Search Results (1,609)

Background: Manure-amended agricultural soil is a critical reservoir of antibiotic resistance genes (ARGs), posing escalating threats to environmental health and food safety. However, the temporal trajectories of ARG prevalence throughout the complete reproductive cycle of cash crops, and their mechanistic linkages with fertilization regimes and microbial community succession, remain inadequately understood. Methods: To bridge this knowledge gap, we conducted an in situ field experiment over the entire growth period of Chinese cabbage at a long-term manure-amended farm in Tianjin, China. Six contrasting fertilization strategies were evaluated: unfertilized control (CK1), unfertilized baseline control (CK2), traditional full-rate combined manure–chemical fertilization (TF), traditional half-rate combined manure–chemical fertilization (T1), half-dose sole manure fertilizer (T2), and half-dose sole chemical fertilizer only (T3). Results: Our results demonstrated that ARG abundance and associated mobile genetic elements (MGEs) exhibited a pronounced transient surge immediately post-fertilization, yet reverted to baseline levels by harvest, revealing a tangible resilience of the soil resistome. Notably, the optimized half-organic fertilization (T2) effectively curtailed the proliferation of manure-derived pathogenic taxa while preserving beneficial keystone phyla (e.g., Acidobacteria and Proteobacteria), indicating a trade-off between nutrient provisioning and ecological filtering. Co-occurrence network analysis further identified MB-A2-108, Saccharimonadales, and Rokubacteriales as pivotal hosts for multidrug-resistant ARGs, underscoring that microbial interspecific interactions—rather than taxonomic richness alone—are the primary drivers of resistome succession. Quantitative risk assessment confirmed that the T2 regimen reduced the composite ARG contamination index (CF_zone) by 25% relative to conventional full fertilization (TF), while maintaining comparable cabbage yields. Conclusions: Collectively, our findings advocate for precision organic fertilization as a nature-based solution that synchronizes nutrient supply with crop demand, curtails ARG propagation, and mitigates long-term agroecological risks. Full article

Organic amendments can alter soil structure, root development, and carbon cycling, yet their coordinated effects remain unclear. Based on a long-term field microplot experiment established in 2009, four amendment systems with equivalent annual N, P, and K inputs but differing in amendment properties and nominal annual organic-material C inputs were compared: maize straw with NPK (CS), pig manure compost with NPK (PMC), biochar with NPK (BIO), and biochar-based fertilizer (BF). After 15 years, dry-sieved aggregate distribution, CT-resolved air-filled pores (>30 μm), peanut root morphology, and easily oxidizable organic carbon (EOC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC) were determined. PMC had the highest CT-resolved total and connected porosities (19.01% and 10.86%), a greater proportion of small macroaggregates, and the largest root surface area. CS produced a greater proportion and mean size of large dry-sieved aggregates and the highest bulk-soil MBC content. BIO and BF showed lower CT-resolved total porosity but greater isolated porosity, anisotropy, mean pore diameter, and pore fractal dimension (collectively termed CT-resolved macropore heterogeneity); these treatments were also associated with greater root volume or length and increased EOC and DOC contents in small macroaggregate- and microaggregate-sized fractions. Root length correlated more strongly with macropore heterogeneity than with total porosity. Because measurements were obtained once from 12 microplots, these relationships and SEM results represent exploratory associations rather than causal pathways. Overall, traditional amendments were associated with aggregation or macropore connectivity, whereas carbonized amendments were associated with greater macropore heterogeneity. BF had the highest percentage of EOC in TOC (52.45%), indicating a greater relative contribution of labile carbon, not increased stable carbon stock. Full article

