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24 pages, 3720 KB  
Article
Effects of Microbial Fertilizer Combined with Organic Fertilizer on Forage Productivity and Soil Ecological Functions in Grasslands of the Muli Mining Area
by Zongcheng Cai, Jianjun Shi, Shouquan Fu, Fayi Li, Liangyu Lv, Qingqing Liu, Hairong Zhang and Shancun Bao
Plants 2025, 14(20), 3156; https://doi.org/10.3390/plants14203156 - 14 Oct 2025
Abstract
To address grassland ecosystem degradation caused by mining disturbance and its severe threats to regional ecological security in alpine mining areas, this study systematically evaluated the synergistic effects of different application ratios of Effective Microorganisms inoculant and organic fertilizers on artificial grassland ecosystem [...] Read more.
To address grassland ecosystem degradation caused by mining disturbance and its severe threats to regional ecological security in alpine mining areas, this study systematically evaluated the synergistic effects of different application ratios of Effective Microorganisms inoculant and organic fertilizers on artificial grassland ecosystem functions in the Muli alpine mining region of the Qinghai-Tibet Plateau, based on field experiments conducted from 2022 to 2024. The results demonstrated significant improvements in production performance. The Y2E2 treatment (0.60 t·hm−2 Effective Microorganisms inoculant + 20 t·hm−2 organic fertilizer) exhibited optimal effects, with aboveground biomass increasing by 75.97% and 68.88% in 2023 and 2024, respectively, compared to the control (p < 0.05), while belowground biomass simultaneously increased by 36.05% and 35.53% (p < 0.05), showing a sustained upward trend. Nutritional quality was markedly enhanced, with the Y2E2 treatment consistently achieving the best performance across both years. Crude protein and ether extract contents increased by 46.18%~46.52% and 62.42%~63.25%, respectively (p < 0.05), while soluble sugar content rose significantly by 19.49%~20.56% (p < 0.05). Concurrently, crude ash and fiber fractions were significantly reduced. Soil physicochemical properties improved substantially, with the Y2E2 treatment in 2024 reducing soil pH and bulk density by 11.10% and 37.20%, respectively (p < 0.05), while increasing soil organic carbon, available nitrogen, and available potassium by 92.94%, 49.25%, and 96.08% (p < 0.05). Soil biological activity was significantly enhanced, as evidenced by increases of 78.33%, 55.69%, 55.87%, and 183.67% in β-glucosidase, dehydrogenase, urease, and acid phosphatase activities, respectively (p < 0.05), alongside rises of 117.64% and 94.78% in microbial biomass carbon and phosphorus (p < 0.05). Mechanistic analysis via structural equation modeling revealed strong positive direct effects of the Effective Microorganisms inoculant–organic fertilizer combination on forage yield (β = 0.27, p < 0.001) and nutritional quality (β = 0.73, p < 0.001). Principal component analysis (cumulative variance explained: 88.90%) further confirmed Y2E2 treatment superior performance in soil improvement, microbial function enhancement, and grassland productivity. In conclusion, the optimal remediation strategy for alpine mining grasslands was identified as the combined application of 0.60 t·hm−2 Effective Microorganisms inoculant and 20 t·hm−2 organic fertilizer. This approach drives ecosystem function restoration through a multidimensional synergistic mechanism involving soil physicochemical amelioration–microbial activity stimulation–nutrient supply optimization, providing both theoretical foundations and practical solutions for ecological restoration of degraded grasslands in similar regions. Full article
(This article belongs to the Special Issue Innovative Fertilization Strategies for Sustainable Agriculture)
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23 pages, 9068 KB  
Article
Stratified Nitrogen Application Enhances Subsoil Carbon Sequestration via Enzyme-Mediated Pathways in Straw-Incorporated Croplands of North China Plain
by Bin Wang, Yanqun Wang, Jingyu Li, Rui Hou, Yulong Liu, Xin Fu, Jie Men, Yingchun Li and Zhengping Peng
Agriculture 2025, 15(19), 2098; https://doi.org/10.3390/agriculture15192098 - 9 Oct 2025
Viewed by 114
Abstract
Nitrogen (N) fertilization critically regulates the storage and availability of soil carbon (C) and N pools. However, the internal mechanism through which stratified N application affects soil organic carbon (SOC) sequestration and soil quality index (SQI) remains unclear. To investigate the effects of [...] Read more.
