Abstract:Cadmium contamination poses a significant threat to agricultural production and human health due to its persistence, toxicity, and potential to accumulate in crops and the food chain. However, there is a need for a comprehensive review that provides scientific guidelines for understanding Cd soil-solution chemistry, decreasing Cd levels in the food chain, and bridging the gap between laboratory research and field applications. This study conducted an in-depth literature analysis of both laboratory and field research to provide a comprehensive analysis of the soil chemistry of cadmium, which is crucial for understanding its bioavailability and mobility. The chemical behavior of Cd in soil is influenced by various factors, such as soil pH, organic matter content, and redox conditions. These factors determine the speciation of Cd, which in turn affects its uptake by plants and its potential to enter the food chain. The phytotoxic effects of Cd are manifold, impacting plant growth, physiological functions, and metabolic processes. Cd can suppress plant growth by inhibiting root and shoot development, reducing chlorophyll content, and disrupting photosynthesis. It also induces oxidative stress by increasing the production of reactive oxygen species (ROS), which can damage cellular components such as lipids, proteins, and DNA. The review also sheds light on the molecular mechanisms underlying plant responses to Cd stress. Two major molecular systems are highlighted: metal transporter families and regulatory transcription factor families. Metal transporters, including NRAMP, HMA, ZIP, ABC, and YSL, play essential roles in Cd uptake from the soil, translocation from roots to shoots, and detoxification within plant cells. These transporters facilitate the movement of Cd through cellular membranes and into subcellular compartments, such as vacuoles, where it can be sequestered to reduce its toxicity. On the other hand, transcription factors like WRKY, MYB, bHLH, and NAC regulate the expression of genes involved in Cd tolerance and detoxification. They activate defense mechanisms that help plants mitigate Cd-induced oxidative damage and maintain cellular homeostasis. Based on the understanding of these molecular mechanisms, the review proposes innovative strategies for the sustainable utilization of Cd-contaminated soils. These strategies integrate molecular design approaches, such as engineering transporters to limit Cd uptake and enhance its sequestration, with phytoremediation techniques that utilize metal-tolerant plant species. By providing scientific guidelines for reducing Cd levels in agricultural products and enhancing food safety protocols, this study bridges the gap between laboratory research and field applications. It offers valuable insights for developing environmentally sustainable agricultural practices in regions affected by Cd pollution, thereby contributing to global food security and environmental protection. The proposed approaches not only aim to decrease Cd accumulation in crops but also seek to improve the overall health and productivity of plants grown in contaminated soils, ensuring safer food supplies for the growing global population. Furthermore, the review emphasizes the importance of these strategies in mitigating the adverse effects of Cd contamination on soil fertility and ecosystem health. By reducing Cd levels in soil and crops, these strategies can help maintain soil fertility, protect biodiversity, and promote the overall health of ecosystems. The integration of different approaches can lead to the development of more resilient agricultural systems that can withstand the challenges posed by Cd contamination and other environmental stresses. This comprehensive review thus provides a foundation for future research and practical applications aimed at addressing the complex issue of Cd pollution in agricultural environments.

Abstract:The turnover and stabilization of soil organic carbon (SOC) play a crucial role in the terrestrial carbon cycle, contributing approximately 25% to natural climate solutions. Particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) are pivotal in the soil carbon dynamics. Soil microorganisms are the primary drivers of the carbon cycle, by decomposing plant residues to form POC via the “ex vivo modification” and accumulating microbial residual carbon via “in vivo turnover”, which then combines with soil minerals to form MAOC. However, the role of microorganisms in POC and MAOC formation is constrained by multiple factors, including nutrient management practices, soil properties, and climatic conditions, which limit the microbial regulation of carbon sequestration in agricultural soils. This review systematically introduced the framework of POC and MAOC. The contributions of growth anabolism (living and residual microorganisms) and non-growth anabolism (enzymes and extracellular polymers) to POC and MAOC were described. It further elucidated the regulatory mechanisms governing POC and MAOC through microbial community structure and physiological functions, whilst analyzing the influencing factors. On this basis, the review systematically considered the mechanisms and approaches by which microorganisms regulate and increase SOC, providing an important basis for constructing a theory of SOC increase based on physical-chemical-biological synergistic regulation.

Abstract:Soil iron-bound organic carbon (Fe-OC) is a quantitatively important and exceptionally stable fraction of the soil organic carbon (SOC) pool. Owing to its relatively high proportion and stability, it plays a key role in mediating the soil carbon cycle and sustaining long-term carbon sequestration. As an effective strategy for enhancing soil carbon sequestration capacity and alleviating the adverse impacts of climate change, vegetation restoration has garnered increasing attention regarding its impacts on soil carbon dynamics and the underlying mechanisms. This review systematically synthesized recent research findings pertaining to the influences of vegetation restoration on soil Fe-OC. First, it sorted out the basic characteristics of Fe-OC, clarifying that Fe-OC binds to iron oxides primarily through adsorption and coprecipitation processes, and meanwhile identified two major formation pathways: microbial-mediated transformation of organic substrates and direct adsorption of plant-derived dissolved organic matter. On this basis, it elucidated the dynamic patterns of Fe-OC under vegetation restoration, its changes are regulated by soil texture and vegetation type (Fe-OC tends to accumulate in coarse-textured soils but decreases in fine-textured soils, and forestland exhibits a stronger Fe-OC accumulation effect than grassland and shrubland). Further, it analyzed key influencing factors, including the composition and molecular properties of SOC, the speciation and reactivity of iron oxides, as well as soil microbial traits, and interpreted the coupled regulatory mechanisms through which vegetation restoration governs the formation, accumulation, and stability of Fe-OC from physical processes (soil aggregate formation and soil moisture regime regulation), chemical reactions (shifts in SOC molecular structure and iron valence transformation), and biological activities (microbial metabolic processes and organic acid exudation). Also, this review identified the existing knowledge gaps and limitations in current research, and proposed that future studies should expand the coverage of diverse climatic zones, accurately quantify the relative contribution ratios of plant- and microbe-derived carbon to Fe-OC pools, strengthen the analysis of the role of soil microbial functions in the formation and stabilization of Fe-OC, and integrate the complex drivers of global change to simulate Fe-OC dynamics under multifactorial scenarios. Only through such comprehensive and interdisciplinary approaches can the intricate mechanistic responses of Fe-OC to vegetation restoration be fully unveiled. This review delineates prospective research directions for the study of soil Fe-OC dynamics under vegetation restoration, facilitates a more comprehensive understanding of the impacts of vegetation restoration on the soil carbon cycle, and provides an important scientific basis for formulating soil carbon sink management strategies to address global climate change.

Abstract:Nitrous oxide (N₂O) is a potent greenhouse gas; thus, understanding its emission mechanisms from agricultural soils is a critical research priority. Previous studies have largely focused on macro-scale drivers like climate and management, leaving a gap in the systematic understanding of how micro-scale soil pore heterogeneity regulates N₂O dynamics. This review addresses this gap by synthesizing current knowledge. It first examines how dynamic changes in soil pore characteristics (e.g., porosity, pore-size distribution, connectivity) govern the transport of water, gases (O₂, N₂O), and solutes, thereby creating distinct microenvironments for N₂O production and diffusion. A key focus is the scenario of straw incorporation. The analysis details how straw management, encompassing application methods, duration, and straw type—interacts with soil physical structure and moisture regimes (particularly wetting-drying cycles) to reshape pore network heterogeneity. Building on this physical foundation, the review then analyzes the consequential biogeochemical effects. It highlights how pore-scale heterogeneity in the distribution and accessibility of carbon/nitrogen substrates and oxygen critically regulates microbial nitrogen transformation processes (e.g., nitrification and denitrification), ultimately controlling N₂O production pathways and the emergence of emission “hotspots.” Furthermore, this synthesis consolidates potential micro-scale mitigation strategies that leverage pore structure manipulation. These include optimizing straw treatment (e.g., biochar production, particle size reduction) and targeting microbial communities to design microenvironments that suppress N₂O formation or enhance its reduction to N₂. In summary, by developing an integrated framework that links pore structure dynamics with microbial biogeochemistry, this review advances the mechanistic understanding of N₂O emissions under straw incorporation. It provides a novel, pore-centric perspective and a theoretical basis for designing innovative farmland management practices aimed at reducing greenhouse gas emissions while supporting sustainable agriculture.