Biochar (BC) and hydrochar (HC) have attracted increasing attention as sustainable soil amendments for improving soil water retention and mitigating agricultural water stress. This review synthesizes and compares the current state of knowledge on the production, physicochemical properties, and hydraulic performance of slow-pyrolysis BC, hydrothermal carbonization hydrochar (HTC HC), and hydrothermal liquefaction hydrochar (HTL HC). The mechanisms governing soil water retention are first examined, followed by a comprehensive review of the effects of amendment properties, feedstock type, thermochemical conversion conditions, particle size, application rate, and soil characteristics on field capacity, permanent wilting point, plant-available water, and water-holding capacity. The available evidence demonstrates that BC generally provides the most consistent improvement in soil hydraulic properties, particularly in coarse-textured soils, whereas the performance of HTC HC is considerably more variable and strongly dependent on hydrothermal conversion conditions and soil characteristics. HTL HC remains largely unexplored but shows promising hydraulic performance and exceptional resistance to biodegradation. Apparently contradictory findings among published studies are shown to arise largely from interactions among feedstock and conversion conditions, resulting amendment properties, soil characteristics, application conditions, and differences in hydraulic evaluation, highlighting the need for integrated mechanistic frameworks rather than interpretation based on individual factors. A comparative assessment of the three materials further considers ecotoxicity, biodegradation, life-cycle assessment, and techno-economic analysis. Overall, BC is currently the most mature soil amendment technology, HTC HC offers important advantages for wet biomass utilization, and HTL HC represents a promising but underdeveloped alternative. Future research should emphasize standardized evaluation methods, long-term field validation, and integrated mechanistic approaches linking production conditions, amendment properties, soil characteristics, and application conditions to enable predictive, application-specific design of carbonaceous soil amendments for sustainable soil water management. Full article

Organic amendments derived from agro-livestock residues offer a promising approach for soil restoration and nutrient recycling within circular economy frameworks. Nevertheless, their agronomic efficacy and environmental suitability may be contingent upon the formulation of the amendments and the properties of the soil. This study presents a preliminary evaluation of customized organic amendments derived from solid materials, such as biochar and green compost, and liquid residues, including cattle manure slurry, urban compost tea, and cattle digestate. These were applied either individually or as solid–liquid mixtures to two distinct Iberian soils. The study involved amendment characterization, seed germination assays, and a two-month greenhouse experiment with barley (Hordeum vulgare L.) to assess the effects on soil physicochemical properties, microbial activity, and plant development. The solid–liquid impregnation process facilitated the transfer of nutrients and potentially limiting elements from liquid residues to solid matrices, thereby altering amendment composition and mitigating some risks associated with the direct application of liquid residues. Mixtures based on biochar and compost generally alleviated excessive salinity and trace metal constraints, although responses varied depending on the liquid amendment and soil type. Biochar-containing amendments markedly increased soil total carbon, suggesting their potential to contribute to soil carbon sequestration. The effects of amendments were strongly dependent on soil type: acidic soil exhibited more pronounced pH improvement, whereas the carbonate-rich alkaline soil buffered several chemical changes but was more susceptible to alkalinization and sodium inputs. Urban compost tea consistently exhibited inhibitory effects on germination, plant development, and dehydrogenase activity, although these effects were partially mitigated when combined with solid amendments. Overall, the findings underscore the potential of tailored amendment mixtures to enhance residue valorisation, while highlighting the necessity for soil-specific evaluation prior to field application. Full article

To evaluate how composted agricultural and forestry organic materials function as components of horticultural growing media, a pot experiment was conducted with chrysanthemum (Chrysanthemum morifolium Ramat.) grown in a cinnamon-soil-based medium. The composted material, produced from chestnut shells, chicken manure, and spent mushroom substrate, was incorporated at 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50% (v/v). Water-extractable dissolved organic matter (WE-DOM) was characterized by excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis (EEM-PARAFAC), together with the fluorescence index (FI), biological index (BIX), humification index (HIX), and fluorescence regional integration (FRI). Growing-medium physicochemical properties, chrysanthemum traits, and an entropy-weighted comprehensive evaluation were also assessed. Compost amendment increased soil organic matter (SOM), dissolved organic carbon (DOC), total nitrogen, and total phosphorus, lowered pH, and was associated with improved porosity and water-retention characteristics. FI ranged from 1.810 to 2.371 and exceeded 1.9 at amendment rates of 30–35%, suggesting a greater contribution from microbially derived DOM. BIX, HIX, and P_V,n/P_Ⅲ,n were generally higher in amended treatments than in the control, although their responses were non-monotonic across amendment rates, suggesting greater contributions from recently produced DOM and stronger humification-related fluorescence signals. EEM-PARAFAC resolved five fluorescent components. C1, C2, C3, and C5 were predominantly humic-like, whereas C4 displayed both protein-like and humic-like features. With increasing amendment rate, the relative contributions of C1–C4 generally increased, whereas that of C5 declined, suggesting a shift from the native soil fluorescence profile toward a more complex DOM composition influenced by compost inputs and subsequent biological transformation. Chrysanthemum height, stem diameter, flower number, and biomass were generally more favorable at amendment rates of 30–40%. The entropy-weighted evaluation yielded the highest overall response score at 30%, while the 35% treatment also maintained a high score. Considering WE-DOM fluorescence characteristics, growing-medium properties, and plant performance together, a volumetric amendment rate of 30–35% represents a relatively favorable range for the tested composted material under the present pot-experiment conditions. Full article

