Search Results (233)

Delayed sowing has become a key constraint on winter wheat production in the Guanzhong Plain, Shaanxi Province, China, due to the widespread adoption of late-maturing maize and the delayed harvest of preceding crops. A two-year field experiment was conducted on the Guanzhong Plain to elucidate the physiological mechanisms behind yield reduction under delayed sowing and to explore potential mitigation strategies. The study examined the effects of sowing time (normal, 10-day delay, and 20-day delay) and plastic film mulching on yield components, crop development, and water and nitrogen uptake and use in winter wheat. Compared to normal sowing, delayed sowing significantly reduced grain yield (7.64–17.19%), spike number (11.65–21.3%), 1000-grain weight (5.2–9.05%), growth duration (7–16 d), dry matter accumulation (21.79–58.07%), and partial factor productivity of nitrogen fertilizer (7.64–17.2%). Late sowing slowed overall growth and development, shortened the growth cycle, and suppressed root system expansion and plant height, particularly under the 20-day delay. However, plastic film mulching under delayed sowing improved seedling emergence, root growth, tiller number (8.42–51.23%), water use efficiency (10.15–18.15%), and nitrogen productivity, thereby mitigating the adverse effects of delayed sowing on resource capture. Mulching enabled wheat sown with a 10-day delay to achieve yields comparable to normal-sown crops and alleviated 9.1–10.3% of the yield loss under a 20-day delay, although it did not fully restore yields to the non-delayed level. These findings provide practical insights for managing winter wheat under delayed sowing conditions. Full article

To evaluate the optimal substitution ratio of organic fertilizer for chemical nitrogen fertilizer and its underlying mechanisms, a pot experiment was conducted in the rhizosphere soil of oat (Avena sativa) on the Qinghai–Tibet Plateau. Five treatments were established: CK (control), T1 (chemical fertilizer alone), T2 (100% organic fertilizer substitution for chemical nitrogen fertilizer), T3 (30% organic fertilizer substitution for chemical nitrogen fertilizer), and T4 (60% organic fertilizer substitution for chemical nitrogen fertilizer). We analyzed soil carbon fractions, microbial community structure, carbon-cycling enzyme activities, and yield responses and applied partial least squares–structural equation modeling (PLS-SEM) to identify key regulatory pathways. The results showed that 30% organic substitution (T3) was associated with optimized soil carbon pools, improved microbial community composition, and enhanced carbon-cycling enzyme activities, while reducing the abundance of potentially harmful fungi. Structural equation modeling indicated that β-glucosidase activity and the relative abundance of Proteobacteria were the primary drivers of yield, together explaining 76% of its variation. The ecosystem multifunctionality index (EMF) was significantly and positively correlated with yield. In summary, under the conditions of this experiment, 30% organic fertilizer substitution achieved a favorable balance between soil ecological functions and crop yield, providing a valuable reference for sustainable nutrient management in oat production in high-altitude cold regions. Full article

Agroforestry is defined as a multifunctional approach to land management that enhances biodiversity and soil health while mitigating environmental impacts compared to intensive agriculture. The efficacy of maize cultivation in agroforestry systems is significantly influenced by nutrient competition. The factors that influence this phenomenon include the dimensions and configuration of the tree rows, as well as the availability of nutrients. This study examined the effect of nitrogen fertilization, tree line spacing, and seasonal changes on the productivity and the leaf spectral characteristics of the intercropped maize (Zea mays L.) within a willow-based agroforestry system in eastern Hungary. The experiment involved the cultivation of maize with two spacings (narrow and wide field strips) and four nitrogen levels (0, 50, 100, and 150 kg N ha⁻¹) across two growing seasons (2023–2024). The results demonstrated that yield-related parameters, including biomass, cob size and weight, and grain weight, exhibited a strong response to nitrogen level and tree line spacing. The reduction in spacing resulted in a decline in maize productivity. However, a high nitrogen input (150 kg N ha⁻¹) partially mitigated this effect in the first growing season. Vegetation indices demonstrated a high degree of sensitivity to annual variations, particularly with regard to tree competition and weather conditions. Multispectral vegetation indices exhibited a heightened responsiveness to environmental and management factors when compared to indices based on visible light (RGB). The findings of this study demonstrate that a combination of optimized tree spacing and optimized nitrogen management fosters productivity while maintaining agroecological sustainability in temperate agroforestry systems. Full article

