Search Results (127)

The priming effect (PE), a microbially mediated process, critically regulates the balance between carbon sequestration and mineralization. This study used soils from different soil depths (0–20 cm, 20–40 cm, and 40–60 cm) under Picea schrenkiana forest in the Tianshan Mountains as the research object. An indoor incubation experiment was conducted by adding three concentrations (1% SOC, 2% SOC, and 3% SOC) of ¹³C-labelled glucose. We applied ¹³C isotope probe-phospholipid fatty acid (PLFA-SIP) technology to investigate the influence of readily labile organic carbon inputs on soil priming effect (PE), microbial community shifts at various depths, and the mechanisms underlying soil PE. The results indicated that the addition of ¹³C-labeled glucose accelerated the mineralization of soil organic carbon (SOC); CO₂ emissions were highest in the 0–20 cm soil layer and decreased trend with increasing soil depth, with significant differences observed across different soil layers (p < 0.05). Soil depth had a positive direct effect on the cumulative priming effect (CPE); however, it showed negative indirect effects through physico-chemical properties and microbial biomass. The CPE of the 0–20 cm soil layer was significantly positively correlated with ¹³C-Gram-positive bacteria, ¹³C-Gram-negative bacteria, and ¹³C-actinomycetes. The CPE of the 20–40 cm and 40–60 cm soil layers exhibited a significant positive correlation with cumulative mineralization (CM) and microbial biomass carbon (MBC). Glucose addition had the largest and most significant positive effect on the CPE. Glucose addition positively affected PLFAs and particularly microbial biomass. This study provides valuable insights into the dynamics of soil carbon pools at varying depths following glucose application, advancing the understanding of forest soil carbon sequestration. Full article

This article presents a review of several non-exclusive pathways for the sequestration of soil organic carbon, which can be classified into two large classical groups: the modification of plant and microbial macromolecules and the abiotic and microbial neoformation of humic substances. Classical studies have established a causal relationship between aromatic structures and the stability of soil humus (traditional hypotheses regarding lignin and aromatic microbial metabolites as primary precursors for soil organic matter). However, further evidence has emerged that underscores the significance of humification mechanisms based solely on aliphatics. The precursors may be carbohydrates, which may be transformed by the effects of fire or catalytic dehydration reactions in soil. Furthermore, humic-type structures may be formed through the condensation of unsaturated fatty acids or the alteration of aliphatic biomacromolecules, such as cutins, suberins, and non-hydrolysable plant polyesters. In addition to the intrinsic value of understanding the potential for carbon sequestration in diverse soil types, biogeochemical models of the carbon cycle necessitate the assessment of the total quantity, nature, provenance, and resilience of the sequestered organic matter. This emphasises the necessity of applying specific techniques to gain insights into their molecular structures. The application of appropriate analytical techniques to soil organic matter, including sequential chemolysis or thermal degradation combined with isotopic analysis and high-resolution mass spectrometry, derivative spectroscopy (visible and infrared), or ¹³C magnetic resonance after selective degradation, enables the simultaneous assessment of the concurrent biophysicochemical stabilisation mechanisms of C in soils. Full article

Soil degradation exerts profound impacts on soil ecological functions, global food security, and human development, making the development of effective technologies to mitigate degradation a critical research focus. Microorganisms play a leading role in rehabilitating degraded land, improving soil hydraulic properties, and enhancing soil structural stability. Mosses contribute to soil particle fixation through their unique rhizoid structures; however, the mechanisms underlying their interactions in mixed inoculation remain unclear. Therefore, this study addresses soil and water loss caused by rainfall erosion in the cold black soil region. We conducted controlled laboratory experiments cultivating Bacillus subtilis and cold-adapted moss species, evaluating the erosion mitigation effects of different biological treatments under gradient slopes (3°, 6°, 9°) and rainfall intensities (70 mm h⁻¹, 120 mm h⁻¹), and elucidating their carbon-based structural reinforcement mechanism. The results indicated that compared to the control group, Treatment C significantly increased the mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates by 121.6% and 76.75%, respectively. In separate simulated rainfall events at 70 mm h⁻¹ and 120 mm h⁻¹, Treatment C reduced soil loss by 95.70% and 96.75% and decreased runoff by 38.31% and 67.21%, respectively. Crucially, the dissolved organic carbon (DOC) loss rate in Treatment C was only 21.98%, significantly lower than that in Treatment A (32.32%), Treatment B (22.22%), and the control group (51.07%)—representing a 59.41% reduction compared to the control. This demonstrates the following: (1) Bacillus subtilis enhances microbial metabolism, driving carbon conversion into stable pools, while mosses reduce carbon leaching via physical barriers, synergistically forming a dual “carbon protection–structural reinforcement” barrier. (2) The combined inoculation optimizes soil structure by increasing the proportion of large soil particles and enhancing aggregate stability, effectively suppressing soil loss even under extreme rainfall erosion. This study elucidates, for the first time, the biological pathway through which microbe–moss interactions achieve synergistic carbon sequestration and erosion resistance by regulating aggregate formation and pore water dynamics. It provides a scalable “carbon–structure”-optimized biotechnology system (co-inoculation of Bacillus subtilis and moss) for the ecological restoration of the cold black soil region. Full article

