Coastal saline–alkali farmland typically experiences poor crop growth and low yields. Clarifying soil quality and identifying the primary constraining factors are crucial for improving productivity. This study systematically investigated the spatial heterogeneity and vertical distribution of soil physicochemical properties in a coastal reclamation area using large-scale field sampling. The results revealed that the plow layer soil in the coastal reclamation zone is characterized by typical saline–alkali conditions, low fertility, and weak nutrient-holding capacity, with a pH range of 8.0 to 9.2. Over 60% of the region had soluble salt (SS) content exceeding 2.0 g/kg, and soil organic matter (SOM), total nitrogen (TN), and cation exchange capacity (CEC) ranged from 7.2 to 24.9 g/kg, 0.45 to 1.42 g/kg, and 1.4 to 15.7 cmol+/kg, respectively. Correlation analysis showed significant positive correlations between SOM and TN, available potassium (AK), and CEC, while a strong negative correlation was found between pH and AP. Vertically, the soil demonstrated a notable risk of salt efflorescence and nutrient leaching. Soil salinity and alkalinity increased with depth, while SOM, TN, available phosphorus (AP), and nitrate content decreased. In conclusion, effectively suppressing soil salinization, lowering pH, and increasing organic matter content are essential strategies for improving soil structure, enhancing nutrient retention, and boosting the quality of coastal saline–alkali farmland.

ABSTRACTLilium tsingtauense Gilg is a rare and endangered wild plant, but there is insufficient research on the environmental drivers of intraspecific variation in its seed and fruit traits. To investigate the responses of variations in seed and fruit traits to geographical and soil factors across different habitats, 37 sample plots were selected for investigation and statistics within an elevation range of 200–1000 m in Laoshan, China. Mature fruit and soil samples were brought back to measure soil nutrient content, fruit size, seed number and seed germination rate. The results showed that: (a) There are differences in geographical and soil factors among the habitats of different L. tsingtauense populations. There were significant differences in elevation, aspect, light intensity, soil water content, soil electrical conductivity, soil organic matter content and soil total nitrogen content among different populations. (b) Fruiting ability responds more readily to environmental changes than fruit and seed traits do. Fruit length, width and thousand‐grain weight were more stable than number of plump seeds per fruit and germination percentage. (c) Significant positive correlations were observed between longitude, elevation, light intensity, soil water content, soil electrical conductivity and fruit and seed traits, while soil total phosphorus content showed a significant negative correlation with fruit and seed traits. Among these, elevation was identified as a potential key environmental factor driving variations in fruit and seed traits of L. tsingtauense. Individuals growing at higher elevations exhibited greater fruit production and higher seed germination rates. These findings reveal the environmental variability in fruit and seed traits of L. tsingtauense and its influencing factors, providing important insights for identifying core conservation areas and guiding habitat restoration for this wild resource.

ABSTRACT Soil organic matter (SOM) acts as a pivotal contributor to maintaining soil fertility, developing sustainable agriculture, and enhancing crop productivity. This study collected 748 soil samples and combined Sentinel-1/2 satellite image data and auxiliary information to construct a SOM content prediction model based on random forest (RF), gradient boosting tree (GBDT), and extreme gradient boosting (XGBoost) using recursive feature elimination (RFE) and Bayesian optimisation. First, RFE was used to screen sensitive features from 46 initial features to reduce data redundancy and noise; then, Bayesian optimisation was used to optimise the hyperparameters of the three models. The results indicated that RFE reduced the number of features to 13, and after Bayesian optimisation, the XGBoost model outperformed both RF and GBDT in predictive performance. Among the features for predicting the SOM content, the green band (B2) was the variable with the highest relative importance (17.22%), followed by elevation (11.47%). The importance of features extracted from Sentinel-2 data reached 76.76%, whereas that of features from Sentinel-1 data was merely 6.38%. SOM content predictions indicated that low-SOM areas were predominantly located in mountainous and semi-mountainous regions, while higher SOM levels were observed in the northern plains and valleys. This study conducted a study on SOM content prediction by integrating optical and radar image data, thereby providing a reference basis for digital soil mapping and dynamic SOM content monitoring in plain areas, and also contributing to the sustainable development of agriculture.

