Abstract:【Objective】In order to adequately meet the growing population"s demand for agricultural products, reducing the application of chemical fertilizers, investing in organic amendments, and improving the efficiency of nutrient use have been recognized as effective ways to guarantee food security. Different soil aggregate sizes exhibit significant variations in terms of water-heat conditions and nutrient distribution, which in turn influence nematode communities to varying extents. However, the impact of reduced chemical fertilizer application combined with different organic amendments on soil nematodes at the aggregate scale remain poorly understood. 【Method】This study investigated the interaction between reduced fertilizer application (2 levels: full chemical fertilizer NPK and 60% reduction in NPK) and organic amendment types (no organic amendment as control, straw, and biochar) in the red soil of dryland agriculture. Each treatment was further divided into four aggregate size classes (> 2 mm, 2-1 mm, 1-0.25 mm, < 0.25 mm). 【Result】The results indicated that the nematode abundance in all treatments with reduced fertilizer application was higher than that of the full chemical fertilizer treatment. Regardless of the fertilizer application, both straw and biochar significantly increased the total nematode abundance, and nematode numbers increased with the increase in aggregate size. Compared to straw application, biochar application generally decreased the abundance of bacterivorous nematodes while increasing the abundance of omnivorous nematodes. Notably, in the 2-1 mm aggregate size class, biochar addition decreased the abundance of bacterivorous and omnivorous nematodes compared to straw, but increased the abundance of fungivores nematodes. Nematode community analysis revealed that as aggregate size decreased, the nematode structure and enrichment indices tended to decrease, indicating greater environmental disturbance. Further analysis showed that, soil pH and moisture were key factors influencing nematode community structure at the larger aggregate scale, while soil organic carbon was the critical factor at the smaller aggregate scale (P<0.01). 【Conclusion】This study revealed that organic amendments, reduced fertilizer application, aggregate size, and their interactions significantly affected nematode communities. Therefore, the rational combination of organic amendment types and reduced fertilizer application should be considered to better protect soil health and guide agricultural production.

Abstract:【Objective】 The southwestern karst region is characterized by both geological fragility and sensitivity, with soil erosion being a significant concern. Biological soil crusts, as widely developed surface coverings, play a crucial role in regulating soil erosion. However, the underlying mechanisms of how biocrusts coverages at varying levels influence soil detachment control under different lithological conditions remain unclear. Therefore, it is essential to investigate the effects of different levels of biocrusts coverages on the process of soil detachment and the main factors influencing this under varying lithological conditions in the southwestern karst region. 【Method】 In this study, we selected moss-dominated biocrusts developed on dolomite and clastic rock, with undisturbed soil serving as a control. Biocrust growth characteristics were determined in situ at five levels of moss coverages (1%～20%, 20%～40%, 40%～60%, 60%～80%, 80%～100%). The soil samples, including undisturbed soil and loose soil, were collected, and scouring experiments were conducted under different hydrodynamic erosion conditions (shear force of water flow ranging from 1.68 to 12.87 Pa). Quantitative relationships between moss coverages, growth characteristics, soil properties, soil detachment capacity, and rill erodibility were established. The differences in soil resistance to water erosion under moss coverage of different lithologies were analyzed, and the main controlling factors influencing soil detachment and erosion resistance were identified. 【Result】 The results indicate that: (1) The overall thickness and biomass of mosses on dolomite were significantly lower than those on clastic rock, while the roughness was the opposite. The thickness, roughness, and biomass of mosses increased with their coverages, following either a power function or exponential growth model, and soil properties were significantly affected by both lithology and moss development (P<0.05). (2) Moss coverages significantly affected soil detachment capacity and rill erodibility (P<0.05). The rill erodibility under moss coverages on dolomite decreased by 54.57%～99.98%, and on clastic rock by 69.11%～99.93%. (3) Regression analysis revealed that soil detachment capacity and rill erodibility in dolomite mosses were controlled by water-stable aggregates and mean weight diameter, while those in clastic rock mosses were controlled by water-stable aggregates. 【Conclusion】 In conclusion, the development of biocrusts significantly improves soil erosion resistance , with variations in water-stable aggregates and mean weight diameter caused by lithology being critical factors influencing soil erosion resistance. The results provide important scientific insights for ecological restoration and biological crust-based soil erosion prediction in the southwestern karst region.

Abstract:【Objective】Soil constraints, including salinization, acidification, and erosion, have evolved into pressing global environmental crises. Salinization, triggered by improper irrigation and inadequate drainage, causes salt accumulation in the soil, rendering it inhospitable for most crops. Acidification, mainly attributed to excessive use of chemical fertilizers and acid rain, disrupts the soil"s pH balance, impeding plants" nutrient absorption. Erosion, aggravated by deforestation and climate change, strips away the fertile topsoil, significantly reducing soil productivity. These issues not only severely threaten food security by limiting crop yields but also degrade soil health, undermining the long - term sustainability of agriculture. Consequently, mitigating soil constraints has become a central concern for the agriculture, environmental science, and policy - making sectors.【Method】This study conducted a quantitative analysis of 3 996 global patents related to soil constraint mitigation technologies (as of 2024) using the authoritative IncoPat patent database. Patents sourced from various regions and periods were meticulously selected. The analysis delved into aspects such as patent filing dates, applicant locations, technological classifications, and types of innovation entities, with the aim of uncovering research and development trends, technological distributions, and the characteristics of different innovators in this field.【Result】The findings revealed that global patent applications exhibit a "three - phase growth pattern". Since 2015, China has taken the lead in innovation activities. Technological advancements are characterized by a "triple - core - driven" structure, with soil salinization reduction technology at its core. Specialized soil conditioners for constrained land, accounting for 42.8% of the total patents, and upgrades to mechanized equipment have emerged as major research hotspots. Enterprises and universities serve as the primary innovation entities, with enterprises focusing on practical applications and commercialization, while universities contribute to fundamental research and technological breakthroughs. To address future challenges, it is essential to enhance research and development in bioremediation technologies, promote interdisciplinary collaboration, establish an integrated "monitoring-governance-evaluation" technical framework, and develop tailored full-chain mitigation models for different soil constraints. Additionally, continuous efforts in the development of novel technologies, materials, and products are vital for safeguarding soil health and ensuring agricultural sustainability.【Conclusion】This study offers a comprehensive overview of the global landscape of soil constraint mitigation technologies through patent analysis. It underscores the urgent need for collective action to address soil constraints, given their far-reaching impact on food security and agriculture. The identified trends and hotspots provide valuable insights for researchers, enterprises, and policymakers to strategically allocate resources. As the global population continues to grow, future research should prioritize sustainable and innovative solutions. By leveraging the strengths of different innovation entities and promoting international collaboration, significant progress will be made in safeguarding soil health and ensuring the long-term viability of agricultural systems.

