Soil organic matter (SOM) molecular composition governs its stability and ecological functions in forest ecosystems. Nevertheless, how land-use changes (LUCs) regulate the SOM molecular composition remains poorly understood, particularly the underlying mechanisms mediated by soil properties. This study investigated the effects of LUCs on SOM molecular composition in a subtropical coastal region and examined the driving roles of soil nutrient availability and enzyme activities. The research was conducted in Huanghai National Forest Park, Jiangsu Province, China, focusing on four land-use types converted from historical wheat cropland (W, as control): monoculture plantations of Ginkgo biloba (G) and Metasequoia glyptostroboides (M), a ginkgo–metasequoia mixed forest (GM), and a ginkgo–wheat agroforestry system (GW). Soil samples were collected from 0 to 20 cm and 20–40 cm layers and analyzed for SOM molecular compositions using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Soil chemical properties and enzyme activity activities were also determined, with redundancy analysis (RDA) and correlation analysis applied to identify key influencing factors. Results demonstrated that LUCs significantly altered SOM molecular composition. The GW system exhibited the highest proportion of labile O-alkyl carbon (42.65%), while the M plantation accumulated greatest levels of stable aromatic carbon (up to 49.25%). During the initial decades following afforestation, soil nutrient availability and enzyme activities were confirmed as pivotal drivers of SOM molecular variation. Specifically, available potassium (AK), ammonium nitrogen (AN), and the carbon/phosphorus (C/P) ratio were significantly correlated with specific SOM components (p < 0.05). The elevated O-alkyl carbon proportion in GW was closely associated with its higher invertase activity. Notably, vertical differentiation in SOM stability was observed across land-use types, with the agroforestry system achieving the highest carbon pool management index in surface soil but showing a weakened capacity for subsoil C stabilization. RDA further confirmed that AK and AN were dominant factors shaping SOM molecular composition. In conclusion, LUCs modulate SOM chemical composition and stability primarily through altering soil nutrient availability and associated enzyme activities. Agroforestry system facilitates labile C accumulation in surface soil, whereas monoculture plantations are more conducive to stable C sequestration, especially in subsoil layers. These findings provide novel mechanistic insights into SOM dynamics following LUCs and offer a theoretical basis for formulating tailored management strategies to enhance C sequestration efficiency in subtropical coastal ecosystems.

Background Addressing soil saline-alkalization is crucial for sustaining cotton production in the arid regions of Xinjiang. This study investigates the efficacy of Micro-Nanobubble oxygenated irrigation (MNBs) compared with conventional flooding (CF) in ameliorating saline-alkali soil and enhancing cotton growth. Methods A field microplot experiment was conducted across four soil salinity levels (0, 3%, 6%, and 9%, with sulfate as the dominant salt). Results The results demonstrated that MNBs effectively reduced topsoil (0~20 cm) salinity and mitigated its associated alkalinity stress by facilitating salt leaching into deeper soil layers (20~60 cm). This irrigation method also significantly improved soil enzyme activities and altered ionic dynamics toward a more favorable balance. Moreover, MNBs enhanced soil bacterial diversity, enriched beneficial phyla such as Proteobacteria and Actinobacteria, and modulated fungal genera including Alternaria and Fusarium, suggesting an improved rhizospheric microbiome. In terms of cotton physiology, Micro-nanobubble oxygenation irrigation significantly enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD) in cotton leaves by 15.84% to 40.69% and 10.11% to 33.63%, respectively, while reducing malondialdehyde (MDA) content by 28.22% to 42.11%, thereby alleviating saline-alkali stress-induced oxidative damage. Additionally, MNBs promoted root growth by 0.96% to 29.90%, increased the leaf area index by 18.68% to 25.50%, and enhanced dry matter accumulation by 6.82% to 33.29%. Ultimately, these improvements led to a higher seed cotton yield. Compared with conventional flooding (CF), the MNBs treatment increased seed cotton yield by 33.78%, 35.93%, 47.11%, and 52.31% across the four salinity levels, respectively. Conclusion In conclusion, micro-nanobubble oxygenation irrigation represents an effective strategy for rehabilitating saline-alkali soils and promoting sustainable agricultural development in arid areas.

Agricultural film microplastics counteract root exudate-induced cadmium behavior changes in soil revealed by PLS-PM analysis.