To investigate the synergistic effects of acidic soil amendments and straw return on soil properties and cadmium (Cd) content in rice under a rice/rape rotation system and to provide a scientific basis for acidic purple soil improvement and heavy metal pollution remediation, a field experiment was conducted with six treatments: no fertilization (CK), NPK (F), NPK + straw return (FT), NPK + calcium magnesium phosphate fertilizer + straw return (FGT), NPK + lime powder + straw return (FST), and NPK + biochar + straw return (FBT). The study evaluated crop yield, soil organic matter (SOM), pH, total Cd, available Cd (DTPA-Cd), and Cd content in rice straw, husk, and grains to elucidate their interactive effects. The results demonstrated that: ① Compared with CK, FGT, FST, and FBT significantly increased SOM (P < 0.05), with FBT elevating SOM by 3.56 g·kg-1 and 9.88 g·kg-1 during the rape and rice seasons, respectively. For crop yield, FBT enhanced rape yield by 61.7%, while FST increased rice yield by 14.4%. ② Relative to F, FGT, FST, and FBT significantly raised soil pH (P < 0.05), with FST increasing pH by 0.99 and 2.66 units in the rape and rice seasons, respectively. Compared to that in CK and F, FT increased total soil Cd by 3.1% and 1.2%, whereas FGT, FST, and FBT reduced total Cd by 9.4%-16.9% and available Cd by 23.1%-30.7%. FBT decreased Cd content in rice grains by 44.2%. ③ Cd enrichment and translocation varied across rice tissues. Enrichment coefficients followed the order straw > husk > grains, and the translocation coefficient from straw to husk was lower than that from husk to grains. ④ Correlation analysis revealed significant negative correlations (P < 0.05) between SOM and DTPA-Cd, total Cd, grain Cd, and straw Cd. In Cd-contaminated acidic purple soil under rice/rape rotation, the combined application of straw return with amendments (e.g., calcium magnesium phosphate, lime powder, biochar) significantly enhanced SOM, crop yield, and soil pH (P < 0.05) and effectively reduced available Cd and Cd content in rice tissues, with the FBT treatment (biochar combined with straw return) demonstrating the most comprehensive improvement.

Fruit quality and yield of citrus orchards are co-regulated by complex interactions among soil properties, microbial communities, and plant physiological processes. However, systematic studies that integrate the soil-microbe-plant-fruit continuum remain limited. This study selected four representative ponkan orchards based on yield and fruit quality performance, and systematically determined and correlated key indicators in the soil-plant-fruit continuum. The results showed that the orchards with higher comprehensive performance exhibited more suitable soil pH, higher contents of soil organic matter and available nutrients, as well as higher activities of soil enzymes including urease and acid phosphatase. Compared with the orchards with lower comprehensive performance, soil bacterial and fungal Chao1, Shannon, and Simpson indices were higher in the orchards with higher comprehensive performance. Among the dominant phyla, the relative abundance of Proteobacteria was significantly higher, while that of Actinobacteria was significantly lower. Leaf photosynthetic indexes (chlorophyll content, net photosynthetic rate, Rubisco activity) of the higher-performing orchards were also significantly higher. Correlation analysis showed that soil microbial diversity and Proteobacteria were significantly positively correlated with soil nutrients, enzyme activities, leaf photosynthesis, fruit quality and yield, while Actinobacteria showed the opposite trend. These results provide a theoretical basis for soil management and high-quality cultivation of ponkan orchards.

Effects of land use changes on soil organic matter content and speciation in volcanic soils of southern Chile

Heavy metal pollution in farmland poses a threat to crop safety and human health, with cadmium (Cd), arsenic (As), and mercury (Hg) being the main pollutants due to their high toxicity and bioaccumulation. Chemical amendment and agronomic regulation are effective measures for the remediation and safe utilization of mildly and moderately polluted farmland, but the effects of different amendments and their regulation mechanisms remain to be clarified. This study investigated the effects of rhamnolipids, ethylenediaminetetraacetic acid (EDTA-Na2), and (NH4)2SO4 (applied individually/jointly) for soil remediation and wheat safety through field experiments. Physicochemical properties and heavy metal forms were determined, and heavy metal contents in different wheat parts were determined to assess migration, enrichment, and safety. Results have shown the treatment containing (NH4)2SO4 significantly increased the soil organic matter (OM, +93.3%-105.3%) content. The combination of (NH4)2SO4 and EDTA-Na2 significantly increased the cation exchange capacity (CEC, +32.7%-54.0%). The application of amendments can promote the transformation of heavy metals from available to residual forms, and soil pH, OM, and CEC are key factors affecting the transformation of heavy metal forms. The bioavailability of heavy metals can be reduced through molecular interactions and interfacial processes. The S2E2 combination significantly enhances soil OM and CEC, achieving effective passivation of soil heavy metals through chelation and adsorption. In wheat, As and Cd are mainly retained in the roots (translocation factor [TF] < 1), while Hg is transported to the stems (TF > 1). All grains meet food safety limits, confirming that the synergistic effect of chemistry and agronomy can achieve safe cultivation of wheat during the remediation process.

