Search Results (98)

Soil organic carbon (SOC) constitutes the largest terrestrial carbon pool and plays a crucial role in climate regulation, soil fertility, and ecosystem functioning. Understanding its spatiotemporal dynamics is particularly important in semi-arid regions, where fragile environments and extensive ecological restoration may alter carbon cycling. The Loess Plateau, the world’s largest loess accumulation area with a history of severe erosion and large-scale vegetation restoration, provides a natural laboratory for examining how environmental gradients influence SOC storage over time. This study used a random forest model with multi-source environmental data to quantify soil organic carbon density (SOCD) dynamics in the 0–100 cm soil layer of the Loess Plateau from 2005 to 2020. SOCD showed strong spatial heterogeneity, decreasing from the humid southeast to the arid northwest. Over the 15-year period, total SOC storage increased from 4.84 to 5.23 Pg C (a 7.9% rise), while the annual sequestration rate declined from 0.046 to 0.020 kg·m⁻²·yr⁻¹, indicating that the regional carbon sink may be approaching saturation after two decades of restoration. Among soil types, Cambisols were the largest carbon pool, accounting for over 44% of total SOC storage. Vegetation productivity emerged as the dominant driver of SOC variability, with clay content as a secondary factor. These results indicate that although ecological restoration has substantially enhanced SOC storage, its marginal benefits are diminishing. Understanding the spatial and temporal patterns of SOC and their environmental drivers provides essential insights for evaluating long-term carbon sequestration potential and informing future land management strategies. Broader generalization requires multi-regional comparisons, long-term monitoring, and deeper soil investigations to capture ecosystem-scale carbon dynamics fully. Full article

Effective residue management is crucial for maintaining soil organic carbon (SOC) in upland rice systems, particularly under diverse fertilization and planting management practices. This study investigates the impacts of residue management in upland rice fields using the CQESTR model through simulation of SOC dynamics over a 20-year period. The first 10 years served as a spin-up period for carbon pool stabilization in the model, followed by simulations under varying nitrogen (N) application rates and planting date management strategies. Experiments for various N application rates and planting times were conducted during 2018–2019 and 2019–2020. In 2019, 30% and in 2020, 100% of the residue was returned, and these data were used for evaluating model performance. Subsequently, we modeled predictions for residue retention levels of 100%, 70%, 50%, and 30% to assess their effects on SOC. The results indicated a good agreement between the simulated and observed data for model performance evaluation with an MSD value of 9.13. Lack of correlation (0.44) accounted for 5% of MSD, indicating a good agreement between the simulated and observed SOC values. The highest change in SOC was observed at 100% residue return under moderately delayed planting, potentially due to higher crop productivity and residue retention, and moderate climatic conditions. Reduced residue retention gradually declined the SOC stocks, especially under low N input. Delays in planting exacerbated negative impacts, possibly due to low crop productivity and reduced residue return. Despite the limited number of years of data and inconsistent management practices, the overall trends highlight the importance of residue retention under different N fertilization and planting management strategies. This research serves as a preliminary study for sustainable management practices to enhance long-term soil carbon sequestration in upland rice systems in southern Thailand. Long-term evaluations are necessary using the observed data and the CQESTR model application for applicable recommendations. Full article

Soil desertification control is a global challenge, and the barrenness of sandy soil limits the growth of plants. To enhance the vegetation growth capacity of sandy soils, the preparation of soil amendments and the experiment of improving desertified soil were conducted. The soil amendment is prepared by mixing polyacrylamide (2.7%), biochar (16.2%), sodium bentonite (16.2%), straw fibers (5.4%), corn straw (2.7%), sheep manure organic fertilizer (54.1%), and composite microbial agents (2.7%). The laboratory experiment was conducted to investigate the effects of varying rates (0, 1.5%, 3%, 4.5%, 6%) of composite soil amendments on the properties of sandy soil and the Lolium perenne L. with a growth period of 30–60 days. The results indicated that the application of composite amendments at different rates maintained the soil pH between 7.0 and 7.5, increased the electrical conductivity, and significantly improved the soil moisture content, soil organic carbon (SOC), total nitrogen (TN), and total phosphorus contents. Under the condition of 3% amendment, the soil TN content increased from 0.74 to 1.83 g·kg⁻¹. The composite amendments remarkably promoted L. perenne growth, as evidenced by increased plant height, dry weight, and nitrogen and phosphorus nutrient content, while the SOC content increased by 1–4 times. The application of composite amendments, prepared by mixing materials such as biochar, organic fertilizer, crop straw, microbial agents, bentonite, and water-retaining agents, enhanced the physicochemical properties of sandy soil and promoted L. perenne growth, and 3% was the most suitable application rate. These findings are expected to advance desertification-controlling technologies and enhance soil carbon sequestration capacity. Full article

