Search Results (185)

The changes in functional groups during in situ co-pyrolysis of tar-rich coal with wheat straw were systematically examined using synchrotron diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) coupled with thermogravimetric analysis (TGA). Dynamic changes in C=C, C-O, and C-O-C groups were monitored and assessed across 50–500 °C, complemented by thermogravimetric analysis to assess synergistic effects. It revealed that co-pyrolysis significantly alters the thermal cracking pathways of oxygenated structures, reducing the overall onset temperature by approximately 150 °C. Specifically, instead of maintaining thermal stability, co-pyrolysis promoted early structural aromatization and advanced the C=O decomposition onset by 50 °C compared to coal, achieving a remarkable functional group cleavage rate of 47%. Additionally, the C=C formation temperature was advanced by 150 °C. Furthermore, co-pyrolysis effectively suppressed the secondary structural transformations observed in biomass by limiting the relative accumulation of C–O–C structures to merely a 5% increase, compared to a 52% surge in wheat straw. Interestingly, while DRIFTS confirms facilitated localized bond cleavage and deoxygenation, TGA reveals a macroscopic negative synergy regarding overall weight loss. These findings provide profound insights into the complex radical interactions during co-conversion, offering a crucial theoretical basis for optimizing coal–biomass co-pyrolysis technologies. Full article

Long-term soil fertility is governed by the metabolic plasticity of microbial communities, particularly during the decomposition of crop residues. This study investigated the straw-associated functional microbial profile associated with straw decomposition under the influence of 62 years of continuous management with mineral fertilization and liming. Using the Biolog EcoPlateTM approach combined with a modified litter-bag protocol, we assessed shifts in metabolic activity patterns of functional guilds and groups. PERMANOVA results revealed that the interaction between liming and fertilization (p < 0.05) was the primary driver of divergence in functional communities, rather than the individual effect of factors. Long-term treatments induced a significant reconfiguration of the functional niche, shifting from the native, generalist microbiome to specialized communities in treated variants, with carbohydrate (CH) guilds as dominant and indicators of community performance. Moderate levels of liming (L1) stimulated metabolic activity and maintained higher functional diversity across amino acid (AA) and polymers (Px) guilds. Intensive liming (L2), in contrast, restricted the activity of most microbial functional groups and favored amine (AM) and carboxylic acid (CX) guilds. Shifts from a generalist microbiome in native soil to specialized communities in treated soils show the capacity of microorganisms to adapt efficiently under agronomic management. Full article

Nitrous oxide (N₂O) emissions in cereal-based rotations often show short-lived peaks after fertilization, but their contribution to annual budgets and their responsiveness to straw management remain poorly quantified. We combined a 13-year legacy fertilization experiment with two years of high-frequency N₂O monitoring in a rice–wheat rotation in central China to quantify post-fertilization peak windows and test how straw-return rate modulates these windows and annual emissions. Five long-term treatments were compared: an unfertilized control (CK), straw only (2M, 12 t ha⁻¹ yr⁻¹), mineral fertilizer (NPK), and NPK with 6 or 12 t ha⁻¹ yr⁻¹ straw (MNPK and 2MNPK). Under N input, wheat-season emissions dominated annual totals, with the ratio of wheat-season to annual N₂O emissions (WN/TN, where WN denotes wheat-season N₂O emissions and TN denotes annual cumulative N₂O emissions) of ~73–75% for NPK and MNPK, significantly higher than in CK and the straw-only control. Decomposition of annual fluxes showed that 56.6–65.4% of N₂O in N-applied treatments occurred within short windows after the two wheat-season fertilizations, whereas rice-season peaks were small and largely insensitive to treatment. Planned contrasts expressed as geometric mean ratios (GMRs) with 95% confidence intervals (CIs) highlighted a strong management leverage point: increasing straw from 6 to 12 t ha⁻¹ yr⁻¹ with NPK reduced annual and wheat-season N₂O by ~47% and 58%, respectively, primarily by lowering peak magnitude and shortening peak duration. Microbial analyses suggested that treatment effects on N₂O were better reflected by community compositional shifts (β-diversity) than by α-diversity, while amoA abundance showed guild-specific responses. Collectively, this study provides an event-window quantification framework that links high-frequency field measurements to a specific, actionable mitigation lever (straw-return rate) in rice–wheat systems. Together, these results identify wheat-season post-fertilization windows as the main control points for annual N₂O in rice–wheat rotations and show that pairing NPK fertilization with higher straw return can temper short-lived peaks. By explicitly pinpointing when (which windows) and how (attenuating peak magnitude and duration) mitigation is achieved, our findings offer a management-ready and transferable basis for targeted N₂O abatement in double-cropping systems. Full article

