Abstract:【Objective】This study aimed to clarify the effects of organic-inorganic regulating material mulching on the pore structure of saline-alkali topsoil and select suitable mulching materials for crop seed germination.【Method】Four experimental treatments were set up, namely CK (native soil), JX1 (composted cow dung + (a mixture of HA, CaO, MgO, SiO₂, and Na₂SeO₃)), JX2 (spent substrate + (a mixture of HA, CaO, MgO, SiO₂, and Na₂SeO₃)), and JX3 (composted straw + (a mixture of HA, CaO, MgO, SiO₂, and Na₂SeO₃)). A field operation involving digging V-shaped ditches→sowing→applying amendments→rolling was adopted. Soil structure and its pore characteristics were analyzed using micro-computed tomography (micro-CT) scanning, combined with field experiments and mathematical statistical analysis.【Result】The results showed that all treatments reduced soil bulk density and improved soil water capability and saturated hydraulic conductivity. Specifically, the saturated hydraulic conductivity of JX2 and JX3 was 2.4 times that of CK, and their soil water capability increased by 17.8%–19.5%. In terms of pore structure, different mulching material significantly affected the quantity and distribution characteristics of soil pores: The JX2 and JX3 showed significantly increased total porosity and connected porosity, while JX1 had lower total porosity; JX3 was dominated by macropores with fewer micropores, whereas JX2 had a more balanced pore size distribution. Comparison of pore structure parameters revealed that JX2 and JX3 had similar values of fractal dimension, anisotropy, and circularity ratio, but the Euler number of JX2 was significantly lower than that of JX3. This indicated that both treatments enhanced the complexity and stability of the pore structure, and JX2 had better pore connectivity. These pore structure optimizations significantly improved the microenvironment for seed germination, thereby increasing the emergence rate and improving the seedling growth traits of foxtail millet, with JX2 showing particularly notable effects.【Conclusion】In conclusion, Organic-inorganic amendment mulching can enhance soil structural performance by optimizing the pore characteristics of saline-alkali soil and create a suitable soil microenvironment for crop seed germination. Among the tested materials, the spent mushroom substrate residue-based (JX2) and straw-based (JX3) regulating materials showed showed the most significant effects.effects, These combinations are effective technical approaches for efficiently regulating the microenvironment of coastal saline-alkali soil and breaking surface soil compaction.

Abstract:【Objective】The argillic horizon is a subsurface secondary layer formed by the accumulation of soil clay particles, and its thickness exerts a crucial regulatory effect on soil processes and vegetation growth in Alfisols. Understanding its spatial distribution is critical for effective land management, particularly in agriculturally important regions such as Northeast China. However, there is still limited knowledge of the spatial variability in argillic horizon thickness, and predictive studies on this topic are scarce. Traditional understanding has largely relied on extensive field surveys combined with geostatistical methods, which are often resource-intensive and may not be efficient over large regions. This study aims to develop a robust predictive model to map the spatial distribution of argillic horizon thickness across the three northeastern provinces of China by integrating limited soil profile observations with a rich set of environmental covariates. 【Method】A total of 311 soil profile samples with argillic horizons were collected in Northeast China. These samples incorporated data from recent field surveys and historical soil records. Consistent with the SCORPAN framework, 71 environmental covariates were selected to correspond to relief, climate, organism, and soil factors. Dual feature selection was conducted via Pearson correlation analysis and the Boruta algorithm. The quantile regression forest (QRF) model was then adopted for spatial modeling, cross-validation, and uncertainty estimation. Rigorous evaluation of model performance and uncertainty estimation was conducted through 50 repetitions of 10-fold cross-validation, and accumulated local effects (ALE) plots were generated to interpret the relationship between key predictors and the target variable. 【Result】The average results from 50 iterations showed that the model achieved a coefficient of determination (R2) of 0.32, a root mean square error (RMSE) of 24.34 cm, and a mean absolute error (MAE) of 19.47 cm. This performance is significantly superior to that of most regional and national scale soil thickness prediction studies (R2 = 0.11–0.41). The prediction interval coverage percentage (PICP) was 86.2%, which is close to the predefined 90% prediction interval (PI), indicating high reliability of the uncertainty estimation. Soil and climate factors were generally more influential than organism and relief factors, with soil thickness (ST) identified as the most critical driving factor. The spatial prediction results indicated a distinct decreasing trend in argillic horizon thickness from the southwest to the northeast. The western and southwestern regions of the study area exhibited the thickest argillic horizons (mostly over 80 cm, with some regions ranging from 100 to 125 cm), while the northern, eastern, and southeastern regions had thinner ones (mostly 20–35 cm, with some regions below 20 cm). High prediction uncertainty was concentrated in mountainous and hilly regions with sparse soil survey points. 【Conclusion】This study confirms the feasibility of mapping argillic horizon thickness using a machine learning approach combined with environmental covariates, even in large, complex landscapes with limited soil observations. Future research could focus on integrating proxies for parent material and pedogenic age to enhance model accuracy, as well as exploring the spatial prediction of other argillic horizon properties (e.g., upper boundary and compactness). This study not only addresses the gap in argillic horizon thickness prediction in Northeast China, but also offers valuable insights for optimizing regional land management strategies.