Soil organic carbon (SOC) mineralization plays the critical role of regulating carbon sequestration potential. This process is strongly influenced by agricultural practices, particularly tillage regimes and straw management. However, the complex interactions between tillage methods, straw types, and application rates in terms of SOC dynamics, especially in semi-arid agroecosystems like eastern Inner Mongolia, remain poorly understood. In this study, we assessed the combined effects of no tillage (NT) vs. rotary tillage (RT), three straw types (maize/MS, wheat/WS, and oilseed rape/OS), and three application rates (0.4%/low, 0.8%/medium, and 1.2%/high) on SOC concentration and mineralization using controlled laboratory incubation with soils from long-term plots. The key findings revealed that NT significantly increased the SOC concentration in the topsoil (0–20 cm) by an average of 14.5% compared to that in the RT. Notably, combining NT with medium-rate wheat straw (0.8%) resulted in the achievement of the highest SOC accumulation (28.70 g/kg). SOC mineralization increased with straw inputs, exhibiting significant straw type × rate interactions. Oilseed rape straw showed the highest specific mineralization rate (33.9%) at low input, while maize straw mineralized fastest under high input with RT. Therefore, our results demonstrate that combining NT with either 0.8% wheat straw or 1.2% maize straw represents an optimal application strategy, as the SOC concentration is enhanced by 12–18% for effective carbon sequestration in this water-limited semi-arid region. Therefore, optimizing SOC sequestration requires the integration of appropriate crop residue application rates and tillage methods tailored to different cropping systems. Full article

Excessive chemical fertilizers degrade soil and increase greenhouse gas (GHG) emissions. Organic substitution of nitrogen fertilizers is recognized as a sustainable agricultural-management practice, yet its dual role in carbon sequestration and emissions renders the net GHG balance (NGHGB) uncertain. To assess the GHG mitigation potential of organic substitution strategies, this study analyzed GHG fluxes, soil organic carbon (SOC) dynamics, indirect GHG emissions, and Net Primary Productivity (NPP) based on a long-term field positioning experiment initiated in 2016. Six fertilizer regimes were systematically compared: no fertilizer control (CK); only phosphorus and potassium fertilizer (PK); total chemical fertilizer (NPK); 1/3 chemical N substituted with sheep manure (OF1); dual substitution protocol with 1/6 chemical N substituted by sheep manure and 1/6 substituted by straw-derived N (OF2); complete chemical N substitution with sheep manure (OF3). The results showed that OF1 and OF2 maintained crop yields similar to those under NPK, whereas OF3 reduced yield by over 10%; relative to NPK, OF1, OF2, and OF3 significantly increased SOC sequestration rates by 50.70–149.20%, reduced CH₄ uptake by 7.9–70.63%, increased CO₂ emissions by 1.4–23.9%, decreased N₂O fluxes by 3.6–56.2%, and mitigated indirect GHG emissions from farm inputs by 24.02–63.95%. The NGHGB was highest under OF1, 9.44–23.99% greater than under NPK. These findings demonstrate that partial organic substitution increased carbon sequestration, maintained crop yields, whereas high substitution rates increase the risk of carbon emissions. The study results indicate that substituting 1/3 of chemical nitrogen with sheep manure in maize cropping systems represents an effective fertilizer management approach to simultaneously balance productivity and ecological sustainability. Full article

Exploring the mechanisms by which green agricultural production reduces emissions and enhances carbon sequestration in soil can provide a scientific basis for greenhouse gas reduction and sustainable development in farmland. This study uses a combination of meta-analysis and field experiments to evaluate the impact of different agricultural management practices and climatic conditions on soil organic carbon (SOC) and the emissions of CO₂ and CH₄, as well as the role of microorganisms. The results indicate the following: (1) Meta-analysis reveals that the long-term application of organic fertilizers in green agriculture increases SOC at a rate four times higher than that of chemical fertilizers. No-till and straw return practices significantly reduce CO₂ emissions from alkaline soils by 30.7% (p < 0.05). Warm and humid climates in low-altitude regions are more conducive to soil carbon sequestration. (2) Structural equation modeling of plant–microbe–soil carbon interactions shows that plant species diversity (PSD) indirectly affects microbial biomass by influencing organic matter indicators, mineral properties, and physicochemical characteristics, thereby regulating soil carbon sequestration and greenhouse gas emissions. (3) Field experiments conducted in the typical green farming research area of Chenzhuang reveal that soils managed under natural farming absorb CH₄ at a rate three times higher than those under conventional farming, and the stoichiometric ratios of soil enzymes in the former are close to 1. The peak SOC (19.90 g/kg) in the surface soil of Chenzhuang is found near fields cultivated with natural farming measures. This study provides theoretical support and practical guidance for the sustainable development of green agriculture. Full article