The anaerobic thermal decomposition of plant biomass produces raw materials such as wood charcoal, wood oil, or biogas, which can be used to replace conventional fossil fuels. This enables the development of environmentally friendly alternatives to traditional fuels without the need to develop new technologies, such as engines. The aim of the study was to verify the substances produced during the anaerobic thermal decomposition process of wheat straw. Measurement was carried out by pyrolysis at eight selected temperatures between 350 °C and 1050 °C, with an increase of 100 °C. The analysis was performed on a pyrolyzer coupled to a gas chromatograph (PY/GC-MS). An ANOVA test was used to detect the significance of the results. Based on the ANOVA analysis, the distribution of compound classes in the three temperature regimes was statistically significant. Phenolic compounds reached their highest relative abundance (or relative content) at 650 °C, while PAHs (polycyclic aromatic hydrocarbons) were absent below 550 °C and increased sharply above 850 °C. The results illustrate the thermal decomposition pathway of straw biomass: low-temperature pyrolysis favors the formation of oxygen-rich bio-oils, while higher temperatures increase aromatic condensation and PAH production. Full article

Straw returning, a core practice in conservation tillage, promotes sustainable intensification; however, it faces challenges such as inefficient decomposition, nutrient competition, and pathogen accumulation. To address these limitations, this study aimed to develop a multifunctional microbial consortium specifically designed for straw-incorporating cropping systems. The consortium comprises four Bacillus strains with complementary enzymatic systems, isolated from diverse ecological niches. It exhibited robust lignocellulolytic enzyme production, with manganese peroxidase (7709.33 U/L), laccase (450.65 U/L), endo-β-1,4-glucanase (154.67 U/mL), and filter paper activity (309.18 U/L). The consortium significantly enhanced rice straw degradation by 37.18% and increased nitrogen (N) release by 16.13% compared to the control. Moreover, the consortium exhibited a 67.56% inhibition rate against Magnaporthe oryzae and reduced both the incidence rate and disease index of leaf blast and panicle blast. Field trials revealed increases in the rice grain yield of 9.63% and 6.94% when applied alone and 6.75% and 5.18% when co-applied with straw residues. These findings highlight the multifunctional agricultural potential of the consortium and provide a sustainable strategy to overcome the limitations of straw-incorporating farming systems. Full article

Salinity is a key abiotic stress limiting crop growth. Accurate quantification of carbon budgets and their environmental responses is critical for sustainable cotton production, yet regional-scale assessments remain scarce. To clarify the evolutionary patterns and driving mechanisms of soil organic carbon (SOC) in saline cotton fields of arid Central Asia, this study focused on Xinjiang and modified the RothC model by integrating salinity adjustment factors and vegetation carbon decomposition indices, simulating SOC dynamics (1980–2022) with multi-source data. Results showed the improved model achieved high accuracy in capturing SOC dynamics in salinized cotton fields. Spatially, SOC exhibited high levels south of the Tianshan Mountains and low levels in southwestern Xinjiang; temporally, it showed an overall fluctuating upward trend, though both high- and low-value zones displayed localized declines. Geodetector analysis revealed fertilizer application as the primary driver of SOC spatial variation, followed by straw return, precipitation, and temperature, with most factors showing synergistic enhancement effects. Human management (fertilization and straw return) is the core regulator of SOC, and its synergy with natural factors shapes SOC spatiotemporal patterns. The salinization-adapted RothC model provides a novel framework for arid cotton field SOC simulation, offering scientific support for carbon pool optimization and sustainable agriculture in arid regions. Full article

