Search Results (374)

Biological soil crusts (BSCs) play key roles in arid, semi-arid regions and ecological marginal habitats. This study focused on four types of sand-fixing plantations established in 1990 in alpine sandy land (Salix psammophila, SL; Caragana korshinskii, NT; Salix cheilophila, WL; Populus simonii, XYY). Soil samples were collected from bare sand, algae crusts, and moss crusts. Soil particle size distribution, physicochemical properties, and enzyme activity were determined. Then bacterial communities were analyzed using high-throughput (Illumina) sequencing and the correlations among these three factors were examined. The results showed that: (1) From bare sand to algae and moss crusts, the content of fine particles (clay + silt) gradually increased. (2) Soil water content (SWC), nutrients and enzyme activities increased progressively. (3) In the study area, the dominant bacterial phyla of BSCs included Pseudomonadota, Cyanobacteria, Actinobacteriota and Vibrionota. Principal Coordinates Analysis (PCoA) and Analysis of Similarities (ANOSIM) results showed that BSCs drive the differentiation of bacterial communities during succession, while forest stands influence their spatial distribution. (4) Spearman’s correlation and redundancy analysis (RDA) showed that available phosphorus (AP), alkaline hydrolyzable nitrogen (AN), soil organic matter (SOM), catalase (CAT), pH, soil water content (SWC), and alkaline phosphatase (ALP) are key physicochemical factors shaping the bacterial community structure of BSCs. Mantel’s test confirmed that these variables mediated BSCs’ bacterial community structure. This study elucidates the mechanisms underlying ecological restoration via BSCs and provides a theoretical basis for future restoration efforts in alpine sandy land. Full article

Phenolics in Sphagnum can inhibit its microbial decomposition. Climate warming and drainage have driven vascular plants, such as Ericaceae, to expand into Sphagnum-dominated peatland. However, the impact of fine root invasion by Rhododendron auriculatum Hemsl. on Sphagnum decomposition and changes in phenolic compounds remains unclear. This study compared Sphagnum decomposition in a Sphagnum palustre L.-dominated peatland and an R. auriculatum (Sapling)–S. palustre peatland by examining the microscopic structure of S. palustre and microbial community composition. Decomposition was higher in the R. auriculatum–S. palustre peatland. On this site, bacterial metabolic types such as aerobic chemoheterotrophy and chemoheterotrophy had higher relative abundances, as did fungal trophic modes, including those with combined ectomycorrhizal, ericoid mycorrhizal, and saprotrophic functions. Acid phosphatase, laccase, total nitrogen (TN), C/N ratio (C:N), and pH differed significantly across decomposition stages. Microbial communities are affected by physicochemical factors and enzyme activities. Untargeted metabolomics revealed more downregulated than upregulated phenolics, cinnamic acids, and tannins, indicating loss of phenolic compounds. In summary, R. auriculatum fine root invasion altered enzyme activities and physicochemical properties, driving the restructuring of bacterial and fungal trophic modes and accelerating S. palustre cell wall and hyaline cell decomposition. Full article