The integration of manure and straw substantially affects soil organic carbon (SOC) dynamics, transformation, and long-term stabilization in agricultural systems. Dissolved organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MOC) are the three main components of the SOC pool, each influencing soil carbon dynamics and nutrient cycling. Current research gaps remain regarding how combined fertilization practices affect the inputs of plant-originated and microbe-derived carbon into SOC pools and stability mechanisms. Our investigation measured SOC fractions (DOC, POC, MOC), SOC mineralization rate (SCMR), microbial necromass carbon, lignin phenols, enzyme activities, and microbial phospholipid fatty acids (PLFAs) over a long-term (17 years) field experiment with four treatments: mineral fertilization alone (CF), manure-mineral combination (CM), straw-mineral application (CS), and integrated manure-straw-mineral treatment (CMS). The CMS treatment exhibited notably elevated levels of POC (7.42 g kg⁻¹), MOC (10.7 g kg⁻¹), and DOC (0.108 g kg⁻¹), as well as a lower SCMR value (1.85%), compared with other fertilization treatments. Additionally, the CMS treatment stimulated the buildup of both bacterial and fungal necromass while enhancing the concentrations of ligneous biomarkers (vanillin, syringyl, and cinnamic derivatives), which correlated strongly with the elevated contents of fungal and bacterial PLFAs and heightened activity of carbon-processing enzymes (α-glucosidase, polyphenol oxidase, cellobiohydrolase, peroxidase, N-acetyl-β-D-glucosidase). Furthermore, fungal and bacterial microbial necromass carbon, together with lignin phenols, significantly contributed to shaping the composition of SOC. Through random forest analysis, we identified that the contents of bacterial and fungal necromass carbon were the key factors influencing DOC and MOC. The concentrations of syringyl phenol and cinnamyl phenols, and the syringyl-to-cinnamyl phenols ratio were the primary determinants for POC, while the fungal-to-bacterial necromass carbon ratio, as well as the concentrations of vanillyl, syringyl, and cinnamyl phenols, played a critical role in SCMR. In conclusion, the manure combined with straw incorporation not only promoted microbial growth and enzyme activity but also enhanced plant- and microbial-derived carbon inputs. Consequently, this led to an increase in the contents and stability of SOC fractions (DOC, POC, and MOC). These results suggest that manure combined with straw is a viable strategy for soil fertility due to its improvement in SOC sequestration and stability. Full article

Soil organic carbon (SOC) represents the most dynamic component of the soil carbon pool and is pivotal in the global carbon cycle. Global temperature rise and increasing drought severity are now indisputable realities, making soil organic carbon cycling under climate warming a critical research priority. This review elucidates the mechanism of the SOC response to temperature increase in terms of both extrinsic and intrinsic factors. The extrinsic factors are temperature elevation methods, rainfall, and land use. Different methods of temperature increase have their own unique advantages and disadvantages. Indoor warming methods exclude other factors, making temperature the only variable, but tend to ignore carbon inputs. In situ field warming and soil displacement methods help researchers explore the response of the complete ecosystem carbon cycle to temperature increase but cannot exclude the interference of factors such as rainfall. Elevated rainfall mitigates the adverse effects of elevated temperatures on organic carbon sequestration. In addition, the response of SOC to temperature elevations vary among different land use types. The temperature sensitivity of SOC is higher in peatland (high organic matter) alpine meadows (colder regions). The intrinsic factors that affect the response of SOC to elevated temperatures are SOC components, microorganisms, SOC temperature sensitivity, and SOC stability. The SOC decomposition rate is influenced by variations in the ratios of decomposable (easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC)) and stabilizing (inert organic carbon (IOC), alkyl carbon, and aromatic carbon) SOC to total organic carbon (TOC). Furthermore, temperature elevations also affect the soil microenvironment, resulting in microbial community reorganization such as changes in bacterial and fungal ratios and abundance. At the same time, soil aggregates, clay minerals, and iron and aluminum oxides protect the SOC, making it difficult to be utilized by microbial decomposition. The systematic clarification of the mechanism behind the SOC response to higher temperatures is crucial for accurately predicting and modeling global carbon cycles and effectively responding to the loss of SOC pools due to global temperature elevations. Full article