Improved estimation of soil organic matter content in the Yellow River delta using spectral data optimization and environmental variables integration

Monoculture and mixed sowing are common practices for restoring degraded alpine meadow grasslands. To investigate the effects of different sowing patterns on soil bacterial community characteristics in alpine artificial grasslands, this study examined a 20-year-old established artificial grassland, systematically analyzing plant community attributes, soil physicochemical properties, and the diversity and functional structure of soil bacterial communities under various monoculture and mixed-sowing treatments. The results showed that: (1) Mixed-sowing treatments significantly improved soil physicochemical properties and plant community characteristics. The P4 (Elymus nutans + Poa pratensis + Festuca sinensis + Poa crymophila) mixed-sowing treatment notably enhanced vegetation performance and soil conditions. Compared with the monoculture P1 (Elymus nutans) treatment, aboveground biomass (AGB) and soil organic matter (SOM) content increased by 57.23% and 68.25%, respectively, indicating that perennial grass mixtures improve soil water and nutrient retention, thereby promoting plant growth. (2) Microbiome analysis revealed that mixed sowing significantly optimized the structure of rhizosphere bacterial communities. Operational Taxonomic Units (OTUs), which represent sequence-based taxonomic units and their abundance information, were most abundant in the P4 mixed-sowing treatment, reaching a total of 5685 OTUs. In terms of bacterial diversity indices, the OTU richness, Ace index, and Chao1 index in the P4 mixed-sowing treatment were 26.12%, 25.81%, and 24.34% higher, respectively, than those in the monoculture P1 treatment, with all differences being statistically significant (p < 0.05). (3) Mantel test and redundancy analysis (RDA) revealed that soil electrical conductivity (SEC) and pH were negatively correlated with bacterial diversity indices, while soil organic matter (SOM) was identified as the key environmental driver shaping bacterial community assembly. In summary, appropriate grass mixtures effectively enhance "plant-soil-microbe" interactions, leading to improved soil fertility and optimized bacterial communities, representing a viable strategy for long-term ecological restoration and sustainability of alpine artificial grassland ecosystems. The P4 treatment-comprising a four-species mixture of Elymus nutans, Poa pratensis, Poa crymophila, and Festuca sinensis-achieved the best overall performance.

The co-occurrence of microplastics (MPs) and cadmium (Cd) in agricultural soils poses ecological risks, yet their interactions in flooded rice paddies remain unclear. Therefore, this study investigated the individual and combined effects of polyethylene MPs (mPE) and Cd on rice (Oryza sativa L.) growth, Cd accumulation, and soil microbial communities. Combined stress (5 mg/kg Cd + 1% mPE) significantly reduced rice growth (4.1-13.8% in plant height) and increased Cd accumulation in roots, stems, and seeds, driven by MP-enhanced Cd bioavailability. MPs altered soil pH, organic matter (OM), and moisture content (MC), indirectly suppressing yield. Microbial analysis revealed decreased bacterial alpha diversity (0.86-8.36%), favoring Cd-tolerant taxa (e.g., Solirubrobacteraceae), while fungal responses were weaker under flooding. Structural equation modeling indicated that Cd exerted direct toxicity through tissue accumulation, whereas MPs acted indirectly by modifying soil properties and inducing oxidative stress. Under co-exposure, MPs intensified Cd-induced oxidative stress, enhancing both direct and indirect toxicity pathways. Mantel tests identified DTPA-extractable Cd (r = 0.70) and OM (r = 0.55) as key drivers of Cd uptake. These findings highlight the complex interplay of MPs and Cd in rice paddies, with implications for managing co-contaminated agroecosystems.

