Soil Diversity Research Articles

From waste to resource: Assessing the feasibility of municipal sludge as a fertilizer from a soil and microbial perspective

Municipal sludge is rich in nutrients and microbial populations, making it a potential soil amendment to enhance fertility. This study aimed to investigate the impact of municipal sludge application on microbial populations and assess its suitability as a fertilizer. The results indicated a significant increase in organic matter content in sandy soil after municipal sludge application (from 9.57 to 23.62 mg·kg−1). Available potassium and phosphorus levels improved from poor to intermediate, and available nitrogen reached an excellent level. Plant parameters such as wet weight, diameter, root length, and aboveground height also showed improvement with municipal sludge addition. High-throughput sequencing revealed Shannon and Simpson indices exceeding 5.26 and 0.98, respectively, across all substrates except B1, indicating enhanced microbial community structure and diversity in sandy soil. Redundancy analysis highlighted the pivotal role of total phosphorus, available phosphorus, organic matter, available nitrogen, total nitrogen, and available potassium in enriching microbial abundance and diversity. In conclusion, using municipal sludge as fertilizer is feasible and beneficial for soil safety, fertility, and microbial populations enhancement.

Joint effect of black carbon deriving from wheat straw burning and plastic mulch film debris on the soil biochemical properties, bacterial and fungal communities

Black carbon (BC) formed after straw burning remains in farmland soil and coexists with plastic mulch film (PMF) debris. It is unclear how BC influences soil multifunctionality in the presence of PMF debris. In this study, we determined the joint effects of BC and PMF debris on soil biochemical properties and microbial communities. We conducted a soil microcosm experiment by adding BC formed by direct burning of wheat straw and PMF debris (polyethylene (PE) and biodegradable PMF (BP)) into soil at the dosages of 1 %, and soils were sampled on the 15th, 30th, and 100th day of soil incubation for high-throughput sequencing. The results showed that the degradation of PMF debris was accompanied by the release of microplastics (MPs). BC decreased NH4+-N (PE: 68.63 %; BP: 58.97 %) and NO3−-N (PE: 12.83 %; BP: 51.37 %) and increased available phosphorus (AP) (PE: 79.12 %; BP: 26.09 %) in soil containing PMF debris. There were significant differences in enzyme activity among all the treatments. High-throughput sequencing indicated that BC reduced bacterial and fungal richness and fungal diversity in PMF debris-exposed soil, whereas PMF debris and BC resulted in significant changes in the proportion of dominant phyla and genera of bacteria and fungi, which were affected by incubation time. Furthermore, BC affected microorganisms by influencing soil properties, and pH and N content were the main influencing factors. In addition, FAPRPTAX analysis indicated that BC and PMF debris affected soil C and N cycling. These findings provide new insights into the response of soil multifunctionality to BC and PMF debris.

The Soil Bacterial Community Structure in a Lactarius hatsudake Tanaka Plantation during Harvest.

Lactarius hatsudake Tanaka is a mycorrhizal edible mushroom with an appealing taste and rich nutrition. It is also a significant food and has medicinal value. In this study, the plantation of L. hatsudake during the harvest period was taken as the research object, and this article explores which bacteria in the soil contribute to the production and growth of L. hatsudake. The soil of the control (CK) and the soil of the mushroom-producing area [including the soil of the base of the mushroom (JT) and the mycorrhizal root soil (JG)] was collected in the plantation. The three sites' bacterial community structure and soil diversity were analyzed using high-throughput sequencing technology, and a molecular ecological network was built. Soil bacteria in the L. hatsudake plantation had 28 tribes, 74 classes, 161 orders, 264 families, 498 genera, and 546 species. The dominant phyla were Proteobacteria and Acidobacteria, and the dominant genera were Burkholderia_Caballeronia_Paraburkholderia, Acidothermus, Bradyrhizobium, Candidatus_Xiphinematobacter, and Granulicella. The α-diversity of soil bacteria in JT was significantly lower than that in JG and CK, and the β-diversity in JT samples was significantly different from that in JG and CK samples. The size and complexity of the constructed network were smaller in JT samples than in JG and CK samples, and the stability was higher in JT samples than in JG and CK samples. The positive correlation between species in JT samples was dominant. The potential mycorrhizal helper bacteria (MHB) species of L. hatsudake was determined using correlation and differential group analysis. The results support future research on mycorrhizal synthesis, plantation management, and the function of microorganisms in the soil rhizosphere of L. hatsudake.