Biochar has been used to improve soils and promote sustainable agricultural development. The effects of applying different doses of biochar on soil aggregate structure and stability, aggregate-associated microbial communities, aggregate carbon fractions, and underlying mechanisms in planted forest soil ecosystems remain unclear. This study aimed to explore the effects of biochar amendment (7 years) on carbon stabilization in plantation soils. The effects of biochar application (0%, 0.5%, 1.0%, 2%, 4%, and 6%) on water-stable aggregate distribution, stability indices such as mean weight diameter (MWD), geometric mean diameter (GMD), and fractal dimension (D), aggregate-associated microbial communities (fungal and bacterial phospholipid fatty acids (PLFAs)), and carbon fractions such as soil organic carbon (SOC), easily oxidized organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC), microbial biomass carbon (MBC), recalcitrant organic carbon (ROC) and black carbon (BC) were investigated based on a seven-year in situ field experiment in a Eucalyptus plantation in northern Guangxi. The results showed that after 7 years, biochar application significantly increased the proportion of macroaggregates (≥0.25 mm). The MWD and GMD increased significantly with increasing biochar application rates, whereas D decreased significantly, indicating enhanced soil structural stability. Biochar significantly increased the abundance of fungi and bacteria across all aggregate size classes and changed the microbial community structure towards conditions that promoted increased carbon stabilization. Additionally, biochar application significantly increased both recalcitrant (ROC and BC) and labile carbon (EOC, POC, DOC, and MBC) in all aggregate fractions, with the largest increments in macroaggregates. Based on correlation analysis and structural equation modeling (SEM), we speculated that biochar might enhance the physical protection and chemical sequestration of organic carbon by optimizing the physical structure of the aggregates and synergizing with the microbial carbon pump. The 7-year application of biochar significantly enhanced the SOC content in plantation soils, primarily by increasing recalcitrant organic carbon, demonstrating that biochar application constitutes a viable approach to augmenting persistent soil carbon stabilization in plantation ecosystems. The 4% and 6% treatments produced the largest responses for most of the measured indicators, underscoring the importance of biochar application. Full article

The disposal of stone mine tailings (SMTs) near agricultural lands has become a major environmental concern because of their elevated concentrations of environmentally hazardous metals (EHMs). The minimization of the potential detrimental effects of soil pollution on crop cultivation and food safety are the major concerns in modern agricultural practice. Vermitechnology has emerged as a sustainable bioconversion approach for biotically stabilizing mine tailings into a nature-friendly organic amendment. However, the agronomic potential and environmental safety of vermiprocessed stone mine tailings remain poorly understood. To fill this research gap, this study assessed the effectiveness of mine-tailing-derived vermicompost as an organic amendment for Solanum lycopersicum L. (tomato) cultivation. Vermicompost was prepared from both inorganic mine tailings and organic cow dung (1:1 and 2:1 ratios, w/w) together using earthworm Eisenia fetida species. The results demonstrated that the treatment amended with 1:1 vermicomposted tailings supplemented with the recommended dose of chemical fertilizer (T3) outperformed all other treatments by enhancing soil microbial activity, the concentration of bioavailable NPK, improved fruit yield, different biochemical parameters, and reduced post-harvest bioavailable Cr, Ni, Cu, Pb, and Cd concentration. Severity Adjustment Margin of Exposure (SAMOE) analysis indicated estimated dietary risk (Class 5) for Cr (VI) and Cd in tomatoes grown on untreated mine tailings, whereas vermicompost-amended treatments reduced the risk to low or negligible levels. Overall, the findings suggest that vermicomposted stone mine tailings emerged as a potential complementary soil amendment and an eco-friendly strategy which improve crop growth while reducing metal availability and its associated health risks. Full article