Nitrogen (N) fertilization critically regulates the storage and availability of soil carbon (C) and N pools. However, the internal mechanism through which stratified N application affects soil organic carbon (SOC) sequestration and soil quality index (SQI) remains unclear. To investigate the effects of stratified N application on C sequestration and SQI in both topsoil and subsoil, this study established six treatments (N0:0, N1:0, N4:1, N3:2, N2:3, N1:4) and analyzed soil biochemical indicators. The results showed that compared to N1:0, stratified N fertilization did not significantly improve soil C and N content in the 0–20 cm layer. In contrast, the N2:3 and N1:4 treatments even led to a significant reduction in soil C and N pools in the topsoil. In the 20–40 cm, compared to N1:0, stratified N fertilization increased SOC, TN, labile C fractions, N fractions (particulate organic N and microbial biomass N), enzyme activity and C pool management index (CPMI), increasing by 0.52–7.94%, 2.05–8.42%, 4.77–42.59%, 14.46–56.01%, 6.34–45.82%, and 31.26–51.93%, respectively. In 0–20 cm, compared to N0:0, N application increased SQI by 24.84–45.77%, and N2:3 and N1:4 treatments were lower SQI than N1:0. Furthermore, N2:3, N3:2, and N1:4 treatments in 20–40 cm were higher than other treatments. N fertilizer application drives the synergistic changes in C and N fractions by regulating enzyme activity and stoichiometric ratio, thus affecting CPMI and SQI. Thus, the 3:2 stratified N fertilization (0–20 cm:20–40 cm) method achieves synergistic dual-layer enhancement-maintaining surface C and N pools while boosting subsoil C sequestration and quality-through enzyme-mediated precision regulation of C/N stoichiometry. The study provides a scientific foundation for integrated C emission reduction and cropland quality enhancement in the North China. Full article
(This article belongs to the Section Agricultural Soils)
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25 pages, 5825 KB  
Article
Multi-Centennial Disturbance History and Terrestrial Carbon Transfers in a Coastal Forest Watershed Before and During Reservoir Development
by John A. Trofymow, Kendrick J. Brown, Byron Smiley, Nicholas Hebda, Rebecca Dixon and David Dunn
Forests 2025, 16(10), 1549; https://doi.org/10.3390/f16101549 - 8 Oct 2025
Viewed by 266
Abstract
Multi-centennial C budgets in forested watersheds require information on forest growth, detritus turnover, and disturbances, as well as the transfer to and fate of terrestrial C in aquatics systems. Here, a sediment gravity core was collected from a drinking water reservoir in Canada, [...] Read more.
Multi-centennial C budgets in forested watersheds require information on forest growth, detritus turnover, and disturbances, as well as the transfer to and fate of terrestrial C in aquatics systems. Here, a sediment gravity core was collected from a drinking water reservoir in Canada, and analyzed for temporal changes in charcoal, magnetic susceptibility, carbon, and nitrogen. These indicators were used to assess disturbance history and terrestrial C sequestration in sediments. During the reservoir development period from 1910 to 2012, charcoal flux and magnetic susceptibility increased ca. 10 years after nearby fire and forest-clearing events associated with reservoir expansion. Total C and δ13C gradually declined during the development period, likely due to increased inputs of mineral soil from human activity. Concurrently, total terrestrial C sequestered in sediments, estimated using three or eight marker compounds, ranged between 3557 and 5145 Mg C/100 yrs, accounting for 11%–17% of DOC exports to the reservoir (30,640 Mg C/100 yrs), as estimated from a previously developed terrestrial carbon budget model. In comparison, mixed-severity fires burned around the reservoir during the pre-development period (pre-1910), as evidenced by stand ages and/or increases in charcoal flux. In general, decreased terrestrial C flux was associated with higher-severity fires that burned between 1870 and 1890 and perhaps around 1790. Further, comparisons show that soil erosion was up to 3× greater in the development versus the pre-development period. Overall, this investigation revealed the impact of land use change and fire on watershed carbon budgets and advanced a previously developed pyGC-MS methodology that demonstrated the amount of terrestrial and aquatic C being buried in sediment. It also identified the fraction of terrestrial C that was exported from the forest to the reservoir and sequestered in the sediment, uncommon data that could inform current and future landscape C budget modelling studies in this region. Full article
(This article belongs to the Special Issue Erosion and Forests: Drivers, Impacts, and Management)
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13 pages, 1338 KB  
Article
Response of Depth-Stratified Soil Quality to Land-Use Conversion and Its Limiting Factors in Tropical Ecosystems
by Yanmin Li, Tianqi Zhang and Shihang Wang
Land 2025, 14(10), 2010; https://doi.org/10.3390/land14102010 - 7 Oct 2025
Viewed by 197
Abstract
Land degradation is known to alter soil properties and quality; however, its depth-dependent effects across contrasting land-use types and the key factors limiting soil recovery remain poorly quantified in tropical ecosystems. This study established a forest degradation gradient on Hainan Island, China, encompassing [...] Read more.