In the context of advancing sustainable local building materials, this study evaluates the mechanical impact of polypropylene (PP) fiber reinforcement on adobe bricks, specifically addressing the novel variable of fiber addition timing relative to the traditional 45-day biological fermentation process. Two experimental scenarios were investigated: fiber addition before fermentation and fiber addition after fermentation. In the pre-fermentation scenario, the unreinforced control specimen achieved the highest mean compressive strength (1.92 MPa), followed by reduced values of 1.66 MPa (0.25%), 1.60 MPa (0.50%), and 1.55 MPa (1.00%). In the post-fermentation scenario, the control recorded 1.81 MPa, while the PP-reinforced mixtures reached 1.73 MPa (0.25%), 1.65 MPa (0.50%), and 1.77 MPa (1.00%). Across both stages, PP fibers consistently decreased in strength due to weak bonding at the fiber–soil interface, as their hydrophobic nature disrupts the fermentation-derived biopolymer network formed by straw decomposition. Overall, this study highlights the limitations of synthetic fiber reinforcement within biologically stabilized adobe and contributes to the ongoing development of sustainable earthen construction systems. Full article

The mobilization of complex microbial communities from natural resources can be a valuable alternative to the use of single-species biofertilizers when it comes to the decomposition of plant residues. However, the functioning and interaction of microorganisms within these communities remain largely unexplored. Our task was to investigate the cellulose-degrading community using the biofertilizer BAGS (peat-based compost with straw) as an example and define its active component. For this, we monitored the succession of the biofertilizer’s taxonomic composition during two consecutive rounds of its six-month composting process, varying in the applied mineral fertilization. The amount of added nitrogen significantly affected the performance of the biofertilizer, contributing to its high cellulolytic activity. Based on the network analysis, the biofertilizer’s mature phase was determined, and its characteristic ASVs (amplicon sequence variants) were described. Metagenomic analysis of this phase revealed MAGs (metagenome-assembled genomes) corresponding to these ASVs, which contained genes for cellulose and aromatics degradation, as well as genes for nitrogen and sulfur pathways, including anaerobic nitrate reduction and thiosulfate oxidation. Thus, we propose that the cellulose-decomposing bacterial component of BAGS, associated with the mature phase, occupied different trophic niches, not limited to cellulose degradation, which should be considered when designing natural or artificial microbial systems for the decomposition of plant residues. Full article

The sustainable utilization of rice straw is challenged by its recalcitrant lignocellulosic structure, especially under low-to-moderate field temperatures. In this study, a novel microbial consortium (SXJG15) mainly containing Sphingobacterium, Azospirillum, and Pseudomonas was enriched from overwintering rice stubble in Zhejiang, China, and evaluated for its rice straw degradation efficiency at 25 °C. Over an 18-day cultivation period, SXJG15 achieved a 52.5% degradation of total rice straw, including 60.2% cellulose, 76.3% hemicellulose, and 40.7% lignin. High extracellular enzymatic activities, including cellulases (up to 80.3 U/mL) and xylanases (up to 324.8 U/mL), were observed during the biodegradation process. 16S rRNA gene sequencing and metagenomics analyses revealed a succession of dominant taxa, including Sphingobacterium, Azospirillum, and Cellulomonas. Further, CAZy annotation indicated that the SXJG15 enzyme system was rich in glycoside hydrolases (42.7%) and glycosyltransferases (34.2%), demonstrating its high potential for lignocellulose degradation. This study uniquely demonstrates the mesophilic (moderate temperature 25 °C) efficiency of SXJG15 in lignocellulose breakdown, provides new insights into the microbial mechanisms of straw decomposition, and lays a foundation for bioenergy and soil fertility applications for developing a sustainable agriculture system. Full article