Co-occurring contaminants in riparian soils posed a growing threat to the sustainable development of the Yellow River Basin. However, understanding of the co-occurrence patterns and key drivers of heavy metals (HMs), antibiotics, and neonicotinoid insecticides (NNIs) at the watershed scale remains limited. Therefore, we selected surface soil along the Yellow River to analyze its content characteristics, spatial patterns, and interrelationships. Detection rates of NNIs, antibiotics, and HMs in soils exceeded 99%. The average content of total NNIs (∑8NNIs) was 5.118 ng/g, with thiacloprid (1.667 ng/g) being the predominant component (32.5%). Total antibiotics averaged 0.412 ng/g, dominated by quinolones (47.8%) and macrolides (30.9%). The concentrations of As, Cr, and Zn among the HMs were 5.7-18.0 μg/g, 53.4-91.1 μg/g, and 35.6-94.3 μg/g, respectively, exceeding their background values at 36%, 21%, and 37% of the sampling sites, respectively. Soil organic matter content and pH negatively correlated with NNIs but positively with HMs, while fine soil particles positively correlated with both. Furthermore, ∑8NNIs (7.680 ng/g) and the contents of thirteen antibiotics (∑13ABX, 13.956 ng/g) in corn-cultivated soils were higher than in other cropped types, while ∑8NNIs (0.780 ng/g) and ∑13ABX (0.003 ng/g) in reed marshes were lower than in other cultivated soils. Health and ecological risks were generally low across the study area, but some specific sites posed potential integrated contamination risks. The study provided scientific data on the environmental fate and risks of NNIs, antibiotics, and HMs in riparian soils of large-scale watersheds, and underscored the need for more efficient usage practices and integrated watershed management strategies.

Abstract. Peatlands cover about 3 % of the earth's land surface, while storing about 20 % of the total global soil organic carbon. These carbon stocks are largely at risk, as many peatlands have deteriorated since the Industrial Revolution due to conversion to agricultural land by drainage. Globally, peatland drainage is responsible for over 3.5 % of anthropogenic greenhouse gas emissions. Approximately 75 % of these emissions originate from warm climate regions. Mitigation of these emissions can be achieved by rewetting degraded peatlands. This study focuses on a warm Mediterranean sub-tropical climate peatland that has been cultivated for the past ∼70 years (Hula Valley, Israel). The historic marsh was drained in 1957 for agricultural use and underwent a hydrological restoration project for elevating and stabilizing groundwater table since 1994. This land management history resulted in a sedimentary peat column that can be divided into three distinct sub-sections: drained, rewetted and pristine peat. This setting enables studying the drainage and rewetting effects on soil organic matter (SOM) degradation and preservation under warm climates. For this purpose, five sediment cores, 4 m long each, were excavated from cropland located over the historic marsh area. Locations were chosen to match previous studies on this site. Each soil profile was characterized using Rock-Eval® thermal analysis of the organic matter, and short-term soil aerobic respiration experiments. Integration of these results with historic SOM content data and with SOM modelling was used to explore the long-term process and rate of degradation. We found that the mean SOM content in the top one meter of the soil profile declined from 68±4 % to 21±2 % by weight over the past 66 years, excluding the compaction effect. In comparison to the drained section, the rewetted and pristine sub-sections have a mean SOM of 33±2 % and 64±2 %, respectively. A peak in pyrite concentration beneath the recent water table-level, was observed in most profiles, indicating anaerobic conditions and sulfur recycling. Rock-Eval® thermal analysis demonstrated that during decomposition, the residual SOM became more oxidized and contained a lower proportion of thermally labile SOM, with a significant difference found between drained and rewetted peat. These results imply that the raising of the water table (∼30 years ago) effectively helped preserving organic matter compared to the drained section. Long-term SOM field data were integrated and studied using an SOM decomposition model and by incorporating respiration fluxes. The resulting trends highlighted that the first few decades of exposure are highly significant for the fate of the carbon stock, leading to substantial CO2 emissions. These emissions were lower by 60 %–85 % after 70 years. Furthermore, our results suggest that currently, approximately 13 %–21 % of SOM persists as resistant organic matter in the degraded peat.