Land degradation is known to alter soil properties and quality; however, its depth-dependent effects across contrasting land-use types and the key factors limiting soil recovery remain poorly quantified in tropical ecosystems. This study established a forest degradation gradient on Hainan Island, China, encompassing mature forest, secondary forest, rubber plantation, and areca plantation. Soil physical (e.g., bulk density, porosity, water content, field capacity) and chemical (e.g., organic matter, nitrogen, phosphorus, and potassium fractions) properties were measured at three depths (0–20 cm, 20–40 cm, and 40–60 cm). A soil quality index (SQI) was constructed using principal component analysis, and obstacle degree modeling was applied to identify major limiting factors. The results showed that degradation of mature forests significantly reduced topsoil (0–20 cm) quality regardless of subsequent land-use type. In contrast, changes in medium (20–40 cm) and deep (40–60 cm) soil quality were land-use dependent. Conversion to secondary forests and areca plantations resulted in negligible effects, whereas transformation into rubber plantations significantly enhanced soil quality at medium and deep depths. Obstacle degree analysis identified available phosphorus, rather than nitrogen, as the primary limiting factor for soil quality in the region, accounting for 39.7% of all limitations across land-use types. This study demonstrates that the effects of tropical forest degradation on soil quality exhibit dual dependence on both soil depth and land-use type in tropical settings. Furthermore, it highlights the essential role of available phosphorus management in guiding soil restoration and sustainable land-use strategies in these vulnerable ecosystems. Full article
(This article belongs to the Special Issue Land Resource Use Efficiency and Sustainable Land Use)
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19 pages, 3909 KB  
Article
The Effects of Long-Term Manure and Grass Mulching on Microbial Communities, Enzyme Activities, and Soil Organic Nitrogen Fractions in Orchard Soils of the Loess Plateau, China
by Qi Wang, Luxiao Guo, Xue Gao, Songling Chen, Xinxin Song, Fei Gao, Wei Liu, Hua Guo, Guoping Wang and Xinping Fan
Agriculture 2025, 15(19), 2084; https://doi.org/10.3390/agriculture15192084 - 6 Oct 2025
Viewed by 337
Abstract
Organic manure and grass mulching are widely recognized as modifiers of soil microbial communities and nutrient dynamics; however, the combined effects of these practices on nitrogen fractionation and microbial functionality in orchard ecosystems remain poorly understood. This study conducted a comprehensive evaluation of [...] Read more.
Organic manure and grass mulching are widely recognized as modifiers of soil microbial communities and nutrient dynamics; however, the combined effects of these practices on nitrogen fractionation and microbial functionality in orchard ecosystems remain poorly understood. This study conducted a comprehensive evaluation of soil nitrogen fractions, enzymatic activity, microbial diversity and functional traits in walnut orchards under three management practices: organic manure (OM), grass mulching combined with manure (GM), and chemical fertilization (CF) in China’s Loess Plateau. The results revealed that OM and GM significantly enhanced soil nutrient pools, with GM elevating total nitrogen by 1.96-fold, soil organic carbon by 97.79%, ammonium nitrogen by 128%, and nitrate nitrogen by 54.56% relative to CF. Furthermore, the OM significantly increased the contents of total hydrolysable nitrogen, amino sugar nitrogen, amino acid nitrogen, ammonia nitrogen, hydrolysable unidentified nitrogen, non-acid-hydrolyzable nitrogen compared to the CF and GM treatments. Meanwhile, ASN and AN had significant effects on mineral and total nitrogen. The OM and GM had higher activities of leucine aminopeptidase enzymes (LAP), α-glucosidase enzyme, β-glucosidase enzyme (βG), and N-acetyl-β-D-glucosidase enzyme (NAG). Microbial community analysis revealed distinct responses to different treatments: OM and GM enhanced bacterial Shannon index, while suppressing fungal diversity, promoting the relative abundance of copiotrophic bacterial phyla such as Proteobacteria and Chloroflexi. Moreover, GM favored the enrichment of lignocellulose-degrading Ascomycota fungi. Functional annotation indicated that Chemoheterotrophy (43.54%) and Aerobic chemoheterotrophy (42.09%) were the dominant bacterial metabolic pathways. The OM significantly enhanced the abundance of fermentation-related genes. Additionally, fungal communities under the OM and GM showed an increased relative abundance of saprotrophic taxa, and a decrease in the relative abundances of potential animal and plant pathogenic taxa. The Random forest model further confirmed that βG, LAP, and NAG, as well as Basidiomycota, Mortierellomycota, and Ascomycota served as pivotal mediators of soil organic nitrogen fraction. Our findings demonstrated that combined organic amendments and grass mulching can enhance soil N retention capacity, microbial functional redundancy, and ecosystem stability in semi-arid orchards. These insights support the implementation of integrated organic management as a sustainable approach to enhance nutrient cycling and minimize environmental trade-offs in perennial fruit production systems. Full article
(This article belongs to the Section Agricultural Soils)
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20 pages, 1043 KB  
Article
Multi-Criteria Decision-Making Algorithm Selection and Adaptation for Performance Improvement of Two Stroke Marine Diesel Engines
by Hla Gharib and György Kovács
J. Mar. Sci. Eng. 2025, 13(10), 1916; https://doi.org/10.3390/jmse13101916 - 5 Oct 2025
Viewed by 353
Abstract
Selecting an appropriate Multi-Criteria Decision-Making (MCDM) algorithm for optimizing marine diesel engine operation presents a complex challenge due to the diversity in mathematical formulations, normalization schemes, and trade-off resolutions across methods. This study systematically evaluates fourteen MCDM algorithms, which are grouped into five [...] Read more.