Abstract:【Objective】Soil salinization can not only lead to the deterioration of soil physical and chemical properties, but also can seriously harm the growth and development of crops, causing severe harm to agricultural production and the ecological environment. Using microorganisms to improve the quality of salinized soil is a clean and efficient way, but there are also problems, such as the single function of microorganisms and the limited improvement effect. Nevertheless, and algae-bacterial consortium can fully exert the synergistic effect of algae and bacteria and enhance the effect of algae and bacteria on soil. However, at present, there are few related studies on the improvement of salinized soil using the algae-bacterial consortium.【Method】In this study, five microalgae and ten bacteria were isolated from salinized soil. After comparing the changes of biomass and specific growth rate in algae or bacteria under different salt stress, three salt-tolerant algae and four salt-tolerant bacteria were screened out. Afterwards, the three salt-tolerant algae and four salt-tolerant bacteria were combined into different algae-bacterial consortia. By comparing the changes in photosynthetic pigment content of algae in each algae-bacterial consortium, three salt-tolerant algae-bacterial consortia were further selected. Subsequently, the changes in EPS secretion and desalination effects were analyzed under different degrees of salt stress, and the optimal consortium of algae-bacteria was identified. Moreover, 18S-rDNA sequencing or 16S-rDNA sequencing was performed on algae-1 and bacteria-8, and the phylogenetic trees were constructed using the neighbor-joining method, respectively. Finally, the algae1-bacteria8 consortium was applied to salinized soils to improve soil quality.【Result】According to the constructed phylogenetic tree, algae-1 was identified as Borodinellopsis sp., and bacteria-8 belonged to Bacillus sp. After 10-day culture, the exopolysaccharide (EPS) secretion of algae and bacteria increased significantly by 44.56% and 43.19% at treatments of 15 g·L-1 and 20 g·L-1 salt stress, respectively. The soluble salt content of the solution decreased significantly, and the salt removal rate reached 57.89% and 57.55% at treatments of 15 g·L-1 and 20 g·L-1, respectively. When Borodinellopsis, Bacillus, and algae-bacterial consortium were respectively inoculated into salinized soil surface for 30 days, EPS content in soil was significantly increased by 51.72%, 8.20% and 185.88%, and the salinity of soil leaching solution decreased by 5.10%, 3.45% and 7.00%, respectively. Moreover, the salinity of the soil leaching solution inoculated with an algae-bacterial consortium was significantly lower than that of the soil inoculated with algae or bacteria alone. Concurrently, the total nitrogen content of soil in algae-bacterial consortium was significantly increased by 55.33% compared with the initial group, while no significant changes were observed in treatments of algae or bacteria alone.【Conclusion】Collectively, although both soil microalgae and bacteria can reduce soil salinity, algae-bacterial consortium have better effects on salinized soil than algae or bacteria alone. This study will provide an important theoretical basis for improving salinized soil with an algae-bacterial consortium.

Abstract:【Objective】Organic fertilization is one of the most important measures to maintain the fertility level of agricultural soil. However, it is still unclear whether soil fertilization can effectively cope with the frequent occurrence of compound extreme weather events and maintain the stability of soil organic carbon (SOC). Moreover, soil dissolved organic matter (DOM) is an important indicator to measure the dynamic changes of SOC and also a core participant in the process of SOC accumulation and stability. Nevertheless, it is still unclear how extreme weather events may affect DOM and consequently its contribution to SOC accumulation and stability. 【Method】A short-term simulation experiment was conducted using rice paddy soils, and headspace gas sampling, gas chromatography, ultraviolet-visible absorption and fluorescence spectroscopy were applied to compare the effects of high temperature (32 ℃)-precipitation on the emission of CO2 and spectral characteristics of soil DOM in different fertilized soils (PK: phosphorus-potassium fertilizer; NPK: nitrogen-phosphorus-potassium fertilizer, LOM: low-volume organic manure; and HOM: high-volume organic manure). 【Result】The results revealed that (1) the variation range of cumulative soil CO2 emissions in the organic fertilization treatments (LOM and HOM) was relatively small, ranging from 8.92% to 14.17% during high-temperature or high-temperature after precipitation incubations. This effectively increased the resilience of organically fertilized soil in response to external high temperature-precipitation events. (2) Compared with the first day (Day 1) of high-temperature incubation, the soil DOM content in LOM and HOM treatments significantly increased by 7.81-14.74 mg·kg-1 (P<0.05). However, the HOM treatment significantly reduced the soil DOM aromaticity (SUVA254), hydrophobicity (SUVA260), and various fluorescent substances, indicating that under high temperature stress, organic fertilization only changed the structural composition of soil DOM and did not promote the emission of CO2. (3) High temperature incubation after precipitation (Day 28) significantly reduced the soil DOM content by 64.05%-80.44% (P<0.05) when compared with Day 14. Also, organic fertilization significantly increased the SUVA254 and SUVA260 indices of soil DOM and the humification index (HIX) compared with other treatments, thereby reducing CO2 emissions. The increase in protein-like substances (fluorescence peaks B and T) caused by organic fertilizer itself did not lead to an increase in soil CO2 emissions.【Conclusion】Overall, organic fertilization, especially the organic substitution of 25%-50% nitrogen fertilizer, can improve the stability of soil organic carbon, enhance its agricultural adaptability in extreme weather events under the conditions of this study. The findings of this study provide a scientific basis for optimizing agricultural fertilization models, and promoting sustainable agricultural development.

Abstract:A study was conducted to assess the feasibility of using an inexpensive water quality meter for rapid measurement of electrical conductivity (EC) of purple soils and determining fertility levels with EC. A total of 78 purple soil samples from the top layer (0-20 cm) were collected. With a soil-to-water ratio of 1:2.5, the equivalent ECs, displayed in the form of equivalent total dissolved solids (ETDS), were measured using a water quality meter. The ECs of each soil sample were measured with a laboratory EC meter under the same soil-water ratio. Simultaneously, seven fertility indicators, including pH, organic matter, available nitrogen, available phosphorus, available potassium, water-soluble calcium, and water-soluble magnesium, were determined. And the comprehensive fertility level of purple soils was evaluated based on these seven fertility indicators. The results revealed that the water quality meter exhibited good stability and accuracy. The ETDS obtained by the water quality meter had extremely significant positive correlations (P<0.01) with soil fertility indicators such as available nitrogen, available phosphorus, available potassium, water-soluble calcium, and water-soluble magnesium. It could be inferred that the ETDS reflected the abundance and shortage of the soil nutrients to a certain extent. Besides, there was a close correlation between the ETDS and the comprehensive soil fertility index, allowing for direct characterization of soil fertility levels based on the ETDS value. Consequently, when the ETDS obtained by a water quality meter (soil-to-water ratio of 1:2.5) ≥ 250 mg·L-1, it means that the fertility level of the purple soils is high; an ETDS value of 200~250 mg·L-1 indicates a relatively high fertility level; an ETDS value of 100~200 mg·L-1 suggests a medium fertility level; an ETDS value of 50~100 mg·L-1 indicates a lower fertility level; while the ETDS value < 50 mg·L-1 indicates a very low fertility level. However, when the ETDS value exceeds 400 mg·L-1, caution is advised due to potential excessive soil salt content from overfertilization or other factors. Therefore, the fertility level of purple soil can be characterized based on rapid EC measurements using a water quality meter, providing a new technical means for rapid assessment of soil fertility levels.