Abstract:As a critical interface between plants and microorganisms, the cell wall frequently undergoes compositional or structural alterations during its interactions, a process known as cell wall modification. Such modifications not only influence plant-microbe interactions but also play a regulatory role in enhancing plant tolerance to aluminum toxicity in acidic soils. Therefore, investigating whether microorganisms can alleviate aluminum toxicity through the modulation of plant root cell wall properties holds significant scientific importance and practical application potential. This review summarizes the regulatory mechanisms of microbial action on root cell walls with respect to root cell wall dynamics, focusing on the patterns and characteristics of microbial-induced root cell wall modifications. Furthermore, it discusses potential sites and molecular pathways involved in this process that contribute to improved plant resistance to aluminum toxicity under acidic conditions. The review aims to provide a theoretical foundation for a deeper understanding of plant-microbe interaction mechanisms and to offer novel insights for the development of a synergistic system integrating "aluminum-tolerant crops" with functional microorganisms.

Abstract:Periphyton (PHT), widely distributed in aquatic ecosystems, function as critical multi-interface carriers across water-sediment-atmosphere boundaries, playing vital ecological roles in energy flow, element cycling, and pollutant remediation. This work reviews recent advancements in the fields of PHT research, both in domestic and international contexts, emphasizing on the analysis of community structures and the corresponding characteristics exhibited under varying environmental conditions. The ecological functions of PHT within aquatic ecosystems are explored, along with the identification of key environmental factors like environmental conditions and media that influence its growth and ecological functions. PHT plays a crucial role in nutrient cycling within aquatic ecosystems. As primary producers, they offer essential nutrients to the ecosystem and serve as effective bioindicators of water quality, with the ability to bioaccumulate heavy metals. Key environmental factors such as temperature, light availability, and pH regulate the growth of PHT, with dominant species in the community shifting in response to changing environmental conditions. Furthermore, anthropogenic activities, nutrient loading, and soil conditions significantly influence the composition, structure, and functional dynamics of PHT communities. Additionally, this work evaluates the potential of the application of PHT-based research to environmental management, sustainable agricultural practices, as well as ecological amendment, with an emphasis on innovative eco-engineering solutions. According to these findings, present study recommends that future work should undertake more in-depth and systematic investigations into the roles of PHT in the degradation and treatment of emerging contaminants, the integration with multidisciplinary approaches and advanced technologies, as well as their applications in other fields. This review aims to provide a theoretical framework and scientific guidance for interdisciplinary research and industrial development on identifying PHT community structures, enhancing ecological functions, and advancing sustainable ecological restoration practices.

Abstract:【Objective】 The Northeast of China is one of the most important grain production base for China. In recent years, unreasonable use of cultivated land in this region has caused a decline in soil fertility, posing a severe threat to the nation’s food security. To ensure sustainable agricultural practices, it is important to develop a rapid and reliable method for monitoring variations in soil physicochemical properties. 【Method】This study focused on the Youyi Farm in the Sanjiang Plain as the research area, aiming to evaluate the feasibility of Sentinel-2 multi-temporal remote sensing imagery in predicting key soil fertility properties. A total of 103 surface soil samples in cropland were collected, and Sentinel-2 images acquired during the potential bare-soil periods (April, May, and June) from 2019 to 2023 were selected to build a Random Forest regression model for predicting soil organic matter, total nitrogen, total phosphorus, and total potassium. To investigate the temporal effects of images on the prediction performance and to identify optimal temporal combinations for high-precision prediction of these soil fertility properties, the images were organized along two temporal axes. First, the images were divided into seven-year groups(five single-year groups: 2019, 2020, 2021, 2022, and 2023, and two multi-year groups: 2020—2022 and 2019—2023). Then, within each year-group, the images were further divided into four month-groups (three single-month-groups: April, May, and June, and one multi-month-group: April—June). Finally, the combination of the seven year-groups and four month-groups produced 28 distinct year-month temporal groupings. For each grouping, all available Sentinel-2 images were synthesized by median compositing to produce 28 synthetic images that served as inputs to the Random Forest model. 【Result】The results indicate that soil organic matter was predicted with the highest accuracy among the four fertility properties, with an R² of 0.62 and an RMSE of 6.58 g·kg^-1. The prediction accuracy of soil total nitrogen was similar to that of organic matter, with an R² of 0.58 and an RMSE of 0.34 g·kg^-1. Total phosphorus predictions were not sufficiently accurate for practical applications, with the highest accuracy of an R² of 0.13 and RMSE of 0.01 g· kg^-1. The total potassium achieved a relatively high prediction accuracy of an R² of 0.53 and RMSE of 1.55 g·kg^-1. 【Conclusion】The results in different year-groups and month-groups indicated that (1) multi-year synthetic images outperformed single-year synthetic images in prediction accuracy, and (2) the synthetic images from May showed the highest prediction accuracy among the monthly groupings. These findings demonstrate that careful temporal selection and multi-temporal synthesis of Sentinel-2 imagery can improve the prediction accuracy of soil organic matter, total nitrogen, and total potassium in the cultivated land of Northeast China. In contrast, Sentinel-2 spectral bands alone are difficult to effectively predict total phosphorus content. Integrating auxiliary environmental variables (such as topography, climate, or cultivation management) or employing alternative remote sensing data may be necessary to achieve higher accuracy. Overall, this study provides methodological guidance and technical support for regional-scale soil fertility monitoring and mapping in the Sanjiang Plain.