ABSTRACTSubstantial interspecific variation in both drought responses and soil functioning among woody species poses significant challenges for predicting drought impacts on soil functioning in species‐rich tropical and subtropical forests. However, critical knowledge gaps remain regarding how soil functions respond to drought across different plant species. We conducted a three‐phase (10 months of well‐watered conditions, 1 month of drought treatment, and 2 months of rewetting) seedling experiment to assess how drought impacts on eight rhizosphere soil functions related to carbon, nitrogen, and phosphorus cycling vary across 10 woody species. We tested whether plant species' preferences to arid versus moist habitats and functional traits could predict variation in the resistance and recovery of soil functions to drought. We found that soil functions of species adapted to the arid habitat or those possessing stronger drought‐tolerant traits (e.g., lower leaf water potential at turgor loss point) showed comparable resistance to their counterparts. Species with lower root N:P ratios and root non‐structural carbon concentrations consistently recovered faster in all four measured soil enzyme activities. Our results demonstrate that root chemical traits, particularly root N:P ratios and root non‐structural carbon concentrations, strongly predict soil enzyme activity recovery from drought. These findings significantly improve our understanding and prediction of drought impacts on soil functioning in species‐rich forests.

In sub-Saharan regions, soil fertility is a major concern for plant productivity, influenced by physical, chemical, and biological components. Among biological properties, the recruitment of soil microbial communities by plant roots is influenced by both physico-chemical soil properties and plant characteristics, dependent on species or genotypes. Here, rhizosphere bacterial communities associated with five fonio genotypes cultivated under three pedoclimatic conditions were investigated. Rhizosphere soils were collected for high-throughput 16S rRNA gene sequencing to characterize soil bacterial diversity. Additional parameters were assessed to classify soil fertility of the three pedoclimatic conditions and to evaluate relationships between the bacterial community’s composition and soil fertility variables. Principal Component Analysis revealed a clear effect of pedoclimatic condition, whereas genotype had no significant impact on soil chemical properties or enzyme activities. Overall, soils were low in fertility, with Boukoumbe soil standing out for its higher chemical values and enzyme activities. For example, Boukoumbe reached 1.48% organic carbon, compared to 0.61% in Gogounou and 0.36% in Ina. Similarly, total nitrogen and available phosphorus were also higher in Boukoumbe. Regarding bacterial community, there is no impact of pedoclimatic condition and genotype on their richness and diversity. However, Bray-Curtis index revealed a significant difference in bacterial community structure among pedoclimatic conditions, but not among fonio genotypes. This suggests, in rhizosphere, bacterial community structure is more modulated by soil properties than crop genotypes. Proteobacteria and Bacteroidota were most abundant phyla, varying significantly across pedoclimatic conditions. Moraxellaceae and Oxalobacteraceae bacteria were most abundant families within Proteobacteria, while Chitinophagaceae and Weeksellaceae dominated in Bacteroidota. Our study highlighted the significant roles of soil pH, as well as sulfate and nitrate content, in shaping bacterial communities. These findings offer valuable insights into the bacterial communities associated with fonio and their key drivers.

In intensive cropping systems, limited understanding of how residues with contrasting biochemical qualities decompose leads to nutrient immobilization, poor nutrient release synchrony and persistent residue burning challenges. The decomposition dynamics of various crop residues displayed unexpected variations at both the early and late stages, with the precise underlying factors for these differential responses to diversity remaining unclear. We hypothesized that the chemical composition and biochemical diversity of crop residues specifically difference in lignin, cellulose, hemicellulose, protein, phenol, nitrogen content and C: N ratio would substantially influence their decomposition dynamics and associated microbial and enzymatic responses at different time points. In an incubation experiment, we examined nine treatments, each with three replicates: maize stover (T1), rice straw (T2), cotton stalks (T3), redgram stalks (T4), greengram residue (T5), blackgram residue (T6), sunhemp residue (T7), soybean residue (T8), and sorghum stover (T9). We closely monitored the transformation of lignocellulose, total phenols and proteins in these crop residues using the litter bag method alongside measurements of soil enzyme activities and microbial population dynamics. Results revealed distinct decomposition patterns, where legume-based residues (sunhemp (T7), greengram (T5), blackgram (T6) and soybean (T8)) exhibited rapid degradation of lignocellulosic fractions and protein content within 60 days, associated with early peaks in microbial populations and enzyme activities (cellulase, xylanase, laccase and lignin peroxidase). In contrast, residues high in lignin, C:N ratio, lignin: N ratio and phenol: N ratio such as redgram stalks (T4), maize stover (T1), rice straw (T2), cotton stalks (T3) and sorghum stover (T9) decomposed more slowly, showing prolonged microbial activity and enzyme induction up to 120 days. Total phenol content initially declined (0-30 days after incorporation) and subsequently increased, reflecting the release and transformation of bound phenolics. Principal component analysis (PCA) revealed that residue biochemical traits, especially nitrogen content, lignin level and phenol content, strongly influenced microbial succession and enzymatic response. Overall, the decomposition sequence of biochemical components followed the order: lignin < cellulose < hemicellulose < proteins, and the enzyme activity followed the order: lignin peroxidase < cellulase < xylanase. These findings emphasize the importance of residue quality in regulating decomposition dynamics and offer actionable strategies for tailoring residue management to enhance nutrient cycling and soil health.