Morchella sextelata a species of high nutritional and economic value, is widely cultivated. To investigate how different cultivation environments affect the soil physicochemical properties and microbial communities associated with common morel, this study established cultivation plots under three distinct settings: apple orchard canopies, dry upland fields, and paddy fields. The objective was to compare the differential impacts of common morel cultivation on soil environmental conditions across these habitats. The results indicate that cultivating common morel effectively enhances soil fertility. Across all environments, soil hydrolyzable nitrogen (HN), available potassium (AK), and organic matter content were higher than in the control. In apple orchard and dryland soils, total phosphorus (TP), total potassium (TK), available phosphorus (AP), and pH values were also elevated compared to the control, with most differences reaching significant levels. Solid Sucrase (S-SC) activity increased in all environments compared to the control, with values of 17.52 mg/d/g in PG, 17.39 mg/d/g in HD, and 21.68 mg/d/g in DT soils. Soil Amylase (S-AL) activity was higher in PG (451.28 μg/h/g) and HD (475.38 μg/h/g) soils. In contrast, Soil-acid phosphatase (S-ACP) activity was significantly elevated in DT soil (2922.08 nmol/h/g). PG soil exhibited significantly higher activities of Solid-Catalase (S-CAT), Solid polyphenol oxidase (S-PPO), and Solid Urease (S-UE), with S-CAT reaching 952.5 μmol/h/g. Following common morel cultivation, bacterial richness and diversity decreased across all conditions, while fungal richness increased but diversity declined. At the phylum level, Proteobacteria remained the dominant bacterial group, accounting for 26.78% in PG, 28.27% in HD, and 20.05% in DT soils. Ascomycota was the predominant fungal phylum, comprising 68.03% in PG, 72.16% in HD, and 68.94% in DT soils. Predicted bacterial functional pathways were primarily associated with metabolism, genetic information processing, environmental information processing, and cellular processes. Key metabolic pathways included carbohydrate metabolism, amino acid metabolism, and metabolism of cofactors and vitamins. fungal functional guilds were mainly classified as pathotrophic, pathotrophic–saprotrophic, pathotrophic–saprotrophic–symbiotrophic, and saprotrophic. Among these, saprotrophic and pathotrophic guilds showed higher abundance compared to the control. This shift is characterized by a reduction in both the diversity and abundance of beneficial microorganisms, alongside an increase in the richness of harmful microbial taxa. The combined effect of these factors disrupts the soil microbial equilibrium. The findings of this study provide a theoretical foundation for the cultivation of common morel and the management of associated soils. Full article

Acidified soils in greenhouse vegetable systems constrain crop production and soil ecological functions. This study investigated the effects of different amendment treatments on soil ecological factors in acidified soils under greenhouse spinach cultivation in Baoqing County, China. Three treatments were established: farmyard manure alone (T1), Haijuneng soil amendment, an alkaline oyster-shell-based soil conditioner, alone (T2), and the combined application of farmyard manure and Haijuneng soil amendment (T3). High-throughput sequencing of the 16S rRNA gene combined with functional prediction was used to analyze soil bacterial community characteristics and their relationships with soil physicochemical properties and enzyme activities. The results showed that soil pH increased significantly under T2 compared with T1 (4.59 vs. 4.14), along with higher exchangeable calcium (16.11 vs. 12.20 cmol kg⁻¹) and exchangeable magnesium (5.54 vs. 3.83 cmol kg⁻¹). In contrast, T3 showed the highest organic matter content (48.54 g kg⁻¹) and phosphatase activity. Compared with T1, both T2 and T3 increased urease activity and altered bacterial community structure and functional composition, while microbial diversity was highest under T2. Soil pH and available phosphorus were the main factors driving bacterial community variation, whereas pH, exchangeable calcium, and exchangeable magnesium were significantly correlated with multiple dominant genera and KEGG level 2 pathways. Overall, the amendment strategies showed distinct effects: compared with the conventional practice of farmyard manure alone, Haijuneng soil amendment alone was more effective in partially alleviating soil acidification, whereas its combined application with farmyard manure was more favorable for soil organic matter accumulation and enhancing soil phosphorus supply potential. Full article

A two-year field experiment was conducted in Tengchong, Yunnan, to evaluate the effects of tobacco monoculture (TM) and maize relay intercropping with tobacco (TIM) on subsequent tobacco growth and the rhizosphere microenvironment. Results showed that TIM significantly increased plant height by 11.8% and maximum leaf length by 12.4% at the vigorous growth stage without reducing yield. Although leaf chloride content increased and the potassium-to-chloride ratio decreased, both remained within high-quality ranges. Relay-cropped silage maize yielded 4.86 t·hm⁻², adding 1.70 × 10⁴ CNY·hm⁻². TIM reduced nitrogen accumulation in aboveground tobacco and temporarily lowered soil organic matter and available potassium, while increasing acid phosphatase, peroxidase, and urease activities. Soil bacterial α-diversity increased, with enrichment of beneficial genera, including Candidatus Solibacter, Talaromyces, and Penicillium. Metabolomics identified 1043 metabolites, with upregulation of galactinol, N-acetyl-L-tryptophan, and 3-dehydroshikimic acid, enriched in cyanogenic amino acid and cysteine–methionine pathways. PLS-PM and Mantel analyses indicated that relay-cropped maize indirectly regulates nutrient availability via microbial and metabolic pathways. These results show that maize relay intercropping creates a soil “legacy effect,” shifting the system from direct nutrient competition to microbially mediated nutrient buffering. Full article