Selecting an appropriate Multi-Criteria Decision-Making (MCDM) algorithm for optimizing marine diesel engine operation presents a complex challenge due to the diversity in mathematical formulations, normalization schemes, and trade-off resolutions across methods. This study systematically evaluates fourteen MCDM algorithms, which are grouped into five primary methodological categories: Scoring-Based, Distance-Based, Pairwise Comparison, Outranking, and Hybrid/Intelligent System-Based methods. The goal is to identify the most suitable algorithm for real-time performance optimization of two stroke marine diesel engines. Using Diesel-RK software, calibrated for marine diesel applications, simulations were performed on a variant of the MAN-B&W-S60-MC-C8-8 engine. A refined five-dimensional parameter space was constructed by systematically varying five key control variables: Start of Injection (SOI), Dwell Time, Fuel Mass Fraction, Fuel Rail Pressure, and Exhaust Valve Timing. A subset of 4454 high-potential alternatives was systematically evaluated according to three equally important criteria: Specific Fuel Consumption (SFC), Nitrogen Oxides (NOx), and Particulate Matter (PM). The MCDM algorithms were evaluated based on ranking consistency and stability. Among them, Proximity Indexed Value (PIV), Integrated Simple Weighted Sum Product (WISP), and TriMetric Fusion (TMF) emerged as the most stable and consistently aligned with the overall consensus. These methods reliably identified optimal engine control strategies with minimal sensitivity to normalization, making them the most suitable candidates for integration into automated marine engine decision-support systems. The results underscore the importance of algorithm selection and provide a rigorous basis for establishing MCDM in emission-constrained maritime environments. This study is the first comprehensive, simulation-based evaluation of fourteen MCDM algorithms applied specifically to the optimization of two stroke marine diesel engines using Diesel-RK software. Full article
(This article belongs to the Special Issue Marine Equipment Intelligent Fault Diagnosis)
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14 pages, 1878 KB  
Article
Role of Fungi in N2O Emissions from Nitrogen-Fertilized Lawn Soil
by Zhifeng Xun, Mingzhu Zhao, Xueya Zhao, Mi Wang, Yujing Liu, Xueying Han, Yiming Zhang, Yanhua Wu and Zhi Quan
Nitrogen 2025, 6(4), 90; https://doi.org/10.3390/nitrogen6040090 - 1 Oct 2025
Viewed by 238
Abstract
Urban lawns are a predominant form of vegetation in sports grounds and greenbelts. Nitrogen (N) fertilization is widely used to sustain lawn productivity. However, it also promotes nitrous oxide (N2O) emissions, a potent greenhouse gas. The microbial mechanisms underlying N2 [...] Read more.
Urban lawns are a predominant form of vegetation in sports grounds and greenbelts. Nitrogen (N) fertilization is widely used to sustain lawn productivity. However, it also promotes nitrous oxide (N2O) emissions, a potent greenhouse gas. The microbial mechanisms underlying N2O emissions from fertilized lawn soils remain poorly understood. In this study, we conducted a controlled incubation experiment with four N application rates [0 (N0), 100 (N100), 200 (N200), and 300 kg·ha−1·yr−1 (N300)] to investigate N2O emissions and associated microbial processes in urban lawn soil. Biological inhibitors combined with high-throughput sequencing were used to quantify the inhibitor-sensitive fraction of fungi and bacteria contributing to N2O emissions. Our results showed that N fertilizer significantly increased N2O emissions, with the highest emission observed under N200. The fungi inhibitor-sensitive fraction accounted for ~45% of total N2O emissions, significantly higher than that of bacteria (~31%). Dominant fungal phyla included Ascomycota, Basidiomycota, and Zygomycota, with N fertilization significantly increasing the relative abundance of Ascomycota and decreasing that of Basidiomycota. Redundancy analysis revealed strong positive correlations between Ascomycota abundance and N2O emissions across N treatments. At the genus level, Pyrenochaetopsis, Myrothecium, and Humicola were positively associated with N2O production and identified as key functional taxa. These findings demonstrate that moderate N fertilization can disproportionately stimulate fungal-driven N2O emissions in urban lawns. The results provide a scientific basis for optimizing N fertilization strategies in green spaces, with implications for N policy and sustainable landscape management. Full article
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15 pages, 1942 KB  
Article
Predictive URANS/PDF Modeling of Unsteady-State Phenomena in Turbulent Hydrogen–Air Flames
by Mohamed Boukhelef, Mohammed Senouci, Mounir Alliche, Habib Merouane and Abdelhamid Bounif
Fluids 2025, 10(10), 258; https://doi.org/10.3390/fluids10100258 - 29 Sep 2025
Viewed by 251
Abstract
The escalating global demand for primary energy—still predominantly met by conventional carbon-based fuels—has led to increased atmospheric pollution. This underscores the urgent need for alternative energy strategies capable of reducing carbon emissions while meeting global energy requirements. Hydrogen, as a clean combustible fuel, [...] Read more.