Abstract:Abstract: 【Objective】This study aimed to comprehensively evaluate the ameliorative effects of amendments application on acid red soil. 【Method】A field trial was conducted in an acid red soil region of Zhuji City, Zhejiang Province. Three acid soil amendments were tested: a vermicompost-oyster shell powder-biochar composite amendment (C), a high-alkalinity biochar amendment (B), and a silicon-calcium-potassium-magnesium amendment (S), with an untreated control (CK). Through the measurement of twenty specific indicators selected from four major categories (soil acidity, nutrient supply, microbial community characteristics, and plant productivity) that reflect fundamental ecological processes, we analyzed the effects of different treatments on ecosystem multifunctionality (EMF). 【Result】The results showed that compared with CK, three amendments significantly reduced soil acidity, with B treatment demonstrating the most pronounced acid-reducing effect (61.81% decrease in exchangeable Al3+ and 62.23% decrease in exchangeable acidity). C treatment elevated total nutrients and available phosphorus content by 14.99%-22.43% relative to CK. Compared with CK, all amendments significantly increased bacterial diversity and evenness, while C and S treatments further enhanced bacterial community stability. Regarding plant productivity, B and C treatments increased yields by 26.87% and 25.47%, respectively, compared with CK, while treatment S enhanced aboveground biomass by 27.30% relative to CK. Evaluation of ecosystem multifunctionality revealed that C, B, and S treatments improved EMF by 112.38%, 95.98%, and 129.71%, respectively, compared with CK. 【Conclusion】These findings demonstrate that while amendments significantly enhanced EMF in acid soil, their effects on specific ecological indicators vary. Therefore, during practical implementation, suitable soil amendments should be selected and applied based on the characteristics and types of the acid soil.

Abstract:【Objective】 Coastal saline-alkali lands represent a critical yet fragile ecosystem where soil carbon dynamics are simultaneously influenced by natural salinity stress and anthropogenic management practices. Clarifying this interactive mechanism is essential for understanding carbon sequestration potential and for developing adaptive management practices in coastal agroecosystems under salinity stress. Specifically, we sought to determine how different fertilization strategies modulate the response of soil carbon pools and microbial processes to varying degrees of salt stress over a short temporal scale. Thus, the specific objective was to clarify the effects of the interaction between salinity and fertilization on the short-term turnover of soil organic carbon in coastal saline-alkali soils and to elucidate the underlying microbial driving mechanisms.【Method】 The soil used for this study was collected from a typical coastal saline area in the Bohai Rim region and subjected to a 30-day controlled pot experiment. Three salinity gradients (0 g·kg-1, 2 g·kg-1, and 4 g·kg-1 NaCl) were established and combined with four fertilization treatments: control (CK), chemical fertilizer (NPK), chemical fertilizer plus straw (NPKS), and bio-organic fertilizer (BF). A systematic analysis was carried out, encompassing measurements of soil carbon fractions (such as dissolved organic carbon and mineral-associated carbon), peroxidase activity, microbial community structure (via high-throughput sequencing), and the expression of key functional genes related to the carbon cycle. 【Result】 Significant interactive effects between salinity and fertilization were observed across most of the measured soil and microbial parameters. Compared to the non-saline condition, the NPKS treatment under moderate salinity (2 g·kg-1) significantly increased soil dissolved organic carbon content (about 39%) and enhanced peroxidase activity, suggesting a stimulated decomposition of added organic materials. Concurrently, this treatment shifted the microbial community structure, favoring r-strategists over K-strategists, indicating a microbial functional adaptation towards faster growth and resource exploitation under the combined input of organic substrate and mild salt stress. In contrast, higher salinity (4 g·kg-1) markedly compromised the stability of iron-bound organic carbon, with its content decreasing by over 50% in the control treatment, highlighting a severe disruption of mineral-organic matter associations under strong saline conditions. The microbial r/K strategy composition showed a strong correlation with soil pH, which was itself modulated by the fertilization treatments. Furthermore, the expression of carbon cycle functional genes exhibited a clear non-linear response to salinity, reaching its peak at the 2 g·kg-1 salinity level, which points to a hormesis-like effect where low-level stress temporarily enhances microbial metabolic potential.【Conclusion】 The results demonstrate that the combined application of chemical fertilizer and straw can facilitate the transformation of active carbon pools in the short term by modulating microbial community function towards a more metabolically active state. However, elevated salinity constrains carbon stability primarily by weakening mineral protection mechanisms, thereby potentially offsetting the benefits of organic amendments in highly saline environments. This study provides insights into the short-term microbial regulation of carbon cycling in saline environments and highlights the importance of integrated management strategies that consider salinity thresholds. The findings imply that tailoring fertilization practices, such as straw incorporation, to specific salinity levels could optimize short-term carbon turnover and contribute to the sustainable management of coastal saline-alkali soils.