Monoculture plantations often face challenges of soil degradation and declining ecosystem services. Intercropping is beneficial to improving soil quality; however, the long-term effects of intercropping woody plants with medicinal herbs on soil ecosystems remain unclear. This study aimed to investigate the temporal effects of different durations of poplar intercropping with Aralia elata on soil physicochemical properties, enzyme activities, and soil microbial community structure. Soil samples were collected from the 0–20 cm soil layer, with composite samples obtained by mixing four soil cores per plot. We determined soil physicochemical properties, including pH, total carbon (TC), total nitrogen (TN), and total phosphorus (TP); soil enzyme activities, including invertase, urease, phosphatase, and β-N-acetylglucosaminidase (NAG); and soil microbial community structure using high-throughput sequencing of the bacterial 16S rRNA gene and fungal ITS region. Intercropping significantly affected soil chemical properties and enzyme activities in poplar plantations. Compared with the monoculture control (Y), TN (p < 0.01) and TC (p < 0.01) contents increased significantly in the 3- and 7-year intercropping treatments. The activity of β-N-acetylglucosaminidase (NAG) was enhanced following poplar–Aralia elata intercropping. In addition, intercropping significantly changed the composition and structure of soil microbial communities. In summary, introducing Aralia elata into poplar plantations can effectively improve soil fertility and reshape soil microbial community structure. This positive effect is time-dependent and becomes more significant with a 7-year intercropping duration. Poplar–Aralia elata intercropping represents a feasible management strategy to enhance ecological sustainability and soil health in plantation ecosystems of Northeast China. Full article

Integrating biochar with plant growth-promoting rhizobacteria (PGPR) is a promising strategy for sustainable soil management; however, the synergistic mechanisms governing rhizosphere microbial assembly remain inadequately understood. In this study, we investigated the combined effects of maize biochar (YM) and Bacillus amyloliquefaciens (BA) on tomato performance, soil physicochemical properties, and bacterial community dynamics via a controlled pot experiment. The results demonstrated that the synergistic treatment (YMBA) significantly enhanced tomato yield by 18.3% compared to the control, outperforming individual applications. This promotion was coupled with a comprehensive improvement in soil fertility, characterized by significant increases in soil organic matter (SOM), available nutrients (N, P, and K), and the activities of urease and acid phosphatase. High-throughput sequencing revealed that YMBA treatment significantly restructured the rhizosphere bacterial community, significantly increasing microbial richness and diversity. Notably, the synergistic application promoted the recruitment of beneficial taxa, particularly within the phylum Pseudomonadota. Mantel test analysis further elucidated that SOM and available phosphorus (AP) were the primary environmental drivers shaping the bacterial community turnover. Our findings suggest that biochar acts as a functional niche that facilitates B. amyloliquefaciens colonization and modulates the indigenous microbiota, providing a theoretical framework for utilizing cross-trophic synergies to optimize crop productivity and soil health. Full article

Purpose: Black soils in Northeast China are declining in fertility under intensive fertilization, motivating strategies that integrate crop residue return with microbial inoculation. We conducted a field experiment to test whether maize straw return combined with compound microbial inoculants improves soil properties, bacterial communities, and soybean performance. Methods: A field experiment compared four treatments: fertilization alone (F), fertilization + inoculants (CF), fertilization and straw (SF), and fertilization and straw with inoculants (CSF). Soil physicochemical properties, enzyme activities, 16S rDNA-based bacterial communities, and soybean agronomic yield were measured across growth stages. Results: CSF produced the highest soybean performance, and increased yield by 3.91–5.46% compared with F. CSF increased soil pH, moisture, and nutrient availability (notably available P and K) and enhanced sucrase, urease, catalase, and acid phosphatase activities compared with other treatments. Bacterial communities were dominated by Acidobacteriota and Proteobacteria. CSF increased bacterial abundance and shifted community composition, and pH and available P were key factors associated with community variation. Conclusions: Co-applying maize straw and compound microbial inoculants enhances soybean yield while improving soil biochemical functioning and reshaping bacterial communities in black soil. Full article

