Search Results (575)

Red clay in humid-hot environments suffers from severe water sensitivity and rainfall-induced slope instability, while traditional cement/lime stabilization faces high carbon emission challenges. Existing studies on plant ash-modified red clay mainly focus on basic mechanical properties, while systematic research on water retention characteristics and slope stability under extreme rainfall in humid-hot climates remains insufficient. To address this gap, this study proposes a sustainable stabilization method using agricultural waste-derived plant ash for red clay modification in humid-hot regions. Red clay exhibits distinct engineering behaviors owing to its unique physicochemical properties, leading to compromised slope stability and reduced resistance to rainwater infiltration. In this study, red clay was stabilized with 5%, 10%, 15%, and 20% plant ash. Laboratory tests evaluated compaction characteristics, shear strength, and water retention, supported by microstructural analysis via scanning electron microscopy (SEM). Slope stability under rainfall conditions was further simulated using ABAQUS 2022 software. Key findings include: (1) The addition of plant ash significantly altered the compaction properties. As the plant ash content increased from 0% to 20%, the maximum dry density of the modified red clay decreased linearly from 1.68 g/cm³ (unmodified soil) to 1.53 g/cm³, while the optimum moisture content rose from 21.86% to 23.85%. (2) The mechanical properties exhibited a non-linear response, peaking at 10% ash content. At this optimum dosage, the unconfined compressive strength, cohesion, and internal friction angle increased by 70.4%, 83.0%, and 37.1%, respectively, compared to untreated soil. (3) Plant ash enhanced water retention capacity, shifting the soil-water characteristic curve (SWCC). The modified soil demonstrated faster dehydration at low suction but improved water retention at high suction. The permeability coefficient decreased by an order of magnitude. Microstructural analysis revealed reduced porosity and fracture infilling by cementitious gels. (4) Numerical simulations confirmed that 10% plant ash reduced maximum slope displacement from 0.96 m to 0.61 m under heavy rainfall (90 mm total precipitation over 36 h, peak intensity 90 mm/day), elevating the safety factor from 0.85 to 1.45. Failure modes transitioned from deep-seated slip to localized shallow erosion. These results demonstrate that plant ash is a sustainable and effective additive for red clay slope stabilization in tropical climates. Full article

Soil salinization commonly prevails in global arid and semi-arid areas, shrinking farmland and endangering ecological, agricultural and social sustainability. Therefore, it is essential to develop effective strategies for salinized soil remediation. In this study, soil samples were collected from Nanliang Farm in Yinchuan, China. Compound microbial strains (CMS) and humic acid (HA) were selected as soil amendments. A total of eight treatments with different application rates of CMS and HA were set up in pot cultivation experiments, where oil sunflower was planted. The results showed that both amendments effectively elevated soil water content and chlorophyll content, as well as multiple physiological indices of sunflower. Meanwhile, they decreased soil total salinity, proline content and malondialdehyde (MDA) content. For single humic acid treatments, Treatment F1 achieved the optimal amelioration effect: it reduced soil total salinity by an average of 24.34%, and increased sunflower plant height, leaf area and aboveground fresh weight by 5.84%, 95.01% and 77.40%, respectively. Among the single CMS treatments, Treatment S3 performed best, with an average reduction of 31.04% in soil total salinity, and increases of 5.66%, 2.85% and 8.16% in plant height, leaf area and aboveground fresh weight correspondingly. Notably, among all eight groups, the control group CK1 exhibited the most prominent improvement effect, which was significantly superior to F1 and S3. This finding suggests that long-term application (one year or more) of CMS can produce an especially strong ameliorative effect on salinized soil. Full article

The massive generation of coal-based solid wastes (CBSWs) poses severe environmental challenges globally, while widespread soil degradation threatens food security and ecosystem stability. This review critically evaluates the technical feasibility and agro-ecological benefits of valorizing CBSWs—including coal gangue, fly ash, gasification slag, and desulfurization gypsum—as soil amendments within a circular economy framework. We systematically examine the physicochemical characteristics of major CBSW types, analyze modification methods that enhance their performance and safety, and assess their multifaceted effects on soil physical structure, chemical properties, nutrient dynamics, heavy metal immobilization, and microbial communities. A dedicated section addresses environmental risks, particularly toxic element leaching, and outlines integrated control strategies from source selection to post-application monitoring. Critical knowledge gaps persist regarding long-term contaminant stability under climate change scenarios, molecular-scale immobilization mechanisms, and economic scalability. Future research must prioritize advanced low-energy modification technologies, robust long-term field studies, and harmonized international regulations. We conclude that with scientifically guided modification and stringent risk management, CBSWs can be transformed into safe, multifunctional soil conditioners, simultaneously addressing industrial waste management and contributing to global restoration of degraded soil health. Full article