Spent mushroom substrate (SMS) is a major agricultural byproduct whose complex lignocellulosic matrix hinders direct reuse and poses environmental risks when stockpiled. This study evaluated whether pretreatment with plant growth-promoting rhizobacteria (PGPR) could enhance SMS as a soil amendment for blueberry cultivation. Two PGPR-treated SMS formulations, along with raw SMS and a blank control, were applied to blueberry seedlings in a 10-month greenhouse experiment. Plant height, rhizosphere soil nutrients, enzyme activities, lignocellulose fractions, and the microbial communities were monitored over three growth phases and four sampling points. PGPR-treated SMS significantly increased blueberry height gain during the fast-growing phase (June–September) and sustained elevated levels of organic carbon, nitrogen, phosphorus, and potassium throughout the experiment. Activities of cellulase, xylanase, laccase, peroxidase, protease, and lipase were markedly enhanced, accompanied by reduced lignin and cellulose contents and persistently high glucose availability. The amendments reshaped bacterial and fungal communities, enriching Bacillota, Acidobacteriota, Acidibacter, and Hyphomicrobium, and increasing alpha diversity, with clear structural separation from controls in principal coordinate analysis. Correlation and principal component analyses linked improved plant growth to nutrient availability, enzyme stimulation, and specific microbial taxa. These findings indicate that PGPR-treated SMS acts as a multifunctional amendment that promotes lignocellulose degradation, sustains soil fertility, and restructures the rhizosphere microbiome, offering a sustainable recycling strategy for horticultural production. Full article

The physicochemical properties and applicability of cow manure biochar (CMB) as a soil conditioner and horticultural substrate amendment for halophyte growing on deteriorated coastal soils were assessed in this study. A typical commercial substrate (50% coco peat, 25% peat moss, 12% perlite, 7% vermiculite, and 6% zeolite) was used to compare elemental composition, thermal stability (TGA/DTG), surface morphology, pore structures (BET, FESEM), and functional groups (FT-IR) of CMB. In addition, 10% (w/w) CMB was added to coastal soils in the Saemangeum and Sinan-gun regions in order to assess changes in the physicochemical soil quality. In comparison to the commercial substrate, the analytical results showed that CMB had higher concentrations of essential mineral elements (such as K, Ca, P, Zn, and Na), a higher proportion of carbon (25.69%), and more accessible phosphorus (3490.97 mg/kg). Additionally, compared to the commercial substrate, CMB showed a nearly 19-fold larger specific surface area (77.53 m²/g) and increased micropore volume, suggesting better potential for soil aeration and water retention. Cultivating halophytes (Salicornia herbacea L. (glasswort) and Suaeda japonica Makino (seepweed)) in a 9:1 (v/v) substrate-to-CMB mixture for five weeks resulted in successful early germination and robust seedling establishment. Incorporating 10% CMB into coastal soils also substantially increased available phosphorus, total organic carbon (TOC), and organic matter (OM), demonstrating CMB’s effectiveness in enhancing nutrient availability and supporting soil carbon sequestration. All things considered, this study offers a practical framework for using biochar made from livestock manure as a sustainable substrate supplement to reclaim degraded coastal environments and advance biosaline agriculture. Full article

Excessive N application in Camellia oleifera plantations exacerbates soil acidification and N₂O emissions, intensified by the input of Al-accumulating litter. Biochar is a promising amendment, yet how litter decomposition interacts with N and biochar to modulate acidification and greenhouse gas emissions remains unclear. To understand how decomposition of Al-accumulating litter interacts with N and biochar in the soil acidification process and gas emissions, a twelve-month laboratory incubation study was conducted using a fully factorial, three-factor completely randomized design to examine litter decomposition. The experimental factors included nitrogen fertilization, biochar amendment, and litter input level. The results showed that litter transiently activated biochar alkalinity, raising pH to 5.7–6.3, but subsequent organic acid release drove sustained re-acidification (ΔpH −0.4 to −0.5). This pH trajectory controlled denitrification: early high pH favored complete denitrification (nosZ > nirK), while later acidification inhibited N₂O reductase, boosting N₂O emissions under single litter and N. Litter-C primed native soil organic carbon, doubling cumulative CO₂ emissions. Biochar further elevated CO₂ emission rate by 7.6% under double litter input treatment via porous-microsite priming. These results demonstrated that litter quantity dictates a temporal switch from biochar alkali activation to organic acid overrun, creating an acid rebound that amplifies N₂O while sustaining CO₂ release. Optimizing litter retention and biochar application timing is essential to break the acid-N₂O feedback in intensively managed C. oleifera systems. Full article