Abstract:【Objective】Newly reclaimed red soils are generally characterized by high acidity and low organic matter content, which severely constrain soil fertility improvement and crop productivity. This study aimed to evaluate the effects of combined application of organic materials and calcium-based amendments (lime and calcium salts) on soil fertility enhancement and acidification control in newly reclaimed red soil.【Method】A field experiment was conducted in Ji’an, Jiangxi Province (since 2023) with six treatments: chemical fertilizer alone (CK); CK plus natural humic material (9 000 kg·hm?2), biostimulant (1 500 kg·hm?2), organic fertilizer (7 500 kg·hm?2), and 1 500 kg·hm?2 calcium salt (T1); CK plus the same organic materials combined with 3 000 kg·hm?2 calcium salt (T2); CK plus the same organic materials combined with 1 500 kg·hm?2 lime (T3); CK plus the same organic materials combined with 3 000 kg·hm?2 lime (T4); and CK plus the same organic materials combined with 7 500 kg·hm?2 fermented residue (T5). Soil physicochemical properties, carbon fractions, and crop growth were analyzed using physical fractionation, scanning electron microscopy, and multivariate statistical methods.【Result】The addition of lime and calcium salts significantly regulated soil acidity, with soil pH increasing by up to 16.2%, and markedly enhanced phosphorus availability, as available phosphorus increased by more than six fold. Application of natural humic materials rapidly increased soil carbon pools, with soil organic carbon and particulate organic carbon increasing by up to 84.0% and 263.9%, respectively. However, the sole application of fermented residue aggravated soil acidification and reduced carbon stability. Microscopic observations and multivariate analyses further demonstrated that the combined application of natural humic materials with low rates of lime or calcium salts synergistically improved soil pore structure, increased microbial biomass carbon and dissolved organic carbon (by up to 94.6% and 122.7%, respectively), and substantially promoted both aboveground and belowground biomass of rapeseed (increases exceeding 7-fold).【Conclusion】The combined application of organic materials and calcium-based amendments effectively regulates soil acidification, enhances carbon stability, and promotes coordinated improvement of soil fertility and crop growth in newly reclaimed red soil. This strategy provides a scientific basis and technical reference for the rapid improvement of soil quality in newly reclaimed farmland.