Composition and Assembly of the Endophytic Fungal Community of Alpine Rhododendron Hosts Along Elevation Gradients

Alpine mountain ecosystems are highly sensitive to global warming and threatened by climate change. Elevation gradients are frequently used as space-for-time surrogates for climate change in mountain ecosystems due to their correspondence with climate variables over short geographic distances. However, the distribution patterns of fungal communities in perennial woody plants along elevations in this ecosystem and how elevation and host identity affect them remain unclear. In this work, we used Illumina MiSeq DNA sequencing technology to study the rhizosphere soil fungal community and root and leaf endophytic fungal community assembly of alpine Rhododendron communities across a 3,100- to 4,100-m elevation gradient on Jiaozi Mountain, Southwest China. The abundance and diversity of fungi in different compartments varied among elevation gradients and hosts. The fungal community assembly in each compartment was mainly influenced by stochastic processes. However, the contribution of homogeneous selection, dispersal limitation, and drift varied among host identities and elevations in different compartments. The diversity and composition of rhizosphere soil, root, and leaf guilds and the overall abundance of fungal functional groups tracked the Rhododendron host identity more closely than elevation did. Most indicator taxa of fungi were putative saprotrophs. These findings will improve our understanding of the maintenance of alpine Rhododendron communities along elevation gradients. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

A review of factors affecting the soil microbial community structure in wetlands.

Microbial community in wetland soils is crucial for maintaining the stability of the wetland ecosystem. Nevertheless, the soil microbial community is sensitive to the environmental stress in wetlands. This leads to the possibility that the microbial community structure may be influenced by environmental factors. To gain an in-depth understanding in the response of microbial community structure in wetland soils under different environmental factors, this review comprehensively explores the factors of natural conditions (e.g., different types of wetland, soil physical and chemical properties, climate conditions), biological factors (e.g., plants, soil animals), and human activities (e.g., land use, soil pollution, grazing). Those factors can affect microbial community structure and activities in wetland soils through different ways such as (i) affecting the wetland soil environment in which soil microorganisms survived in, (ii) influencing the available nutrients (e.g., carbon, nitrogen) required for microbial activity, and (iii) the direct effects on soil microorganisms (toxicity or promotion of resistant species). This review can provide references for the conservation of microbial diversity in wetland soils, the maintenance of wetland ecosystem balance, and the wetland ecological restoration.

Land use changes effect by slash and burn cultivation to understory diversity composition and soil degradation

This study contributes to understanding ecological changes in land use following slash-and-burn land clearing. This study aimed to compare the richness and density of plant species and soil fertility in farmland cultivated for one year (1 Y), three years (3 Y), and five years (5 Y) after slash-and-burn, with the conditions in the secondary forest (SF) in Berau Regency of East Kalimantan. Understory plant taxon types, numbers, and soil organic matter were measured in each region using a series of nested plots. The size of each observation plot was 20 x 100 m. Data on understory vegetation composition was collected using 1 x 1 m mini plots at 20 sampling points and divided into five blocks, with a 10 m spacing between sampling points on each property. Understory vegetation species and cover percentage, litter cover percentage, open soil percentage, and soil fertility were measured for each observation plot. The results showed that the land cover percentage increased each year during the 5 years transition from secondary forest to farmland. Furthermore, within the 5 years, there was a change in understory species, particularly the presence of grasses and sedges at 3 and 5 years after the land use change. However, the transition from secondary forest to farmland within 5 years did not alter soil organic matter and total nitrogen.