The combined application of straw biochar and nitrogen fertilizer is an increasingly studied strategy to enhance soil fertility and crop yield. Optimizing the biochar-nitrogen interaction could be a choice for increasing nitrogen use efficiency (NUE) and reducing nitrogen loss in dryland agriculture. However, the mechanisms by which it regulates nitrogen allocation and absorption in foxtail millet (Setaria italica) are still limited in terms of mechanical understanding. Based on preliminary experiments, the optimal biochar-nitrogen interaction for soil nutrient absorption was identified. A field experiment was conducted with six treatments in an arid region of northwestern China: N1C1 (N1: 130 kg ha⁻¹ + C1: 100 kg ha⁻¹, control group), N2C4 (N2: 195 kg ha⁻¹ + C4: 250 kg ha⁻¹), N3C1 (N3: 260 kg ha⁻¹ + C1: 100 kg ha⁻¹), N3C2 (N3: 260 kg ha⁻¹ + C2: 150 kg ha⁻¹), N3C3 (N3: 260 kg ha⁻¹ + C3: 200 kg ha⁻¹), and N3C4 (N3: 260 kg ha⁻¹ + C4: 250 kg ha⁻¹). The results demonstrated that the biochar–nitrogen ratio significantly influenced topsoil total nitrogen, microbial biomass carbon (SMBC), and microbial biomass nitrogen (SMBN). All biochar-to-nitrogen combinations sharply increased soil total nitrogen by 133.11–151.52% compared to pre-sowing levels, providing a fundamental base for microbial-driven nitrogen transformation. Low nitrogen addition is more conducive to biomass accumulation, with N2C4 significantly increasing by 62.82%. Although a high biochar-to-nitrogen ratio reduced leaf relative chlorophyll content (SPAD) by 5.72–16.18% and net photosynthetic rate (Pn) by 16.09–52.65% at the heading stage, these did not compromise final yield. Importantly, N2C4, N3C1, and N3C4 significantly increased spike ¹⁵N abundance by 71.45%, 13.21%, and 19.43%, respectively. N2C4 grain production increases by 53.77–110.57% in two years and was positively correlated with spike ¹⁵N abundance, reflecting high nitrogen partial factor productivity. In conclusion, a reasonable biochar-nitrogen interaction enhances nitrogen allocation and grain yield by stimulating microbial activity and strengthening soil–plant synergy, the certified strategy effectively supports sustainable dryland agriculture by simultaneously increasing productivity and improving soil health. Full article

Nitrogen (N) and water are key resources for crop production and improving the efficiency with which they are used remains a major global challenge in intensive cropping systems. Here, we report how crop yield, N and water use efficiency, N surplus, and economic benefits can be improved from optimized management and crop rotations. A conventional winter wheat–summer maize double cropping (CN/WM) rotation in a three-year field experiment in the North China Plain is compared with alternative optimized rotations. The first three optimized treatments were wheat–summer maize rotation with optimized N and irrigation rates, tillage and straw management (ON/WM), and partial manure substitution (ONM/WM) or biochar addition (ONB/WM); the fourth optimized treatment was winter wheat–summer maize–spring maize producing three harvests in two years (ON/WMM); and the last was spring maize incorporating green manure during the fallow season for one harvest per year (ON/GM). The results showed that the ON/WM, ONM/WM, and ONB/WM had comparable yields to CN/WM, but significantly increased N use efficiency by 19–41% and water use efficiency by 13–20% and reduced N surplus to 353–531 kg N ha⁻¹ 2yr⁻¹. From these three optimized treatments, the ONM/WM performed better, with a comprehensive evaluation index of 0.66 and the highest economic benefits. The ON/WMM and ON/GM treatments also significantly increased N and water use efficiency but resulted in relatively low crop yields and profits; nevertheless, they significantly reduced water use and are suitable for water saving cropping systems. We concluded that optimized management-combined manure with synthetic N fertilization in wheat–summer maize rotations can achieve high crop productivity, environmental, and economic benefits, which contribute to a more sustainable crop production. Full article