Abstract:【Objective】 This study aimed to investigate the erosion characteristics and sediment carbon loss patterns at different slope positions in the long and gentle slope farmland of the black soil region in Northeast China. The research focused on the full - growth - period coverage of soybean and maize, and at the same time, optimized the cover management factor(C - factor)model to provide a theoretical basis for erosion control and carbon sequestration in this specific geographic area. 【Method】 The research was conducted in the Fuhe small watershed of Bin County, Heilongjiang Province. Runoff plots were established at three distinct slope positions: the upper slope, middle slope, and lower slope. Through in situ artificial simulated rainfall experiments, the study systematically analyzed the impacts of soybean and maize coverage on runoff generation, sediment yield, and sediment carbon loss. The dynamic relationship between water and sediment was explored. Furthermore, by integrating two key vegetation parameters, crop coverage and plant height, a comprehensive and optimized C - factor model was constructed to improve prediction accuracy. 【Result】 The results demonstrated that under the coverage of soybean and maize, the runoff and sediment yield in all plots followed a "V"-shaped trend, initially decreasing and then increasing as the crop growth periods progressed. The optimal stages for reducing runoff and sediment were identified as the beginning of the grain filling stage for soybean(with reduction rates of 33.76%～40.33% and 89.96%～94.54%, respectively) and the tasseling stage for maize (46.32%～54.23% and 92.67%～96.29%, respectively). Comparatively, maize exhibited superior erosion resistance capabilities to soybean. Regarding spatial distribution, the erosion sensitivity across different slope positions followed the hierarchy of lower slope > middle slope > upper slope. Statistical analysis showed that runoff volume, sediment yield, and sediment concentration in runoff were all highly significantly negatively correlated with both crop coverage and plant height. The optimized model integrating these parameters (C=-0.595log (0.01V)×(0.00491H+1.65048)) demonstrated a significant improvement, reducing the root mean square error (RMSE) by 59% compared to traditional models. Additionally, sediment carbon loss was significantly negatively correlated with crop coverage and plant height. Maximum crop coverage was found to reduce total sediment carbon loss by 91.04%～96.12%, with the most effective stages being soybean grain filling and maize tasseling. Notably, 32.65%～69.91% of the total sediment carbon loss was contributed by large sediment particles (> 0.25 mm). 【Conclusion】 This study successfully reveals the specific patterns of soil and sediment carbon loss under the full-growth-period coverage of large-grain crops on long and gentle slopes in the black soil region. The research highlights the critical role of crop phenology and slope position in influencing erosion processes. The findings and the optimized C-factor model provide a robust theoretical foundation for developing effective erosion prevention measures and enhancing carbon sequestration strategies in the long and gentle slope farmland of the Northeast China black soil region.

Abstract:【Objective】Green manure cultivation in orchards plays a positive role in improving soil physicochemical properties, such as soil structure, and in reducing soil erosion. However, the mechanisms by which green manures mitigate soil erosion in sloping orchard systems remain unclear. 【Method】This study was conducted using runoff plots in a citrus orchard to systematically monitor runoff and sediment yield under natural rainfall conditions in plots planted with ryegrass (Lolium perenne), hairy vetch (Vicia villosa), and white clover (Trifolium repens), compared with bare tilled(bare soil)control plots. The effects of green manure plant characteristics, stem thickness, plant height, root length, and vegetation cover, on soil structural properties (porosity, bulk density, average infiltration rate) and organic matter content, as well as their relationships with runoff and sediment production, were analyzed. 【Result】The results showed that (1) Green manure plant traits significantly improved from initial to peak flowering. Hairy vetch exhibited the greatest plant height and root length, ryegrass had the optimal stem thickness, and white clover achieved the highest vegetation cover. (2) Soil bulk density and porosity were closely correlated with green manure root length: more developed root systems were associated with lower bulk density and higher porosity (P < 0.05). At peak flowering, green manure plots showed a significant decrease in bulk density and notable increases in porosity and average infiltration rate compared to the seedling stage, whereas the bare tilled control exhibited opposite trends. Organic matter content increased in all plots from seedling to peak flowering, but the smallest increase occurred in the bare control. Among treatments, hairy vetch showed the greatest reduction in bulk density (-8.69%) and the largest increases in porosity (+8.22%) and organic matter (+45.88%). Also, ryegrass demonstrated the best infiltration performance, followed by white clover. (3) Root length exerted strong influences on subsurface flow (effect strength = 0.66) and sediment yield (0.71), while plant height and vegetation cover primarily affected surface runoff (0.62) and sediment yield (0.61) by dissipating rainfall energy and resisting overland flow. Over a full annual cycle, including growth, residue decomposition, and tillage periods, the average runoff and sediment yields followed the order: bare tillage > hairy vetch > white clover > ryegrass, clearly indicating the superior overall erosion control by ryegrass. Although the hairy vetch plots recorded the lowest sediment concentration in runoff, temporal analysis revealed distinct performance patterns. Specifically, white clover was most effective in reducing runoff and sediment during the early growth stages (seedling/initial flowering) due to its rapid establishment, whereas ryegrass performed best during peak flowering, decomposition, and the non-growing season, owing to its persistent biomass and robust root system. 【Conclusion】Intercropping ryegrass and white clover in sloping citrus orchards provides the most effective control of soil and water loss. These findings provide theoretical support for the strategic mixing and temporal scheduling of green manure species, tailored to specific ecological functions in different agroecological zones.

Abstract:【Objective】Soil erosion is serious in the Three Gorges Reservoir area, and green manure mulching can help improve soil structure and enhance erosion resistance. However, the regulation mechanism of green manure on soil erosion resistance is affected by vegetation characteristics and rainfall distribution, and the seasonal response is not clear, Therefore, it is important to clarify the seasonal response characteristics of different mulching treatments on soil erosion resistance, and to screen suitable green manure in the reservoir area.【Method】This study used typical citrus orchards in the Three Gorges Reservoir Area as the research objects and set up three mulching treatments: clear tillage, white clover, and Kentucky bluegrass. The vegetation characteristics, soil physical and chemical properties, and six soil erosion resistance indicators under each treatment were measured in April, June, August, and October. The Comprehensive Soil Erosion Resistance Index (CSRI) was constructed with six erosion resistance indicators to further quantitatively evaluate the influence of different green manure coverages on soil erosion resistance.【Result】The results showed that soil erosion resistance under different mulching treatments showed seasonal variation rules, with the strongest soil erosion resistance in April-June, declining in August under the influence of high temperature and heavy precipitation, and rebounding but not reaching the peak in October. Compared with clean tillage, green manure significantly improved soil physicochemical properties, and CSRI under Kentucky bluegrass and white clover cover was 1.94 and 2.33 times higher than that of clean tillage, respectively. Multivariate statistical analysis showed that CSRI was mainly driven by vegetation characteristics and soil nutrients together, and the key factors were root weight density (RMD), soil total nitrogen (TN) and organic carbon (SOC). 【Conclusion】These results show that green manure mulching significantly improves soil structure and enhances soil erosion resistance, and the effect of Kentucky bluegrass cover is superior to that of white clover.

Abstract:【Objective】The Three Gorges Reservoir area, as a typical key region for soil erosion in the Yangtze River Basin, has received widespread attention. However, the differential responses of surface runoff and sediment production to rainfall typologies in the Three Gorges Reservoir Area remain underexplored. 【Method】This study systematically analyzed runoff-sediment dynamics in relation to land use and rainfall characteristics using a comprehensive 3-year dataset (2021-2023) from the Fugou experimental watershed in Wanzhou District, Chongqing, which includes 108 rainfall-runoff events monitored from 8 natural full-slope and 1 standard bare slope plot (as control), representing typical landforms in the Three Gorges Reservoir area. The area of the full-slope plots in this study ranges from 407 to 1539 m², with slopes between 14° and 25°. The standard runoff plot has an area of 100 m² and a slope of 15°. All plots were characterized by purple soil, while the surface coverage of other land-use plots ranged from 73% to 85%. 【Result】The results showed that: (1) During the observation period, rainfall was primarily classified into three types: Type A (low frequency, long duration, heavy rainfall amount, moderate rainfall intensity), Type B (medium frequency, short duration, moderate rainfall amount, heavy rainfall intensity), and Type C (high frequency, medium duration, light rainfall amount, light rainfall intensity). Among these, Type C exhibited the highest frequency in the study area, while Type A was identified as the principal rainfall type inducing slope runoff and sediment yield. The critical rainfall intensity and maximum 30-min rainfall intensity triggering erosion on bare slopes were 3.60 times and 1.41 times those of the other land use plots, respectively. (2) The multi-year average runoff and sediment yield from bare slopes were 2.63 to 4.03 times and 5.71 to 9.84 times those of the other land use plots, respectively. Sediment production in cropland and arboreal woodland showed the highest sensitivity to Type A rainfall events, whereas grassland sediment yield was most sensitive to Type C rainfall. Bare slopes and shrubland sediment yields demonstrated peak sensitivity to Type B rainfall. (3) The contribution of rainfall types to runoff and sediment yield from bare slopes and the other land use plots was influenced by the land use types. The impact of rainfall types on runoff generation from bare slopes was weaker than that on the other land use plots, but their influence on sediment production exceeded that of the other land use plots. Also, the average runoff reduction efficiency and sediment reduction efficiency of the other land use reached 72.13% and 98.72%, respectively. Grasslands demonstrated higher sediment reduction efficiency than other measures, and the maximum runoff-sediment reduction benefits of conservation measures occurred during Type B rainfall events. Analysis of variance contribution rates revealed the following order of influence on slope runoff and sediment yield: land use (50.30%～70.37%)> rainfall type with land use (0.30%～5.70%)> rainfall type (23.93%～49.40%) in descending order. In addition, the impact of rainfall patterns on slope runoff and sediment yield was significantly influenced by land use.【Conclusion】The results indicate that implementing soil erosion control in the Three Gorges Reservoir Area requires comprehensive consideration of rainfall characteristics to deploy targeted measures. Simultaneously, it is proposed that when implementing comprehensive soil and water conservation management in the study area, appropriate measures should be identified under the premise of considering the regional climate. These findings provide a scientific basis and practical guidance for soil erosion prevention and control in the study area.