Abstract:【【Objective】Hemerocallis citrina Baroni, an important cash crop in China, has become a pillar industry in Yunzhou District, Datong City, Shanxi Province. Plant growth retardants could effectively delay the flowering period of H. citrina and regulate its growth and development. However, the effect of plant growth retardants on soil microbiota remains unexplored. Thus, this study aimed to clarify the impact of plant growth retardants on soil microbial community structure. 【Method】 This study was conducted in 2023 in Datong City, Shanxi Province. Plant growth retardants uniconazole (S3307) and paclobutrazol (PP333) were sprayed on H. citrina with three treatments: uniconazole 500 mg L-1 and paclobutrazol 500 mg L-1, water was used as the control, and each treatment was repeated three times. The rhizosphere soil was collected from each plot at the full bud stage, and the fine roots, plant residues, stones, and other debris were removed through a 10-mesh sieve. Then the response of the rhizosphere bacterial community to plant growth retardants was analyzed using 16S rRNA and internal transcribed spacer (ITS ) amplicon sequencing technology. 【Result】The results showed that paclobutrazol and uniconazole treatments had no significant effect on the Shannon index and Chao 1 index of the rhizosphere microbial community. However, both treatments increased the total operational taxonomic units (OTUs ) and unique OTUs of the rhizosphere soil bacteria. At the phylum level, paclobutrazol treatment increased the relative abundance of beneficial microorganisms such as Proteobacteria, Actinobacteria, Acidobacteria, and Ascomycota. Under the genus level classification, the relative abundance of Fusarium in soil after paclobutrazol treatment was significantly increased by 9.68%, whereas uniconazole treatment increased the relative abundance of Cyathus by 25.13% compared with the control. 【Conclusion】 Plant growth retardant treatments have the potential to improve the richness and diversity of rhizosphere bacterial communities as well as change the population structure of soil microorganisms in the rhizosphere of H. citrina.

Abstract:Soil viruses act as invisible regulators in ecosystems, profoundly influencing virus-host interactions and soil health by encoding diverse auxiliary metabolic genes. Through processes such as lysing host bacteria to release nutrients, facilitating the transfer of functional genes, and regulating microbial community metabolism, they serve as critical drivers of functional succession and maintenance in soil ecosystems. This review systematically summarizes the roles of soil viruses in nutrient compensation and element cycling (e.g., carbon fixation, nitrogen fixation, sulfur cycling, and phosphorus metabolism), ecological environment improvement (e.g., pH regulation and saline-alkali land remediation), pollutant degradation, plant health promotion, control of antibiotic-resistant bacteria, and modulation of human health. Furthermore, the paper highlights limitations in current research, such as the lack of in-depth functional analysis methods and insufficient coverage of diverse habitats. Future studies should focus on exploring viral genetic resources and their safe engineered applications to provide innovative solutions for sustainable agriculture and pollution remediation.

Abstract:【Objective】Establishing ecology-based soil heavy metal thresholds is critical for accurately assessing regional ecological quality, managing contaminated sites effectively, and promoting the sustainable development of soil ecosystems. This study aims to derive such thresholds for copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) under different land use patterns by integrating extensive ecotoxicological data and accounting for key soil properties. 【Method】It was systematically compiled and screened ecotoxicological data, yielding 118, 123, 61, and 100 valid entries for Cu, Zn, Pb, and Cd, respectively. The dataset covered 29 terrestrial plant species, 4 terrestrial invertebrate species, and 10 soil ecological process indicators, with accompanying soil properties including pH, clay content (CL), organic matter (OM), and cation exchange capacity (CEC). The data were normalized, accounting for aging-leaching effects and soil property influences. Predictive models for 10% effect concentration (EC10) were developed based on soil properties. Species sensitivity distribution (SSD) was applied using weighted average models derived from multiple best-fitting distribution functions to reduce uncertainty related to reliance on a single distribution. 【Result】The result revealed that (1) Soil pH was the primary factor influencing the ecotoxicity of the heavy metals, with significantly higher thresholds observed in alkaline soils compared to acidic soils. (2) The order of ecotoxicity was Cd >> Cu > Zn > Pb. (3) Thresholds varied substantially across land use types: agricultural land and protected natural areas showed the lowest thresholds, reflecting the strictest ecological protection requirements. However, park and residential lands presented intermediate values, while commercial & service and industrial & mining lands had the highest thresholds. (4) The derived ecological thresholds based on land use and pH-specific categories differed notably from current standards in Europe and the United States, mainly due to differences in derivation methods, ecological receptor coverage, protection levels, and incorporation of soil properties. 【Conclusion】This study compiled extensive ecotoxicological data for Cu, Zn, Pb, and Cd and developed toxicity threshold prediction models incorporating key soil properties (pH, CL, OM, CEC) following aging-leaching normalization and soil property normalization. The results provide a scientifically supported and practical framework for refining soil environmental quality standards and support differentiated ecological risk management based on land use and soil properties.

Abstract:【Objective】The unique micro-oxygen environment of the rice rhizosphere constitutes a critical hotspot that governs the transport and transformation of pollutants. However, the chemical-microbial mechanisms for absorbing cadmium（Cd） and phenanthrene uptake by manipulation of the rhizosphere micro-oxygen environment are still unclear. 【Method】This study conducted a pot experiment using the mid-season rice cultivar ""Huanghuazhan"". The dissolved oxygen content in the rhizosphere was elevated by inserting plastic droppers to investigate the mechanisms by which this modulated micro-oxygen environment inhibits the uptake of Cd and phenanthrene in rice. 【Result】The results indicated that the increased rhizospheric oxygen content （up to 1.7-fold） led to reductions in the accumulation of Cd （24.2%–61.1%） and phenanthrene （26.1%–50.6%） in rice. First, the increased oxygen content in the rice rhizosphere promoted the formation of Amorphous Ferric Iron Phosphate （AFIP-Fe） on the root surface （up to a 1.5-fold increase）. This enhancement thereby strengthened the adsorption and sequestration of Cd and phenanthrene, constructing a root barrier that effectively impeded pollutant uptake. Secondly, the aerobic environment reshaped the rhizospheric microbial community structure, forming a functional microbiota dominated by core functional flora such as Sphingomonas sp. and Mycobacterium sp. Consequently, the abundance of genes related to Cd resistance and polycyclic aromatic hydrocarbon （PAH） degradation increased by 2.2 to 5.6-fold, which enhanced the microbial-mediated bio-immobilization of Cd and the biodegradation of phenanthrene. Redundancy analysis （RDA） showed that dissolved oxygen was the key environmental factor driving microbial community succession and influencing the forms of pollutants. 【Conclusion】In conclusion, this study confirms that improving the micro-oxygen environment promotes the formation of root iron plaque and functional rhizosphere microbiota, which synergistically acted to inhibit the uptake of Cd and phenanthrene in rice. These findings provide a novel theoretical basis and a potential technical approach for the safe utilization of contaminated farmland.