Protected cultivation of pepper in southern China’s red soil region often leads to soil degradation and continuous cropping obstacles. To investigate whether biochar can alleviate these problems by regulating the soil microenvironment, pot and incubation experiments were conducted from 2021 to 2023 with biochar application rates of 0~10% (w/w). The results showed that appropriate biochar application significantly improved pepper yield and soil quality. Under the 6% biochar treatment, pepper yield and dry matter accumulation increased by 89.05% and 36.79%, respectively, compared to the control. Soil bacterial and fungal abundances increased by 346.61% and 107.37%, and their OTU numbers rose by 64.13% and 35.15%, respectively. Biochar application also elevated soil pH, organic matter, available potassium, and total nitrogen contents, improved aggregate stability, and enhanced the activities of urease, catalase, sucrase, and acid phosphatase. Furthermore, biochar altered the rhizosphere microbial community structure and increased bacterial diversity. These findings demonstrate that biochar can promote pepper growth by improving soil physicochemical properties, enzyme activities, and microbial community structure, providing a viable strategy for mitigating continuous cropping obstacles in protected cultivation. Full article

Ledum palustre (L. palustre) is widely used in drug development because of its antibacterial and analgesic effects. However, wild L. palustre is often affected by wildfires, resulting in unstable yields. Forest fires represent a major disturbance in northern forest ecosystems and profoundly affect shrub vegetation and its associated rhizosphere microbial communities. In this study, we investigated a fire chronosequence (1991, 2004, 2012, 2017, and 2020) to systematically examine the morphological traits of L. palustre, rhizosphere soil physicochemical properties, and microbial community characteristics and to identify the key drivers underlying these patterns. The results revealed that postfire recovery time significantly influenced the morphological traits of L. palustre. The biomass, branch number, basal diameter, and plant height of the shrubs at the 1991 burned site increased by 270.49%, 36.11%, 79.32%, and 191.36%, respectively (p < 0.05). From unburned soils, 29 bacterial and 29 fungal isolates were obtained, with Bacillus sp. and Oidiodendron sp. being the dominant culturable bacterial and fungal taxa, respectively. With increasing postfire recovery time, soil moisture, total nitrogen, ammonium, nitrate, soil organic carbon, acid phosphatase (AP) and N-acetyl-β-D-glucosaminidase (NAG) activity significantly decreased. Early fire disturbance markedly altered soil microbial abundance and community composition, leading to an overall decrease in bacterial α diversity. The bacterial community structure at the 2020 burn site and the fungal community structure at the 2012 burn site significantly differed. Mantel tests revealed significant positive correlations between branch number and basal diameter (p < 0.01) and significant negative correlations between plant height and stem density (p < 0.001). Soil carbon and hydrolysable nitrogen were significantly positively correlated with AP and NAG activities (p < 0.001). Moreover, soil physicochemical properties significantly shaped soil microbial community structures, with bacterial communities in early postfire sites driven by total carbon and nitrogen (p < 0.05), whereas fungal communities in the 2012 burned site were influenced primarily by β-N-acetylglucosaminidase (BG) activity (p < 0.05). Fire disturbance drives successional changes in the rhizosphere microbial community structure and function by altering the soil nutrient status and enzyme activity, which in turn influences the morphological traits of L. palustre. This study provides a theoretical basis for improving the yield of L. palustre by exploring the variation in rhizosphere microorganisms. Full article