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

Abstract:【Objective】High soil penetration resistance(PR)limits global crop growth and sustainable agricultural productivity. Heavy soil texture, low soil organic matter, and low topsoil water content during summer significantly increase PR under a subtropical monsoon climate in southern China. However, the specific mechanisms controlling these processes remain elusive. Thus, the objectives were to investigate the applicability of various penetration resistance characteristic models in red soils with different parent materials and identify key influencing factors, and assess the ameliorative effects of mechanical- and bio-tillage on PR in Ultisols.【Methods】This study investigated four red soils derived from different parent materials in China’s humid subtropical climate, including granitic (GS), Quaternary red clayey(CS), argillaceous shale(AS), and red sandstone red soil(SS). Key parameters measured included soil PR, water content(SWC), bulk density(r), organic matter (SOM) and texture. We evaluated the performance of five PR models (soil water content model, soil matric potential model, soil water content and bulk density model, soil matric potential and bulk density model, and saturated stress model) and identified their influencing factors in red soils, assessed the ameliorative effects of mechanical- and bio-tillage on PR in Ultisols, and determined the PR threshold for four red soils using the least limiting water range. 【Results】Among the five characteristic models of soil PR, the saturated stress model provided a better fit (lower SSE and higher R²)for the four red soils, followed by the soil water content model, the soil water content and bulk density model, and the soil matric potential model. PR in red soils increased with decreasing water content, exhibiting a sharp increase once the water content fell below a critical value(～ 0.32 cm³·cm^-3). The PR of low bulk density soils (1.3 g· cm^-3) experienced a sharp increase at low water contents, whereas that of high bulk density soils (1.5 g·cm^-3) showed a dramatic increase at high water contents. Soil texture (clay content) was a primary factor influencing PR of different parent material red soils, while SOM had negligible effects. When the soil water content was 0.25 cm³·cm^-3, mechanical tillage (deep tillage with 30 cm ploughing depth) reduced PR by ～1 034 kPa in the 0～40 cm depth compared to control treatment (no-tillage), whereas bio-tillage achieved a reduction of ～785 kPa in the same depth and reduced PR (～1 500 kPa) in the subsoil. The critical PR thresholds of the four red soils exceeded 2 500 kPa, and thresholds for clayey red soils were higher than those for sandy red soils. 【Conclusion】The saturated stress model proved highly effective for predicting red soil PR in of southern China. SWC, r and texture played the primary factors influencing PR across different parent material red soils, with clayey red soils (CS and AS) exhibiting higher PR thresholds than sandy red soils (GS and SS). This research provides a scientific basis for identifying the occurrence of seasonal drought and rationally selecting tillage practices for drought prevention in subtropical red soil regions of China through the lens of soil penetration resistance.

Abstract:【Objective】Southeast Zhejiang is an important ecological barrier and an enrichment area of characteristic agricultural resources along the southeast coast of China, possessing rich selenium (Se) resources. A detailed understanding of the spatial heterogeneity of soil selenium and its controlling factors is fundamental for planning Se-enriched agriculture and managing land resources sustainably. However, systematic investigations on the spatial distribution patterns of soil selenium and its key driving factors in this region remain insufficient. 【Method】This study selected Wenzhou City, a representative area with complex geology and diverse land use within southeastern Zhejiang, as the research focus. The primary objectives were to: 1) characterize the spatial distribution of Se in surface soils; 2)evaluate the influences of various natural and anthropogenic factors on soil Se content; and 3)identify the dominant factors controlling its spatial variability. Following the technical specifications for 1: 50, 000 land quality geochemical surveys, a systematic sampling strategy was designed and implemented, collecting 25, 753 topsoil samples(0-20 cm depth). Field investigations of geology and geomorphology, laboratory analyses of soil nutrients, heavy metals, and selenium content, as well as GIS-based spatial analysis, correlation analysis, and multiple regressions, were comprehensively integrated to systematically explore the spatial distribution patterns of soil Se and its primary controlling factors in Wenzhou.【Result】The results revealed that the average Se content in the topsoil soils of Wenzhou City was 0.32 mg·kg^-1, with a range of 0.03 to 2.54 mg·kg^-1.The coefficient of variation was 40%, indicating a moderate degree of variability. The Se-rich soil (selenium content ≥ 0.4 mg·kg^-1) accounted for 25.6% of the total area of the region.Also, the geostatistical analysis demonstrated a strong spatial autocorrelation for soil Se, with an effective range of approximately 13.35 km based on the best-fitted exponential semivariogram model (R²=0.994). In addition, the spatial distribution exhibited a clear regional pattern, characterized by significantly higher Se levels predominantly in the central part of the city, encompassing low mountainous and hilly areas like Ouhai and Ruian, compared to the eastern and western regions. Stratigraphic unit, soil parent material, geomorphic type, soil type, land use type, and soil texture all had significant effects on soil Se variation, among which parent material played the most dominant role. Soil Se content was significantly negatively correlated with soil pH, while showing significant positive correlations with organic matter, total nitrogen, and heavy metals. Multiple regression analysis indicated that soil type, parent material, pH, and arsenic content were the primary factors controlling soil Se spatial differentiation.【Conclusion】The spatial differentiation of surface soil Se in Wenzhou City is the result of the combined action of multiple factors such as geological background, soil physical and chemical properties, and human activities. These findings provide a scientific basis for regional land quality evaluation and the rational development and utilization of Se-rich characteristic agriculture.