Climate change, driven by rising atmospheric concentrations of greenhouse gases (GHGs) such as CO₂, poses the most pressing environmental challenges today. Soil carbon (C) sequestration emerges as a crucial strategy to mitigate this issue by capturing atmospheric CO₂ and storing it in soil organic carbon (SOC), thereby reducing GHG levels and enhancing soil health. Although soil is the largest terrestrial C sink, capable of storing between 1500–2400 petagrams (Pg) of C, the practical potential for SOC sequestration through regenerative practices is still widely debated. This review examines the biotic, abiotic, structural, physical, and chemical limitations that constrain soil C sequestration, along with the human dimensions that influence these processes. It explores the role of plant physiology, root architecture, microbial interactions, and environmental factors in determining the efficacy of SOC sequestration. Furthermore, it discusses the potential innovative strategies, including photosynthetic modifications, root system engineering, microbial bioengineering, and the application of advanced materials such as C-capturing minerals, poly-carboxylic compounds, and nanomaterials, to enhance C capture and storage in soils. By providing a comprehensive understanding of these factors, this review aims to inform future research and policy development, offering pathways to optimize soil C sequestration as a viable tool for climate change mitigation. Full article

Fertilization management constitutes a critical determinant of agroecosystem productivity. Reasonable fertilization can increase the organic matter content in soil; however, the potential mechanism of how different fertilization regimes impact soil carbon sequestration is unclear. We hypothesized that the combined application of biochar and organic fertilizer would enhance soil carbon sequestration by improving soil physicochemical conditions, increasing microbial activity, and promoting the accumulation of stable forms of carbon. This study systematically investigated different regimes, including the application of chemical fertilizer alone (SCN), chemical fertilizer with biochar (SCB), chemical fertilizer with organic fertilizer (SCO), and chemical fertilizer with both biochar and organic fertilizer (SCBO), on soil physiochemical properties, enzyme activities, labile organic carbon fractions, microbial carbon fixation gene expression, and community composition. The results demonstrated that (1) the application of organic materials significantly enhanced soil nutrient levels and enzyme activities, with the best performance from SCBO; (2) the organic materials increased the labile soil organic carbon (SOC) content and the carbon pool management index, with SCO showing the highest at 69.82%; (3) SCB and SCBO improved the stability of soil carbon components by increasing the proportion of Aromatic C; and (4) the carbon fixation genes ACAT and sdhA exhibited the highest abundance in SCBO. In parallel, the relative abundance of Actinomycetota increased with the application of organic materials, reaching its peak in SCBO. Mantel testing revealed a strong correlation between microbial community composition and SOC, emphasizing the importance of SOC in microbial growth and metabolism. Moreover, the strong correlation between carbon fixation genes and aromatic carbon suggested that specific carbon forms, particularly aromatic structures, played a critical role in driving microbial carbon fixation processes. Full article

Ecological restoration has increasingly been employed to reverse land degradation and increase carbon (C) sink, especially in ecologically fragile karst areas. Microbial necromass carbon (MNC) constitutes a critical pool within soil organic carbon (SOC), contributing substantially to long-term C sequestration through mineral stabilization. However, its distribution patterns across soil profiles and grassland restoration stages in karst areas remain unclear. To address this knowledge gap, the contents of bacterial necromass C (BNC), fungal necromass C (FNC), and their contributions to SOC were estimated based on glucosamine and muramic acid contents across the soil profile (0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, and 80–100 cm) for four subalpine restoration stages (grazing enclosure for 5, 11, 17, and 25 years) in the karst region. Our findings demonstrated that both soil depth and grassland restoration stages effectively influenced the BNC and FNC contents. On average, the soil BNC, FNC, and total MNC at the depth of 80–100 cm reduced by 70.50%, 59.70%, and 62.18% compared with in topsoil (0–20 cm), respectively. However, the FNC/BNC ratio gradually increased with the increase in soil depth, which was 43.15% higher at 80–100 cm soil depth than in topsoil, suggesting that the accumulation efficiency of FNC was higher compared to BNC in the deep soil. The BNC, FNC, and MNC were positively correlated with the grassland restoration stage, while FNC/BNC ratio had a negative relationship with the restoration stage (R² = 0.45, p < 0.001). FNC contributed significantly more to SOC (28.6–36.4%) compared to BNC (7.7–9.9%) at all soil depths, indicating that soil fungal necromass has an essential effect on SOC sequestration. The results of the random forest model and distance-based redundancy analysis identified that pH, soil water content, and dissolved organic carbon were the three most essential predictors for the contribution of MNC to SOC. Our study highlights the importance of microbial necromass to SOC accumulation, providing significant scientific implications for the C pool management during the restoration of degraded grasslands in karst regions. Full article