Water and nitrogen are the key factors restricting the productivity improvement of onion in the Hexi Oasis. Unreasonable water and fertilizer management not only increases input costs, but also causes environmental pollution of farmland soil, thereby affecting the sustainable development of agriculture. To explore the effects of the water–nitrogen interaction and optimized combination schemes on onion yield, water–nitrogen use efficiency, and economic benefits under mulched drip irrigation in the Hexi Oasis, a four-year (2020–2023) water–nitrogen coupling regulation experiment was conducted at the Yimin Irrigation Experimental Station in Minle County, Hexi Corridor. The onion was used as the test crop and three irrigation levels were established, based on reference crop evapotranspiration (ET_c): low water (W1, 70% ET_c), medium water (W2, 85% ET_c), and sufficient water (W3, 100% ET_c), as well as high nitrogen N3 (330 kg·ha⁻¹), medium nitrogen N2 (264 kg·ha⁻¹), and low nitrogen N1 (198 kg·ha⁻¹). Meanwhile, no nitrogen application N0 (0 kg·ha⁻¹) was set as the control at three irrigation levels. This study analyzed the effects of different water and nitrogen supply conditions on onion quality, yield, water–nitrogen use efficiency, and economic benefits. A water–nitrogen economic benefit coupling model was established to optimize water–nitrogen combination schemes targeting different economic objectives. The results revealed that medium-to-high water–nitrogen combinations were beneficial for improving onion quality, while excessive irrigation and nitrogen application inhibited bulb quality accumulation. Both yield and economic benefits increased with the increasing amount of irrigation, whereas excessive nitrogen application showed a diminishing yield-increasing effect, simultaneously increasing farm input costs and ultimately reducing the economic benefits. In the four-year experiment, the N3W3 treatment in 2020 achieved the highest yield, economic benefits, and net profit, reaching 136.93 t·ha⁻¹, 20,376.3 USD·ha⁻¹, and 14,320.8 USD·ha⁻¹, respectively, with no significant difference from the N2W3 treatment. From 2021 to 2023, the N2W3 treatment achieved the highest yield, economic benefits, and net profit, averaging 130.87 t·ha⁻¹, 28,449.5 USD·ha⁻¹, and 21,881.5 USD·ha⁻¹, respectively. Lower irrigation and nitrogen application rates mutually restricted the water and nitrogen utilization, resulting in low water use efficiency, irrigation water use efficiency, nitrogen partial factor productivity, and nitrogen agronomic use efficiency. The relationship between the irrigation amount, nitrogen application rate, and the economic benefits of onion fits a bivariate quadratic regression model. This model predicts that onion’s economic benefits are highly correlated with the actual economic benefits, with analysis revealing a parabolic trend in economic benefits as water and nitrogen inputs increase. By optimizing the model, it was determined that when the irrigation amount reached 100%, the ET_c and nitrogen application rate was 264 kg·ha⁻¹, and the economic benefits were close to the target range of 27,000–29,000 USD·ha⁻¹; this can be used as the optimal water and nitrogen management model and technical reference for onion in the Hexi Oasis irrigation area, which can not only ensure high yield and quality but also improve the use efficiency of water and nitrogen. Full article

One of the main factors influencing wheat productivity is nitrogen (N) management. This study examined the impact of varying N-fertilizer rates on spring wheat yield and N use efficiency by adjusting the “source-sink” relationship between assimilates and N accumulation and transport. The objective was to identify the optimal N rate for the region. The field experiment included five N-fertilizer rates: 0 kg ha⁻¹ (N1), 52.5 kg ha⁻¹ (N2), 105.0 kg ha⁻¹ (N3), 157.5 kg ha⁻¹ (N4), and 210.0 kg ha⁻¹ (N5). Results indicated that the yield response was not proportional to N-fertilizer rates, with maximum biomass (6029 kg ha⁻¹) and grain yield (2625 kg ha⁻¹) achieved under N3. N fertilization primarily increased yield by regulating pre-anthesis translocation of assimilate and N. Assimilate translocation peaked at 105 kg N ha⁻¹, increasing by 8.5–133.7% compared to other treatments. With increasing N input, N absorption efficiency and N partial factor productivity declined. The highest N agronomic use efficiency was observed under N3, which was 19.5–176.34% higher than other treatments. Overall, moderate N input (≈105 kg ha⁻¹) optimizes yield and N-use efficiency, offering guidance for sustainable N management in dryland spring wheat production. Full article