Flooding and farmyard manure (FYM) application trigger complex, non-linear redox reactions that govern micronutrient availability in calcareous soils, yet predictive modelling of these dynamics using machine learning (ML) remains largely unexplored, and the present study was designed to address this gap. To this end, seven supervised ML algorithms—Ridge Regression, Support Vector Regression (SVR), Random Forest (RF), Extreme Gradient Boosting (XGBoost), Gradient Boosting Machine (GBM), Artificial Neural Network (ANN), and Cubist—were compared under a unified nested cross-validation scheme to predict DTPA-extractable Fe, Mn, Cu, and Zn concentrations in a flooding incubation experiment comprising 10 contrasting calcareous soils (Entisol, Mollisol, Inceptisol, Vertisol) from the Atabey Plain (Isparta, Türkiye), two FYM doses, and five flooding durations (n = 100). Under Leave-One-Out Cross-Validation (LOO-CV), rule- and tree-based ensemble methods consistently outperformed linear and neural network models, with Cubist achieving the best performance for Fe (R² = 0.812) and Mn (R² = 0.915), XGBoost for Cu (R² = 0.929), and GBM for Zn (R² = 0.919). However, a stricter leave-one-soil-out (LOSO) validation with grouped inner cross-validation revealed that this accuracy is element-specific in its transferability: Mn predictions remained robust on previously unseen soils (R²cv = 0.739) and Fe moderate (R²cv = 0.412), whereas Cu and Zn did not generalise beyond the soils used for training, indicating that their high within-soil accuracy reflects soil-specific rather than transferable structure. SHAP analysis revealed that flooding duration was the dominant predictor of Fe and Mn availability, amorphous Fe oxide content was the primary driver for Cu, and plant-available phosphorus (Olsen-P) was the principal feature for Zn. These findings demonstrate that combining ensemble ML with SHAP interpretability enables element-specific, cross-soil-validated and mechanistically interpretable prediction of micronutrient dynamics under varying redox and organic amendment conditions, while highlighting cross-soil transferability as a critical consideration for deploying such models in calcareous agroecosystems. Full article

Organic fertilization is a key strategy for improving soil structure and fertility in China’s Vertisols, yet the trade-offs among soil quality enhancement, grain yield performance, and nutrient use efficiency under different organic amendment regimes remain insufficiently elucidated. Based on a unique 43-year field fertilization experiment, this study systematically evaluated the effects of long-term chemical fertilization (NPK) alone, low-dose (NPKLS) and high-dose straw incorporation (NPKHS), combined chemical fertilizer with cattle manure (NPKCM), and pig manure (NPKPM) fertilization on soil physical, chemical properties, crop yields and plant nutrient utilization efficiency. The results showed that NPKCM and NPKPM significantly improved soil physical properties by reducing soil bulk density, improving soil pore structure, and enhancing soil water retention capacity and saturated hydraulic conductivity. Although long-term manure application led to slight soil salt accumulation, the rate of accumulation remained substantially lower than that associated with commercial organic fertilizers and did not approach the crop salinity damage threshold, suggesting low ecological risk. Compared with NPK treatment, manure amendment effectively counteracted soil acidification induced by prolonged chemical fertilization, while also significantly increasing soil total phosphorus and available phosphorus content, and elevated the proportion of active phosphorus (PAC). The improved soil phosphorus activation capacity and comprehensive soil quality further contributed to substantial increases in wheat grain yield under NPKCM and NPKPM treatments. Despite these agronomic benefits, the additional nitrogen and phosphorus inputs from manure resulted in soil nutrient surpluses, which considerably reduced nitrogen and phosphorus partial factor productivity as well as agronomic efficiency. In contrast, straw incorporation treatments (NPKLS, NPKHS) sustained stable crop yield without notable declines in nutrient efficiency, positioning them as a greener and more sustainable approach to balancing grain production with resource use efficiency. These findings highlight the need to integrate nutrient credits from manure into fertilization program. Given the 43-year evidence, fertilization strategy should consider not only the nutrients supplied by manure but also the quantities exported through harvested products, with adjustments based on annual soil fertility analyses. Such nutrient budgeting is essential to maximize fertilizer use efficiency, prevent excessive phosphorus accumulation, and maintain balanced soil fertility over time. Full article