Straw incorporation, as a widely recommended agronomic practice, has been continuously enhancing global crop production and soil–water conservation. However, the absence of a direct predictive capability for the long-term residual biomass of incorporated straw, based on management practices, constrains an accurate assessment of its effectiveness for soil conservation. To address these knowledge gaps, this study conducted systematic 4-year in situ monitoring of decomposition pits with varying incorporation amounts (A6 with 6 kg ha⁻¹, A8 with 8 kg ha⁻¹, A10 with 10 kg ha⁻¹, A12 with 12 kg ha⁻¹, and A14 with 14 kg ha⁻¹) and burial depths (D1 with 0–10 cm, D2 with 10–20 cm, D3 with 20–30 cm, D4 with 30–40 cm, D5 with 40–50 cm) to analyze long-term decomposition dynamics. Furthermore, time-dependent equations for post-incorporation residual biomass were developed based on management variables (incorporation amount and burial depth) to enhance the accuracy of soil loss prediction. The results showed that the higher incorporation amounts accelerated decomposition, with the residual straw ratios (RSRs) reduced by 27.4–62.2% compared to lower amounts at equivalent burial depths. Decomposition slowed with depth, and the RSR increased significantly with greater burial depth, rising at rates of 0.2–1.2% cm⁻¹ (p < 0.05). The RSR decreased significantly with longer incorporation duration at rates of 6.9–18.6% a⁻¹ (p < 0.05), with deeper soil layers exhibiting greater decline rates than shallower depths. The relationship between RSR and landfill amount (m), burial depth (d), and landfill years (a) is represented as follows: RSR = 10^1.62 a⁻¹ m^−0.54 d^0.45 (R² = 0.76). Based on this equation, the soil loss ratios (SLRs) under continuous straw incorporation for 4 years were estimated, and the results suggest that constant straw incorporation exerts cumulative effects, progressively reducing the SLR. This study provides the theoretical foundation for promoting and managing straw incorporation practices. Full article

Returning straw to the soil is increasingly recognized as a sustainable practice that enhances soil fertility and promotes carbon sequestration. However, it can also accelerate the decomposition of soil organic carbon (SOC) and CO₂ emissions, raising concerns about carbon loss. This study aimed to clarify the biological and environmental drivers of SOC mineralization across soil depths in a semi-arid system. A 79-day incubation experiment was conducted using wheat straw applied at four rates (0, 3500, 7000, and 14,000 kg ha⁻¹) to soils from 0–10, 10–20, and 20–30 cm. Cumulative CO₂ release, SOC, dissolved organic carbon (DOC), and extracellular enzyme activities were quantified, and relationships were analyzed using correlation and structural equation modeling. Compared with the control, straw return increased cumulative CO₂ emissions by 48–126%, SOC by 9–21%, and DOC by 17–32%. Enzyme activities of β-glucosidase and N-acetylglucosaminidase were 25–64% higher under straw treatments. Structural modeling revealed that enzyme activity had a stronger direct effect on SOC mineralization than chemical properties. These results support the co-metabolism theory, stimulating microbial metabolism to enhance both straw- and native-SOC decomposition. Overall, straw return improves nutrient cycling but increases CO₂ emissions, underscoring the need for optimized management to balance soil fertility with carbon mitigation. Full article

This study evaluated the potential of individual and co-inoculation with Bacillus velezensis (Bv) and Pseudomonas helmanticensis (Ph) as microbial decomposers for corn straw. The co-inoculation (BP) treatment demonstrated the highest total mass loss for cellulose, hemicellulose, and total straw, significantly outperforming the single-strain treatments (Bv and Ph) and the non-inoculated control (CK). All inoculated treatments consistently enhanced degradation over time and lowered pH compared to CK. High-throughput sequencing revealed that inoculation dramatically reshaped the soil microbial community. All treatments reduced microbial ASVs and bacterial alpha diversity (ACE, Chao1, Shannon), with the most pronounced effect observed for Bv. Beta diversity analysis showed distinct, treatment-specific clustering. Critically, FUNGuild analysis indicated a significant functional shift, with all inoculants increasing saprotroph abundance and decreasing pathotrophs. The BP consortium exhibited a synergistic effect, driving saprotroph dominance to >96%. These results demonstrate that the synergistic co-inoculation enhances straw decomposition by restructuring the microbial community towards functional dominance of saprotrophs. Full article