Abstract:【Objective】The interactions between heavy metals and mineral particles play a key role in the passivation/activation of heavy metals, significantly impacting on soil health, food safety and ecological stability. However, quantitative characterization of the type and intensity of these interactions remains challenging. 【Method】Based on orbital hybridization theory, this study quantitatively evaluated the polarization, polarization-induced covalent interactions and Coulomb interactions of the heavy metal Pb²⁺ on mineral surfaces.【Result】The results show that: (1) The surface charge number follows the order: montmorillonite > silica > kaolinite > hematite. However, the order of surface negative charge density and electric field strength is kaolinite > silica > montmorillonite > hematite, due to differences in specific surface area. (2) The adsorption capacity of Pb²⁺ depends on the surface charge number, consistent with its trend, while the adsorption strength is governed by the surface electric field. (3) Effective charge coefficients of Pb²⁺on soil mineral surfaces, quantified using orbital hybridization theory, averaged as follows: kaolinite (1.848 ± 0.038) > montmorillonite (1.782 ± 0.062)> silica (1.615 ± 0.029)> hematite (1.516 ± 0.036). Based on the effective charge coefficient, the type and intensity of the adsorption force of Pb²⁺ on mineral surfaces could be assessed. (4) The adsorption of Pb²⁺ on the surfaces of montmorillonite, kaolinite, and silica is primarily driven by Coulombic forces, which account for more than half of the total adsorption energy. In contrast, adsorption on the surface of hematite is mainly governed by covalent interactions, contributing approximately 65%. Additionally, polarization effects depended on the surface electric field and polarization-induced covalent interactions play a crucial regulatory role in the adsorption of Pb²⁺. (5) Infrared spectroscopy analysis revealed that the absorption peak of the Si-O bond on the surface of silicon-containing minerals shifted to higher frequencies (blue shifts) as the surface electric field increased. This shift indicates an enhanced polarization-induced covalent interaction between O atoms and Pb²⁺ on the mineral surfaces. Also, the strong electric field on the surface of hematite enhances the polarization of the -OH group and H₂O molecules, leading to the formation of covalent interactions between Pb²⁺ and -OH groups. Consequently, the Fe-O-Fe bonds are strengthened as the pH increases. 【Conclusion】This study demonstrates that the adsorption of Pb²⁺ on the surface of soil minerals has polarization and polarization-induced covalent effects, and quantitatively evaluates its contribution. The effective charge coefficient of Pb²⁺ increases with the increase of surface electric field strength, and the polarization and polarization-induced covalent interaction between mineral surface and Pb²⁺ increase with the increase of pH. This indicates that polarization and polarization-induced covalent interaction have an important influence on the interaction between Pb²⁺ and the mineral surface. Additionally, this research establishes a theoretical foundation for the directional regulation of heavy metal passivation/activation in soils through modulation of interfacial forces.

Abstract:【Objective】Dissolution reactions of clay minerals are one of the essential processes contributing to natural soil acidification and mineral weathering. However, the surface reaction mechanism of mineral dissolution remains unclear. 【Method】The strong electric field generated by the surface charges of minerals induces a new type of covalent bonding between the oxygen (O) atoms on the mineral surface and the hydrogen (H⁺) ions, a phenomenon known as polarization-induced covalent bonding (PICB). In this study, montmorillonite (MMT), kaolinite (KLI), and illite (ILI) were selected to explore the interfacial reaction mechanisms promoting the dissolution of clay minerals by PICB using mineral dissolution analysis and hydrothermal experiments. 【Result】The dissolution density of mineral elements increases with decreasing pH, and the initial stage of mineral dissolution aligns with the three processes of chemical weathering: desalination, desilicification, and ferrallitization. The PICB significantly enhanced the H⁺ adsorption energy density (γ_H(0)), and the absolute value of γ_H(0) increased with the decrease of pH, indicating an interaction between H⁺ and the mineral. Also, the surface was stronger under low pH conditions, and a consistent critical pH of 3.0 was observed based on both the theoretical analyses of γ_H(0) and the dissolution density of mineral elements as a function of pH. At pH < 3.0, the PICB was significantly enhanced, resulting in a notably weakened Si-O bonding energy and a substantial increase in the dissolution efficiency of silicate minerals. Although the dissolution behaviors of various minerals exhibited significant variations in response to pH, they can be described as a function of γ_H(0), indicating that γ_H(0) has an important influence on the structure of clay minerals. Moreover, the enhancement of γ_H(0) resulted in a higher content of SiO₂ in the hydrothermal reaction products of MMT, accompanied by a subsequent reduction in the residual products represented by Al₂O₃. 【Conclusion】This study quantified the impact of H⁺-mineral bonding on the chemical weathering of minerals and revealed that the PICB between H⁺ and surface O atoms of minerals enhanced the γ_H(0) of H⁺ on the mineral surface and weakened the Si-O bond energy, thus significantly affecting the dissolution reactions of clay minerals. The results provide theoretical insights for proposing targeted modulation techniques aimed at enhancing the structural stability of minerals.

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

Abstract:【Objective】This study aimed to investigate the regulation mechanisms of different improvement measures on soil structure and humus characteristics of soda saline-alkali land.【Method】A field comparative experiment was conducted to study the effects of conventional (CK), biochar (T1), organic fertilizer (T2), and compound modifier (T3) on aggregate stability, humus composition, and soybean yield in soda saline meadow soil.【Result】The results showed that compared with CK, T1, T2 and T3 treatments significantly promoted the transformation of microaggregates to macroaggregates. The effect of T3 treatment was the most significant, and the mass fraction of >2 mm aggregates increased by 12.66% (P<0.05), which was significantly higher than that of T1 and T2. T3 treatment significantly improved nutrient availability by reducing soil pH by 3.02% and simultaneously increasing available phosphorus (67.84%) and alkali-hydrolyzable nitrogen (7.98%) content. The average weight diameter and geometric mean diameter of soil increased by 7.99% and 2.39%, respectively, and the organic carbon content of microaggregates (0.053-0.25 mm)increased by 24.58%-31.14%, which was significantly higher than other treatments. In terms of humus components, the contents of humic acid, fulvic acid, and humin in each particle size of T3 treatment increased by 19.95%-29.62%, 3.64%-6.48%, and 7.33%-36.92%, respectively, which were better than those of T1 and T2 treatments. T3 treatment significantly increased the complexity of humus, and the ratio of E4/E6 significantly increased by 84.84%. The PLS-PM structural equation model revealed that soil organic carbon (path coefficient 0.96) significantly affected aggregate stability by regulating total humic acid (1.13) and humin (1.29). Yield analysis showed that T3 treatment achieved a soybean yield of 2 654 kg·hm^-2 by increasing plant height (61.32%) and pod number per plant (11.96%), with an increase of 42.67%.【Conclusion】The results showed that the compound modifier (T3) complicated the molecular structure of large-grained aggregates by reconstructing the molecular structure of humus, promoted the increase of cementing materials, increased the content of organic carbon, significantly increased the mass fraction of aggregates with >2 mm particle size and the stability of soil aggregates, and effectively improved the soil structure of the plough layer of soda-saline meadow soil. This provides a theoretical basis for the improvement of soda saline-alkali land and the synergistic improvement of production capacity.

Abstract:【Objective】Anoxic microsites significantly inhibit the loss of soil organic carbon (SOC). Soil aggregates, as potential sites for the development of anoxic microsites, are closely related to the accumulation of SOC, yet few studies have investigated the impact of anoxic microsites on SOC within soil aggregates.【Method】This study collected soil samples from four types of ecological restoration and employed soil incubation and gas chromatography to calculate the extent of anoxic protection. The dry sieving method was used to obtain inner and outer soil samples from macroaggregates, and the abundance of anoxic microsites and organic matter components was compared.【Result】The results showed that natural shrubland and grassland had higher extents of anoxic protection, at 33.5% and 36%, respectively, followed by planted forests at 15.9%, and croplands had the lowest at -8.9%. The inner layers of macroaggregates had higher Fe²⁺ content, a greater abundance of anoxic microsites, and higher relative contents of aromatic hydrocarbons, lipids, and lignin. Soil respiration rate was significantly negatively correlated with the extent of anoxic protection.【Conclusion】The results indicate that a stable soil physical environment is crucial for the effectiveness of anoxic protection. Anoxic microsites selectively protect reduced organic matter in the inner layers of macroaggregates and, to some extent, inhibit the loss of SOC, providing new insights into soil carbon cycling and carbon sink functions.