The individual application of salt-tolerant plant growth-promoting rhizobacteria (ST-PGPR) or organic amendments exhibits certain limitations in remediating saline-alkali soils. This study developed a co-application treatment by combining a functionally complementary ST-PGPR consortium (Bacillus velezensis and Bacillus marisflavi) with optimized organic amendments (biochar at 22.5 t·ha⁻¹ and sheep-manure organic fertilizer at 7.5 t·ha⁻¹) to enhance soil quality and wheat growth. Compared with the control, the combination of the ST-PGPR consortium with organic amendments significantly reduced soil electrical conductivity by 52.69%. while soil organic matter, alkaline nitrogen, available phosphorus, and available potassium increased by 54.37%, 7.68%, 11.85%, and 39.57%, respectively (p < 0.05). The activities of sucrase, urease, and catalase also increased by 147.69%, 28.56%, and 30.26%, respectively (p < 0.05). Furthermore, the combined treatment significantly promoted wheat growth, increasing plant height, root length, and fresh weight by 12.11%, 26.60%, and 35.00%, respectively (p < 0.05), while alleviating osmotic and oxidative stress. β-diversity analysis revealed distinct microbial community compositions across treatments, and microbial composition indicated that Actinobacteriota and Starmerella were enriched under the co-application. Additionally, the co-application significantly enhanced the complexity and interconnectivity of the bacterial network, while reducing the stability of the fungal network. Partial least squares path and random forest models identified soil chemical properties as the key factors driving wheat growth. This synergistic system presents a promising and sustainable strategy for remediating saline-alkali soils and enhancing crop productivity. Full article

In intensive vegetable production systems, long-term reliance on chemical fertilizers often leads to soil degradation and microbial imbalance, highlighting the need for sustainable biotillage strategies. In this study, a long-term field experiment examined how vegetable–earthworm co-cultivation (VE) combined with different fertilization regimes affects vegetable yield, soil physicochemical properties, and microbial communities. VE significantly improved vegetable yield, with full chemical fertilization (VE_IF100) and a 30% reduction in chemical fertilizer supplemented with organic fertilizer (VE_IF70) increasing yields by 30.86% and 26.02%, respectively, relative to full fertilization without earthworms (CK_IF100). VE also moderated soil pH toward neutrality. VE_IF100 decreased the soil C/N ratio, whereas VE_IF70 increased it and enhanced available hydrolyzable nitrogen, indicating a more balanced nutrient transformation. Microbial analysis revealed that VE_IF100 reduced bacterial abundance while strongly increasing fungal abundance, decreasing the bacteria-to-fungi ratio from 3.51 to 0.53. In contrast, VE_IF70 restored the bacteria-to-fungi ratio to 1.65 and increased fungal diversity, with the Shannon and Chao1 indices exceeding those in VE_IF100. Bacterial genera associated with nutrient cycling and plant growth promotion (e.g., Brevundimonas, Anaeromyxobacter) were enriched under VE_IF70, while fungal taxa with antagonistic and biocontrol potential (e.g., Chaetomium, Arthrobotrys) also increased. Redundancy analysis identified the soil C/N ratio (ranging from 5.94 to 8.60 across treatments) as a key driver of both bacterial and fungal community structures, whereas pH exerted a stronger influence on fungi. Random forest analysis indicated that the annual total vegetable yield was primarily driven by fertilization and available phosphorus in VE systems, whereas pH and bacterial abundance were the main drivers in CK systems. Overall, earthworm inoculation combined with partial organic fertilizer substitution improved soil conditions, reshaped microbial communities, and maintained high yield, demonstrating a practical strategy for sustainable vegetable production. Full article

Urea production plays a crucial part in the worldwide agricultural economy, providing a primary supply of nitrogen for fertilizers. For storage and transport, urea is synthesized in granular form, and the prilling technology is frequently employed. In this technique, the hot liquid feed passes through an atomizer to produce small droplets, which then fall along the high tower. During the falling process, the liquid droplets gradually become solid because the internal energy is removed by the cooling air, which flows upward from the bottom. Typically, three consecutive thermal phases are analyzed for the solidification process: the liquid droplet cooling, solidification when the surface reaches freezing point, and the solid particle cooling. In this paper, the temperature distribution across the radius of the urea particles was analyzed using a heat transfer equation, which is considered a two-phase Stefan problem. The system of partial differential equations is solved numerically using the finite difference method and the enthalpy method. The temperature of the cooling air at various heights of the tower and the degree of solidification of different particle sizes were estimated and compared with data obtained from the urea factory to assess their reliability. The validation demonstrated a strong correlation between the model estimates and the real plant observations. Full article