Эколого-биологические методы формирования устойчивых лесомелиоративных комплексов в степных и полупустынных ландшафтах европейской территории России

The arid region of the European territory of Russia includes a zone of dry steppe (dark chestnut soils) and a semi-desert zone (light chestnut and brown soils). There is practically no woody natural vegetation in the region on elevations and plains, and on the prevailing complexes of zonal soils, forest plantations are characterized by low durability. Materials and methods. The work used the results of field (expedition) and laboratory studies of the growth, condition, durability, productivity of protective forest plantations of tree and shrub species in various soil and hydrological conditions of the dry-steppe and semi desert zones. Results and discussion. The author’s developments made it possible to recommend a reliable range of trees and shrubs for the creation of forest-reclamation plantations in each agroforestry area and soil ecological niche. It was revealed that when selecting the assortment, a significant role should be given to selection and genetic methods of using seed and planting material well adapted to local conditions (drought-, salt- and frost-resistant and healthy genotypes). The main reason for the early drying of protective plantations on complex light chestnut soils of the dry-steppe and semi-desert zones has been established. Taking into account the extremely arid conditions and the main causes of their drying, the concept of increasing their stability and effectiveness in adverse growing conditions is given. Agroforestry zoning and groups of soil forest suitability by type and classification, as well as groups of longevity of the main tree species are given. Conclusion. The large diversity of soils contributes to the formation of a stepped profile in adult cereals. Woody species shrink when their root system comes into contact with salt horizons. Ecological techniques are reduced to the correct selection of tree species that correspond to a specific ecological background. The technological use of differentiated agricultural cultivation techniques involves the use of moisture-saving technologies. Biological measures include biological reclamation of unsuitable soils and methods of breeding and genetic improvement of the qualitative composition of forest reclamation plantations. Suggestions for practical applications and directions for future research. The results of the work can be used by managers and specialists of forestry enterprises, researchers, graduate students, students of educational institutions. The assortment of trees and shrubs can be used in the design of plantings of various types on different soils.

Maize-alfalfa intercropping alleviates the dependence of multiple ecosystem services on nonrenewable fertilization

Phosphorus is a nonrenewable source of fertilization, which will challenge the future of food production and cropland sustainability worldwide. Crop diversity is known to promote greater productivity, yet the capacity of crop diversity to alleviate productivity dependence on nonrenewable fertilization and promote multiple ecosystem services remains virtually unknown. Here, we conducted a field experiment to quantify the contribution of maize-alfalfa intercropping to soil biodiversity and multiple ecosystem services under contrasting phosphorus fertilization levels. Results showed that unfertilized intercropping can support higher levels of ecosystem services such as soil microbial habitat, plant-soil mutualism, nutrient cycling, and soil carbon storage compared to phosphorus-fertilized monoculture. Intercropping could optimize the delivery of soil diversity and multiple ecosystem services override phosphorus, including microbial diversity, weighted ecosystem services, productivity stability and sustainability, and soil microbial habitat were 5–30 times higher, respectively. Unfertilized intercropping also helped to reduce important tradeoffs between productivity and soil microbial diversity compared with fertilized monoculture. Together, our results provide evidence that intercropping can optimize crop use of phosphorus, and promote multiple important ecosystem services, which can help alleviate global dependence on nonrenewable, and often environmentally deleterious fertilizer inputs.

Harnessing Soil Diversity: Innovative Strategies for Potato Blight Management in Central-Eastern Poland

Faced with increasing climate challenges, this pioneering study introduces groundbreaking approaches to ensure the resilience of potato crops in east-central Poland. Our research was aimed at developing an innovative, cost-effective system tailored to the diverse local conditions of this region. Conducted between 2018 and 2020, the study analyzed integrated and organic production systems across different soil types and potato varieties. The experiment was conducted using a randomized block design with three replications in two locations. Integrated production systems involve the strategic use of mineral fertilization and chemical protection to optimize crop growth and health, whereas organic production systems rely solely on natural inputs and biological pest control methods. Integrated practices, enhanced by mineral fertilization and chemical protection, notably delayed the onset of late blight by 16 days and extended the critical infection period by 17% compared to their organic counterparts. Remarkably, the integrated systems resulted in a 49% increase in total production and a 52% increase in commercial yields, demonstrating their effectiveness in enhancing crop resilience. Different potato varieties exhibit varied responses to cultivation systems, influencing both yield and disease resistance. Further investigation into these varietal responses can help optimize cultivation practices, leading to improved efficiency and sustainability in potato farming. Location and soil conditions have a significant impact on potato yield and the spread of potato blight. Specific soil properties such as pH levels, organic matter content, soil texture (clay, silt, and sand composition), moisture retention capacity, and nutrient availability are crucial in determining potato productivity and disease dynamics. Further research into these soil properties and the adaptation of varieties to local conditions can contribute to increased productivity and stability in potato production. This study not only paves the way toward sustainable agriculture but also highlights the crucial role of soil diversity in shaping resilient farming practices. Potato producers in the eastern-central region of Poland should implement integrated production systems using mineral fertilization and chemical plant protection, adapted to local soil conditions and potato varieties. These practices can delay the appearance of late blight and increase the total and marketable potato yield. Further research on soil properties and variety adaptation may increase production stability and efficiency. Promoting soil diversity and modern technologies will ensure resilient and sustainable agricultural production in the face of climate change.