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

Abstract:【Objective】This study aimed to elucidate the mechanism by which sorbitol-chelated potassium (SK) promoted nutrient uptake and utilization in wheat leaves.【Method】In this study, sorbitol-chelated potassium was used as the test foliar fertilizer and wheat cultivar Tainong 108 as the experimental material to elucidate the effects of foliar application of different potassium forms on leaf physiological and biochemical traits as well as phyllosphere microbial community structure. Structural equation modeling (SEM) was further employed to quantify the contribution of each factor to wheat yield, thereby providing a theoretical basis for the yield-enhancing mechanisms of chelated potassium fertilizers.【Result】Results from two consecutive field seasons showed that, compared with potassium chloride(K) and a mixture of sorbitol and potassium chloride (S+K), the SK treatment significantly affected wheat leaf physiological and biochemical characteristics and bacterial richness. (1) Mean yield increases were 24.74% and 18.76%, respectively. (2) Grain Mn concentration increased by 16.14% and 12.12%, grain K by 45.68% and 21.96%, late grain-filling stage leaf K by 81.01% and 24.44%, and maturity stage leaf C by 2.52% and 1.95%. (3) Activities of catalase, peroxidase and superoxide dismutase were better maintained, while malondialdehyde content decreased by 25.65% and 7.51%; the activities of protein synthesis enzymes (nitrate reductase, glutamine synthetase and glutamate-pyruvate transaminase) were sustained during mid-to-late grain filling satge. (4) Relative abundance of Firmicutes rose by 57.36% and 50.00%, whereas Actinobacteria declined by 21.63% and 4.26% and Cyanobacteria by 36.05% and 62.03%.【Conclusion】SK treatment enhanced yield and grain quality through the synergistic regulation of wheat leaf element content, antioxidant capacity and protein synthesis enzyme activities. SEM further demonstrated that all measured indicators were directly or indirectly linked to final grain yield.

Abstract:【Objective】Intensive orchard management in semi-arid regions has caused soil quality degradation and declining ecosystems’ multifunctionality, thereby threatening production sustainability. While green manure mulching shows promise for sustainable orchard management, the mechanistic impact on soil quality and ecosystem multifunctionality remains unclear.【Method】This study investigated the impact of four green manure mulching treatments- no mulching, gramineae monoculture (ryegrass, Lolium perenne L.), legume monoculture (white clover, Trifolium repens L.), gramineae-legume mixture(1: 1)on soil quality and ecosystem multifunctionality in semi-arid orchards.【Result】The results revealed that green manure mulching substantially enhanced soil quality, with legume monoculture showing superior performance(89.0% and 88.5% increases versus grass and mixed systems, respectively). All treatments stimulated soil enzyme activities and alleviated microbial limitations (carbon: 5.8%-8.6%; nitrogen: 5.0%-14.7%), collectively increasing ecosystem multifunctionality by 87.4%-100.2%.【Conclusion】This study reveals that green manure mulching effectively enhances soil ecosystem multifunctionality in semi-arid orchards, with legume-based systems(monoculture or mixed)recommended for implementation.

Abstract:【Objective】This study was designed to explore the effects of crop straw returning on soil and crop growth is an important approach to regulating soil nutrients and crop growth. 【Method】In this study, treatments including no straw returning (CK), reduced straw returning (1/3 straw returning with low stubble retention, straw removal, and deep rotary tillage (1/3FSX); 2/3 straw returning with high stubble retention, straw removal, and deep rotary tillage (2/3FSX)), and full straw returning (full straw returning with deep rotary tillage (FSX); full straw returning with deep plowing (FS)) were simultaneously set up in two locations. The effects of different straw returning treatments on wheat seedling growth and soil properties were investigated. 【Result】 Compared with CK, reduced straw returning at all experimental sites significantly increased the plant height, stem diameter, and root length of wheat seedlings. Among these treatments, the plant height and stem diameter under 1/3FSX were significantly higher than those under other treatments. Meanwhile, straw returning significantly inhibited the wheat germination rate, with the strongest inhibitory effect observed in the FS treatment. Compared with CK, all straw returning treatments significantly increased the soil available nutrient content and the straw decomposition rate under reduced straw returning with deep rotary tillage was significantly higher. Also the soil straw decomposition rate and available potassium content under 1/3FSX were significantly higher than those under other treatments. Compared with CK, straw returning at all experimental sites increased soil microbial abundance. The abundances of bacteria and actinomycetes under reduced straw returning were significantly higher than those under other treatments, and 1/3FSX showed a greater increase in the abundances of soil fungi, bacteria, and actinomycetes. Furthermore, the wheat seedling biomass at all experimental sites was significantly positively correlated with soil available nutrient content and soil microbial abundance. Soil available nutrients exerted the main explanatory effect on the variation in wheat biomass, while microorganisms mainly affected soil available nutrients. Specifically, soil fungi and actinomycetes jointly promoted the increase in soil available potassium content, thereby promoting the improvement of wheat biomass.【Conclusion】Reduced straw returning with deep rotary tillage can improve soil porosity, promote the abundances of fungi and actinomycetes, enhance efficient straw decomposition, and rapidly activate available potassium, thereby promoting a more significant increase in wheat biomass. Among all treatments, 1/3FSX exhibits the best effect.

Abstract:【Objective】Viruses play a crucial role in regulating soil microbial community and host dynamics. However, the efficient extraction and enumeration of soil viruses remain challenging due to the complexity of soil environments. This study aimed to enhance the efficiency of soil virus detection by optimizing both the viral extraction protocol and epifluorescence microscopy observation conditions. 【Method】Soil samples were collected from the long-term brown soil fertilization experimental station at Shenyang Agricultural University. Three key factors affecting soil virus extraction efficiency and enumeration results were evaluated: (1) antifade agents (the commercial anti-quenching agent Fluoromount-G^TM and a laboratory-prepared antifade agent); (2) disruption methods (blender, vortex mixer, ultrasonic cell disruptor, and water bath shaker); and (3) soil-to-liquid ratios (30: 100 and 50: 100; mass: volume). Viral particles were stained using SYBR Green I and enumerated under an epifluorescence microscope. The optimized protocol was subsequently applied to brown soil, black soil, and meadow soil to validate its general applicability. 【Result】Without an antifade agent (Fluoromount-G^TM or laboratory-prepared antifade agent), viral particles were difficult to observe under the 100× objective. The application of Fluoromount-G^TM significantly increased virus counts to 3.75 × 10⁸ virus-like particles (VLPs) g^-1, outperforming the laboratory-prepared antifade agent. The disruption method significantly affected virus extraction efficiency (P < 0.05). The blender (650 W, 50 Hz) treatment for 3 minutes achieved the highest extraction efficiency, significantly surpassing the vortex mixer and water bath shaker, whereas no viral particles were observed with the ultrasonic cell disruptor treatment. In addition, increasing the soil-to-liquid ratio also significantly enhanced virus extraction efficiency (P < 0.05), with the 50: 100 ratio resulting in a 1227.10% increase in virus counts compared to the 30: 100 ratio. The validation results demonstrated that the optimized method consistently yielded stable and reliable viral counts across all three soil types, with significant differences in viral abundance observed among them, confirming its broad applicability. 【Conclusion】In summary, this study established an efficient, stable, and widely applicable epifluorescence microscopy method for soil virus enumeration through the systematic optimization of the disruption method, soil-to-liquid ratio, and antifade agent. The optimized method significantly enhances the extraction efficiency and counting accuracy of soil viruses, thereby providing robust technical support for soil viral ecology research.