Abstract:The escalating organic co-contamination in arable soils poses a severe threat to soil microecological health and sustainable agricultural development, presenting an urgent challenge to synergistically enhance cropland productivity and maintain microecological function. This review systematically summarizes the ubiquity, complexity, and microecological risks associated with organic co-contamination in cultivated lands, delving into the significant challenges and opportunities for reconstructing the health of cropland soil microbiomes under such stress. Given the limitations of traditional remediation methods, which are often insufficient and costly for complex co-contamination, a frontier strategy is needed. Emphasis is particularly placed on the application potential of modern molecular biology techniques, specifically Synthetic Microbiomes (SynMicro), in restoring the health of contaminated soil microbiomes. The review elucidates cutting-edge strategies for constructing functionally defined and structurally simplified synthetic microbial communities by integrating advanced techniques including metagenomics (to understand community structure and potential function), culturomics and high-throughput screening (to accelerate the isolation of functional microbial resources), genome-scale metabolic modeling (to enable rational design and prediction of microbial interactions), and Artificial Intelligence/Machine Learning (to facilitate intelligent design and optimization of SynMicro consortia). This work forecasts the promising prospects of SynMicro engineering in achieving synergistic multiple objectives critical for soil health reconstruction under co-contamination, such as enhanced pollutant reduction, effective soil-borne disease control, and improved soil fertility through optimized nutrient cycling. By highlighting the potential of SynMicro-based strategies empowered by these frontier technologies and outlining the current challenges, this review aims to provide novel theoretical insights and practical technical pathways for the reconstruction of cropland soil microecological health, ultimately contributing to ensuring national food security and promoting sustainable agricultural development.

Abstract:【Objective】Iron oxides play a pivotal role in the migration of heavy metals in natural environments, with humic acid (HA), a major organic component in soils and water bodies, potentially exerting significant regulatory effects on these processes. This study aims to systematically investigate the transformation kinetics of ferrihydrite (Fh) into crystalline iron oxides (lepidocrocite Lp, goethite Gt, and magnetite Mt) and its impact on cadmium (Cd) sequestration.【Method】Using transmission electron microscopy (TEM) coupled with energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS), this study conducted a controlled experiment involving Fh-Cd (control) and Fh-HA-Cd systems. Fe(II) was introduced as a catalyst to initiate the transformation, which was monitored over 168 h. The study examined the effects of HA (initial concentration 4.94 mmolL-1) and Cd (initial concentration 88.29–94.27 μmolL-1) on mineral phase evolution, Cd adsorption, and retention mechanisms.【Result】The results revealed that in the Fh-Cd system, Lp (48.08%) and Gt (43.49%) formed rapidly within 6 h, with Lp continuing to transform into Gt by 120 h, and a small amount of Mt (4.82%) emerging by 168 h. In contrast, in the Fh-HA-Cd system, HA significantly inhibited the transformation rate, resulting in slower formation of Lp and Gt, with a final mineral composition at 168 h of Fh (2.63%), Lp (42.79%), and Gt (54.6%), and no detectable Mt. During the transformation, the solid-phase HA concentration decreased from 4.94 mmolL-1 to 4.49 mmolL-1, and Cd concentration in the solid phase dropped sharply after 6 h before stabilizing, with the Fh-HA-Cd system exhibiting 5%–10% higher solid-phase Cd than the Fh-Cd system. TEM-high angle annular dark field and EDS analyses showed that C and Cd were initially closely associated with Fh; post-transformation, Lp and Gt retained strong Cd adsorption but exhibited significantly reduced C adsorption. EELS line scans further indicated that C was primarily retained on Fh surfaces and within defects/porosities of Lp, with carbon functional groups (C-H, C=O, C-OH) desorbing during transformation, while Cd was retained through multiple mechanisms including adsorption, structural substitution, and physical encapsulation in the newly formed iron oxides.【Conclusion】This study demonstrates that HA significantly influences Cd’s geochemical behavior by suppressing iron oxide transformation and enhancing Cd adsorption. These findings provide valuable scientific insights into the interaction mechanisms among iron oxides, organic matter, and heavy metals, offering a theoretical basis for understanding and managing Cd contamination in natural systems.

Abstract:Soil is a unique “quantum mechanics” system, and significant orbital hybridization effects occur at soil solid-liquid interfaces. Orbital hybridization effects play a critical regulatory role in soil properties, processes, and functions. However, this concept has not been given much attention in the context of soil solid-liquid interfaces. In the present study, the structure and properties of soil solid-liquid interfaces were quantitatively described based on classical interfacial reaction theory, and atom/ion orbital hybridization in the electric field at the soil particle surfaces as well as its influence on ion-particle and particle-particle interactions were characterized. The intrinsic correlation and regulatory pathways were elucidated for different soil environmental processes, such as mineral weathering, soil acidification, heavy metal passivation/activation, soil water movement, and phosphorus transport. They reveal a multi-scale coupling and multi-process linkage mechanism spanning: subatomic orbital hybridization effects → microscale interfacial reactions → mesoscale soil particle interactions → macroscale soil processes and functions. This cross-scale research framework provides a crucial theoretical foundation for advancing soil system functionality, enhancing cultivated land quality, and strengthening agricultural environmental protection. The atom/ion orbital hybridization effects at the soil solid-liquid interfaces fundamentally arise from the interactions between the electric field and atoms. Future researches should prioritize advancements in the following domains: 1) Synergistic integration of modern analytical techniques and quantum mechanical theories to elucidate surface reaction mechanisms governed by orbital hybridization; 2) Development of precise predictive models for water-soil-solute transport dynamics; 3) Revealing multiscale coupling mechanisms between microscopic soil processes and macroscopic manifestations; and 4) Establishing a quantum mechanics-based core theoretical framework for soil science.

