alkaline stress, spraying exogenous iron favored the growth of the two cultivars of rice, with a 32.68% and 39.82 increase in fresh weight, a 2.20-fold and 2.16-fold increase in pigment, respectively, and an 80.28% and 100.00% increase in net photosynthetic rate, respectively, as compared with the iron-deficiency treatment. Transcriptome analysis showed that we found a higher number of differentially expressed genes (7785 differentially expressed genes) in response to exogenous Fe spraying in the soda-salt sensitive variety TH899. The differentially expressed genes that are common to the two cultivars are primarily enriched in metabolic pathways, including plant hormone signal transduction (map04075) and phenylpropanoid biosynthesis (map00940). Specifically, among these genes, 14 are differentially expressed in the carotenoid biosynthetic metabolic pathway. The differentially expressed genes specific to the salinity-tolerant variety CB9 were mainly enriched in the metabolic pathways of glyoxylate and dicarboxylic acid methyl metabolism (map00630), and carbon fixation in photosynthetic organisms (map00710), among which 20 genes were significantly expressed in the pathway for carbon fixation in photosynthetic organisms (map00710). The research results offer specific theoretical support for enhancing the salt tolerance of rice. Full article