Abstract:【Objective】Yak dung is an important factor affecting the nutrient cycling of soil in alpine grassland ecosystems, and changes in soil enzyme activity can effectively measure the soil nutrient cycling processes. This study aims to explore the temporal and spatial variations in soil enzyme activity under the addition of yak dung in alpine meadows. 【Method】A fluorescence analysis method using 96-well microplate enzyme assays was employed. This study focused on key enzymes involved in soil carbon and nitrogen transformation processes (β-glucosidase (BG), peroxidase (PER), phenol oxidase (PPO), β-N-acetylglucosaminidase (NAG), and leucine aminopeptidase (LAP)) in alpine meadow soils of the eastern margin of the Tibetan Plateau, aiming to investigate the potential effects of yak dung decomposition across different temporal scales (varying decomposition periods during warm and cold seasons) and spatial gradients (under the dung(D0), 10 cm away (D10), and 20 cm away (D20)) on soil enzyme activities. 【Result】The results indicate that (1) The decomposition of yak dung in both warm and cold seasons significantly increased the activities of BG, PER, PPO, NAG, and LAP, with the highest enzyme activity observed under D0. As the decomposition time progressed from warm to cold seasons and the distance from the dung increased, soil enzyme activity gradually decreased; (2) The decomposition of yak dung in both seasons significantly enhanced the total soil nutrients (total carbon, total nitrogen, total phosphorus) and available nutrients (ammonium nitrogen, nitrate nitrogen, available phosphorus), soil moisture, and pH, although the impacts of decomposition time on these soil environmental factors varied between seasons. The correlation between soil physicochemical properties and enzyme activity in the cold season was significantly stronger than in the warm season, with the C/N ratio in the cold season having the most pronounced effect on enzyme activity. 【Conclusion】The addition of exogenous nutrients led to the redistribution of nutrients and organic matter, with changes in enzyme activity exhibiting spatial and temporal gradient distribution characteristics, which were significantly correlated with the distance from the dung (radiating outward) and soil depth (extending downward).

Abstract:【Objective】This study aimed to investigate the effects of different land use types and soil profiles on ammonia-oxidizing microorganisms and nitrogen (N) cycling processes, with a focus on the community distribution and functional roles of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and complete ammonia oxidizers (Comammox) in agricultural soils under different management regimes.【Method】Soil samples(0-100 cm)were collected from three typical farmland ecosystems in Changshu, Jiangsu Province, including rice-wheat rotation, orchard, and vegetable fields, during both spring and summer. Soil physicochemical properties were determined, and microbial community composition and abundance were analyzed using quantitative PCR and high-throughput sequencing. In addition, microcosm incubation experiments with nitrification inhibitors were conducted to determine nitrification and N₂O production rates, enabling clear quantification of microbial contributions to soil nitrogen transformations.【Result】The ammonia oxidation rate and N₂O emission rate of the surface soil are the highest, with mean values of 6.1 ± 1.0 mg·kg^-1·d^-1(calculated by N, the same as below) and 17.9 ± 6.1 ng·kg^-1·d^-1, respectively, and both declined significantly with depth. The N₂O emission rate in rice-wheat soils (17.5 ± 5.6 ng·kg^-1·d^-1) was significantly higher than that in vegetable soils (1.5 ± 0.5 ng·kg^-1·d^-1). Within the rice-wheat system, summer exhibited a significantly higher N₂O emission potential than spring. Among ammonia oxidizers, AOB contributed most to nitrification, accounting for 56.6% in surface soils and up to 64.9% in subsurface layers, while the contribution of Comammox increased with depth. Microbial functional gene abundance and diversity showed pronounced vertical heterogeneity and were strongly influenced by land use type. Correlation analysis indicated that microbial gene abundance was significantly positively correlated with nitrification rates, and that ammonium nitrogen and dissolved organic carbon were the key factors regulating both nitrification and N₂O emissions. Structural equation modeling further revealed that AOB gene abundance was a major determinant of ammonia oxidation rates and that ammonia oxidation processes were positively linked to N₂O emissions.【Conclusion】This study systematically evaluated the effects of land use and soil profile on the functional differentiation of ammonia-oxidizing microorganisms. The findings demonstrated that AOB dominate ammonia oxidation across soil layers, while Comammox play an increasingly important role in deeper soils, and that both groups jointly regulate the potential mechanisms of N₂O emissions. These results provide theoretical support for developing microbe-oriented strategies for agricultural nitrogen management.

Abstract:【Objective】Crop straw input and nutrient supply may influence microorganism-mediated formation and transformation of soil organic carbon (SOC). However, the mechanisms by which straw and nutrient supply influence SOC transformation remain unclear. The objective of this study was to explore how and to what extent straw-derived carbon (C) can be assimilated by microbes into necromass following crop straw amendment combined with nitrogen and phosphorus nutrients supply. 【Method】Using a ¹³C-labelled rice straw, the 300-day incubation experiment examined the pattern of microbial assimilating straw-derived C in necromass (indicated by ¹³C-amino sugar dynamics) and its accumulation efficiency (CAE) as affected by nutrient supply levels. 【Result】The results showed that straw C could be transferred into microbial necromass rapidly as evidenced by the production of ¹³C-labelled individual and total amino sugars. There were higher amounts of ¹³C-amino sugars and CAE during the early stage of straw incubation (before 30 days), but a strong decline of total ¹³C-amino sugars, especially bacterial necromass (decreased by 18%-28% across treatments)was observed during the middle and later stages. The effect of nutrient supply on microbial assimilation of straw C was highly time-dependent, that is, no significant effect in the early stage and significant inhibition in the later stage. Specifically, nutrient supply did not have pronounced effects on straw C incorporation into amino sugars but significantly decreased ¹³C-amino sugars and CAE towards the end of incubation, suggesting an accelerated turnover of newly-formed amino sugars in treatments of straw combined with nitrogen and phosphorus supply. This might be related to potential changes of microbial strategies regarding nutrient acquisition and C allocation, highlighting the complex relationship between extraneous C and nutrient availability. Noteworthy, the total amino sugars (including ¹³C-labelled and unlabelled)were higher in nutrient supply treatments despite lower amounts of ¹³C-amino sugars, suggesting that crop straw addition with nutrient supply stimulated microbial transformation of native SOC components into necromass via microbial C pump mechanisms. 【Conclusion】This study highlights that straw input could stimulate microbial-derived C production and accumulation by accelerating microbial anabolism via microbial C pump. The nutrient supply exerted an overall negative effect on the straw-derived microbial necromass accumulation in the long term, but stimulated native SOC-derived necromass contribution. It is suggested that the microbial necromass accumulation from newly added (fresh organic matter) and old soil carbon (inherent SOC) needs to be further investigated when evaluating the impacts of straw input on SOC formation and transformation. These findings advance the understanding of the mechanisms of microbial control over SOC formation and sequestration following extraneous organic matter input under varying nutrient conditions.