The escalating global demand for primary energy—still predominantly met by conventional carbon-based fuels—has led to increased atmospheric pollution. This underscores the urgent need for alternative energy strategies capable of reducing carbon emissions while meeting global energy requirements. Hydrogen, as a clean combustible fuel, offers a promising alternative to hydrocarbons, producing neither soot, CO2, nor unburned hydrocarbons. Although nitrogen oxides (NOx) are the primary combustion by-products, their formation can be mitigated by controlling flame temperature. This study investigates the viability of hydrogen as a clean energy vector by simulating an unsteady, turbulent, non-premixed hydrogen jet flame interacting with an air co-flow. The numerical simulations employ the Unsteady Reynolds-Averaged Navier–Stokes (URANS) framework for efficient and accurate prediction of transient flow behavior. Turbulence is modeled using the Shear Stress Transport (SST k-ω) model, which enhances accuracy in high Reynolds number reactive flows. The combustion process is described using a presumed Probability Density Function (PDF) model, allowing for a statistical representation of turbulent mixing and chemical reaction. The simulation results are validated by comparison with experimental temperature and mixture fraction data, demonstrating the reliability and predictive capability of the proposed numerical approach. Full article
(This article belongs to the Special Issue Turbulence and Combustion)
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16 pages, 6257 KB  
Article
Effects of Different Organic Amendments on Aggregate-Associated Humus Carbons and Nutrients in a Paddy Soil
by Qilin Wang, Xiaohou Shao, Zhaomeng Wu and Wei Li
Agronomy 2025, 15(10), 2302; https://doi.org/10.3390/agronomy15102302 - 29 Sep 2025
Viewed by 292
Abstract
The degradation of soil structure in paddy fields is critical, and the application of organic amendments is an effective way to enhance soil structure and function. However, the mechanisms by which different organic amendments influence soil aggregate-associated humus carbon and nutrients remain unclear. [...] Read more.
The degradation of soil structure in paddy fields is critical, and the application of organic amendments is an effective way to enhance soil structure and function. However, the mechanisms by which different organic amendments influence soil aggregate-associated humus carbon and nutrients remain unclear. Considering this, four treatments were employed in a randomized complete block design with three replications: (1) chemical fertilizer (CK); (2) chemical fertilizer plus organic amendment (MC); (3) chemical fertilizer plus organic amendment containing Bacillus subtilis (FT); and (4) Chemical fertilizer plus organic amendment containing polyacrylamide (PM). The results showed that all soil improvement measures significantly increased the proportion of macroaggregates (>2 mm and 2–0.25 mm), primarily the 2–0.25 mm fraction (34.53–48.46%), and the mean weight diameter (MWD), compared to CK. Soil organic carbon (SOC), humic acid carbon (HAC), fulvic acid carbon (FAC), humin carbon (HUC), total nitrogen (TN), and total phosphorus (TP) were predominantly concentrated within the macroaggregates. Relative to CK, the PM increased the HUC content in large aggregates (>2 mm) and significantly enhanced HAC by 19.53% within the same fraction, while the FT significantly boosted FAC by 31.78% in the >2 mm fraction. Furthermore, MC, FT, and PM treatments significantly enhanced SOC, TN, and TP contents within large macroaggregates compared to CK, with PM generally showing the highest SOC and TN levels, and FT being the highest in terms of TP in large aggregates (though differences among treatments were non-significant). Correlation analysis revealed that only in large aggregates did SOC show significant positive correlations with humus carbon fractions (except HAC), as well as with TN and TP. The amendments, particularly PM, effectively enhanced nutrient and humus carbon accumulation within large aggregates and improved aggregate stability. Notably, PM strengthened the direct pathways for the formation of SOC and humus carbon. In summary, the combined application of chemical fertilizer and organic amendments, containing polyacrylamide positively influenced aggregate stability and nutrient accumulation in paddy soil. Full article
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19 pages, 304 KB  
Article
Fermentation-Based Preservation of Okara and In Vitro Evaluation of Its Application in Dairy Cattle Diets
by Yi-Hsuan Chen, Yi-Wen Fang, Po-An Tu, Ching-Yi Chen and Han-Tsung Wang
Fermentation 2025, 11(10), 559; https://doi.org/10.3390/fermentation11100559 - 27 Sep 2025
Viewed by 493
Abstract
Okara, a protein-rich byproduct of soymilk production, is highly perishable because of its high moisture content. This study evaluated the preservation and nutritional value of okara fermented by lactic acid bacteria for use in dairy cattle diets. Fermentation effectively reduced pH within 2 [...] Read more.