Background Rhizosphere microorganisms play a critical role in plant growth and medicinal quality, yet their altitudinal patterns and interactions with soil nutrients and bioactive compounds in Angelica sinensis ( A. sinensis ) remain poorly understood. Methods Using Illumina MiSeq sequencing, we analyzed bacterial, fungal, arbuscular mycorrhizal (AM) fungal, and archaeal diversity across an altitudinal gradient, alongside soil physicochemical characteristics and bioactive components. Results As cultivation elevation increased, bacterial and fungal diversity initially increased significantly and then stabilized ( p &amp;lt; 0.05). In contrast, AM fungal and archaeal communities remained relatively stable. Bacterial communities varied significantly across altitudes (stress &amp;lt; 0.1, p = 0.001), as did soil nutrients and enzyme activities ( p &amp;lt; 0.05). Bioactive components, except for ferulic acid, varied significantly with altitude. Redundancy analysis (RDA) confirmed that altitude and soil factors are key drivers of microbial community assembly. Mantel tests and structural equation modeling (SEM) demonstrated significant correlations between soil properties, microbial diversity, and medicinal properties of A. sinensis ( p &amp;lt; 0.05). Conclusion The mid-to high elevation zone (2520–2717 m) was identified as optimal for both yield and bioactive compound accumulation. These findings deepen the understanding of how microbes adapt to different altitudes in medicinal plants and offer a framework for precise cultivation of A. sinensis , thereby supporting the high-altitude symbiosis theory.

The coupling between tree biomass and soil microhabitats is central to subtropical forest soil functioning, yet species- and stage-specific tree–soil interactions remain understudied. This study quantified these interactions in two dominant species—Cunninghamia lanceolata (Lamb.) Hook. (C. lanceolata) and Quercus fabri Hance (Q. fabri)—across five diameter at breast height (DBH) classes (5–10, 10–15, 15–20, 20–25, 25–30 cm). Soil quality was characterized via the Soil Quality Index (SQI) based on 16 physicochemical and enzyme activity parameters, while random forest models identified biomass importance. Soil properties and enzyme activities varied with diameter class (p &lt; 0.05): C. lanceolata showed a unimodal pattern (minimum at 15–20 cm DBH), whereas Q. fabri increased consistently (peaking at 20–30 cm DBH). The diameter class × species interaction significantly influenced SQI (p &lt; 0.01): Q. fabri showed higher SQI than C. lanceolata at larger DBH, and vice versa at smaller DBH. Aboveground biomass dominated SQI variation in C. lanceolata (weight = 0.57), whereas belowground biomass dominated in Q. fabri (weight = 0.52; model R2 &gt; 0.75). These findings demonstrate that DBH size and species identity jointly shape soil microenvironments, providing a mechanistic basis for informed subtropical forest management.