Albic soils in Northeast China are characterized by low fertility due to factors such as high viscosity, acidity, and carbon depletion. To address these challenges and promote sustainable crop production, biochar and manure have been suggested as soil amendments. However, the mechanisms behind these improvements remain unclear. This study involved a pot experiment to explore how varying levels of biochar application (0.5%, 1.0%, and 2.0%), alone or combined with cow manure (0.5%), affect soil properties. The dual application of biochar (2.0%) and manure (0.5%) elicited synergistic improvements in soil functionality, surpassing individual treatments. The total organic carbon (TOC) increased by 10.4% and 54.9% relative to that associated with biochar-only (2.0%) and manure-only (0.5%) amendments, respectively, with concurrent structural shifts toward stabilized carbon forms—evidenced by elevated alkyl C content (16.3%) and alkyl C/O–alkyl C ratios (22.8%). Soil physical structure was enhanced, as total porosity (5.64%) rose by 2.0% and pH (6.0) increased by 4.7% compared to sole biochar application. Microbial community analysis revealed that the combined treatment amplified bacterial diversity (Chao1 index 26.9%) and catalase activity (67.0%) while reducing Acidobacteria dominance (24.0%), which was indicative of improved metabolic adaptation. These findings demonstrate that biochar–manure coupling drives carbon sequestration through dual mechanisms: (1) physical stabilization via pore architecture modification and (2) biochemical modulation through microbial network complexity. Full article

The carbon emissions from the cement industry account for approximately 8% of global carbon emissions, which exerts significant pressure on the environment. In this paper, the microbial-induced calcium carbonate precipitation (MICP) technology was introduced into the carbonization modification research of recycled hardened cement powder (RHCP), and the carbon sequestration performance of RHCP under different pressures was studied. The physicochemical properties of the carbonated products were characterized by microscopic testing methods, and the carbon sequestration mechanism under different pressures was obtained. Subsequently, carbonated RHCP (C-RHCP) was tested as a partial cement substitute for solidified sludge to evaluate its mechanical and durability properties. The results show that when the pressures were 0.3 and 0.5 MPa, the carbon sequestration capacity of RHCP was relatively good, reaching 59.14 and 59.82 g/kg, respectively. Since the carbon sequestration amounts under the two pressures were similar, and considering the energy consumption, in this study, a reaction pressure of 0.3 MPa was selected to prepare C-RHCP. Compared with pure cement, the 28-day unconfined compressive strength (UCS) of the sludge cured with 30% C-RHCP increased by 12.08%. The water stability coefficient of the solidified sludge in the C-RHCP group was greater than 1 after soaking for 7, 14, and 21 days, while the water stability coefficient of the cement group decreased to 0.92 at 14 days. After 20 freeze–thaw cycles, the mass losses of the cement group, the RHCP group, and the C-RHCP group were 31.43%, 38.99%, and 33.09%, respectively. This research not only provides an environmentally friendly strategy for the resource utilization of RHCP but also pioneers a new synergistic model that combines microbial mineralization with the modification of industrial solid waste. It demonstrated significant scientific value and engineering application prospects in reducing carbon emissions in the cement industry and promoted sustainable geotechnical engineering practices based on the “waste–waste” principle. Full article

Soil amendments such as limestone and gypsum can influence microbial carbon use efficiency (CUE) by altering nutrient stoichiometry, particularly nitrogen (N) and phosphorus (P). However, their effects beyond the topsoil, especially under no-till systems, remain unclear. This study assessed microbial CUE through substrate use efficiency (SUE) following glucose addition as a factor influencing carbon (C) sequestration potential. Two experiments were conducted in tropical soil. The first evaluated the addition of ¹⁴C-glucose (G) to soil treated with lime, lime + gypsum, and a control, with or without the addition of N. The second compared limestone + gypsum and control treatments, incorporating G with N and P. Soil microbial respiration (CO₂ emission) was measured after 14 and 42 days. In the surface soil (0–10 cm), CUE increased with limestone or limestone + gypsum when N was applied. In the subsoil (40–60 cm), these amendments enhanced CUE compared to untreated soil in the absence of N. Treatments with G+N+P or G+P improved CUE in the surface soil. At the same time, G+N+P increased CUE in the subsoil regardless of acidity alleviation. Differences in ¹⁴CO₂ evolution indicated higher microbial CUE with acidity correction. Balanced N and P applications significantly enhanced CUE, highlighting the importance of both soil acidity correction and nutrient availability for microbial carbon processing. Full article