Abstract:Polluted soils typically harbor a complex and widespread array of organic contaminants that seriously endanger ecological security and public health. The utilization of the microbiome to degrade organic pollutants in soil is regarded as a green, safe and cost-effective technique. Comparing with the traditional single-strain method, the bioremediation method based on the synthetic microbiome has obvious advantages. However, this method still has some problems and challenges concerning with the complex soil contamination with multiple organic pollutants. An in-depth investigation of the process and mechanism of the organic pollutant elimination in soil using synthetic microbiomes has become a research hotspot in bioremediation. This paper reviews the advantages and problems encountered in applying synthetic microbiomes to eliminate organic pollutants in soil, clarifies the methods for designing and constructing microbiomes for organic pollutant degradation, and analyzes the role and mechanism of synthetic microbiomes in eliminating soil organic pollutants. currently, synthetic microbiome is still at its early stage in the field of soil bioremediation, with more crucial data being needed. Future efforts must intensify research into synthetic-microbiome optimization, the combined use of synthetic microbiomes with other organisms, and multidisciplinary integration and technological innovation, thereby providing a robust foundation for developing safe, efficient, and feasible biological strategies for the remediation of soil organic pollution.

Abstract:【Objective】 This study aimed to investigate the occurrence characteristics and ecological risks of manure-based fertilizer estrogens (estradiol [E2], estriol [E3], and bisphenol A [BPA]) in different soil types (yellow-brown soil, brown soil, black soil, and red soil) in China. The research sought to elucidate the influence of soil physicochemical properties on estrogen speciation, degradation, and bioavailability, and to establish a framework for optimizing ecological risk models. 【Method】 Four representative agricultural soils were collected, air-dried, and sieved. Cattle manure containing E2 (356.91 ± 0.27 μg·kg?1), E3 (227.58 ± 1.18 μg·kg?1), and BPA (862.21 ± 0.42 μg·kg?1) was mixed with soils at a 1:10 ratio (manure:soil) and incubated for 0–60 d under controlled conditions. Estrogen speciation (organic solvent-extractable, water-soluble, humic acid-bound, and humin-bound forms) was quantified using sequential extraction and HPLC analysis. Soil properties (pH, organic matter, cation exchange capacity, etc.) were measured via standardized methods. Ecological risks were evaluated using risk quotients (RQ) based on predicted no-effect concentrations (PNEC) and estrogen equivalency (EEQ) models. 【Result】 The result revealed that soil type significantly influenced estrogen dynamics. Black soil, with high organic matter (59.73 g·kg?1), exhibited the highest bound-state retention (humic acid-bound BPA: 33.92 μg·kg-1; bound-state total 17β-E2 equivalent: 11.35 μg·kg?1), leading to low short-term risks (E2 RQ = 0.086) but potential long-term risks due to delayed release. In contrast, red soil, with low organic content (8.25 g·kg?1) and acidic pH (5.02), showed elevated extractable state proportion, resulting in high immediate risks (E2 RQ=1.78; BPA RQ=0.73) despite faster degradation (only 6.63%, 6.36% and 1.76% extractable state of E2, E3 and BPA were transferred by day 60 respectively). In both yellow-brown soils and brown soils, the three target estrogens predominantly existed in bound states by day 60 of aging. E2 and E3 underwent significantly more biodegradation than BPA, while environmental risks were primarily contributed by E2 and BPA, presenting medium-to-high risk levels. Correlation analysis revealed extractable state estrogen content was negatively associated with pH and positively linked to organic matter (P<0.01). 【Conclusion】 This study highlights the critical role of soil-specific properties in modulating estrogen speciation and ecological risks. High-organic soils favored bound-state retention, delaying risks, while low-organic acidic soils amplified extractable state bioavailability, necessitating urgent mitigation. Current risk models, which prioritize extractable state concentrations, underestimate long-term hazards from bound-state reservoirs. The findings advocate for integrating speciation dynamics and soil heterogeneity into risk analysis to enable precision management of estrogen contamination in agricultural systems. This approach supports the transition from "total concentration control" to "speciation-targeted mitigation" for sustainable soil health and food safety.

Abstract:Soil is the largest organic carbon reservoir in terrestrial ecosystems. It serves as both a carbon source and a carbon sink and plays a critical role in achieving carbon neutrality goals. Biochar, a carbon-rich material, is produced by thermally cracking waste biomass or organic matter under oxygen-limited conditions. Due to its significant carbon sequestration effects and stability, biochar has become an important technical tool for improving and sequestering soil carbon. This review systematically elucidates the mechanisms of soil carbon sequestration mediated by biochar. It focuses on how the characteristics of the raw material (source, composition, and structure), the parameters of its preparation (pyrolysis temperature), and the conditions of its application (dose and duration of action) influence the efficacy of soil carbon sequestration. The review also analyzes the regulatory effects of environmental factors, such as nitrogen addition/deposition, temperature gradients, and soil texture, on biochar-mediated soil carbon sequestration. Based on the current state of research, future studies should focus on the dynamic response mechanisms of subsoil carbon pools, the evolution patterns of carbon stability under long-term application, and the interactive effects between biochar and inorganic carbon pools. This will provide the necessary theoretical support for developing a carbon-neutral application system based on biochar technology.

Abstract:Soil chemistry has developed rapidly over the past few decades and has formed a relatively complete theoretical system and technical system. Scientific apparatus represented by synchrotron radiation sources are playing an increasingly important role in the research of soil chemistry. The related technologies based on synchrotron radiation, with their unique advantages, can conduct in-situ analysis on the cycling of elements and substances in complex environments at the molecular level, providing more comprehensive technical support for the research covered by soil chemistry, such as soil mineral chemistry, soil organic chemistry, soil inorganic nutrient chemistry and soil pollution chemistry. Significant advances have been made in several areas, including the identification of poorly crystalline minerals, the structural and spatial resolution of organo (metal)-mineral complexes, and the characterization of the morphology and spatial distribution of heavy metals. In recent years, the combination of synchrotron radiation with other spectral and imaging techniques has been increasingly applied in soil research, greatly promoting the development of geochemistry. In this paper, it has been reviewed the progress made in the field of soil chemistry by related technologies based on synchrotron radiation sources and other combined technologies. Finally, prospects for the development of synchrotron radiation sources, for the further integration of complementary techniques, and for the application of related technologies based on synchrotron radiation to the actual soil environment are proposed.