Soil salinization threatens agricultural production, and increasing extreme rainfall may alter natural leaching processes in coastal saline–alkaline soils. However, the relationships among salt ion migration, alkalinity changes, nutrients, and bacterial communities under natural rainfall leaching remain unclear. Therefore, a phased natural rainfall leaching experiment was conducted from June to September 2025 using moderate to severe NaCl-type saline–alkaline soil from Dongying in the Yellow River Delta. The results showed that natural rainfall leaching significantly reduced soluble salt ions, especially Na⁺, Cl⁻, and SO₄²⁻, and rapidly alleviated early salt stress. However, soil pH did not decline continuously with salt reduction, but fluctuated under the buffering effect of the carbonate system, indicating that desalination was not necessarily accompanied by alkalinity alleviation. Available nutrients showed stage-dependent changes, with HN and AK increasing around the middle leaching stage. Bacterial community composition and co-occurrence networks also changed during leaching, and these changes were more closely associated with salt ions and HCO₃⁻/pH than with available nutrients. These results suggest that post-rain management of saline–alkaline soils should not rely only on total salinity, but should also consider major salt ions, pH/HCO₃⁻, and nutrient availability. Full article

Northeast China’s black soil region serves as a critical cornerstone of national food security, yet accelerating soil degradation, characterized by declining soil organic matter (SOM) and rising bulk density (BD), threatens the productive capacity of its farmland. Understanding how soil physicochemical properties regulate crop yields in this ecologically heterogeneous landscape is essential for sustainable agricultural development. Here, 2916 soil samples from 201 counties across six ecological zones were analyzed in conjunction with county-level rice and maize yield records. Our findings revealed that crop yield determinants are fundamentally governed by regional resource endowment characteristics rather than uniform factors. In areas characterized by sandy soil texture, low precipitation (<400 mm yr⁻¹), and inherently low fertility, elevated bulk density (BD, >1.34 g cm⁻³) and alkaline soil conditions (pH > 7.0) constitute the primary constraints to productivity through restricting root development. Conversely, in regions with fertile mollisols and high baseline soil organic matter (SOM > 40 g kg⁻¹), nutrient dynamics emerge as the dominant yield-regulating factors. For volcanic soil landscapes with strong phosphorus fixation capacity, available phosphorus deficiency represents the critical bottleneck for maize production. Path analysis further demonstrates that BD and pH operate predominantly through indirect mechanisms, modulating SOM accumulation and nutrient cycling rather than directly constraining yield. Threshold analysis identified that BD exceeding 1.34 g cm⁻³ and SOM below 26 g kg⁻¹ markedly reduce productivity, while SOM levels above 40 g kg⁻¹ yield diminishing marginal returns. These findings advance our mechanistic understanding and provide scientific foundations for spatially differentiated soil conservation and precision nutrient management strategies essential for sustaining grain production capacity in northeast China’s black soil region. Full article