The key objectives of contemporary agriculture are restoring biodiversity, preserving ecosystem health, reducing the effects of climate change, and producing safe and healthy foods. Maintaining high soil fertility while reducing greenhouse gas emissions requires a precise assessment of how fertilization and crop rotation affect carbon and nutrient cycles in agroecosystems. Fertilization affects soil conditions, which alters the environment for soil microbial development and influences the number and composition of soil microbial communities, leading to changes in nutrient and carbon cycling. There is a lack of long-term experimental data on the impact of fertilizer treatments on soil CO₂ emissions, soil microbial communities, and their interactions. The novelty of this study is that it identified the fertilization effects on soil carbon sequestration, soil properties, and microbial communities in the context of a long-term fertilizer experiment in Luvic Chernozem. The fertilization treatments that were continuously pplied for 64 years under a four-crop (wheat, barley, corn, and bean) rotation were nitrogen (N), phosphorus (P), potassium (K), NP, NK, PK, NPK, and control. The chemical and microbiological soil properties and soil CO₂ emissions were monitored. The highest organic carbon content was observed under the NPK (1.42%) and NP (1.43%) treatments. N fertilizer application most significantly affected soil properties, including pH, electrical conductivity, and soil organic carbon content, altering the environment for soil microbial development and influencing the number and composition of soil microbial communities. On average, the field-measured soil C-CO₂ emissions were the most intensive under NP (2.76 kg ha⁻¹ h⁻¹), NPK (2.83 kg ha⁻¹ h⁻¹), and PK (2.51 kg ha⁻¹ day⁻¹) treatments. Full article

Microbially induced carbonate precipitation (MICP) is the precipitation of CaCO₃ crystals, induced by microbial metabolic activities such as ureolysis. Various applications of MICP have been proposed as innovative biocementation techniques. This study aimed to verify the feasibility of ureolysis-driven MICP applications in deep-subsurface environments (e.g., enhanced oil recovery and geological carbon sequestration). To this end, we screened sludge collected from a high-temperature anaerobic digester for facultatively anaerobic thermophilic bacteria possessing ureolytic activity. Then, we examined the ureolysis-driven MICP using a representative isolate, Bacillus haynesii strain SK1, under aerobic, anoxic, and strict anaerobic conditions at 30 °C, 40 °C, and 50 °C. All cultures showed ureolysis and the formation of insoluble precipitates. Fourier transform infrared spectroscopy analysis revealed precipitates comprising CaCO₃ at 30 °C, 40 °C, and 50 °C under aerobic conditions but only at 50 °C under anoxic and strict anaerobic conditions, suggesting efficient MICP at 50 °C. Interestingly, an X-ray diffraction analysis indicated that calcium carbonate crystals that were produced under aerobic conditions were in the form of calcite, while those that were produced under anoxic and strict anaerobic conditions at 50 °C were mostly in the form of vaterite. Thus, we demonstrated ureolysis-driven MICP under high-temperature and O₂-depletion conditions, suggesting the potential of MICP applications in deep-subsurface environments. Full article