Soil nutrient loss and infertility in rocky desertification areas severely constrain ecological restoration. Exploring the impacts of external field remediation technologies on soil quality in these regions may offer novel strategies for soil enhancement and ecosystem recovery. This study conducted a three-month experiment to investigate the impact of continuous electric (ET, 20 V) and magnetic (MT, 200 mT) field treatments on soil nutrients, enzyme activities, and bacterial communities in simulated moderate and severe rocky desertification soils. Results showed that although an overall declining trends in total contents of key soil nutrients (Total nitrogen, total phosphorus, and total potassium), both electric and magnetic field treatments effectively mitigated the decreases of total nitrogen and potassium content (with the exception of total phosphorus) in rocky desertification soils, while improving their available contents compared to the control (CK). Electric field application significantly reduced the pH of moderate and severe rocky desertification soils through electrolysis, shifting the soil from alkaline (pH 7.69 and 7.73, respectively) to slightly acidic (pH 6.71 and 6.37, respectively); Both electric and magnetic field treatments enhanced urease and sucrase activities in moderately and severely rocky desertified soils. Compared to the CK, the increases were 21.92%, 4.46%, 5.70%, and 66.43% in moderately rocky desertified soil, and 10.06%, 42.15%, 20.66%, and 0.93% in severely rocky desertified soil, respectively. Their effects on phosphatase and catalase activities varied with the degree of rocky desertification. However, in severely rocky desertified soil, both treatments significantly increased phosphatase and catalase activities by 19.55%, 24.63%, 61.07%, and 38.05% compared to the CK, respectively. Furthermore, both electric and magnetic treatments significantly reduced bacterial α-diversity (chao1, ACE, Shannon, Simpson, and Pielou J indices) but optimized community structure by enriching dominant phyla with specific ecological functions, such as Pseudomonadota (7.63–41.10%), Bacteroidota (13.52–69.29%), and Verrucomicrobiota (38.26–104.81%). Functional prediction revealed that the abundances of dominant pathways (such as chemoheterotrophy, aerobic chemoheterotrophy, and nitrogen fixation) was enhanced following both treatments. Mantel analysis further indicated strengthened correlations among soil nutrients, enzyme activities, and bacterial communities, particularly under magnetic field treatment. These findings demonstrate that electric and magnetic field applications effectively facilitate nutrient cycling, stimulate enzyme activities, and optimize microbial community structure, thereby improving soil ecological functions and overall quality in rocky desertification regions, highlighting their potential for ecological restoration in karst areas. Full article

Clarifying the responses of microbial communities in distinct microhabitats like roots, the soil, and litter layers to secondary succession is critical for predicting the effects of global climate change on ecosystem functions. We investigated the microbial activities, compositions, and networks in these microhabitats of Fagus lucida forests ranging from 40 to 200 years. The results showed that soil physicochemical properties decreased with forest succession, except for NH₄⁺-N and available phosphorus, which decreased at the early stage. All vector angles of extracellular enzyme stoichiometry that were greater than 45° indicated that phosphorus was the key limiting element for microorganisms. The microbial community shifted from r- to K-strategists with forest succession, displaying the replacement of most bacterial phyla by Proteobacteria and Acidobacteriota, and an increase in the Acidobacteriota: Proteobacteria ratio, especially in the soil and litter layers. Soil properties, particularly NH₄⁺-N and pH, significantly affected the bacterial diversity and structure. Moreover, the bacterial network complexity increased with succession, particularly in the litter layer, and the topological properties of bacterial networks showed a stronger influence on microbial activities compared with those of fungal networks. The richness of keystone taxa in the litter layer was higher than in the soil layer and roots. However, the fungal community dominated by symbiotrophs showed lower sensitivity to soil nutrient changes and greater resilience to forest succession, displaying stable diversity and decreased network complexity, particularly in the roots. Ectomycorrhizal fungi (e.g., Russula) dominated the fungal guilds, and their abundance increased with forest succession, accompanied by a decrease in pathogenic fungi. Plant roots with significantly higher phosphatase activities played a stronger role than soils in structuring the litter microbial community, as reflected by similar carbon- and nitrogen-acquiring enzyme activities, microbial compositions, a greater share of taxa, and closer community distance. Our results revealed the increasingly important role of plant roots with forest succession in structuring the microbial community and nutrient cycling in the soil and litter layers. Full article