Abstract:【Objective】In arid and semi-arid regions, the coexistence of drought and high salinity imposes severe constraints on crop establishment, impairing seed germination and early seedling growth, consequently causing substantial agricultural losses. Seed priming with nanoparticles represents an emerging, economically viable, and environmentally sustainable approach to enhance crop performance under adverse conditions. Thus, harnessing this new approach in developing sustainable strategies to improve plant stress resilience is imperative.【Method】This study investigated the efficacy of cerium oxide nanoparticles (CeO2 NPs) as a seed priming agent in alleviating the detrimental effects of combined drought-salinity stress (simulated by 60 000 mg·L-1 polyethylene glycol (6% PEG-6000) and 50 mmolL-1 saline-alkali (NaCl：Na2SO4=9：4，pH adjusted by NaHCO3)) on alfalfa (Medicago sativa L.). Seeds were treated with CeO2NP suspensions (0, 1.0, 2.5, 5, 10, 15, and 20 mg·L-1) for 12 h and subsequently subjected to stress conditions for 14 d.【Result】The results demonstrated that drought-salinity stress significantly suppressed germination and seedling growth. However, priming with CeO2 NPs notably mitigated these inhibitory effects in a concentration-dependent manner, with the most pronounced improvements observed at 5 mg·L-1. At this optimal concentration, significant enhancements were recorded in germination potential, germination rate, germination index, vigor index, root length, shoot height, and fresh biomass compared to the non-primed stress group. Also, 5 mg·L?1 CeO2NP treatment also reduced membrane damage, as indicated by lower relative electrical conductivity (REC) and malondialdehyde (MDA) content, and decreased hydrogen peroxide (H2O2) accumulation under combined stress. Concurrently, it elevated the activities of antioxidant enzymes (catalase and ascorbate peroxidase) and the concentrations of osmoregulatory compounds (proline and soluble sugars). Correlation analysis revealed strong positive associations among growth parameters, which were negatively correlated with membrane injury indices. These findings suggest that CeO2 NP priming strengthens the synergistic interaction between the antioxidant system and osmotic adjustment, thereby preserving membrane integrity and promoting germination and seedling growth under combined stress. 【Conclusion】In conclusion, seed priming with 5 mg·L?1 CeO2 NPs effectively improves alfalfa establishment under drought-salinity stress conditions, offering a promising nano-agronomic strategy for sustainable crop production in marginal environments.

Abstract:【Objective】This study aimed to evaluate the effects of long-term straw and straw ash application on rice yield and soil potassium (K) supply capacity.【Method】Based on a long-term field experiment initiated in 2010 in Jinxian, Jiangxi Province, four treatments were established: no straw return and no fertilizer (CK), chemical fertilizer alone (NPK), full straw return combined with chemical fertilizer (NPK+RS), and full straw ash return combined with chemical fertilizer (NPK+RA). Soil samples (0-20 cm) were collected after the late rice harvest in 2023 to determine total K and different K fractions, K content at different adsorption sites of clay minerals, K release kinetics, and quantity/intensity (Q/I) relationship, and rice yield was analyzed accordingly.【Result】Fertilization significantly increased rice yield and soil K content. Under equal NPK nutrient inputs, NPK+RS and NPK+RA increased average annual yields of early rice by 5.22% and 3.53%, and late rice by 3.68% and 2.41%, respectively, compared with NPK. Water-soluble K showed little variation among fertilization treatments. Compared with NPK, non-exchangeable K in NPK+RS and NPK+RA increased by 13.16% and 17.12%, respectively. NPK+RA significantly enhanced exchangeable K, effective K, and total K by 5.41%, 2.87%, and 3.09%, respectively, and its exchangeable and effective K contents were 7.88% and 4.99% higher than those under NPK+RS. Fertilization significantly increased K contents at clay mineral adsorption sites. Compared with NPK, K contents at the mineral surface (p sites), edge (e sites), and interlayer (i sites) increased by 45.07%, 10.09%, and 6.27%, respectively, under NPK+RS; the corresponding increases under NPK+RA were 49.46%, 16.97%, and 11.91%. During K release, no significant differences were observed among fertilization treatments in the rapid-release stage. In the slow-release stage, compared with NPK, cumulative K release increased by 19.69% and 9.07%, and the release rate increased by 19.66% and 9.09% under NPK+RS and NPK+RA, respectively, with NPK+RS showing significantly higher values than NPK+RA. In addition, Q/I analysis indicated that both NPK+RS and NPK+RA optimized soil K supply capacity and intensity more effectively than NPK.【Conclusion】Under equal NPK nutrient inputs, straw and straw ash return combined with chemical fertilizer were superior to chemical fertilizer alone in improving rice yield and enhancing soil K supply capacity. Considering the adverse environmental impacts of straw burning, direct straw return combined with chemical fertilizer is recommended for preferential promotion.