Biochar and organic fertilizer applications are widely recognized as effective strategies for mitigating greenhouse gas emissions and controlling agricultural non-point source pollution in agroecosystems. However, the combined effects of these two approaches on greenhouse gas emissions and agricultural non-point source pollution remain insufficiently understood. Through consecutive field-based positioning plot trials, this study systematically examined the individual and combined effects of biochar and organic fertilizer amendments on N runoff loss (WTN) and gaseous emissions (N₂O and NH₃), N-cycling functional microbial communities, and soil physicochemical properties. Results demonstrated that conventional chemical fertilization resulted in 20.70% total N loss (4.48% gaseous emissions, 15.22% runoff losses). Biochar and organic fertilizer applications significantly reduced WTN losses by 8.06% and 7.43%, respectively, and decreased gaseous losses by 2.01% and 1.88%, while concurrently enhancing plant N uptake and soil residual N. Random forest analysis combined with partial least squares structural equation modeling revealed that soil organic carbon directly modulated nitrogen runoff losses and indirectly influenced aggregate stability and macroaggregate formation. Dissolved organic carbon (DOC) and recalcitrant organic carbon (ROC) exhibited dual regulatory effects on NH₃ volatilization through both direct pathways and indirect mediation via aggregate stability. Notably, biochar and organic fertilizer amendments induced significant compositional shifts in nirS- and nirK-type denitrifying microbial communities. pH, cation exchange capacity (CEC), and iron oxide–carbon complexes (IOCS) were identified as key factors suppressing N₂O emissions through inhibitory effects on Azoarcus and Bosea genera. Our findings demonstrate that biochar and organic fertilizers differentially modulate soil physicochemical properties and denitrifier community structure, with emission reduction disparities attributable to distinct mechanisms’ enhanced aggregate stability and modified denitrification potential through genus-level microbial community restructuring, particularly affecting Azoarcus and Bosea populations. This study offers valuable insights into the regulation of carbon sources for nitrogen management strategies within sustainable acidic soil vegetable production systems. Full article

Cotton production in Mediterranean regions is increasingly constrained by limited water availability, making it essential to identify genotypes that can maintain yield under reduced irrigation. In this study, four partially interspecific cotton lines (Pa7) and the commercial cultivar Celia were evaluated under two nitrogen rates designed to test resource-use efficiency and three irrigation regimes across two growing seasons in Greece. A strip–split plot design with three replications was used, and field data were analyzed with ANOVA, stability indices, and multivariate tools (Additive Main Effects and Multiplicative Interaction—AMMI, and Genotype plus Genotype × Environment—GGE biplots). Results showed that moderate irrigation consistently ensured stable seed cotton yields, whereas a higher water supply increased the plant height without proportional yield benefits, while fertilizer supplied in the specific quantities showed a lower impact on yield stability. Genotype × environment interactions were highly significant: Celia confirmed its high stability, while line M3 combined good stability with favorable agronomic traits. Yield was strongly associated with boll weight and lint percentage, indicating their usefulness as indirect selection criteria. These findings highlight the agronomic potential of partially interspecific cotton lines and demonstrate that moderate irrigation can sustain productivity while reducing water inputs, contributing to a more efficient use of resources in cotton production under water-limited conditions. These results provide practical insights for breeding and water management strategies aiming to sustain cotton productivity under Mediterranean water-limited conditions. Full article

The aim of the study was to assess the impact of fertilizer type (urea, compound fertilizer), biodegradable coating type (linseed oil or hemp oil based) and nitrogen dose (135 and 180 kg N·ha⁻¹) on the yield of corn intended for silage. A three-year field experiment was conducted using a randomized block design with three replicates. The test plant was corn intended for silage. The field experiment was conducted in a factorial design comprising three experimental factors: fertilizer type (two levels), coating type (two levels), and fertilizer dose (two levels). Controlled-release fertilizers (CRF) based on biodegradable coatings are an emerging solution in sustainable nitrogen management, yet their field-scale performance remains insufficiently validated. This study investigated how biodegradable coatings based on linseed and hemp oils affect nutrient release dynamics and maize yield under three-year field conditions. The study represents the first field validation phase translating laboratory coating characteristics into agricultural performance metrics. Statistical analysis (ANOVA, Tukey’s test) showed that in the first year of the study, the greatest impact on plant height and corn yield was observed in the case of type of fertilizer used (η²_p up to 17.83%), type of coating (η²_p up to 63.15%) and their interaction (η²_p up to 11.92%). The symbol η²_p (partial eta squared) represents a measure of effect size in analysis of variance (ANOVA). The largest plant size (average 307–310 cm) and the highest yield (107.33 t·ha⁻¹) were obtained in the case of yields in which compound fertilizer or urea with coatings were used in relation to the series in which fertilizers without coatings were applied (differences up to 11 t·ha⁻¹). Statistical analysis using repeated measures ANOVA confirmed a significant time effect, with fertilizer effectiveness declining in subsequent years of the experiment (p < 0.05). In the experiment, no effect of the tested factors on the number of corn cobs was found (η²_p < 2.27%). The highest fresh matter yield for silage production was obtained with coated NPK compound fertilizer (98.80 t·ha⁻¹), representing a 48% increase compared to the unfertilized control (66.90 t·ha⁻¹). The results of the study indicate that the use of coated compound fertilizers—NPK has the most beneficial effect on yield and biometric parameters of plants in the first growing season after their soil application. The enhanced nutrient release from biodegradable coatings provided greatest benefits in the first growing season, with diminishing effects in subsequent years due to coating degradation and residual soil nutrient accumulation. Full article