Understanding the complex interplay among altitudinal gradients, tree species diversity, structural attributes, and soil carbon (C) is critical for effective coniferous forest management and climate change mitigation. This study addresses a knowledge gap by investigating the effects of altitudinal gradient on coniferous tree diversity, biomass, carbon stock, regeneration, and soil organic carbon storage (SOCs) in the understudied temperate forests of the Hindu-Kush Kalam Valley. Using 120 sample plots 20 × 20 m (400 m²) each via a field inventory approach across five altitudinal gradients [E1 (2000–2200 m)–E5 (2801–3000 m)], we comprehensively analyzed tree structure, composition, and SOCs. A total of four coniferous tree species and 2172 individuals were investigated for this study. Our findings reveal that elevation indirectly influences species diversity, SOCs, and forest regeneration. Notably, tree height has a positive relationship with altitudinal gradients, while tree carbon stock exhibits an inverse relationship. Forest disturbance was high in the middle elevation gradients E2–E4, with high deforestation rate at E1 and E2. Cedrus deodara, the dominant species, showed the highest deforestation rate at lower elevations (R² = 0.72; p < 0.05) and regeneration ability (R² = 0.77; p < 0.05), which declined with increasing elevation. Middle elevations had the highest litter carbon stock and SOCs values emphasizing the critical role of elevation gradients in carbon sink and species distribution. The regeneration status and number of trees per ha in Kalam Valley forests showed a significant decline with increasing elevation (p < 0.05), with Cedrus deodara recording the highest regeneration rate at E1 and Abies pindrow the lowest at E5. The PCA revealed that altitudinal gradients factor dominate variability via PCA1, while the Shannon and Simpson Indices drives PCA2, highlighting ecological diversity’s independent role in shaping distinct yet complementary vegetative and ecological perspectives. This study reveals how altitudinal gradients shape forest structure and carbon sequestration, offering critical insights for biodiversity conservation and climate-resilient forest management. Full article

Climate change and overgrazing significantly constrain the sustainability of meadow land and vegetation in the livestock industry on the Tibetan–Plateau ecosystem. In context of climate change mitigation, grassland soil C sequestration and forage sustainability, it is important to understand how manure regimes influence SOC stability, grassland soil, forage structure and nutritional quality. However, the responses of SOC fractions, soil and forage structure and quality to the influence of manure gradient practices remain unclear, particularly at Tianzhu belt, and require further investigation. A field study was undertaken to evaluate the soil bulk density, aggregate fractions and dynamics in SOC concentration, permanganate oxidizable SOC fractions, SOC stabilization and soil nutrients at the soil aggregate level under manure gradient practices. Moreover, the forage biodiversity, aboveground biomass and nutritional quality of alpine meadow plant communities were also explored. Four treatments, i.e., control (CK), sole sheep manure (SM), cow dung alone (CD) and a mixture of sheep manure and cow dung (SMCD) under five input rates, i.e., 0.54, 1.08, 1.62, 2.16 and 2.70 kg m⁻², were employed under randomized complete block design with four replications. Our analysis confirmed the maximum soil bulk density (BD) (0.80 ± 0.05 g cm⁻³) and micro-aggregate fraction (45.27 ± 0.77%) under CK, whilst the maximum macro-aggregate fraction (40.12 ± 0.54%) was documented under 2.70 kg m⁻² of SMCD. The SOC, very-labile C fraction (Cfrac₁), labile C fraction (Cfrac₂) and non-labile/recalcitrant C fraction (Cfrac₄) increased with manure input levels, being the highest in 2.16 kg m⁻² and 2.70 kg m⁻² applications of sole SM and the integration of 50% SM and 50% CD (SMCD), whereas the less-labile fraction (Cfrac₃) was highest under CK across aggregate fractions. However, manures under varying gradients improved SOC pools and stabilization for both macro- and micro-aggregates. A negative response of the carbon management index (CMI) in macro-aggregates was observed, whilst CMI in the micro-aggregate fraction depicted a positive response to manure addition with input rates, being the maximum under sole SM addition averaged across gradients. Higher SOC pools and CMI under the SM, CD and SMCD might be owing to the higher level of soil organic matter inputs under higher doses of manures. Moreover, the highest accumulation of soil nutrients,, for instance, TN, AN, TP, AP, TK, AK, DTPA extractable Zn, Cu, Fe and Mn, was recorded in SM, CD and SMCD under varying gradients over CK at both aggregate fractions. More nutrient accumulation was found in macro-aggregates over micro-aggregates, which might be credited to the physical protection of macro-aggregates. Overall, manure addition under varying input rates improved the plant community structure and enhanced meadow yield, plant community diversity and nutritional quality more than CK. Therefore, alpine meadows should be managed sustainably via the adoption of sole SM practice under a 2.16 kg m⁻² input rate for the ecological utilization of the meadow ecosystem. The results of this study deliver an innovative perspective in understanding the response of alpine meadows’ SOC pools, SOC stabilization and nutrients at the aggregate level, as well as vegetation structure, productivity and forage nutritional quality to manure input rate practices. Moreover, this research offers valuable information for ensuring climate change mitigation and the clean production of alpine meadows in the Qinghai–Tibetan Plateau area of China. Full article