Abstract:【Objective】 The application of antibiotics has significantly advanced animal husbandry and agriculture. However, the resulting contamination by antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) poses a severe threat to the ecological environment and human health. This study aims to systematically investigate the effects of different land use types within the same region on the distribution of ARB and ARGs in soil. 【Method】This study collected 210 soil samples from six typical land use types (vegetable fields, wheat fields, flower gardens, orchards, nurseries and livestock farms) in the Jinji River basin of Beijing. The abundance of total cultivable bacteria, chlortetracycline-resistant bacteria, sulfamethoxazole-resistant bacteria, and representative ARGs in the soil was measured. Additionally, the structural characteristics of representative soil microbial communities were analyzed using high-throughput sequencing technology. 【Result】The results indicate that the resistance contamination in Zhang Town and Longwantun Town of the Jinji River basin was the most severe. The abundance of ARB, ARGs, and intI1 in vegetable field soil was significantly higher than that in other land use types (P<0.05). Bacteroidetes, Firmicutes, Saccharibacteria, and Deinococcus-Thermus were the dominant bacterial phyla in the soil. Also, Lysobacter and Devosia were identified as the main host bacteria for ARGs, and they showed significant positive correlations with sul1, sul2, tetG, tetX, and intI1 (P<0.05). 【Conclusion】Based on our results, the resistance level of vegetable field soil in the Jinji River sub-basin was significantly higher than that of other land use types. Thus, it is essential to focus on the optimized application of organic fertilizers to reduce the potential risks of soil microbial resistance and ecological health.

Abstract:【Objective】The intricate interactions between introduced plant growth-promoting rhizobacteria (PGPR) and the indigenous microbial community are pivotal determinants of inoculation efficacy and plant health. While the direct mechanisms of PGPR are well-studied, the role of resident microbes in modulating their activity remains less understood. This study focuses on Sphingomonas sp. HJY, a known growth-promoting bacterium for rice, aims to elucidate how specific indigenous bacteria influence its plant growth-promoting capacity and to uncover the fundamental mechanisms behind this interaction. Clarifying this synergy is crucial for advancing the knowledge of rhizosphere ecology and optimizing microbial inoculation strategies. 【Method】 A batch of bacteria was isolated from rice rhizosphere soil, and indigenous bacterial helpers that promoted the growth of HJY were screened by both co-culture assay and supernatant-culture assay. The bacterium with the most pronounced promotion effect was selected as a representative and identified by full-length 16S rRNA gene sequencing. To elucidate the mechanism of facilitation, the selected helper strain was cultured under iron-rich and iron-limited conditions. Its siderophore production was quantified using the Chrome Azurol S(CAS) assay. Subsequently, the impact of its filter-sterilized supernatant from both iron conditions on HJY growth was compared. Finally, a pot experiment with natural soil was conducted to assess the influence of the indigenous bacterial helper on the ability of HJY to promote rice growth. 【Result】 The results showed that the indigenous bacterium labeled B35 exhibited the most significant promotion effect on HJY growth. The biomass of HJY was increased by 71.2% and 95.4% by B35 cells and its sterile supernatant, respectively, with the latter being significantly more effective. This strain was identified as Bordetella petrii. Under iron-limited conditions, the siderophore secretion by B35 was significantly higher than under iron-sufficient conditions. Moreover, the iron-limited supernatant enhanced the growth-promoting effect on HJY by 13.89% compared with the iron-sufficient supernatant, indicating that siderophores secreted by B35 were one of the main factors promoting HJY growth. Soil inoculation experiments demonstrated that, at 18 days, the plant height, fresh biomass, chlorophyll content, and root length of rice treated with HJY + B35 sterile supernatant were increased by 5.9%, 11.6%, 12.7%, and 21.2%, respectively, compared with those treated with HJY alone. In contrast, the corresponding indices for rice treated with HJY + B35 cells were increased by 4.4%, 7.6%, 5.1%, and 8.0% compared with HJY alone. These results indicated that both B35 and its sterile supernatant could enhance the growth-promoting effect of HJY on rice, with the supernatant treatment showing a superior effect to the bacterial cell treatment. Inoculation with B35 alone or its supernatant alone had no significant effect on rice growth. 【Conclusion】 In conclusion, this study demonstrates that the indigenous bacterium Bordetella petrii B35 enhances the plant growth-promoting activity of Sphingomonas sp. HJY through a facilitative interaction driven largely by siderophore production. This interaction significantly improves HJY's efficacy in promoting rice growth in natural soil, with the direct application of the helper's metabolites yielding the strongest effect. These findings provide novel insights into the complex network of rhizosphere microbial interactions, highlighting how targeted exploitation of specific facilitative relationships—such as cross-feeding via siderophores—can be a crucial strategy for optimizing the performance of PGPR inoculants. This study, therefore, offers a theoretical foundation for designing more effective and stable synthetic microbial consortia for sustainable agriculture.

Abstract:【Objective】Continuous cropping obstacles (CCOs) represent a critical constraint on the sustainable development of the strawberry industry, with core mechanisms involving soil phenolic acid accumulation, microbial community imbalance, and functional degradation. Although existing studies have demonstrated close correlations between phenolic acid autotoxic substances and microbial community changes, the dynamic evolution patterns and causal relationships of phenolic acid-microbiome interactions at the field scale remain unclear. Thus, this study aims to reveal the dynamic changes of phenolic acids, enzyme activity responses, and microbial community structure evolution in strawberry soil under long-term continuous cropping conditions. Also, the results will clarify the driving mechanisms of phenolic acid-microbiome interactions in CCO formation, and provide theoretical basis for developing precise regulation strategies. 【Methods】Greenhouse strawberry continuous cropping soils (0, 2, 5, 15, and 18 years) were selected as research objects to measure soil physicochemical properties, enzyme activities (urease, catalase, acid phosphatase, and sucrase), and phenolic acid contents (p-hydroxybenzoic acid, ferulic acid, and p-coumaric acid). Illumina MiSeq high-throughput sequencing technology was employed to analyze bacterial and fungal community structures, and redundancy analysis (RDA) was innovatively combined with structural equation model to construct causal networks of phenolic acid-microbiome-soil function interactions. 【Results】The results revealed that long-term continuous cropping resulted in significant soil acidification(pH decreased from 7.35 to 6.20), with continuous accumulation of phenolic acids reaching 247.3 mg·kg^-1 at 18 years. Soil enzyme activities exhibited “increase-then-decrease” nonlinear dynamics, peaking at 5 years of continuous cropping (urease activity reached 1 527 U·g^-1 h^-1), followed by a significant decline at 15 and 18 years. In addition, microbial community analysis revealed that continuous cropping led to a 23.6% reduction in bacterial Shannon diversity, a 43.3% decrease in the bacteria/fungi ratio, and an increase in the relative abundance of pathogenic fungi (e.g., Fusarium). Redundancy analysis first confirmed that p-coumaric acid (p-CA) was the dominant factor explaining bacterial community variation (18.9%), while ferulic acid (FA) was the key factor explaining fungal community variation (21.2%). The structural equation model further revealed that phenolic acids affected microbial communities through dual pathways of direct inhibition (path coefficient = -0.85) and indirect regulation (via soil acidification), with phenolic acids serving as the direct dominant factor inhibiting bacterial communities, while fungal community structure was primarily directly regulated by soil acidification. 【Conclusion】This study elucidated the formation mechanism of CCOs through the “phenolic acid accumulation-soil acidification-microbial imbalance” cascade, revealing the specific effects of phenolic acid as key factors at the field scale. These findings provide a theoretical foundation for developing green prevention and control strategies for CCOs based on microbiome regulation, offering technical support for the sustainable development of the strawberry industry.