Soil extracellular enzymes serve as critical drivers in the cycling of nutrients within ecosystems, and their stoichiometry can effectively reveal the metabolic resource limitations of soil microorganisms. However, extracellular enzyme activities, microbial metabolic characteristics, and their influencing factors in different grassland types in the Qilian Mountains have rarely been studied. This study focuses on alpine meadows (TJs), swampy meadows (HBs), and temperate desert grasslands (DLHs) in the Qilian Mountains. Extracellular enzyme activity and stoichiometric characteristics in the 0–30 cm soil layer were analyzed to explore the limiting factors on microbial metabolism and clarify the main driving factors affecting nutrient limitation. Compared with swampy meadows and temperate desert grasslands, alpine meadows exhibited greater extracellular enzyme activity, as revealed by the results. Statistical analysis revealed that enzyme activity exhibited a significant positive correlation with nitrate nitrogen (NO₃⁻-N), total phosphorus (TP), total potassium (TK), available potassium (AK), and dissolved organic carbon (DOC), while showing a significant negative correlation with soil moisture content (SWC) (p < 0.05). Vector analysis of soil enzymes showed that soil microorganisms in the three grassland types are limited by carbon (C) and phosphorus (P). Among them, DLH microorganisms are highly restricted by carbon, while HB microorganisms are highly restricted by phosphorus. Random forest results showed that total phosphorus (TP), available potassium (AK), nitrogen-to-phosphorus ratio (N: P), nitrate nitrogen (NO₃⁻-N), and readily oxidizable carbon (ROC) contribute significantly to vector length, while total potassium (TK), soil organic carbon (SOC), particulate organic carbon (POC), bulk density (BD), and carbon–nitrogen ratio (C: N) contribute significantly to vector angle. A partial least squares path model (PLS-PM) revealed that although microbial metabolic limitation is influenced by specific soil factors, the comprehensive effect of soil physicochemical properties is the dominant factor regulating microbial carbon and phosphorus limitation. This study provides valuable data and insights that elucidate the metabolic characteristics of soil microorganisms across different grassland types in the Qilian Mountains, thereby improving the mechanistic understanding of soil nutrient cycling and supporting evidence-based strategies for the sustainable management and conservation of these fragile ecosystems. Full article

This study explored the effects of one mineral fertilizer and two microbial inoculants and their combined applications on soil physicochemical properties, bacterial community structure, and plant growth of Cymbidium faberi under potted cultivation, aiming to provide theoretical and technical support for the sustainable cultivation of ornamental orchids. A single-factor randomized block experiment was designed with eight treatments: control (CK), mineral sulfosulfuric acid potassium (HF), Bacillus subtilis (KC), Trichoderma harzianum (HC), mineral sulfosulfuric acid potassium + Bacillus subtilis (HK), mineral sulfosulfuric acid potassium + Trichoderma harzianum (HH), Bacillus subtilis + Trichoderma harzianum (KH), and mineral sulfosulfuric acid potassium + Bacillus subtilis + Trichoderma harzianum (HKH). Plant growth traits, soil properties, and soil bacterial community characteristics were measured. The effects of inoculant agents on Cymbidium faberi growth, soil environment, and bacterial community, as well as their interaction relationships, were systematically analyzed. The combination of three inoculants significantly promoted plant height and leaf thickness in Cymbidium faberi. Compared with CK, the relative abundance of Pseudomonadota and Bacteroidota in HH treatment increased by 6.0% and 11.0%, respectively, while the relative abundance of Acidobacteriota and Verrucomicrobiota decreased by 6.0% and 12.0%, respectively. Venn diagram analysis revealed 146 ASVs shared among all treatments. KC, HC, and HF had more unique ASVs, whereas HK and HKH had the fewest. Principal component analysis (PCA) was used to visualize differences in bacterial community structure. Significant differences among treatments were confirmed using ANOSIM. Ecological network analysis indicated predominantly positive (cooperative) associations among bacterial taxa, with HKH showing the highest proportion of positive edges, suggesting stronger bacterial cooperation. Correlation analysis showed that Patesibacteria, Acidobacterita, and Planctomycetota were significantly negatively correlated with pH and TP, while Bacteroidota, Actinomycetota, and Methylomirabilota were significantly positively correlated with pH. The Mantel analysis revealed a significant positive correlation between bacterial community composition and richness and pH. Further analysis using the structural equation model revealed that soil nutrients and bacterial communities were the main factors affecting plant growth. This study clarifies the response rules of plant growth, soil physicochemical properties and rhizosphere bacterial communities to different mineral fertilizer and microbial inoculant combinations, and provides a practical basis for the rational screening of functional inoculants and the construction of healthy rhizosphere microecosystems in Cymbidium faberi pot cultivation. Full article