Soil acidification threatens N availability, but the effects of maize straw and biochar on organic N fractions in acidic black soil are unclear. We examined the effects of straw (1.5%, 3%) and biochar (1%, 2%) with fertilizer on soil acidity, N fractions, and enzyme activities in a pot experiment with soybean. All amendments raised soil pH, but total exchangeable acidity decreased only at high doses (S3, B2). High-dose straw (S3) increased amino acid N by 21.74% and decreased amino sugar N by 33.33%, with urease (+30.1%) and invertase (+29.8%), indicating accelerated organic N mineralization. For inorganic N, S3 raised NH₄⁺-N by 47.0%, while B2 raised NO₃⁻-N by 30.4%, but low doses (S1.5, B1) reduced inorganic N. B2 increased total N (+5.6%) and total acid-hydrolysable N (+2.9%), with unknown N up by 11.9%, but suppressed catalase and dehydrogenase, suggesting N stabilization. Amino acid N correlated positively with available N and invertase, while amino sugar N correlated negatively with available N. Thus, straw promotes labile N, and biochar stabilizes N; high doses are recommended for acidic black soil fertility. Full article

Saline–alkali soils are characterized by low fertility and productivity, which can be potentially improved by applying organic fertilizers. We hypothesized that conventional and modified organic fertilizers would exhibit distinct functional advantages in regulating crop performance, nitrogen (N) loss, and saline–alkali soil fertility. A soil-column experiment was conducted to compare chemical fertilizer (CF) with conventional (CF + OF), biochar-amended (CF + BOF), and functional microorganism-inoculated organic fertilizer (CF + MOF) for sorghum production, ammonia (NH₃) volatilization, and soil fertility. Compared with CF, organic fertilizer treatments did not significantly increase grain yield, although CF + OF showed greater yield potential through improved leaf biomass and grain number per panicle. CF + MOF reduced N use efficiency by 43.2%, whereas organic fertilizer application altered grain quality, particularly protein and tannin contents. Cumulative NH₃ volatilization decreased by 8.9–16.7% under organic fertilizer treatments, with the greatest reduction observed in CF + OF. All organic fertilizer treatments increased soil available N contents and improved soil quality index (SQI), while CF + BOF showed the strongest improvement in available phosphorus and potassium, and total N contents. Overall, different organic fertilizers exhibited distinct functional characteristics under short-term observation. CF + OF showed advantages in balancing crop production and NH₃ mitigation, whereas CF + BOF mainly improved soil nutrient status. Long-term agronomic and ecological benefits require validation under multi-season field conditions. Full article

Soil salinization has become a major constraint on sustainable agricultural development and the improvement of crop productivity. However, the effects of biochar combined with different organic amendments on the microbial ecology of saline–alkaline soils and crop performance remain insufficiently understood. This study evaluated the effects of different amendment strategies, including sole applications of fulvic acid (FA), organic fertilizer (OF), and biochar (BC), as well as their combinations. Soil bacterial community composition, richness, and diversity, oat agronomic traits, hay yield, and forage quality indicators were assessed. Spearman correlation analysis and the Mantel test were employed to examine the relationships among soil physicochemical properties, microbial communities, and crop performance. Combined applications exerted stronger effects on modulating soil bacterial community composition than sole applications, while FA, BC, or their combinations significantly enhanced bacterial richness and diversity. Crop responses exhibited distinct functional differentiation among combined treatments. The biochar combined with fulvic acid (BC + FA) treatment showed the greatest potential for promoting oat growth and increasing yield, with plant height and stem diameter reaching 99.20 cm and 3.99 mm, respectively, and hay yield increasing by 48.5% compared with the control treatment. In contrast, the biochar combined with organic fertilizer (BC + OF) treatment significantly increased crude protein content (CP) and reduced acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents, indicating improved forage quality. Although the crude fat content was numerically higher under BC + OF, no significant differences were observed among treatments. Correlation analyses further revealed that changes in soil physicochemical properties were associated with variations in several dominant bacterial genera, which were correlated with oat agronomic traits and forage quality indicators. Overall, the combined application of biochar with fulvic acid or organic fertilizer improved saline-alkaline soil microbial characteristics and showed potential for enhancing forage oat yield and quality, with BC + FA primarily improving yield production and BC + OF mainly enhancing forage quality. Full article