Despite the global imperative to enhance carbon sequestration in agricultural landscapes, saline–alkali soils present distinctive soil–microbe constraints that limit our understanding of optimal management strategies. This study addresses critical knowledge gaps regarding the mechanistic relationships between bacterial community structure and carbon stabilization processes in saline–alkali soil. A three-year field experiment was conducted in the Yellow River Delta, China, with two N levels (N1, 270 kg N ha⁻¹; N2, 210 kg N ha⁻¹) and three C treatments (S0, 0 kg C ha⁻¹; S1, 5000 kg C ha⁻¹; S2, 10,000 kg C ha⁻¹). SOC sequestration by straw incorporation increased by 16.34–22.86% and 8.18–11.91%, with no significant difference between the S1 and S2 treatments, because the specific C mineralization rate (SCMR) of the S2 treatment was 13.80–41.61% higher than the S1 treatment. The reduced nitrogen application (N2) enhanced SOC sequestration efficiency by 3.40–12.97% compared with conventional rates, particularly when combined with half straw incorporation. Furthermore, compared with the N1S1 treatment, the N2S1 treatment induced qualitative transformations in carbon chemistry, increasing aromatic carbon compounds (28.79%) while reducing carboxylic fractions (10.06%), resulting in enhanced structural stability of sequestered carbon. Bacterial community analysis revealed distinctive shifts in bacterial composition under different treatments. Half straw incorporation (S1) increased the abundance of oligotrophic strategists (Verrucomicrobiae and Acidimicrobiia) while decreasing copiotrophic bacteria (Bacteroidia), indicating a transition from r-strategy to k-strategy microbial communities that fundamentally altered carbon cycling. Half straw incorporation and reduced N application were beneficial to stabilize SOC composition, reduce mineralization rates, optimize bacterial survival strategy, and thus achieve SOC sequestration. Full article

Maintaining the long-term viability of a wheat–maize planting system, particularly the synchronous improvement of crop production and soil organic carbon (SOC) sequestration, is crucial for ensuring food security in the North China Plain. A field experiment in which wheat–maize was regarded as an integral fertilization unit was carried out in Shanxi Province, China, adopting a split-plot design with different distribution ratios of phosphorus (P) and potassium (K) fertilizer between wheat and maize seasons in the main plot (A) (a ratio of 3:0, A1; a ratio of 2:1, A2) and different application rates of pure nitrogen (N) during the entire wheat and maize growth period (B) (450 kg·ha⁻¹, B1; 600 kg·ha⁻¹, B2). Moreover, no fertilization was used in the entire wheat and maize growth period for the control (CK). The findings showed that A2B1 treatment led to the highest response, with an average wheat yield of 7.75 t·ha⁻¹ and an average maize yield of 8.40 t·ha⁻¹ over the last 9 years. The highest SOC content (15.13 g·kg⁻¹), storage (34.20 t·ha⁻¹), and sequestration (7.11 t·ha⁻¹) were also observed under the A2B1 treatment. Both enhanced crop yield and SOC sequestration resulted from improvements in cumulative carbon (C) input, soil nutrients, and stoichiometry under the A2B1 treatment. It was confirmed that total N (TN), alkali-hydrolysable N (AN), available P (AP), available K (AK), and the ratios of C:K, N:K, and N:P had positive effects on crop yield through the labile components of SOC and on SOC sequestration through microbial necromass C. To conclude, our findings highlight the urgent need to optimize fertilizer management strategies to improve crop production and SOC sequestration in the North China Plain. Full article