Abstract:【Objective】Vegetation restoration is one of the most effective approaches to improve the ecological environment of the dry-hot valley of the Jinsha River, Yunnan province. Exploring the changes in composition and structure of soil nematode communities under artificial and natural vegetation restoration can provide a theoretical basis for the reasonable management of the forest ecosystem in this region. 【Method】 In dry-hot valley of the Jinsha River, Leucaena leucocephala plantation and natural shrub-grass with Phyllanthus emblica and mixed Terminalia franchetii + Pistacia weinmannifolia were selected at low (1,150 – 1,200 m), middle (1,350 – 1,400 m) and, high (1,550 – 1,600 m) altitudes. The effects of the vegetation restoration approach under different altitudes on the functional structure of nematode communities were analyzed by using ecological indices, c-p life history, and nutritional structure indices. 【Result】 1) A total of 17 genera of bacterivores were captured, accounting for 37.3% of the total number, and omnivores-predators belonging to 21 genera, accounted for 53.2%. Also, Aporcelaimus, Acrobeles, and Microdorylaimus were the dominant genera. 2) Nematode trophic taxa were dominated by omnivores-predators and bacterivores, while plant-parasites and fungivores had relatively low proportions. However, the taxa were biased towards K-strategies. 3) The responses of nematode abundance, trophic taxa, and life history strategies to vegetation restoration varied across different altitudes. As the altitude increased, the diversity and stability of the nematode community under T. franchetii + P. weinmannifolia mixed shrub-grass increased gradually, while that under P. emblica shrub-grass showed the opposite trend. However, the L. leucocephala plantation showed the lowest "V" pattern with the middle altitude. Meanwhile, L. leucocephala plantation at the low altitude increased the metabolic footprints of bacterivores and omnivores-predators, implying that the food web was relatively complex and stable. 4) Soil nitrate nitrogen, available phosphorus, and moisture were the main driving factors of nematode community changes in artificial and natural vegetation restoration. 【Conclusion】 We recommend taking L. leucocephala as the main plantation at the low altitude area in the process of vegetation restoration and actively protect the pure and mixed natural shrub-grass at the middle and high altitudes to promote the ecological restoration of degraded soil in the dry-hot valley of the Jinsha River.

Abstract:【Objective】Microbial necromass carbon (MNC) is an important component of the soil organic carbon (SOC) pool and probing the response of MNC to climate change is key to a deeper understanding of the mechanisms of microbial-mediated regulation of SOC formation. There is still a lack of understanding regarding the impact of climate warming on topsoil and subsoil MNC accumulation dynamics in different ecosystems. 【Method】This study conducted a meta-analysis of the effect of warming of 8 sample sites on MNC in different soil layers and its contribution to SOC and on the response of topsoil and subsoil MNC to warming (41 for total amino sugars, 69 for glucosamine, 69 for muramic acid and 26 for galactosamine). 【Result】Warming promoted the accumulation of MNC in different soil layers as a whole, especially in the topsoil (14.3%). This may be related to the differences in plant-carbon input and the spatial heterogeneity of microbial communities in different soil layers under a warming background. However, due to the acceleration of the loss of SOC in the subsoil after warming, the proportion of MNC contribution to SOC in the subsoil (12.5%) was higher than that in the topsoil (11.3%). Furthermore, the positive effect of the accumulation of fungal necromass and their contribution to SOC in different soil layers was greater than that of bacterial necromass, suggesting that the new carbon input directly or indirectly regulated the composition of MNC. Moreover, the impact of warming on the accumulation of MNC in different soil layers is bound up with warming amplitude and years. Lower warming (≤ 2℃) promoted microbial anabolism to increase the accumulation of MNC in the topsoil by 17.2%, while the contribution of MNC in increasing SOC in the subsoil pool was significantly promoted (14.7%) during higher warming (> 2℃). On the timescale of warming, long-term warming (> 5a) changed the microbial activity pattern and had a greater impact on the ratio of MNC to SOC in subsoil (42.8%). Meanwhile, the contribution of microbial necromass to SOC was increased with soil depth in forest and cropland, whereas warming weakened the proportion of subsoil microbial necromass to SOC in grassland. 【Conclusion】Based on our analysis, we suggest that research on the dynamics of microbial-mediated organic carbon accumulation in specific ecosystems in response to warming should focus on the response of microbial necromass in both topsoil and subsoils. This would provide a huge boost to understanding and predicting the sensitivity of SOC dynamics to climate change and its feedback mechanisms.

Abstract:Soil aggregates are an important component and basic unit of soil structure, and their stability is crucial for maintaining soil health and crop productivity. The formation and stability of aggregates are the result of the joint action of biological and non-biological factors, and soil organisms (microorganisms and animals) play a crucial role in this process. A thorough understanding of the relationship between soil organisms and the formation and stability of aggregates is of great theoretical significance in elucidating the process and mechanism of soil quality change. However, systematic summaries of the driving mechanisms and current application status of soil organisms in aggregate formation and stabilization are still lacking. This paper reviews the effects of soil microorganisms and animals on aggregate formation and stabilization and clarifies the aggregate formation process and stabilization mechanisms driven by soil organisms. The study discovers that microorganisms mediate aggregate formation and stabilization through their physical characteristics, secretion of adhesive substances, and decomposition of organic matter, while animals mediate aggregate formation and stabilization through biological disturbance and feeding. Furthermore, the current status of using soil organisms and their products to increase aggregate stability is analyzed, emphasizing the potential application of novel soil biological structural modifiers. In conclusion, prospective research directions are outlined for future investigations. Researchers should concentrate on the following areas: (1) The formation and stabilization mechanism of soil aggregates driven by soil organisms on multi-scale interface processes; (2) The composition and genetic regulation mechanism of microbial extracellular polymeric substances (EPS) and glomalin-related soil protein (GRSP); (3) The influence mechanism of soil archaea and viruses on the formation and stability of aggregates; (4) The formation process and stabilization mechanism of aggregates mediated by soil food web; and (5) Development and application of biological soil structure improvers. This paper aims to provide both theoretical insights and technical guidance for maintaining and improving soil quality.

Abstract:【Objective】This study aimed to evaluate the impact of various phosphorus (P) fertilizer application rates and irrigation methods on rice yield, P uptake, P loss, and P balance in the Taihu Lake Basin. The goal was to optimize nutrient management and mitigate non-point source pollution by assessing the effects of different P levels and water management practices on rice paddies. 【Method】The research applied a two-year field experiment with three P application rates (P2O5 0, 45, and 90 kg·hm-2) and three irrigation strategies: continuous flooding, mild dryness, and severe dryness. Soil and rice samples were collected at harvest. Soil P fractions were analyzed using sequential extraction, and rice yield and P uptake were measured from grain and straw. Runoff and leachate samples were obtained to assess P loss. 【Result】Compared to the control treatment (no phosphate fertilizer), applying P fertilizer increased rice yield by 2.20% to 11.5%. The P2O5 90 kg·hm-2 treatment reduced P agronomic and P use efficiencies by an average of 34.9% and 29.4%, respectively, compared to the application of P2O5 45 kg·hm-2. P application significantly increased the soil Olsen-P and available P fractions (the sum of Resin-P, NaHCO3-Pi, and NaOH-Pi) by 19.1%~62.4% and 36.5%~101%, respectively, while also enhancing P loss from paddy fields by 79.1% to 292%, compared to the control. In addition, the mild and severe dryness strategies significantly reduced P loss, with average decreases of 27.0% and 35.6%, respectively, particularly in runoff, where reductions were 31.5% and 41.3%, compared to flooding. The P2O5 90 kg·hm-2 treatment maintained a P balance for the rice season, while the application of P2O5 45 kg·hm-2 was sufficient to meet rice demands due to the high availability of soil P and Olsen-P higher than 20 mg·kg-1. Structural equation modeling indicated that Olsen-P and NaOH-Pi were the main influencing factors for rice yield, while Resin-P was the main influencing factor of P loss. 【Conclusion】Moderate P fertilization at P2O5 45 kg·hm-2 effectively increased rice yield with minimal P loss. Mild dryness irrigation and appropriate P application based on crop P requirements and soil P levels are vital for maximizing crop yields while minimizing P loss. The findings provide a scientific basis for nutrient management in paddy fields and the control of non-point source pollution in the Taihu Lake Basin.