Parent material is a fundamental determinant of soil pedogenesis, yet its specific role in regulating the molecular composition and vertical evolution of dissolved organic matter (DOM) in paddy soils remains poorly understood. The primary objective of this study was to elucidate how distinct parent materials and soil depths interact to shape DOM chemodiversity. This study investigated 14 paddy soil samples from the plow horizon (Ap, 0–20 cm) and subsoil horizon (Br, 20–50 cm) paddy soils derived from seven parent materials (plate shale: PS, quaternary red clay: QRC, granite: GR, Alluvial Sediment: AS, limestone: LS, sandy gravel: SG, and purple soil: PR). For each composite sample, DOM extraction and subsequent optical characterizations were performed in triplicate (n = 3 analytical replicates). The analysis of soil physicochemical properties was integrated with ultraviolet-visible (UV-Vis) absorption and excitation-emission matrix spectroscopy combined with parallel factor analysis (EEMs-PARAFAC). Our results revealed that parent material significantly dictated the soil chemical microenvironments, with LS, SG, and PR maintaining alkaline profiles, whereas others exhibited distinct surface acidity. Consequently, this microenvironmental heterogeneity profoundly influenced DOM characteristics. While DOM generally shifted towards higher molecular weight and increased aromaticity with depth, its evolutionary trajectory was highly dependent on the parent material. For instance, SG soils preserved a strong autochthonous signature in Ap, whereas GR soils exhibited the highest humification degree. Furthermore, PARAFAC analysis identified a dominant refractory humic-like component (C1 and C2) alongside a highly variable labile protein-like component (C3, 15–40%). Correlation and principal component analyses (PCA) further demonstrated that soil depth and parent material jointly drive DOM evolution, wherein soil organic matter (SOM) abundance showed strong positive associations with total nitrogen (TN), total phosphorus (TP), and available arsenic. These findings underscore that parent material properties are critical variables for understanding soil carbon cycling and managing heavy metal risks in paddy ecosystems. Full article

Exogenous nutrient bags are essential for the artificial cultivation of Morchella sextelata, but the effects of different formulations on yield, nutritional quality, and the soil microecological environment remain unclear. In this study, nine exogenous nutrient bag formulations and one conventional treatment (CK) were evaluated during M. sextelata cultivation. Fruiting time, fresh and dry yields, and nutritional quality indicators were measured, and principal component analysis combined with membership function analysis was used for comprehensive evaluation. Soil physicochemical properties were determined for all treatments, and A7, A3, and CK were selected to represent the best-performing, worst-performing, and conventional treatments, respectively, for soil microbial community analysis. Different formulations significantly affected agronomic and nutritional traits (p < 0.01). A6 showed the shortest fruiting time and the highest fresh and dry yields, whereas A7 had the highest polysaccharide content and ranked first in the comprehensive evaluation. The D values of A7, A6, and CK were 0.789, 0.777, and 0.653, respectively. Soil nutrient analysis showed that morel cultivation markedly altered soil nutrient structure, especially available nutrients and phosphorus-related indicators. Microbial analysis showed that A7 had the highest bacterial richness among the three sequenced treatments and stronger colonization by M. sextelata. Its bacterial and fungal communities were also more closely associated with soil organic carbon. Overall, A6 was more suitable for yield-oriented production, whereas A7 showed the best comprehensive performance when yield, nutritional quality, and soil ecological characteristics were considered together. Full article

To elucidate the effects of nitrogen (N) addition on soil carbon (C), N, and phosphorus (P) cycling in high-altitude orchards on the Qinghai–Tibet Plateau, a three-year field experiment was conducted at an altitude of 3000 m with four N application rates (0, 150, 300, and 450 kg N ha⁻¹, designated as CK, N150, N300, and N450, respectively). We determined soil physicochemical properties, 12 soil enzyme activities, and metagenomic characteristics, and further adopted partial least squares path modeling (PLS-PM) for data analysis and mechanism exploration. The results were as follows: (1) The N300 treatment yielded the maximum C-hydrolase activities and soil organic carbon content, with a 40.6% increase in soil organic carbon compared with the CK group. (2) The N450 treatment resulted in a 365.4% increase in soil nitrate content and significantly reduced the soil pH (from 6.32 to 5.86). Such environmental filtering significantly decreased the relative abundance of Nitrospirota and its core denitrification genes, including nosZ and narI. (3) Continuous N input induced secondary soil P limitation, leading to a more than 90% increase in phosphatase activities under the N450 treatment. Pseudomonadota activated soil P sources by enriching the functional potential of the phn gene cluster. Furthermore, the PLS-PM analysis revealed a significant negative statistical association between P-cycling enzymes and N-cycling functional potential (p < 0.01). This statistical linkage supports the observation of divergent metabolic responses among different element cycles. In conclusion, under the specific experimental conditions tested, an optimal N application rate of 300 kg N ha⁻¹ is recommended to balance agricultural productivity and soil ecological health. The microbiome of alpine apple orchards responds to elevated N input through metabolic trade-offs, namely reducing the functional potential for denitrification and enhancing the P recycling system. These findings provide vital molecular evidence to guide fertilizer reduction, optimize nutrient management, and promote the sustainable development of high-altitude agroecosystems. Full article