The effect of afforestation in infertile mountainous areas is closely related to the soil ecological environment. Soil enzyme activities and the structure and functions of microbial communities are core indicators reflecting soil quality. Clarifying the response patterns of the two to Cyclobalanopsis gilva afforestation in infertile mountainous areas can provide a key scientific basis for targeted improvement of the cultivation efficiency of C. gilva plantations under different site conditions in the eastern subtropical region of China. In this study, 7-year-old C. gilva young forests in infertile mountainous areas and control woodland areas were selected in Shouchang Forest Farm, Jiande, Zhejiang Province, located in the subtropical region of China. Soil enzyme activities and microbial biomass in different soil layers, as well as metagenomes of rhizosphere and bulk soils, were determined to explore the effects and internal correlations of site conditions on soil enzyme activities and microbial community characteristics of C. gilva forests. The results showed that the activities of urease and catalase, as well as the content of microbial biomass nitrogen in the surface soil of infertile mountainous areas, were significantly lower than those in control woodland areas. The shared dominant phyla in the two types of sites included Proteobacteria and Acidobacteria, and the shared dominant genera included Bradyrhizobium. In addition, the relative abundances of three unclassified populations of Proteobacteria and functional genes related to cofactor and vitamin metabolism in the rhizosphere soil of infertile mountainous areas were significantly higher than those in control woodland areas. Meanwhile, the dominant microbial phyla in the rhizosphere soil of infertile mountainous areas had a closer correlation with soil enzyme activities and microbial biomass. This study clarified the ecological strategy of C. gilva young forests adapting to infertile mountainous areas: by increasing the relative abundances of functional genes related to cofactor and vitamin metabolism in rhizosphere microorganisms, promoting the enrichment of microorganisms associated with soil nitrogen cycling, and enhancing the correlations between dominant microbial phyla and soil enzyme activities and microbial biomass, the nitrogen resource limitation on soil microbial activity in infertile mountainous areas is balanced. This finding provides direct guidance for optimizing the afforestation and management techniques of C. gilva in infertile mountainous areas and has important practical value for promoting forest ecological restoration.

The present study was conducted at Regional Agricultural Research Station (RARS), Palem, Nagarkurnool, Professor Jayashankar Telangana Agricultural University, Telangana, India during kharif 2023 and 2024 to evaluate plant density and weed management methods influence on soil enzymes activity. High density planting, recorded significantly higher soil enzyme activities (urease, dehydrogenase, phosphatase and β glucosidase activity) at 30, 60 and 90 DAS except at harvest compared to normal planting. Robotic mechanical intercultivation which was on par with weed free recoded significantly higher soil enzymes activity (urease, dehydrogenase and β glucosidase) compared to herbicides application through drone spaying, robotic spraying and manual spraying at 30 DAS. At 60, 90 DAS and harvest the applied herbicide showed no statistically significant effect on soil enzymes activity, during both the years of experimentation.

Heavy metal contamination of agricultural soils, particularly by zinc (Zn) and cadmium (Cd), threatens food security and ecosystem health. This study evaluated the in situ phytoremediation potential of Ricinus communis L. in Zn- and Cd-contaminated field soils amended with citric acid (CA), spent mushroom substrate (SMS), and their combination (CA+SMS). Across contamination levels, SMS and CA+SMS significantly increased total biomass to 164.70 ± 5.61 and 162.80 ± 4.11 g per plant, respectively, compared with 77.38 ± 3.40 g in the unamended control (one-way ANOVA with Tukey’s HSD, p < 0.05). Accordingly, total Zn extraction increased by 114.86% (SMS) and 104.89% (CA+SMS), while total Cd extraction increased by 112.80% and 99.22%, respectively (p < 0.05). Cd bioconcentration factors (BCF) remained > 1 across all treatments, whereas Zn BCF remained < 0.33. At high contamination, CA+SMS enhanced soil enzyme activities (urease and catalase (CAT)), with CAT reaching 1.98 ± 0.01 mL 0.1 mol L−1 KMnO4 g−1 h−1). SMS maintained seed oil content (∼ 55.71 ± 1.78%). Overall, R. communis is a high-biomass, metal-tolerant candidate for field phytoremediation, and CA+SMS is a practical, low-cost strategy that enhances plant uptake while promoting metal sequestration into less labile reducible/oxidizable/residual fractions relative to exchangeable/carbonate-bound pools.