With the increasing global food production year by year, the effective return of crop straw to the field has become an urgent problem to be solved. This study examined the impact of straw decomposition under different return methods on soil ecosystems, focusing on changes in soil biological characteristics. Simulating modern mechanized agricultural practices, an orthogonal experiment was conducted in the haplic Phaeozem region of Northeast China. The factors studied included the amount, length, and burial depth of straw returning. A comprehensive analysis model was built using path analysis, factor analysis, and response surface methodology to investigate the response of soil ecosystem during straw decomposition. This was assessed from four aspects: soil basic nutrients, organic carbon pool, enzyme activity, and microbial community structure. The study found evidence of a strong synergistic relationship between the soil enzyme system and straw decomposition. Notably, during the mid-phase of straw return (60 days), phosphatase and particulate organic carbon (POC) acted as “mirror” antagonistic indicators. Catalase, soil nitrate nitrogen, and POC were identified as key response indicators in the soil ecosystem post-straw return. The appropriate supplementation of nitrogen during the early (0–45 days) and late (75–90 days) stages of straw return was found to facilitate straw decomposition. These findings provide experimental evidence for the return of corn straw in cold haplic Phaeozem regions and offer scientific support for sustainable agricultural practices and national food security. Full article

Straw return is crucial for sustainable agriculture, but its efficiency is limited by low temperatures in cold regions, especially in saline-alkali soils. This study investigates the degradation process of maize straw and the response of soil properties and microbial communities during the winter low-temperature period in the alkaline farmland of Anda, China. A two-year field experiment with straw return (SR) and no return (NR) treatments was conducted. Straw degradation rates and structural changes (as observed via scanning electron microscope, SEM) were monitored. Soil physicochemical properties and enzyme activities were analyzed. Microbial community composition was characterized using 16S rRNA and ITS sequencing. The cumulative straw degradation rate over two years reached 94.81%, with 18.33% occurring in the first winter freeze–thaw period. Freeze–thaw cycles significantly damaged the straw structure, facilitating microbial colonization. Straw return significantly improved soil properties after winter, increasing field water capacity (3.45%), content of large aggregates (6.57%), available nutrients (P 38.17 mg/kg, K 191.93 mg/kg), and organic carbon fractions compared to NR. Microbial analysis revealed that low temperatures filtered the community, enriching cold-tolerant taxa like Pseudogymnoascus, Penicillium, and Pedobacter, which are crucial for lignocellulose decomposition under cold conditions. The winter period plays a significant role in initiating straw degradation in cold regions. Straw return mitigates the adverse effects of winter freezing on soil quality and promotes the development of a cold-adapted microbial consortium, thereby enhancing the sustainability of alkaline farmland ecosystems in Northeast China. Full article

In the global agricultural production system, maintaining and improving soil quality are core elements for ensuring food security and sustainable agricultural development. As a key indicator of soil quality, the content and dynamic change in soil organic carbon have a profound impact on the physical, chemical and biological properties of soil, and play a decisive role in soil fertility, structural stability, water and fertilizer conservation capacity and microbial activity. However, its decomposition is slow, and a large number of straws returning to the field will impact crop growth; its combination with irrigation is a more reasonable solution, as it can significantly improve the soil environment, increase soil moisture and promote straw decomposition. Therefore, in order to further study the effects of different irrigation methods and straw-returning combinations on soil active-carbon content, an experiment was carried out in long-term arid and semi-arid areas under in-field corn cultivation during 2019–2020. Three irrigation modes were designed—flood irrigation (BI), shallow drip irrigation (SD) and drip irrigation under film (DP)—and straw returning (CS) and no straw returning (CK) were set up, with irrigation applied at critical corn growth stages (internode elongation, heading, bell mouth stage) to support plant growth. The results are as follows: (1) The content of soil organic carbon in different treatments had a gradual upward trend with the advance of growth period; the content of soil organic carbon in DP treatment was significantly higher than that in SD and BI treatment under the same straw returning mode, indicating that drip irrigation under film and straw-returning mode can synergistically improve soil fertility and organic carbon content. (2) Different irrigation methods and straw-returning methods have significant effects on the content of soil active organic carbon components. Different drip irrigation modes can significantly improve the content of soil POC and MBC compared with flood irrigation. The Kos of SD treatment is significantly higher than that of other irrigation treatments, and the CPMI is lower than that of the other two irrigation methods, indicating that the soil organic carbon of SD treatment is more stable. Therefore, under straw-returning conditions, drip irrigation can significantly improve the carbon content of soil components and the management index of soil carbon pool, thus significantly increasing the accumulation of soil organic matter. This study discussed the effects of straw returning on soil organic carbon composition and soil carbon pool index under different irrigation methods to provide theoretical and practical bases for the selection and promotion of straw-returning methods and rational irrigation methods in semi-arid areas. Full article