To address low nitrogen use efficiency (NUE) derived from excessive fertilization in cotton production in the Yellow River Basin, a field study was conducted to evaluate the effects of two planting densities and six nitrogen (N) rate levels. Key results show that a N rate of 225 kg ha⁻¹ optimized root length density and root biomass density. High planting density (105,000 plants ha⁻¹) improved the population-level root traits, photosynthetic radiation interception, and boll number per unit area, though it reduced individual plant root development. Total dry matter peaked at 225 kg ha⁻¹ N, and density increased reproductive dry matter by 7.5–11.9%. Higher N rates reduced reproductive partitioning and root–shoot ratio. While the maximum seed cotton yield (SCY) was 225 kg ha⁻¹, near-maximum yield was achieved at 150 kg ha⁻¹. NUE declined with increasing N, but densification improved agronomic NUE and partial factor productivity by 1.5–6.6% and 3.3–39.3%, respectively. Under the “densification with N reduction” mode, combining a planting density of 105,000 plants·ha⁻¹ with an N rate of 150 kg·ha⁻¹ achieved conventional yield. At the same density, an N rate of 225 kg·ha⁻¹ not only enabled high yield and maintained relatively high NUE but also showed better adaptability to the simplified cultivation mode in Yellow River Basin cotton-growing regions. Full article

In agricultural systems, excessive application of nitrogen fertilizer often leads to low nitrogen use efficiency and environmental pollution. In order to solve this problem, we studied the synergistic effect of biochar and nitrogen fertilizer on pepper yield, quality and rhizosphere soil health. This study was conducted under a temperate continental monsoon climate in Changchun, China. Using ‘Jinfu 803’ pepper (Capsicum annuum L.) as the test material, biochar was prepared from corn straw under oxygen-limited conditions at 500 °C. the comprehensive effects of the combined application of biochar (0, 0.7% soil mass ratio) and nitrogen fertilizer (0, 75, 375, 675 kg/hm² pure nitrogen) on pepper yield, fruit quality, rhizosphere soil physicochemical properties, and microbial community structure were studied. Redundancy analysis (RDA), high-throughput sequencing, and multivariate statistical methods were used to analyze the association patterns between soil environmental factors and microbial functional groups. The results showed that the combined application of biochar and nitrogen fertilizer significantly improved soil porosity (increased by 12.3–28.6%) and nutrient content, increased yield, and improved quality, among which the treatment of 0.7% biochar combined with 375 kg/hm² nitrogen fertilizer (B1N2) had the best effect. Under this treatment, the pepper yield reached 24,854.1 kg/hm², which was 42.35% higher than that of the control (B0N0). Notably, the nitrogen partial factor productivity (PFPN) of the B1N2 treatment (66.3 kg/kg) was significantly higher than that of the corresponding treatment without biochar and was not significantly lower than that of the high-nitrogen B1N3 treatment. The contents of soluble sugar and vitamin C in fruits increased by 51.18% and 39.16%, respectively. Redundancy analysis (RDA) revealed that the bacterial community structure was primarily shaped by soil pH, organic matter, and porosity, while the fungal community was predominantly influenced by alkaline hydrolyzable nitrogen and total nitrogen. Furthermore, the B1N2 treatment specifically enriched key functional microbial taxa, such as Chloroflexi (involved in carbon cycling) and Mortierellomycota (phosphate-solubilizing), which showed significant positive correlations with improved soil properties. In conclusion, B1N2 is the optimal treatment combination as it improves soil physical conditions, increases nutrient content, optimizes microbial community structure, and enhances pepper yield and quality. Full article