Okara, a protein-rich byproduct of soymilk production, is highly perishable because of its high moisture content. This study evaluated the preservation and nutritional value of okara fermented by lactic acid bacteria for use in dairy cattle diets. Fermentation effectively reduced pH within 2 weeks and maintained quality for up to 6 weeks. However, aerobic exposure increased the concentration of ammonia, indicating a decline in stability. In vitro assessments revealed no significant differences in in vitro true dry matter digestibility, in vitro neutral detergent fiber digestibility, or gas production between fermented and fresh okara, although fermented okara had a higher concentration of ammonia nitrogen. In situ analysis revealed slightly lower dry matter effective degradability (ED) in fermented okara, but similar rumen-degradable and undegradable protein fractions. When fermented okara was used to replace soybean meal in total mixed rations, 25–50% inclusion-maintained digestibility and fermentation characteristics, with 25% replacement yielding the highest ED at a low ruminal passage rate (0.02 h−1). Taken together, these results suggest that fermented okara can be strategically incorporated into dairy rations as a sustainable protein alternative, supporting both rumen function and bypass protein supply. Full article
14 pages, 2677 KB  
Article
Effects of Spartina Alterniflora Invasion on Soil Organic Carbon Dynamics and Potential Sequestration Mechanisms in Coastal Wetlands, Eastern China
by Qi Cai, Zhuyuan Yao, Xuefeng Xie, Lijie Pu, Lingyue Zhu, Zhenyi Jia, Shuntao Chen, Fei Xu and Tao Wu
Sustainability 2025, 17(19), 8638; https://doi.org/10.3390/su17198638 - 25 Sep 2025
Viewed by 329
Abstract
Coastal wetlands play a crucial role in carbon sequestration, yet the invasion of Spartina alterniflora (SA) significantly alters the cycling and sequestration of soil organic carbon (SOC) in coastal wetlands. Nevertheless, the potential underlying mechanisms governing the dynamics of SOC in coastal wetlands [...] Read more.
Coastal wetlands play a crucial role in carbon sequestration, yet the invasion of Spartina alterniflora (SA) significantly alters the cycling and sequestration of soil organic carbon (SOC) in coastal wetlands. Nevertheless, the potential underlying mechanisms governing the dynamics of SOC in coastal wetlands following SA invasion remain poorly understood. Here, we investigated the impacts of SA invasion on the dynamics and potential sequestration mechanisms of SOC in the Hangzhou Bay Estuary Wetland, China. Compared to the bare flat (BF), SOC and its fractions in 0–20 cm increased by 1.37–2.24 times after 8 years of SA invasion. Variance partitioning analysis indicated that the combined effects of soil physicochemical properties, soil carbon cycle-related enzymes, and vegetation type were the primary drivers of SOC and its fractions. Redundancy analysis revealed significant positive correlations between SOC and key soil physicochemical properties and enzymes, including sucrase, clay particles, total nitrogen, ammonium nitrogen, and β-glucosidase. Structural equation modeling demonstrated that SA invasion was associated with significant alterations in soil physicochemical properties and positively correlated with both stable and labile carbon fractions, or indirectly linked to these fractions through carbon cycle-related enzymes, thereby substantially positively contributing to SOC. This study supports the hypothesis that the invasion of SA affects the linkage pathway of SOC sequestration and offers valuable guidance for carbon sequestration strategies of coastal wetlands. Full article
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27 pages, 3728 KB  
Article
Soil Aggregate Stability Under Freeze–Thaw Cycles in Mollisols as Evidenced by 15N Distribution
by Yao Wang, Meng Zhou, Xiaoguang Jiao, Liangqian Ma, He Yu, Yimin Chen and Yueyu Sui
Agronomy 2025, 15(10), 2263; https://doi.org/10.3390/agronomy15102263 - 24 Sep 2025
Viewed by 520
Abstract
Freeze–thaw cycles (FTCs) influence soil nitrogen (N) dynamics and soil aggregate stability. However, the driving mechanism affecting aggregate stability from the combined perspective of N components and N distribution by 15N tracing technology in both bulk soils and soil aggregates remains worth [...] Read more.