Forest soil organic carbon (SOC) accumulation is regulated by plant-derived carbon inputs and soil environmental conditions, but the relative roles of litter composition and soil physicochemical properties in regulating SOC fractions remain unclear in high-elevation forest ecosystems. This study aimed to determine whether variation in SOC among different forest types was mainly associated with particulate organic carbon (POC) or mineral-associated organic carbon (MAOC), and to identify the relative roles of litter characteristics, soil physicochemical properties, microbial biomass, and enzyme activities in regulating SOC fractions. Four forest types on the eastern edge of the Tibetan Plateau were investigated: broadleaved poplar forest (PLF), larch forest (LXF), seabuckthorn forest (SBF), and Dasiphora shrubland (DS). PLF had the highest SOC and POC contents (75.8 and 48.5 g kg⁻¹, respectively), whereas MAOC did not differ significantly among forest types. SOC was strongly positively correlated with POC (R² = 0.74, p < 0.001), but not with MAOC, indicating that SOC variation was mainly associated with POC accumulation. PLF litter contained higher labile and recalcitrant carbon components, including soluble sugar (19.9 g kg⁻¹), starch (30.1 g kg⁻¹), lignin (94.6 g kg⁻¹), and litter carbon (404 g kg⁻¹). Partial least squares path modeling showed that soil physicochemical properties had the strongest direct path relationship with SOC variation (p < 0.001), while litter composition was positively associated with microbial biomass and POC formation (p < 0.01). These findings suggest that POC formation was the main fraction-level feature associated with SOC accumulation, while soil properties and litter composition were related to SOC through different pathways. Full article

One of the fundamental recommendations for sustainable agricultural practices is protecting soil biodiversity by increasing the use of organic fertilizers and substrates. According to EU regulations, certain animal by-products (including horn shavings) may be used as crop fertilizers; however, insufficient information is available on the impact of this fertilizer substrate on the soil environment. This study was conducted to determine the effects of annual soil application of horn shavings on selected characteristics of Lumbricidae communities and physicochemical properties of the soil. Experimental plots had the following treatments of cattle horn shavings (CHS): CHS100 (100%; 1.3 t·ha⁻¹; equivalent to 161 kg N/ha), CHS75 (75%; 0.98 t·ha⁻¹), CHS50 (50%; 0.65 t·ha⁻¹), and SL (control without fertilization). After 2 years of application, an electrical method was used to collect earthworms over the following 3 years. Earthworms found belonged to five species representing three ecological groups: Dendrobaena octaedra, Dendrodrilus rubidus tenuis, Lumbricus rubellus, Aporrectodea caliginosa, and Lumbricus terrestris. Significantly higher values of earthworm metrics were demonstrated between the plot with the highest fertilization (CHS100) and the plots with lower horn shavings additions (abundance: CHS100 > CHS75 and CHS50 by a mean of 43.2%; biomass: CHS100 > CHS75 and CHS50 by a mean of 43%). Species richness was not affected but an increase in CHS application led to a greater biodiversity index. CHS treatments affected selected soil parameters to varying degrees, with soil moisture having the greatest influence on the given earthworm traits. Cattle horn shavings used as a fertilizer are a positive promoter of earthworms in soils and further research in this area may be warranted. Full article