Recover of Soil Microbial Community Functions in Beech and Turkey Oak Forests After Coppicing Interventions

Forest management influences the occurrence of tree species, the organic matter input to the soil decomposer system, and hence, it can alter soil microbial community and key ecosystem functions it performs. In this study, we compared the potential effect of different forest management, coppice and high forest, on soil microbial functional diversity, enzyme activities and chemical-physical soil properties in two forests, turkey oak and beech, during summer and autumn. We hypothesized that coppicing influences soil microbial functional diversity with an overall decrease. Contrary to our hypothesis, in summer, the functional diversity of soil microbial community was higher in both coppice forests, suggesting a resilience response of the microbial communities in the soil after tree cutting, which occurred 15–20 years ago. In beech forest under coppice management, a higher content of soil organic matter (but also of soil recalcitrant and stable organic carbon) compared to high forest can explain the higher soil microbial functional diversity and metabolic activity. In turkey oak forest, although differences in functional diversity of soil microbial community between management were observed, for the other investigated parameters, the differences were mainly linked to seasonality. The findings highlight that the soil organic matter preservation depends on the type of forest, but the soil microbial community was able to recover after about 15 years from coppice intervention in both forest ecosystems. Thus, the type of management implemented in these forest ecosystems, not negatively affecting soil organic matter pool, preserving microbial community and potentially soil ecological functions, is sustainable in a scenario of climate change.

Bacterial Community Composition and Functions In Rhizosphere Soil of Four Deciduous Fruit Trees

The purpose of this study was to explore the composition of bacterial communities in the rhizosphere soil of four deciduous fruit trees (pomegranate, peach, cherry, and ginkgo) and to study the bacterial community structure and metabolic function of them. 16S rRNA sequencing technology was adopted to analyze the bacterial community structure, and Tax4Fun was employed to predict the metabolic profiles of the bacterial community. The results showed that the Shannon index, Ace index, and Chao1 index values of the ginkgo rhizosphere soil samples were the largest, indicating that the bacterial diversity of ginkgo rhizosphere soil is the highest. 4764 OTUs were identified for bacteria and were classified as 46 phylums, 113 classes, 175 orders, 247 families, 339 genera, and 504 species. Whether at the phylum level, at the order level, or at the genus level, no significant differences in the composition of bacterial communities were detected among the rhizosphere soils of the four deciduous fruit trees. Proteobacteria, Actinobacteria, Bacteroidota, and Acidobacteriota were the most abundant phyla, and Gammaproteobacteria, Bacteroidota, Alphaproteobacteria, and Alphaproteobacteria were the most abundant orders across all samples. The KOs (KEGG orthology) were mainly involved in 6 KEGG level 1 pathways and 35 KEGG level 2 pathways. The relative abundance of these six pathways was not significantly different in rhizosphere soils among the four deciduous fruit trees at the first KEGG level. The main enrichment pathways of microorganism metabolism at the second KEGG level are consistent, mainly in carbohydrate metabolism, amino acid metabolism, energy metabolism, lipid metabolism, nucleotide metabolism, and the metabolism of cofactors and vitamins. Bangladesh J. Bot. 53(2): 287-295, 2024 (June)

Measurements of soil protist richness and community composition are influenced by primer pair, annealing temperature, and bioinformatics choices.