Abstract:【【Objective】A long-term field experiment was conducted in a typical black soil area in Northeast China to study the changes in soil colloidal phosphorus content in the 0-100 cm profile under no tillage (NT) and traditional tillage (CT). The purpose was to explore the effect of conservation tillage on the content of colloidal phosphorus and analyze the distribution pattern of colloidal phosphorus in soil under different tillage measures. 【Method】 The research area is located at the National Field Science Observation and Research Station of Hailun Farmland Ecosystem, Chinese Academy of Sciences (47°26′N, 126°38′E), where corn soybean rotation is implemented. After the corn harvest, the soil profiles of farmlands were collected and divided into eight layers: 0-5, 5-10, 10-15, 15-20, 20-40, 40-60, 60-80 and 80-100 cm. The contents of colloidal phosphorus and soil physical and chemical indicators in each soil layer were determined to study the variations and distribution patterns of colloidal phosphorus content in the 0 - 100 cm soil profile under straw mulching no-tillage (NT) and conventional tillage (CT). 【Result】NT significantly increased the content of colloidal phosphorus (P < 0.05), with an average increase of 33.40%. In the same soil layer, NT significantly increased the contents of total phosphorus and available phosphorus, and the average contents of molybdate reactive phosphorus (MRP) and molybdate ureactive phosphorus (MUP) (P < 0.05). Among them, MRP increased by 18.44% and MUP increased by 49.19%, but NT significantly decreased the proportion of MRP in colloidal phosphorus in the surface soil by 12.21% (P < 0.05). TPcoll and colloidal MRP were mainly carried by fine particles of 1-220 nm. The average proportion of FPcoll (1 - 220 nm colloidal phosphorus) in each soil layer under NT treatment was 73.47%, and that under CT treatment was 74.34%. The proportion of FMRP (1-220 nm MRP) was 59.64% under NT treatment and 63.22% under CT treatment, and the average proportion of FMRP in the surface soil under NT treatment was 5.66% lower than that under CT treatment. The content of colloidal phosphorus was affected by soil physical and chemical properties, showing a significant negative correlation with bulk density and a significant positive correlation with field capacity, soil porosity, total phosphorus content, available phosphorus, total carbon, and total nitrogen. 【Conclusion】 In conclusion, conservation tillage generally increases the contents of colloidal phosphorus, total phosphorus, and available phosphorus in each soil layer. This change might be due to the influence of NT on soil physical and chemical properties, and the increase in colloidal phosphorus content might increase the risk of phosphorus loss.

Abstract:Extensive human activities, including industrialization, intensive agriculture, and urban construction, coupled with the accelerated pace of socio-economic development, have significantly precipitated and caused a measurable surge in heavy metal concentrations in soil environments. This environmental issue severely degrades the quality of natural environments, thereby engendering substantial threats to human health and ecological safety. Conventional risk assessment techniques have focused on quantifying the total content of heavy metals in soils. However, such approaches are inherently limited to capturing critical insights into speciation changes and bioavailable concentrations, which are essential for accurate ecological risk assessment of heavy metals. In recent years, the diffusive gradients in thin-films (DGT) technique has emerged as an innovative and promising tool for in-situ measurement of heavy metals in soils. DGT is recognized for its stable performance with minimal disturbance to the surrounding natural environment in real-world applications. Based on Fick"s first law, the DGT technique facilitates the analysis of gradient diffusion and buffering kinetics of target pollutants, thereby providing valuable data on their speciation and bioavailability in diverse environmental settings. Furthermore, the integration of the DGT technique with the DGT-induced fluxes in soil/sediments (DIFS) model significantly enhances its applicability, enabling detailed investigations into the dynamic behaviors of heavy metals within soil matrices. This study provides a comprehensive review of the current advancements and prospects of utilizing the DGT technique for soil heavy metal risk assessments. By examining the severity and urgency of heavy metal contamination in soils, the technical advantages of DGT as a precise assessment tool are delineated, and the necessity of its application is emphasized. Through a critical analysis, the principal environmental factors influencing the ecological risks associated with soil heavy metals are identified, including soil composition, pollutant characteristics, and external environmental conditions. Additionally, this study provides an in-depth overview of the DIFS model"s role in visualizing the minute-scale dynamic behaviors of heavy metals under varying soil functional scenarios, highlighting the differences in ecological risks that may arise. In the concluding section, strategic recommendations for advancing DGT applications are outlined, focusing on improving the analytical criteria, enhancing the preparation of binding layer materials, facilitating multi-contaminant enrichment, and integrating multiple analytical techniques. These improvements are crucial for advancing the detection and quantification of heavy metals in complex environmental media. Potential directions for future research are also discussed to further expand the capabilities of DGT and DIFS in the context of soil pollution monitoring and ecological risk assessment.

Abstract:【Objective】Hyperspectral technology provides a novel solution for the rapid and accurate monitoring of heavy metal content in soils. However, models developed using laboratory spectra often have limited generalizability in practical applications. Additionally, directly estimating soil heavy metal concentrations from remote sensing imagery is often hampered by factors such as weather conditions and surface environment at the time of image acquisition, which leads to reduced model accuracy and limits the ability to accurately reflect the spatial distribution of heavy metals in the study area.【Method】In this study, a tailings area in Kuanshan Town, Huize County, Yunnan Province, was selected as the research site. A total of 56 surface soil samples were collected, and both ground-based and image-based hyperspectral reflectance, as well as Pb and Zn concentrations, were obtained. First, the Direct Standardization (DS) algorithm, combined with laboratory spectra, was used to correct the GF-5 imagery. Subsequently, the Box-Cox transformation was applied to normalize the skewed distributions of Pb and Zn concentrations. Then, fractional order derivative (FOD) was performed on the corrected spectra, and the Boruta algorithm was used to identify informative spectral bands. Finally, Random Forest and XGBoost models were developed for the inversion of heavy metal concentrations.【Result】The results indicate that the DS algorithm effectively mitigated the influence of soil particle size and moisture content on image spectra. The Box-Cox transformation resolved the skewness distribution problem of Pb and Zn content. FOD effectively enhanced detailed spectral features, and the optimal feature band combinations selected by the Boruta algorithm significantly improved the inversion accuracy. Furthermore, the XGBoost demonstrated superior predictive performance in handling complex feature interactions and nonlinear regression problems. 【Conclusion】The optimal inversion model for Pb content in the tailings area was a 0.8 Order-Boruta-XGBoost model, while for Zn content it was the 1.6 Order-Boruta-XGBoost model. Both models exhibited good robustness. This study provides a reliable reference method for using hyperspectral technology to invert Pb and Zn content in mining area soils.