The application of forestry waste as organic mulch on soil represents an increasingly recognized management practice. However, studies on how different mulching strategies regulate soil fertility and microbial community responses remain limited. In this study, a field experiment was conducted in plantation forest soil with four treatments: no mulching, fresh forestry waste mulching, composted mulching, and layered mulching. The results indicated that the layered mulching treatment significantly increased the soil comprehensive fertility index by 6.67% relative to the no mulching treatment. Both composted mulching and layered mulching treatments significantly reduced soil bulk density (2.26%–5.26%), increased pH (0.36%–0.48%) and organic matter content (21.90%–25.23%), and markedly enhanced urease (22.45%–26.41%) and protease activities (51.72%–62.68%). Under fresh forestry waste mulching, soil available phosphorus and available potassium increased by 23.21% and 27.07%, respectively, whereas improvements in the soil comprehensive fertility index, enzyme activities, and microbial communities were limited. Bacterial communities were highly responsive to mulching treatments, with composted mulching and layered mulching treatments significantly altering their structure, while fungal communities were comparatively stable across treatments. RDA and Mantel tests linked bacterial shifts mainly to total nitrogen, available potassium, and bulk density, and fungal variation mainly to total nitrogen (all p &lt; 0.05). This study indicates that a layered mulching strategy simulating forest litter layers can enhance soil fertility and enzyme activity and provides an option for improving soil quality through the utilization of forestry waste.

Among the most serious types of land degradation, soil erosion poses a major threat to agricultural productivity, water quality, and ecosystem stability. Using a multidisciplinary approach, this study aimed to identify the spatial patterns of soil erosion and dominant drivers influencing soil loss in the Toplica River Basin in southern Serbia. Soil properties, including texture and organic matter content, were analyzed in samples collected throughout the study area, accounting for variations in altitude, soil type, and land use, to determine the erodibility factor (K). The rainfall erosivity factor (R), topographic factor (LS), and cover management factor (C) were determined using available inputs on rainfall erosivity, topography, land use, and vegetation cover. The Revised Universal Soil Loss Equation (RUSLE) was used to estimate annual soil erosion rates, and GIS tools and cartographic techniques were used to create spatial layers for each RUSLE factor and to generate a detailed erosion risk map. The results showed a mean annual soil loss of 5.45 t ha−1 year−1, with values ranging from 0 to 397.09 t ha−1 year−1, indicating considerable spatial variability. The regression modeling revealed the dominant roles of factors LS (β = 0.828), C (β = 0.731), and their interaction (LS × C, β = 0.561), followed by rainfall-related interactions (R × C, β = 0.268 and R × LS, β = 0.261). Two dominant erosion regimes were distinguished: topography-controlled erosion in mountainous regions and land-use-controlled erosion in low- to moderately sloping agricultural areas. The maps and analyses presented in this study provide a process-based framework for interpreting spatial erosion patterns, identifying critical hotspots and areas with higher erosion risk, and supporting more focused and context-aware conservation strategies.

This study aims to quantify the effects of three fertilization patterns-"chemical fertilizer alone," "organic fertilizer alone," and "mixed application of organic and inorganic fertilizers"-on soil fertility and crop yields. It also assesses the relationships among baseline soil properties, climatic factors, and fertilization effects in the North China Plain. By compiling relevant literature on these three fertilization patterns over the past 30 years in the region and employing meta-analysis methods, this study incorporated 63 wheat-related studies (1,065 datasets) and 34 maize-related studies (631 datasets). The analysis examined the effects of different fertilization methods on crop yield, soil nutrients, microbial carbon and nitrogen content, and soil enzyme activity, as well as the relationships between baseline soil properties, climatic factors, and fertilization outcomes. Results revealed: 1) Short-term application of chemical fertilizers and organic-inorganic composite fertilizers significantly increased wheat yields more than maize yields, whereas organic fertilizer application boosted maize yields more than wheat yields. Organic-inorganic composite fertilization most significantly enhanced soil microbial biomass and key soil enzyme activities, while chemical fertilizer alone showed the weakest improvement effects. 2) Fertilization impacts yield under baseline conditions of soil pH 6-8, soil organic matter content below 15 g/kg, annual mean temperature of 13°C-14°C, and annual precipitation exceeding 500 mm. 3) Long-term application of chemical fertilizers alone shows slowing yield increases, whereas organic-inorganic composite fertilization sustainably boosts yields and mitigates the impact of single factors on production. Unified comprehensive fertilization rates for wheat and maize are recommended as follows: nitrogen fertilizer application of 150-225 kg·ha⁻¹, phosphorus fertilizer of 60-90 kg·ha⁻¹, potassium fertilizer of 30-60 kg·ha⁻¹, supplemented with 7.5-9 tons·ha⁻¹ of organic fertilizer. This approach outperforms single-fertilizer regimes in improving soil microbial properties and enzyme activity, serving as the key to superior yield maintenance. The recommended integrated fertilization rates strike a balance between reducing chemical fertilizer use, stabilizing yields, and enhancing soil fertility, providing practical guidance for fertilizer management in the North China Plain.