Soil monitoring is fundamental for maintaining global soil health, ensuring food security, and achieving sustainable development. While satellite platforms provide invaluable tools for this purpose, the accuracy of soil monitoring heavily relies on the appropriate design of their remote sensing payload parameters. This study focuses on enhancing the accuracy of satellite-based global soil monitoring. Key physicochemical soil parameters—including total nitrogen (TN), soil organic matter (SOM), total salt content (TSS), moisture content (MC), and clay fraction (Clay)—were analyzed. A full-chain analytical validation model integrating “instrument–radiative transfer–soil parameter inversion” was developed. Using spectral measurements and soil sample analyses from the black soil region of Northeast China, the spectral response characteristics of core soil parameters were simulated and cross-validated under varying spectral resolutions and integration times. Results indicate that, under specific parameter configurations, the ‘Linshi-1’ satellite achieved robust TN inversion accuracy with R² > 0.65. SOM consistently exhibited good inversion performance, with RMSE ranging between 5.04 and 5.76 g/kg across various spectral treatments (all < 6 g/kg). TSS inversion demonstrated strong stability, maintaining an RMSE of approximately 0.43–0.44 g/kg at resampled spectral resolutions≥10 nm (corresponding to an SNR > 263). MC inversion accuracy was sensitive to both spectral resolution and regional variations, requiring a resampled resolution below 10 nm for consistently high accuracy. Clay inversion required the highest resolution, achieving an RMSE of less than 6 g/kg only at resampled resolutions of 1 nm or 2 nm (SNR approximately 150–210). These findings guided the design of the ‘Linshi-1’ black soil monitoring satellite system and its hyperspectral payload prototype. This effort establishes a solid theoretical and methodological foundation for future deployment, providing crucial space-based support for China’s black soil resource management and sustainable utilization. Full article

The stability of soil organic carbon (SOC) in high-latitude permafrost regions plays a critical role in the global carbon balance. However, a systematic understanding of SOC pool fractions and their response to warming across different wetland types in the Great Hing’an Mountains remains lacking. In this study, soil samples were collected from forested, shrub, and herbaceous wetlands at depths of 0–60 cm and incubated at 5, 10 and 15 °C. A three-pool first-order kinetic model was employed to analyze SOC mineralization characteristics, carbon pool fractions, and influencing factors. The results showed that SOC mineralization rates exhibited a pattern of rapid increase followed by a peak and gradual decline over time, decreased with soil depth, and increased with temperature. The mineralization potential followed the order of shrub wetlands > herbaceous wetlands > forest wetlands. The temperature sensitivity (Q₁₀) was lowest in the deep soil layer of shrub wetlands (1.2), whereas a deeper soil layer of forest wetlands exhibited the highest Q₁₀ value (3.5). Across the three wetland types, SOC was dominated by the inert carbon pool (61–72%), with forest wetlands showing the highest proportion of inert carbon (72%). The active carbon pool in shrub wetlands was most sensitive to warming, while herbaceous wetlands had the largest inert carbon stock. Soil pH was significantly negatively correlated with the inert carbon pool, whereas soil moisture content showed a significantly positive correlation. Path analysis further revealed that SOC had the largest total effect on inert carbon accumulation, whereas available nitrogen and pH showed the strongest direct associations with Q₁₀. Wetland type was indirectly associated with inert carbon stocks through its influence on soil moisture, pH, SOC, and available nitrogen. These results highlight that both direct and indirect pathways jointly influence SOC stability in permafrost wetlands. Overall, Wetland type and soil physicochemical properties jointly regulate SOC stability and its response to warming. These results suggest that although forest wetlands possess stronger carbon stability, their stable carbon pools may become increasingly vulnerable under climate warming. Full article

Soil microbes play pivotal roles in nutrient cycling and ecosystem functioning across diverse farmland systems. Orchard grass coverage has been demonstrated to effectively alter microbial community structure and promote nutrient cycling. However, the effects of soybean intercropping on soil bacterial community characteristics and nutrient contents in citrus orchards remain poorly understood. In this study, a field experiment was conducted in a citrus orchard involving three planting patterns: clean tillage (CT), natural grass (NG), and soybean intercropping (SI). The physicochemical properties and bacterial community structure of the topsoil (0–40 cm depth) were determined. Results showed that compared with CT, NG and SI significantly increased cation exchange capacity (CEC), soil organic matter (SOM), alkali-hydrolyzable nitrogen (AN), and available potassium (AK). SI further elevated soil pH and available phosphorus (AP) relative to CT and NG. Bacterial diversity ranked SI > NG > CT, with PCoA showing lower community variation under SI. A total of 31 bacterial phyla were detected in the citrus orchard soil, with Cyanobacteria (17.20~40.81%), Proteobacteria (15.04~24.19%), Acidobacteriota (8.95~14.66%), and Chloroflexi (3.93~21.13%) identified as the dominant phyla. SI enriched Cyanobacteria and Proteobacteria but reduced Acidobacteriota, Chloroflexi, and Actinobacteriota. Mantel tests confirmed CEC and SOM as key drivers of bacterial community structure. Overall, soybean intercropping improves soil microecology and exhibits great potential for soil quality improvement in citrus orchards under local conditions. Full article