Abstract:Phosphorus (P) is a critical limiting nutrient in terrestrial ecosystems, and its bioavailability in soils is particularly important in influencing primary productivity and ecosystem carbon sequestration capacity. Mountain ecosystems are highly sensitive to climate changes and exhibit distinct responses to alterations in environmental conditions. The P bioavailability in mountain soils is thus a popular topic in ecological and environmental research, especially in the context of climate warming and increased atmospheric nitrogen (N) deposition. This review integrated a Meta-analysis method to synthesize findings of the response patterns and underlying mechanisms of soil P bioavailability to in situ simulated warming and N addition experiments in China’s mountain soils. This study found that single treatment of warming or nitrogen addition did not reduce the bioavailability of soil P, although there were still debates that were closely related to the initial environmental conditions of different ecosystems. Furthermore, the prospects of future research were provided, underscoring the necessity for long-term and multi-elevation in situ simulation experiments. These experiments are vital for understanding the variations in soil P bioavailability under the dual pressures of warming and N inputs. It is also essential to conduct controlled laboratory experiments to explore the effects of these factors on the transformation of soil P fractions across multiple spatial scales, such as landscape and ecosystem levels. Also, the molecular-level response mechanisms of soil P bioavailability to various climate change factors require further investigation. Additionally, there is a need to optimize the parameters in the P biogeochemical cycling models for predicting the effects of climate warming and varied atmospheric N deposition on soil P bioavailability in mountain ecosystems. These potential results will contribute to a far-reaching understanding of the processes and mechanisms of P biogeochemical cycling in mountains in the context of global climate change, which can become an important theoretical basis for the health and stability of mountain ecosystems.

Abstract:【Objective】 Arbuscular Mycorrhizal Fungi (AMF) are important beneficial microorganisms in soil ecosystems, and their ecological functions have been extensively studied. However, a comprehensive evaluation on the impact of AMF on soil quality is still lacking. 【Method】 In this study, we conducted a bibliometric analysis using CiteSpace and a meta-analysis based on 4, 854 articles retrieved from the Web of Science Core Collection from 2003 to 2023, aiming to systematically summarize the research progress on the effects of AMF on soil quality and to quantify their comprehensive effects on soil physicochemical and biological properties across different ecosystems and environmental conditions. 【Result】 The results revealed a steady increase in the number of publications over the past two decades, indicating growing research interest in this field. The top ten contributing countries in terms of publication size were China, the United States, India, Germany, Brazil, Australia, Spain, Canada, Italy, and France. Notably, China experienced a sharp rise in publication output after 2016, significantly surpassing other countries and becoming a major driving force in the field. Research during this period primarily focused on soil properties, nutrient uptake, glomalin-related soil proteins, elevated CO? concentrations, phytoremediation, and AMF colonization rates. The research emphasis has gradually shifted from enhanced plant nutrient acquisition by AMF to its broader implications for soil ecosystem sustainability. Meta-analysis results showed that AMF inoculation had stronger effects on biological properties than on physicochemical traits. Specifically, AMF significantly enhanced soil bacterial (including actinomycete) abundance, enzyme activities, and plant biomass, and increased soil organic matter and nutrient availability. In contrast, its effect on soil bulk density and pH was not significant. The positive impact of AMF on soil quality was modulated by factors such as fertilization, inoculum source, soil sterilization status, and inoculation timing. 【Conclusion】This study provides a systematic synthesis of the effects of AMF inoculation on soil physicochemical and biological properties, and offers insights into the development of comprehensive indicators for evaluating soil quality improvement by AMF. The findings serve as a scientific basis for promoting the application of AMF in sustainable agriculture and ecological restoration.

Abstract:【Objective】Grasslands cover approximately 40.5% of the Earth’s terrestrial surface and play a crucial role in maintaining the global carbon cycle and regulating climate change. However, with the intensification of human activity and the growing impacts of climate change, grassland ecosystems are experiencing varying degrees of degradation worldwide, leading to a decline in grassland soil quality. Although numerous studies have examined changes in grassland soil quality and their influencing factors across regions and over time, bibliometric analyses exploring the research trajectory and development trends in this field remain limited.【Method】To fill this gap, the present study conducted a bibliometric analysis of 8 089 articles published between 1990 and 2022 in the Science Citation Index Expanded database of Web of Science. The literature retrieval was based on the research topic “TS?=?(grassland) OR TS?=?(rangeland) OR TS?=?(meadow) OR TS?=?(savanna) OR TS?=?(steppe) OR TS?=?(prairie) OR TS?=?(pasture) OR TS?=?(grazing land) AND TS?=?(soil quality)”, and the retrieval period was set from January 1, 1990 to December 31, 2022. The analysis was conducted using the Bibliometrix package in R 3.6.3, VOSviewer 1.6.20, and CiteSpace 5.7.R1 software, focusing on annual publication trends, evolving research themes, international collaboration networks, core contributing authors, and leading journals. In addition, CiteSpace 5.7.R1 was used to perform co-citation analysis and thematic clustering on the 8 089 published articles. The results were visualized using ArcGIS 10.6 and Scimago Graphica 1.0.43.【Result】The results revealed that: (1) The total number of publications on “grassland soil quality” has steadily increased from 1990 to 2022, and the development of the field can be divided into three phases, including the initial stage (1990-2005), the rapid development stage (2006-2010), and the increasing maturity stage (2011-2022); (2) The research hotspots of “grassland soil quality” have shifted from “the impact of soil carbon on grassland soil quality” to “the effects of human activities on grassland soil quality”, and the focal research regions have shifted from “areas with sustainable livestock development and relatively high soil quality” to “areas with severe grassland degradation and poor soil quality”; (3) The grassland soil quality research predominantly encompasses establishing assessment indicator frameworks, analyzing driving factors or key processes, and clarifying assessment purposes and ecological significance. Currently, global studies of grassland soil quality have transitioned from analyzing spatio-temporal patterns to exploring the underlying microscopic mechanisms; (4) The United States and the People’s Republic of China hold leading positions in this field, with extensive global collaboration; (5) Richard D. Bardgett has the highest average citation frequency among researchers, Agriculture Ecosystems & Environment has the highest number of publications, while Soil Biology & Biochemistry is the most frequently cited journal. 【Conclusion】This study elucidates the historical development and current status of research on grassland soil quality, which provides data-driven support for advancing global research on grassland soil quality, enhancing regional grassland management practices, and improving the resilience of grassland ecosystems.