Saline-alkali soil has the potential for agricultural productivity, electrokinetic treatment can be used as a development method. In order to explore and verify the complex changes of saline-alkali soil properties under electrokinetic treatment, the study adopted soil agrochemical analysis and a pot experiment. Firstly, the changes in soil pH and electrical conductivity (EC) under different voltage intensities (8, 16, 24, 32V) and treatment durations (6, 12, 18, 24h) was investigated. Based on the improvement effects and the movement pattern of the alkaline migration zone, the condition of 32V for 24h was selected for further experimentation. Subsequently, the redistribution of soil physicochemical properties after this treatment was evaluated. Furthermore, the feasibility of cultivating Chinese cabbage (Brassica rapa subsp. chinensis) in the treated soil was verified through a pot experiment. Following treatment, the pH in the anode area decreased from 9.10 to 7.24, and the electrical conductivity (EC) reduced from 4.39 to 3.13dS/m, which makes original moderately saline-alkali soil meets the standard of slightly saline soil in expanded anode area. Significant removal of harmful salt ions was achieved, with reduction rates from 13.83 to 83.45% for Na+ and from 14.14 to 74.74% for Cl-. Sulfate (SO42-) was also removed in localized areas. Conversely, the concentrations of base cations (K+, Ca2+, Mg2+) increased in specific zones. The content of soil organic matter (SOM) locally increased by 14.27% to 66.38%, alkali-hydrolyzed nitrogen (AN) increased by 16.29% to 84.52% and available phosphorus (AP) locally increased by 8.82% to116.46% after electrokinetic treatment. The soil texture in most areas was improved. In the pot experiment, the 7th day germination rate of Chinese cabbage increased to 45% near the treated soil's anode, compared with untreated group (CK, 0%). However, the treatment also led to the formation and migration of a highly alkaline zone, soil compaction, and sandification, which require management through agronomic measures. The results indicate promise for improving certain soil properties and agricultural potential, while also revealing several problems that need to be solved.

The Sanjiangyuan Region is an important ecological barrier in China. However， its alpine meadows have undergone intensified degradation due to climate warming and drying and human activities. Green and sustainable measures are urgently needed to restore the degraded meadow soil. A common measure for restoration is the use of fertilizers； however， the effects of bacterial fertilizer and manure on the physical and chemical properties of alpine meadow soil and rhizosphere bacterial communities have not yet been elucidated. To fill this knowledge gap， we analyzed the changes in soil bacteria and soil physical and chemical properties， evaluated the remediation effects of bacterial fertilizer in combination with manure on a moderately degraded alpine meadow in the Sanjiangyuan Region of the Yellow River， and screened for a suitable fertilization scheme to restore the alpine meadows via high-throughput sequencing technology. The results showed that：① The contents of soil water， organic matter， total nitrogen， total phosphorus， and inorganic nitrogen all increased significantly after fertilization with both bacterial fertilizer and sheep manure. The Y1K2 （sheep manure： 1 500 kg·hm-2， bacterial fertilizer： 500 kg·hm-2）， Y2K1 （sheep manure： 3 000 kg·hm-2， bacterial fertilizer： 250 kg·hm-2）， and Y3K1 （sheep manure： 6 000 kg·hm-2， bacterial fertilizer： 250 kg·hm-2） treatments all had significant effects on soil water content and nutrient content. ② In all 12 fertilization treatments， 19 341 bacterial species were detected， and bacterial communities at the phylum level were dominated by Actinobacteriota， Proteobacteria， and Acidobacteriota. Of these treatments， Y3K1 had the highest number of endemic bacteria at 885 species. ③ Fertilization appropriately increased the number of OTU， Shannon index， Ace index， Chao1 index， and Pielou index of the soil bacterial communities， but noticeably decreased the Simpson index. ④ Topologically， the soil bacterial network was characterized by increased complexity after nutrient supplementation， and the network was mainly positively correlated. It had the largest number of edges （1 106） in the Y0K2 treatment（sheep manure： 0 kg·hm-2， bacterial fertilizer： 500 kg·hm-2）. ⑤ A significant correlation existed between bacterial community structure and soil electrical conductivity （SEC） in all treatments （P&lt;0.05）. The first and second axes reached 55.37% and 2.47%， respectively， in explaining the variations in soil bacterial community structure， plant community characteristics， and soil physical and chemical characteristics. SEC was identified as the key factor driving rhizosphere bacterial communities in the degraded alpine meadow. ⑥ According to the function prediction results， the bacterial communities had obvious advantages in aerobic heterotrophic and chemoheterotrophic functions. Thus， bacterial fertilizer in combination with sheep manure improved soil fertility and soil bacterial diversity， with the Y2K1 treatment being the most effective. Namely， a dosage of 3 000 kg sheep manure in combination with 250 kg bacterial fertilizer per hectare achieved the best restoration outcome.