Peat smouldering leads to smoke emissions, which can subsequently have an effect on the soil, causing pollution by deposition and smog. As a consequence, there may be a change in the biological properties of soils, which influences soil fertility. To study the effects of gaseous substances on soil, several laboratory experiments (modelling the potential effects of smoke on soil) were carried out. As a result of the research, the activity of soil enzymes, class of oxidoreductases (catalase, peroxidase, polyphenoloxidase) was decreased after 30-120min of soil treatment with peat smoke. Meanwhile, the enzymes of the hydrolase class (invertase, phosphatase) remained basically unchanged. The pH of soil suspension after smoke exposure decreased by 0.28 units after the first and second experiments. Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, biphenyl, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene and dibenzo[a,h]anthracene were found in soil samples. Some of the substances in the experimental (smoke-treated) samples exceeded background (non-smoked) samples. The total amount of the analysed substances was 493.92ng/g.

Bacterial wilt caused by Ralstonia solanacearum is a devastating soil-borne disease that seriously threatens tobacco yield and quality worldwide. Excessive nitrogen fertilization has been widely implicated in soil microecological imbalance and increased disease incidence; however, the regulatory mechanisms underlying nitrogen reduction remain poorly understood. Here, a randomized block field experiment was conducted with four basal nitrogen application levels, including conventional fertilization and 10%, 20%, and 30% nitrogen reduction. Disease incidence, rhizosphere soil physicochemical properties, enzyme activities, and microbial community structure were systematically assessed using biochemical analyses and high-throughput sequencing. The results showed that moderate nitrogen reduction significantly decreased the rhizosphere abundance of R. solanacearum, leading to a marked reduction in disease incidence and severity. With decreasing nitrogen input, soil pH increased, while moderate nitrogen reduction significantly enhanced available nitrogen, phosphorus, and potassium, microbial biomass carbon and phosphorus, and optimized the activities of urease, acid phosphatase, nitrate reductase, and nitrite reductase. Microbial community analysis revealed that nitrogen reduction reshaped community structure, increased α-diversity, and enriched beneficial genera such as Arthrobacter and Amycolatopsis. Redundancy analysis further identified soil pH, microbial biomass carbon, acid phosphatase activity, and soil organic matter as the primary drivers of microbial community shifts. Overall, these findings demonstrate that moderate reduction of basal nitrogen fertilization effectively suppresses tobacco bacterial wilt by improving rhizosphere soil properties and steering microbial community assembly toward a disease-suppressive state. This study provides both a theoretical basis and practical guidance for sustainable tobacco disease management and nitrogen reduction strategies.

Due to the presence of essential plant nutrients and either acid or alkaline properties, coal ash can be a valuable amendment in improving characteristics and crop productivity of alkaline or acidic soils. This study aimed to evaluate the effects of coal ash application to woodland and arable soils on soil pH, selected soil enzyme activities (dehydrogenase, acid phosphatase, alkaline phosphatase, urease and β-glucosidase) and on vegetative growth of wheat. Two pot experiments were conducted in which wheat (Triticum aestivum var. Willow) was grown in woodland and arable soils amended with ash collected from either the UK or Tanzania, at concentrations of 0, 2, 4, 8 and 16% (w/w). Wheat was grown for 50 days. Soil amendment with UK ash at 0-16 % increased significantly (p&lt;0.001) the pH of woodland and arable soils while amendment with Tanzanian ash at 0-16 % reduced the pH of both soils (p&lt;0.001). Application of low concentrations (0-4%) of UK ash to both soils increased dehydrogenase and urease activities and wheat growth, but these ash concentrations didn’t show any significant effect on alkaline and acid phosphatase activities. Glucosidase activity increased significantly (p&lt;0.001) when woodland soil was amended with 2% of UK ash, then decreased significantly with increasing ash concentration. Application of 16% UK ash also inhibited acid and alkaline phosphatase activities. Application of the Tanzanian ash at low concentration did not have any significant effect on the activities of enzymes studied while application at 8-16% inhibited all enzyme activities. Tanzanian ash did not affect wheat growth parameters when applied to both soils while UK ash improved wheat growth. This study demonstrates that soil amendment with coal ash can either cause beneficial or detrimental effects, depending on the nature of the ash and soil characteristics thus, strategic agronomic use of coal ash is recommended.