Abstract:【Objective】Soil eukaryotes are key indicator organisms for soil health in ecosystems, and changes in their diversity and community structure can effectively reflect the evolution of soil quality. In high-throughput sequencing-based studies on eukaryotic diversity, the selection of amplification primers directly affects the number of sequences of detected taxa, thereby determining the accuracy of biodiversity assessment. However, the impact of primer selection on the assessment of soil eukaryotic diversity remains timidly explored.【Method】 This study focused on soils from seven typical urban land use types in Ningbo City. Amplification was only conducted for two pairs of widely used 18S-rRNA gene V4 region primers (NF1F_18Sr2bR, TAReuk454FWD1F_TAReukREV3R). The study systematically compared the effects of different primers on the assessment of soil eukaryotic community composition and diversity, and analyzed the differences between two bioinformatic methods: Amplicon sequence variants (ASVs) and operational taxonomic units (OTUs). 【Result】That the proportion of amplification in eukaryotes for the NF1F_18Sr2bR primer was significantly higher than that of TAReuk454FWD1F_TAReukREV3R. Different primers exhibited a preference for specific soil eukaryotic taxonomic groups. Specifically, at the ASVs level, the NF1F_18Sr2bR primer preferred fungi, protozoa, nematoda, arthropoda, and annelida; at the OTUs level, the TAReuk454FWD1F_TAReukREV3R primer preferred protozoa and arthropoda, while the NF1F_18Sr2bR primer preferred nematoda, and annelida. Among the primers, NF1F_18Sr2bR was more appropriate for detecting rare species. The rare species of fungi, nematoda, and annelida amplified by this primer accounted for 12.09%, 38.31%, and 58.33% of their total sequences, respectively. In contrast, TAReuk454FWD1F_TAReukREV3R was more suitable for detecting shared species, as it detected 804 shared species OTUs across different land use types, which was higher than that detected by the other primer. Both primer selection and analytical methods collectively determine the differences in α-diversity assessment, but they do not determine the variations in β-diversity or the effects of environmental factors on community structure. In terms of α-diversity, for both primer pairs, the differences in α-diversity among different land uses were greater at the ASV level than at the OTU level. With respect to β-diversity, the explanatory power of the OTUs level for community diversity was higher than that of the ASVs level. 【Conclusion】This study revealed the critical impact of primer selection on the assessment of soil eukaryotic diversity. In future studies, primers and analytical methods should be selected appropriately based on target taxa and research objectives to ensure the accuracy of community structure and diversity assessment.

Abstract:【Objective】The thickness of soil cover is a key factor determining the ecological restoration effectiveness of the open-pit coal mine dump. A reasonable reclamation thickness directly affects the effects of soil erosion control, nutrient retention, and vegetation restoration.【Method】Taking the dump of Fushun West Open-pit Mine as the research object, a platform-slope model with a height of 50 cm, a platform width of 40 cm, and a slope of 25°was constructed. An indoor simulated rainfall test was conducted, and the rainfall duration was 120 min. During the rainfall process, to record the development process of the rill, one section was taken along its longitudinal direction at the top, middle, and bottom, respectively. The width and depth of the trench were measured with a steel ruler, and the length of the trench was recorded simultaneously. The average values were respectively taken as the morphological characteristic parameters of the rill. The measurement time was from the beginning of the self-generated flow. Within the first 20 min, measurements were taken every 2 min, and from 20 to 120 min, measurements were taken every 6 min. Meanwhile, the runoff and sediment yield were collected every two min using the runoff bucket. After 12 h of sedimentation, the supernatant was collected, and the flow rate was measured with a graduated cylinder. The sedimentary soil was dried in an oven at 105℃ to a constant weight, and the moisture content was measured. Afterwards, the runoff volume was estimated as the sum of the water volume measured by the graduated cylinder and the soil moisture content, while the sediment yield was considered as the dry weight of silt and sand. After determining the sediment yield, nutrient con-tent analysis was conducted. Soil organic matter was determined by the potassium dichromate external heating method, total nitrogen was determined by the Kjeldahl nitrogen analyzer method, and available phosphorus and available potassium were determined by ICP-MS. By analyzing the obtained data, the influence mechanism of different soil cover thicknesses on the sediment yield characteris-tics and nutrient loss process of the waste dump was revealed.【Result】(1) Under different soil cover thicknesses, rill erosion was dominant. The process can be divided into the rill head formation stage, the rill erosion development and evolution stage, and the stable stage. The maximum development rates were 0.65-3.0 cm∙min-1, 1.5-16.75 cm∙min-1, and 0.38-1.25 cm∙min-1, respectively. The soil cover thickness was linearly and positively correlated with the time of the maximum sediment yield rate and the time of the maximum sediment content, with R2≥0.93. That is, increasing the soil cover thickness can effectively delay the occurrence of erosion and reduce the output of sediment. (2)Also, the rate of soil nutrient loss decreased with the increase in soil cover thickness. Under the conditions of 10 cm, 20 cm, and 30 cm soil cover, it was 4.34%-55.11%, 4.97%-46.78%, and 2.61%-40.93%, respectively. The overall degree of nutrient loss followed available phosphorus > total nitrogen > available potassium > organic matter. (3) The dynamics of nutrient loss and the rate of sediment yield and flow showed a synergistic change pattern. The cumulative contribution ratios of sediment yield and flow in the first, second, and third stages of erosion ditch development were 2.3%-3.4%, 55%-71%, and 31%-43%, respectively, and the cumulative contribution ratios of sediment yield were 0.7%-3%, 47%-88%, and 13%-52%, respectively. Additionally, the contribu-tion ratios of cumulative nutrient loss were 0.61%-4.8%, 35.10%-81.48%, and 14.48%-63.98%, respectively. The second stage of fur-row development was the main stage of sediment yield and nutrient loss, but the peak loss rate was delayed with the increase of soil cover thickness.【Conclusion】Based on the goal of controlling soil erosion and nutrient loss, it is recommended that in the reclamation project of dumps under similar climate-soil conditions, the soil cover thickness be set at 30 cm.