Soil organic carbon (SOC) is a key parameter of soil quality, and its improvement reduces the risk of desertification and provides several ecosystem services. Groundcovers are efficient for reducing soil degradation through erosion control and the improvement of organic matter. This article shows the effect of groundcovers with the addition of pruning residues on the SOC in olive orchards compared to soil management based on tillage. Four olive fields located in several edaphoclimatic zones of the Andalusia Region (southern Spain) were monitored, and the SOC stock was assessed during four seasons. The spontaneous groundcovers with the addition of shredded pruning residues had significant effects on SOC in all fields. The tillage treatment also increased the SOC content due to the carbon input through spontaneous vegetation and pruning residues, but to a lesser extent than the non-disturbed soil with groundcovers. The climate and soil characteristics of each zone, especially the clay content, determined the magnitude of the SOC increase. Carbon sequestration rates ranged from 0.02 to 3.02 MgC ha⁻¹ yr⁻¹ up to 30 cm in depth, and the SOC stock measured at the end of the four-season study period was significantly higher in the groundcover treatment, making this system sustainable in olive orchards and recommendable for the entailed ecosystem services. Full article

The primary ecological challenges in citrus orchards include soil acidification, nutrient depletion, and significant carbon dioxide emissions resulting from conventional cultivation practices. To address these challenges, citrus peel residues and cassava stalks underwent pyrolysis at 500 °C to generate biochars. Different proportions of these biochars (1%, 2%, and 4%) were applied under controlled laboratory conditions to assess their impact on the mineralization of soil organic carbon in citrus orchards. The results indicated that both types of biochar effectively regulated the soil pH to approximately 5.5. Significantly, the addition of 4% cassava stalk biochar significantly increased the levels of available phosphorus and potassium. The phosphorus levels rose by 512.55%, and the potassium levels surged by 1434.01%. Additionally, the soil organic carbon increased to 16.7 g/kg. Conversely, the citrus peel biochar decreased the availability of phosphorus but resulted in the highest increase in available potassium, at 1523.75%, and elevated the soil organic carbon content to 13 g/kg. Both types of biochar enhanced the soil organic carbon mineralization rate to varying extents with increasing application ratios, simultaneously boosting the cumulative amount of organic carbon mineralized. Among the treatments, cassava stalk biochar displayed the lowest C₀/SOC ratio, of 0.169, indicating its superior carbon retention capacity. Furthermore, cassava stalk biochar showed inhibitory effects on soil catalase and urease activities within the citrus orchard. Overall, the application of 4% cassava stalk biochar appears to be more beneficial for nutrient regulation and carbon sequestration in citrus orchard soils, while also contributing to the reduction in soil acidification by adjusting pH levels. Full article

Biochar (BC) serves a vital function in sequestering carbon, improving nutrient cycles, and boosting overall soil quality. This research explored the enhancement of the chemical and physical properties of soil (alkaline) using nitrogen and biochar (from organic and inorganic sources) in a semi-arid climate during the autumn seasons of 2015–2016 and 2016–2017. The study involved applying biochar at various rates (0, 10, 20, and 30 t ha⁻¹) and nitrogen at different levels (0, 90, 120, and 150 kg ha⁻¹) using urea, poultry manure (PM), and farmyard manure (FYM) as nitrogen sources, which were applied to the field in a randomized complete block design with split-plot arrangement. The application of biochar at the highest rate (30 t ha⁻¹) resulted in a significant increase of over 120% in soil organic matter (SOM), soil organic carbon (SOC), and soil moisture content (SMC). Additionally, it increased total soil nitrogen (STN) by 14.16% and mineral nitrogen (SMN) by 9.09%. In contrast, applying biochar at this rate reduced soil bulk density (SBD), pH, and electrical conductivity (EC) by 28.52%, 3.38%, and 2.27%, respectively, compared to the control. Similarly, applying nitrogen at 150 kg ha⁻¹ using FYM significantly improved SOC, SOM, SMC, and SBD. At the same rate, using PM as a nitrogen source enhanced STN and SMN while reducing soil pH and EC. In conclusion, this study shows that applying biochar at 30 t ha⁻¹ combined with nitrogen at 150 kg ha⁻¹, sourced from either PM or FYM, offers great potential for improving soil fertility and promoting carbon sequestration in alkaline soils of semi-arid regions. These findings highlight the value of integrating BC and organic N sources for enhancing agroecosystem sustainability. Thus, this study provides a promising pathway to enhance soil quality, improve crop productivity, and support sustainable agricultural practices in challenging environments. Full article