The Sanjiang Plain hosts the largest freshwater wetland in Northeastern China and plays a critical role in regional climate stability. However, climate change and human activities have degraded the wetland, forming a successional gradient from the original flooded wetland to dry shrub and forest vegetation with a lower ground water level. This degradation has altered soil microbial structure and functions, reducing ecological and socio-economic benefits. Along this successional gradient, we used Biolog-ECO plates combined with soil enzyme assays (catalase, urease, sucrase, and acid phosphatase) to assess the dynamics of microbial carbon metabolic activity, measured by average well color development (AWCD). The results showed a systematic decline in AWCD values with advancing succession, revealing a pronounced reduction in overall microbial metabolic activity during wetland degradation. This trend correlated with loss of soil moisture, organic carbon, and nitrogen nutrients. Microbial communities in early successional wetland stages (i.e., original natural wetland and wetland edge) preferred labile carbon sources (e.g., carbohydrates, amino acids), while forested stages favored relatively more structural (e.g., polymers, phenolic compounds). These findings indicate that vegetation succession regulates microbial carbon metabolism by modifying soil physicochemical properties, providing insights for wetland restoration.

Climate change has intensified the frequency and severity of urban droughts, exposing urban green spaces to abrupt and extreme water shortage that disrupts plant-microbe interactions and microbial multifunctionality. Understanding how rhizosphere and phyllosphere microbial communities respond to drought and how these shifts influence urban microbial functions is crucial for developing strategies to enhance the resilience of urban ecosystems under climate change. In this study, we conducted microcosm experiments simulating four drought intensities, integrating omics technologies with soil enzyme stoichiometry to investigate the effects of drought on microbial communities associated with Zoysia japonica (Steud) and urban microbial multifunctionality. Our results demonstrate that drought intensities significantly altered the compositions of bacterial and fungal communities in both the rhizosphere and phyllosphere. Moreover, drought enhanced microbial multifunctionality by significantly affecting 21 microbial functional potentials, including carbon fixation and denitrification. Although urban microbial multifunctionality largely returned to the control level after rehydration, five functions remained altered, including phyllosphere organic nitrogen mineralization and soil polyphenol oxidase activity. Biotic factors, particularly rhizosphere bacteria and fungi, directly influenced microbial multifunctionality during drought, whereas abiotic factors, such as electrical conductivity, dissolved organic carbon, and ammonium-nitrogen (NH4+-N), had indirect effects. After rehydration, abiotic factors, especially pH and NH4+-N, emerged as the main direct drivers. These findings underscore a shift from biotic to abiotic regulation of urban microbial multi-functionality across drought and rehydration, emphasizing the vital role of microbial communities in ecosystem resilience and the need to consider both biotic and abiotic factors in urban drought management.

IntroductionUnderstanding the dynamics of soil organic carbon (SOC) in sloping farmlands is critical, as they play a vital role in the global carbon cycle and soil health. Although prior research has focused on physical carbon loss due to erosion, the biological mechanisms by which slope gradients affect microbial carbon cycling remain poorly understood.MethodsSoil samples were collected from maize fields with three slope gradients (30°, 45°, and 60°) across different growth stages. Key indicators were determined as follows: SOC by potassium dichromate oxidation (external heating method); DOC by ultrapure water extraction (1:5 ratio) and organic carbon analyzer; POC by sodium hexametaphosphate dispersion, 53-μm sieving, and chromic acid oxidation; soil Ca2+, Mg2+, and Cl− by EDTA complexometric titration and silver nitrate titration, respectively; invertase (SUC) by 3,5-dinitrosalicylic acid colorimetry; polyphenol oxidase (SPPO) and peroxidase (SPOD) by commercial kits with L-dopa as substrate. Statistical analyses were performed using IBM SPSS 26 (One-way ANOVA with LSD post-hoc test, Pearson correlation analysis) and Origin 2024 (Principal Component Analysis, PCA). Normality of data was verified prior to analysis, and significance was set at P < 0.05.ResultsResults showed that SOC levels decreased with increasing slope steepness, while DOC peaked at 45°. SPPO and SPOD activities (involved in recalcitrant carbon decomposition) were significantly elevated at 60°. SUC activity was positively correlated with DOC, while oxidase activities were positively associated with POC and negatively with Mg2+.DiscussionThis study identifies a critical slope threshold (30°–45°) for DOC loss: DOC availability on steeper slopes stimulates microbial synthesis of SPPO and SPOD, enhancing recalcitrant carbon degradation and potentially intensifying long-term SOC depletion. The identification of this threshold provides insights for designing microbiome-informed strategies to mitigate soil degradation and safeguard ecological security.