Freeze–thaw cycles (FTCs) influence soil nitrogen (N) dynamics and soil aggregate stability. However, the driving mechanism affecting aggregate stability from the combined perspective of N components and N distribution by 15N tracing technology in both bulk soils and soil aggregates remains worth exploring. This study took the farmland Mollisols in Hailun City, Heilongjiang Province, as the research object, and investigated the variations in soil N components and aggregate stability across five freeze–thaw frequencies (1, 3, 5, 9, and 17 cycles) under three freeze–thaw temperatures (−9 °C/5 °C, −18 °C/5 °C, and −26 °C/5 °C) using 15N tracing technology. The results demonstrated that freeze–thaw frequency and temperature both influenced aggregate stability. Specifically, with the increase in freeze–thaw frequency, soil aggregate stability was reduced through decreasing the proportion of macroaggregates (2–0.25 mm), increasing the proportion of silt + clay fractions (<0.053 mm), and reducing the total N (TN) content of silt + clay fractions under higher freezing temperature (−9 °C/5 °C). In contrast, for lower freezing temperature (−18 °C/5 °C and −26 °C/5 °C), the increased freeze–thaw frequency enhances soil aggregate stability by decreasing the proportion of silt + clay fractions, increasing the proportion of microaggregates (0.25–0.053 mm), and reducing the TN contents of microaggregates and silt + clay fractions. These findings are essential for developing strategies to mitigate the adverse effects of FTCs on soil quality and ecosystem functions in cold regions. Full article
(This article belongs to the Special Issue Nitrogen Cycle in Agro-Ecosystems)
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25 pages, 47559 KB  
Article
Dynamics and Driving Factors of Soil Carbon Fractions in Corethrodendron scoparium (Fisch. & C. A. Mey.) Fisch. & Basiner. Sand-Fixing Plantations at the South Edge of Tengger Desert, Northwestern China
by Linqi Shi, Quanlin Ma, Rui Ma, Linyuan Wei, Fang Cheng, Guohong Wu, Runjuan Wang and Qian Wei
Forests 2025, 16(9), 1499; https://doi.org/10.3390/f16091499 - 22 Sep 2025
Viewed by 252
Abstract
Establishing artificial sand-fixing plantations is a key strategy for combating land desertification and enhancing soil carbon sequestration in arid regions. To evaluate the effects of Corethrodendron scoparium (Fisch. & C. A. Mey.) Fisch. & Basiner. plantations on soil carbon storage along the southern [...] Read more.
Establishing artificial sand-fixing plantations is a key strategy for combating land desertification and enhancing soil carbon sequestration in arid regions. To evaluate the effects of Corethrodendron scoparium (Fisch. & C. A. Mey.) Fisch. & Basiner. plantations on soil carbon storage along the southern edge of the Tengger Desert, a systematic investigation of the 0–100 cm soil profile was conducted, using mobile sand dunes as the control (CK). The study analyzed dynamic changes in soil carbon fractions and their driving factors during the succession of C. scoparium plantations. After 40 years of vegetation restoration, total soil carbon, soil inorganic carbon (SIC), and soil organic carbon (SOC) contents increased by 0.87-, 0.77-, and 1.27-fold, respectively, while the Carbon Pool Management Index improved by 1.40-fold. Following 10 years of restoration, SIC content, as well as the ratios of particulate organic carbon/SOC, inert organic carbon (IOC)/SOC, and heavy-fraction organic carbon/SOC, increased with soil depth. In contrast, SOC content, the absolute amounts of SOC fractions, and the ratios of dissolved organic carbon/SOC, easily oxidizable organic carbon/SOC, light-fraction organic carbon/SOC, and mineral-associated organic carbon (MAOC)/SOC all showed decreasing trends with depth. Overall, C. scoparium plantations enhanced the contents of both labile and stable SOC fractions. The proportions of IOC and MAOC within SOC rose from 52.21% and 34.19% to 60.96% and 45.51%, respectively, indicating greater stability of the soil carbon pool. Structural equation modeling and redundancy analysis revealed that soil pH, bulk density, and soil water content were significantly negatively correlated with carbon fractions, whereas total nitrogen, vegetation cover, C/N ratio, electrical conductivity, available phosphorus, and alkali-hydrolyzable nitrogen were identified as the main drivers of carbon fraction variation. Full article
(This article belongs to the Special Issue The Role of Forests in Carbon Cycles, Sequestration, and Storage)
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24 pages, 2271 KB  
Article
Co-Ridge Planting Enhances Yield Advantages of Maize Intercropping with Peanut by Improving Soil Aggregate Stability and the Ecological Stoichiometric Characteristics of Carbon, Nitrogen, and Phosphorus
by Zhiman Zan, Rentian Ma, Jiangtao Wang, Ling Liu, Tangyuan Ning and Nianyuan Jiao
Agronomy 2025, 15(9), 2227; https://doi.org/10.3390/agronomy15092227 - 20 Sep 2025
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Abstract
Long-term maize (Zea mays L.) intercropping with peanut (Arachis hypogaea L.) (M||P) improves soil aggregate stability and phosphorus (P) availability, sustaining farmland productivity. In contrast, co-ridge planting (R-M||P) further enhances yield. However, the relationship between yield increase and improvements in soil [...] Read more.