Intercropping impacts on the plant fine root growth by improving soil fertility and productivity. This study assessed the seasonal dynamics of fine root biomass and nutrient stock of the different intercropping models by planting ginger (WGI), sweet potato (WSP), soybean (WSB), and potato (WPO) in a walnut plantation as compared to pure walnut (CK). Soils in the 0–20 cm and 20–40 cm layers were collected in four seasons, and a membership function was applied to integrate multiple fine-root traits and soil fertility indicators into a comprehensive evaluation value (CEV) for intercropping models. All intercropping models in the same soil layer and season showed increase in biomass and carbon, nitrogen, phosphorus, and potassium stocks of fine root, which clearly showed mean annual fine root nutrients stock in the 0–40 cm layer in autumn and summer and declines in winter; soil organic matter (SOM), alkali-hydrolysable nitrogen (AHN), available phosphorus (AVP), and available potassium (AVK) content in the 0–40 cm layer were highest in winter and spring. All intercropping models significantly (p&lt; 0.05) increased fine root biomass and the accumulation of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) in the 0–40 cm layer as compared to the CK; these indices in the 0–20 cm layer were higher than those in the 20–40 cm layer. Fine root biomass and nutrient stocks were maximum in summer and autumn, particularly the WGI system showed the highest nutrient accumulation. CEV ranged from 0.33 to 2.79 and ranked as WGI &gt; WSB &gt; WPO &gt; WSP &gt; CK. Correlation analysis revealed significant (p&lt; 0.05 or p&lt; 0.01) positive relationships among the CEV, fine root traits, and soil fertility indicators of the 0–40 cm layer. The WGI (walnut + ginger) model was identified as the most effective intercropping of walnut plantation for improving fine root nutrient stock and soil fertility. This highlights the critical role of seasonal fine root dynamics and intercropping in enhancing nutrient retention and cycling in the walnut agroforestry systems.

Soil erosion poses a significant threat to agricultural productivity, ecosystem stability and sustainable land management, particularly in fragile hill landscapes of the Northeastern Himalayas. The soil erodibility factor (K) plays a critical role in determining the susceptibility of soils to detachment and transport by water, with key controls including organic matter, texture, structure and permeability. Despite its importance, knowledge of K variability under different land-use systems in Meghalaya remains limited, constraining effective soil conservation planning. Therefore, this study focused on determining and mapping the soil erodibility factor across the Umsarang micro-watershed, while examining its relationship with critical pedological properties. Forest and agricultural land-use systems were treated as comparative management conditions to assess land-use-induced variability in soil erodibility. The K-factor values ranged from 0.135 to 0.345 t ha h ha-1 MJ-1 mm-1, with forest soils exhibiting higher soil organic matter content (4.32 %) and lower variability in K compared to agricultural soils (3.49 %). Forest soils exhibited balanced texture and greater aggregate stability, resulting in lower and more uniform K-values, whereas agricultural soils showed reduced organic matter and greater variability in K, indicating higher erosion risk. Correlation analysis showed that K increased with silt content and decreased with organic matter, sand and clay fractions, highlighting the combined influence of soil composition and structural stability on erodibility. The generated spatial maps provide a clear visualization of erosion-prone areas and offer a practical tool for prioritizing site-specific soil and water conservation interventions to minimize crop loss. By linking soil properties with erosion vulnerability, the study provides actionable insights for sustainable watershed management, emphasizing the importance of maintaining organic matter, stable soil structure and vegetative cover to reduce erosion risks and enhance long-term soil health, which further safeguards crop yield and health in hilly regions.

Influence of microplastics on soil aggregate formation: Insights into biological binding agents.