Abstract:【Objective】Under the global context of climate change and anthropogenic impacts, soil salinization has become increasingly severe. However, traditional salinization monitoring suffers from being time-consuming, labor-intensive, and costly. Hyperspectral-based salinization monitoring often relies on single mathematical transformations and one-dimensional spectral information, while also exhibiting poor model interpretability. Research utilizing combined spectral transformations to construct spectral indices for salinization estimation urgently requires in-depth exploration. Thus, this study aims to fully exploit spectral information, enhance data sensitivity, and establish a high-precision, interpretable salinization inversion model based on spectral indices.【Method】Dongying City was selected as the study area, where hyperspectral datasets were collected through field surveys, and soil samples were analyzed in the laboratory for salinity determination. The samples were divided into training and testing sets in a 7:3 ratio based on salinity gradients. Spectral data were preprocessed using Savitzky-Golay (S-G) filtering and Multiplicative Scatter Correction (MSC). Four spectral transformations were applied: Reflectance (R), Reciprocal (1/R), Logarithm of Reciprocal (log(1/R)), and Continuum Removal (CR). The Fractional Order Derivative (FOD) transformation was subsequently performed on each form. Ten types of two-dimensional spectral indices were constructed from the combined transformed data at each derivative order. Optimal band combinations and differential orders were identified by assessing correlation coefficients with soil salt content (SSC). Using these spectral indices as features and measured salinity as the dependent variable, four machine learning models—Partial Least Squares Regression (PLSR), Convolutional Neural Network (CNN), eXtreme Gradient Boosting (XGBoost), and Support Vector Machine (SVM)—were constructed. The hyperparameters of all models were optimized using the Bayesian Optimization (BO) algorithm, which iteratively fitted a probabilistic surrogate model to guide the search for hyperparameters that minimize cross-validation error. Each model was trained and tuned via ten-fold cross-validation. Performance was evaluated using the Coefficient of Determination (R2), Root Mean Square Error (RMSE), and Residual Prediction Deviation (RPD). The best-performing model was further interpreted using SHapley Additive exPlanations (SHAP) to identify influential spectral features. 【Result】Results demonstrated that:(1) FOD effectively enhances spectral sensitivity by highlighting gradient information during spectral curve variations; (2) Mathematical transformations combined with FOD significantly improve correlations between spectral data and SSC; (3) The 2-order NDI index after CR treatment achieved the highest absolute correlation coefficient (|r|=0.91) with SSC; (4) The CR-FOD-XGBoost model delivered optimal accuracy (testing set: R2=0.94, RMSE=0.85 g·kg?1, RPD=4.33); (5) In the optimal model, GDI1 contributed most significantly while DI clusters adjacent to zero contributed minimally. 【Conclusion】Collectively, this study demonstrates that combining spectral transformations to construct indices with Bayesian-optimized XGBoost modeling effectively improves soil salinity inversion accuracy, providing scientific foundations for salinization control and ecological sustainability. Future research should focus on enhancing spectral sensitivity responsiveness to further improve model performance, thereby advancing theoretical frameworks for sustainable land-use and environmental conservation strategies.