Continuous cropping obstacles in watermelon are closely linked to rhizosphere microbial imbalance, posing a major threat to the sustainability of the industry in Xinjiang. Exogenous additives are widely used to regulate soil health, yet comprehensive comparisons of their mechanisms and effects remain limited. In this study, a field experiment was conducted under continuous watermelon cropping conditions in Xinjiang to evaluate the impact of eight treatments, including chemical fertilizer (NPK) alone and its combination with organic fertilizer (NPKM), glucose (NPKG), oxalic acid (NPKOA), amino acids (NPKGA), citric acid (NPKCA), and acetic acid (NPKAA), with unfertilized soil as the control (CK). Treatment effects were assessed through soil physicochemical analysis, fruit quality evaluation, and high-throughput sequencing (16S rRNA and ITS). Among all treatments, NPKM showed the greatest improvement in soil fertility, increasing soil organic matter by 13.91%, total nitrogen by 23.08%, and single fruit weight by 35.75% compared to CK. NPKGA also enhanced fruit weight (+33.06% vs. CK) and increased catalase activity, while oxalic acid exhibited the strongest activation of alkaline phosphatase. Microbiome analysis revealed that NPKM and NPKAA significantly reshaped both bacterial and fungal community structures. NPKM enriched beneficial taxa such as unclassified Chitinophagaceae and Lophotrichus, whereas NPKCA enriched the biocontrol bacterium Pseudomonas chlororaphis. Soil organic matter and total nitrogen were identified as key environmental drivers, showing significant positive correlations with core bacterial genera (Dokdonella) and negative correlations with the pathogenic fungus Alternaria. Collectively, this study elucidates the distinct mechanisms of various additives by linking treatment-specific microbial shifts to key soil factors and crop performance, providing a theoretical and technical framework for mitigating watermelon continuous cropping obstacles through rhizosphere environmental regulation. Full article

Sunflower (Helianthus annuus L.) production is severely hindered by continuous cropping obstacles, leading to soil degradation and significant yield declines. This study compared soybean–sunflower (G-H) and maize–sunflower (Z-H) rotations against sunflower monoculture (H-H) to elucidate the mechanisms of soil health restoration associated with crop rotation. Our results demonstrated that Z-H and G-H rotations led to a profound yield increase of 103.19% and 82.35%, respectively, with Z-H improving the 100-grain weight by 52.63%. Soil biological revitalization was evidenced by a 98.29% increase in sucrase activity and a 28.92% rise in alkaline phosphatase activity. Metagenomic analysis revealed that the rotation sequences increased bacterial Chao1 richness by 35.29% and fungal Shannon diversity by 20.17%. Specifically, the rotation treatments proactively recruited beneficial taxa such as Pontibacter (Log₂FC > 3.0) and Panaeolus (Log₂FC = 6.88), while effectively suppressing pathogens such as Ceratobasidiaceae. Co-occurrence network analysis identified a complex bacterial scaffold (199 nodes, 53 modules) that provided greater structural robustness than the fungal network (27 nodes). It is concluded that diversified rotations effectively mitigate continuous cropping obstacles by reactivating nutrient cycling and restructuring the rhizosphere into a stable, modular microbial interactome. This study provides a quantitative framework for utilizing biological strategies to restore soil health in degraded agroecosystems. Full article

The integration of appropriate tillage practices with straw returning can effectively mitigate soil degradation in Northeast China. However, limited research has explored the impacts of different tillage practices combined with varying straw incorporation depths on the structure and diversity of soil microbial communities. In 2016, a field experiment was initiated using a two-factor split-plot design, featuring six treatments: two tillage depths of 10 cm (D10) and 30 cm (D30) combined with three straw management practices—straw mixing incorporation (SM), straw deep burial (SB), and straw removal (SR). Soil samples collected in 2019 were analyzed for multiple soil properties and microbial indices. Results indicated that both straw returning and tillage depth significantly influenced soil organic carbon (SOC), soil total nitrogen (STN), total phosphorus (TP), and total potassium (TK), with the D30 treatment combined with straw returning optimizing soil nutrient contents most effectively. Under straw returning, D10 significantly increased urease activity in the 0–10 cm soil layer, whereas D30 enhanced this enzyme activity in the 10–30 cm soil layer, while β-glucosidase activity was less responsive to tillage depth. For the D10 treatment with straw returning, acid phosphatase activity was markedly higher than that in the straw removal treatment, whereas N-acetyl-β-D-glucosaminidase activity exhibited the opposite trend. Straw-returning methods had no significant effects on the bacterial and fungal Chao1 indices, while the Shannon index was positively correlated with key soil properties. Redundancy analysis (RDA) of microbial community composition at the phylum level and soil environmental factors revealed that soil nutrients in the 0–10 cm soil layer were positively correlated with Actinobacteriota, Ascomycota, and Basidiomycota, whereas the explanatory power of soil nutrients for microbial community variation decreased in the 10–30 cm soil layer. Our results highlight that tillage depth and straw returning can regulate soil microbial community composition and enhance soil nutrient cycling, thereby providing a theoretical basis for optimizing the combined application mode of tillage and straw-returning practices in Northeast China. Full article