Long-term maize (Zea mays L.) intercropping with peanut (Arachis hypogaea L.) (M||P) improves soil aggregate stability and phosphorus (P) availability, sustaining farmland productivity. In contrast, co-ridge planting (R-M||P) further enhances yield. However, the relationship between yield increase and improvements in soil aggregate stability and ecological stoichiometric characteristics under R-M||P remains unclear. Therefore, this study examined the effects of R-M||P on aggregate fractions and stability, bulk density (BD), porosity (Pt), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), total phosphorus (TP), and inorganic phosphorus, along with the ecological stoichiometric characteristics of C, N, and P. R-M||P substantially increased the proportion of topsoil macroaggregates, both mechanically stable (>0.5 mm) and water-stable (>1 mm), compared with flat planting. Additionally, it enhanced WR0.25 and mean weight diameter, substantially reduced BD, and increased Pt. Furthermore, R-M||P significantly increased the concentrations of SOC, TN, TP, AP, Ca2-P, Ca8-P, Al-P, and Fe-P. It also enhanced the contribution rates of SOC, TN, TP, and AP in macroaggregates, leading to increased storage of carbon (SCS), nitrogen (SNS), and phosphorus (SPS). R-M||P significantly elevated C:N and C:P ratios. Phosphorus application increased SOC and nutrient concentrations, positively regulated C:N, and enhanced C, N, and P storage. However, it negatively influenced C:P and N:P ratios. SOC and AP were the main driving factors affecting the intercropping advantage, with explanatory rates of 33.2% and 22.7%, respectively, under R-M||P. These findings suggest that R-M||P combined with P application enhances yield by promoting aggregate stability, increasing the concentrations and storage of C, N, and P, and establishing a new ecological stoichiometric balance. Full article
(This article belongs to the Section Innovative Cropping Systems)
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18 pages, 1741 KB  
Article
Mechanism of Modified Biochar in Mitigating Carbon and Nitrogen Loss in Drought Soil with Green Manure Application
by Ziyang Zhu, Lu Zhang, Fangyuan Chen, Wenyan Duan, Fangfang Li and Di Zhang
Agronomy 2025, 15(9), 2193; https://doi.org/10.3390/agronomy15092193 - 14 Sep 2025
Viewed by 487
Abstract
With the frequent occurrence of global droughts, modified biochar has demonstrated the potential to be an efficient soil amendment, which could affect carbon and nitrogen sequestration in arid soil. Therefore, this study investigated the co-application of pristine biochar (BC), Fe-modified biochar (FB) and [...] Read more.
With the frequent occurrence of global droughts, modified biochar has demonstrated the potential to be an efficient soil amendment, which could affect carbon and nitrogen sequestration in arid soil. Therefore, this study investigated the co-application of pristine biochar (BC), Fe-modified biochar (FB) and H2O2-modified biochar (HB) with green manure during a 70-day laboratory incubation under drought conditions and normal moisture conditions. The emissions were quantified using gas chromatography, while microbial necromass carbon and nitrogen were measured by quantifying the amino sugar content by gas chromatography–mass spectrometry, and other soil carbon and nitrogen fractions were determined through chemical analysis. The results revealed that under drought conditions, compared to BC co-application with green manure, the total carbon loss of FB and HB co-application with green manure was reduced from 24.38% to 13.14% and 14.27%, respectively, and the total nitrogen loss was also reduced from 14.61% to 7.23% and 7.27%, respectively. This reduction occurred because FB and HB protected soil organic matter through iron oxide binding and micropore adsorption, thereby increasing the content of soil total humus acid (>5%) and microbial necromass nitrogen (>16%). In addition, under normal moisture conditions, BC, FB and HB co-application with green manure enhanced microbial activity and promoted the formation of stable total humus acid, thereby enhancing carbon and nitrogen sequestration. In conclusion, this study provides crucial theoretical support for the optimization of the green manure return via modified biochar co-application in arid environments. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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