Resilience mechanisms in soil organic carbon storage after pre-commercial thinning in mixed oak-pine forests.

The present field experiment was undertaken at Wheat and Maize Research Unit, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani to assess the Compatibility and Influence of Microbial Inoculants and their Consortia on Maize Grown on Vertisol during Kharif season of 2022. Ten different treatment combinations were used in the experiment which includes different microbial inoculants and their consortia Azospirillum + Bacillus megaterium (Consortia-I), Azospirillum + Frateuria aurantia (Consortia-II), Azospirillum + Thiobacillus thioxidase (Consortia-III), Azospirillum + Psedomonas strita (Consortia-ⅠⅤ), Azospirillum + Bacillus megaterium + Frateuria aurantia (Consortia-Ⅴ), Azospirillum + Bacillus megaterium + Thiobacillus thioxidase (Consortia-ⅤI), Azospirillum + Bacillus megaterium + Psedomonas strita (Consortia-ⅤII), and control replicated there in RBD (Randomized Block Design). Seed treatment of maize was done with microbial inoculants consortia @ 10 ml kg-1 seed and application at the time of sowing with recommended dose of fertilizers. Significantly higher value, of available N, P2O5 and K2O5 were recorded at tasseling and harvesting stage of maize in treatment receiving RDF + Azospirillum + PSB + ZnSB. Further, DTPA Fe, Mn, Zn and Cu were recorded maximum at tasseling and harvest stage of maize in the treatment receiving RDF + Azospirillum + PSB + ZnSB as soil is deficient in Zn and Fe. The treatment with RDF + Azospirillum + PSB + ZnSB treatment also increased the content and uptake of nitrogen, phosphorus, potassium and micronutrients (Fe, Mn, Zn and Cu) in maize significantly. The soil microbial quality attributes were also improved significantly with RDF + Azospirillum + PSB + ZnSB, the maximum bacterial, actinomycetes and fungal population was seen in the treatment with RDF + Azospirillum + PSB + ZnSB in soil at tasseling and harvest stage of maize. The treatment receiving RDF + Azospirillum + PSB + ZnSB showed the higher values of soil enzymes i.e., dehydrogenase, acid phosphatase, and alkaline phosphates at tasseling and harvesting stage of maize.

Continuous cropping of tobacco can lead to the occurrence of deterioration of soil microbial ecosystems, exacerbation of viral pests, and reduction of quality, whereas corn-tobacco rotation can effectively alleviate the obstacles of continuous cropping. The study objective was to explore the effects of different planting styles on the microbial environment and yield of tobacco. The experiment was carried out in March-October 2023 in a tobacco planting demonstration field in Xianru Township, Dunhua City, Jilin Province. The experiment was conducted on rhizosphere soils of 2 years of corn - 1 year of tobacco, 3 years of corn - 1 year of tobacco, 2 years of continuous tobacco, 3 years of continuous tobacco. Soil nutrients and enzyme activities were determined, and the effects of microbial community structure on tobacco yield were analyzed based on 16S rDNA and ITS sequences. Crop rotation significantly increased the total nitrogen, quick-acting phosphorus and organic matter contents as well as protease activity of the rhizosphere soil, and significantly decreased the peroxidase activity. Crop rotation increased the diversity and richness of bacteria in tobacco-planting soil, while continuous cropping significantly enhanced the richness of the fungal community, and crop rotation could improve the diversity of the fungal community (P < 0.05). The relative abundance of Gemmatimonas was significantly higher in crop rotation than in continuous cropping, while the relative abundance of Penicillium, Asterostroma and Fusarium in the continuous cropping pattern was significantly higher than that in the rotational cropping. Crop rotation pattern tobacco plant dry weight, stem circumference, maximum leaf length and wide leaf were increased, and the proportion of upper and medium tobacco increased. Gemmatimonas was positively correlated with plant height, stem girth and dry weight; Sphingomonas was positively correlated with medium and top-quality cigarettes; at the level of fungal genera, Asterostroma and Fusarium were negatively correlated with agronomic traits of tobacco. Corn-tobacco rotation can effectively improve soil fertility, enrich bacterial communities, and increase the proportion of indicator beneficial bacteria. Continuous cropping leads to increased abundance of pathogenic bacteria. This study provides theoretical support for the mitigation of tobacco continuous cropping disorder and the detection and remediation of farmland soil.