China has approximately 3.43 million hectares of tea plantations, which offer significant potential for carbon sequestration and the reduction of CO₂ emissions. However, the mechanisms underlying the stability and mineralization of soil organic carbon (SOC) in different tea plantations remain unclear. This study aimed to comprehensively evaluate the effects of chemical, physical, and microbial factors on SOC mineralization in tea plantations with different methods of forest conversion to tea plantations and different ages of tea plants. Our findings indicate that forest conversion to tea plantation methods and tea planting age significantly influence SOC mineralization. Specifically, the SOC mineralization in tea plantations reclaimed by clear-cutting and burning (FMT4) was lower than in those reclaimed by partial cutting (MT3, MT30, and MT150). This variation is attributed to differences in the chemical structure of SOC, which showed higher proportions of aromatic C (33.4%) and carbonyl/carboxyl C (7.8%), alongside lower proportions of O-alkyl C, in the FMT4 tea plantation compared to the others. Additionally, SOC mineralization was significantly higher in the MT150 tea plantation (15.23 g C kg⁻¹ SOC) than in the MT3 (10.11 g C kg⁻¹ SOC), MT30 (10.38 g C kg⁻¹ SOC), and MT200 plantations (9.13 g C kg⁻¹ SOC). Notably, although the MT200 tea plantation had a higher proportion of O-alkyl C (42.4%) than the MT3 and MT30 plantations (36.4%), and was similar to the MT150 plantation (43.1%), its SOC mineralization remained lower due to the higher clay content (278 g kg⁻¹). Correlation analysis and random forest analysis further revealed that physical properties, particularly clay content, are the most significant factors regulating SOC mineralization, followed by the chemical structure, such as O-alkyl C and aromatic C, as well as other physicochemical properties like the carbon-to-nitrogen (C/N) ratio, and microbial properties like Gram-positive bacteria. In conclusion, our study highlights the complex interplay of soil physical properties and SOM chemical structure and microbial properties in regulating SOC mineralization, providing valuable insights for improving carbon management in tea plantations. Full article

Intercropping is an effective approach for enhancing soil organic carbon (SOC) sequestration. However, the effects of intercropping on SOC dynamics and the underlying factors in rhizosphere and bulk soils are still unclear. In this study, we examined the impacts of sugarcane monoculture and sugarcane–watermelon intercropping on soil properties, soil respiration, SOC fractions, and microbial C limitation with continuous two years in 2023–2024 years in the Nala area of Guangxi Province. Our results revealed that intercropping significantly decreased CO₂/SOC by 25% and microbial C limitation by 21% in the rhizosphere, with more pronounced reductions observed in bulk soil by 33% and 25%, respectively. This means that the intercropping reduced soil respiration and this effect can be offset by the rhizosphere effects. Additionally, the sugarcane–watermelon intercropping increased the contents of mineral-associated organic carbon (MAOC) by 15~18% and particulate organic carbon (POC) by 34~46%. The random forest analysis indicated that enzyme activities (explaining 20~38% of variation) and soil properties (explaining 22% of variation) were the primary drivers of reduced CO₂ emissions. The PLS-PM showed that intercropping decreased microbial C limitation by influencing soil pH and soil water content (SWC), and then increased MAOC, which finally led to a decline in CO₂ emissions. Overall, these findings highlight the decreasing CO₂ emissions during the use of the intercropping system and the importance of microbial C limitation in the soil C cycle via soil respiration and SOC fractions. Full article

The high-input production mode of rice monoculture (RM) has caused severe soil degradation and biodiversity loss, necessitating a transition toward more sustainable practices. The traditional rice-fish co-culture (RF) may provide valuable insights for this situation. However, it remains elusive how long-term RF system influences soil microbial community structure, enzyme activities, and carbon (C) sequestration. Here, a study was conducted at two representative RF areas in Lianshan Zhuang and Yao Autonomous County. At Shatian (P1), three treatments included rice monoculture (RM1) and 2-year and 5-year RF (RF2, RF5). At Gaoliao (P2), the experimental treatments included rice monoculture (RM2) and 15 and 30 years of RF (RF15, RF30). We collected the surface layer (0–20 cm) soils. Then, we analyzed the chemical properties, phospholipid fatty acids (PLFA), and enzyme activities to investigate the effects of their variation on soil C sequestration. The results showed that RF treatments significantly increased soil organic C (SOC) content. Specifically, RF2 and RF5 treatments promoted the SOC content by 4.82% and 13.60% compared with RM1 treatment at P1, respectively; RF15 and RF30 treatments increased the SOC content by 23.41% and 31.93% compared with RM2 treatment at P2, respectively. Additionally, RF5 treatment significantly increased the biomass of the soil microbial community in comparison with RM1 treatment, as did RF15 treatment and RF30 treatment compared with RM2 treatment, including the contents of total PLFA and the PLFA of gram-positive bacteria (G+), gram-negative bacteria (G−), actinomycetes, fungi, and bacteria. Activities of β-glucosidase, cellobiohydrolase, β-1,4-N-acetylglucosaminidase, and urease significantly increased in RF5 and RF30 treatments. The piecewise SEM results indicated that the changes of total PLFA content and the PLFA content ratio of fungi to bacteria were related to contents of dissolved organic C (DOC) and total N (TN) under different RF durations, which are key indicators affecting SOC content. Overall, SOC storage increases with the RF durations, and soil microbial community structure may drive soil C sequestration under long-term RF, which provides a scientific significance and practical value in promoting the sustainability of agricultural ecosystems, enhancing the potential of soil as a carbon sink, and addressing global climate change. 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