Protists are a diverse and understudied group of microbial eukaryotic organisms especially in terrestrial environments. Advances in molecular methods are increasing our understanding of the distribution and functions of these creatures; however, there is a vast array of choices researchers make including barcoding genes, primer pairs, PCR settings, and bioinformatic options that can impact the outcome of protist community surveys. Here, we tested four commonly used primer pairs targeting the V4 and V9 regions of the 18S rRNA gene using different PCR annealing temperatures and processed the sequences with different bioinformatic parameters in 10 diverse soils to evaluate how primer pair, amplification parameters, and bioinformatic choices influence the composition and richness of protist and non-protist taxa using Illumina sequencing. Our results showed that annealing temperature influenced sequencing depth and protist taxon richness for most primer pairs, and that merging forward and reverse sequencing reads for the V4 primer pairs dramatically reduced the number of sequences and taxon richness of protists. The data sets of primers that targeted the same 18S rRNA gene region (e.g., V4 or V9) had similar protist community compositions; however, data sets from primers targeting the V4 18S rRNA gene region detected a greater number of protist taxa compared to those prepared with primers targeting the V9 18S rRNA region. There was limited overlap of protist taxa between data sets targeting the two different gene regions (80/549 taxa). Together, we show that laboratory and bioinformatic choices can substantially affect the results and conclusions about protist diversity and community composition using metabarcoding.IMPORTANCEEcosystem functioning is driven by the activity and interactions of the microbial community, in both aquatic and terrestrial environments. Protists are a group of highly diverse, mostly unicellular microbes whose identity and roles in terrestrial ecosystem ecology have been largely ignored until recently. This study highlights the importance of choices researchers make, such as primer pair, on the results and conclusions about protist diversity and community composition in soils. In order to better understand the roles protist taxa play in terrestrial ecosystems, biases in methodological and analytical choices should be understood and acknowledged.

Microbial Community Shifts in Tea Plant Rhizosphere under Seawater Stress: Enrichment of Beneficial Taxa.

Seawater intrusion has a significant impact on the irrigation quality of agricultural water, thereby posing a threat to plant growth and development. We hypothesized that the rhizosphere of tea plants harbors beneficial microorganisms, which may improve the tolerance of tea plants to seawater stress. This study utilized 16s and ITS techniques to analyze microbial community shifts in the tea plant rhizosphere and non-rhizosphere under seawater stress conditions. The findings suggest that seawater stress leads to a reduction in microbial diversity, although the rhizosphere microbial diversity in stressed soils showed a relatively higher level. Moreover, the rhizosphere of the tea plant under seawater stress exhibited an enrichment of plant growth-promoting rhizobacteria alongside a higher presence of pathogenic fungi. Network analysis revealed that seawater stress resulted in the construction of a more complex and stable rhizosphere microbial network compared to normal conditions. Predictions of bacterial potential functions highlighted a greater diversity of functional groups, enhancing resource utilization efficiency. In general, the rhizosphere microorganisms of tea plants are jointly selected by seawater and the host. The microorganisms closely related to the rhizosphere of tea plants are retained and, at the same time, attract beneficial microorganisms that may alleviate stress. These findings provide new insights into plant responses to saline stress and have significant implications for leveraging vegetation to enhance the resilience of coastal saline soils and contribute to economic progress.

Microbial co-occurrence network demonstrates spatial and climatic trends for global soil diversity

Despite recent research efforts to explore the co-occurrence patterns of diverse microbes within soil microbial communities, a substantial knowledge-gap persists regarding global climate influences on soil microbiota behaviour. Comprehending co-occurrence patterns within distinct geoclimatic groups is pivotal for unravelling the ecological structure of microbial communities, that are crucial for preserving ecosystem functions and services. Our study addresses this gap by examining global climatic patterns of microbial diversity. Using data from the Earth Microbiome Project, we analyse a meta-community co-occurrence network for bacterial communities. This method unveils substantial shifts in topological features, highlighting regional and climatic trends. Arid, Polar, and Tropical zones show lower diversity but maintain denser networks, whereas Temperate and Cold zones display higher diversity alongside more modular networks. Furthermore, it identifies significant co-occurrence patterns across diverse climatic regions. Central taxa associated with different climates are pinpointed, highlighting climate’s pivotal role in community structure. In conclusion, our study identifies significant correlations between microbial interactions in diverse climatic regions, contributing valuable insights into the intricate dynamics of soil microbiota.

Soil-plant-gall relationships: from gall development to ecological patterns.

The adaptive nature of the galler habit has been tentatively explained by the nutrition, microenvironment, and enemy hypotheses. Soil attributes have direct relationships with these three hypotheses at the cellular and macroecological scales, but their influence has been restricted previously to effects on the nutritional status of the host plant on gall richness and abundance. Herein, we discuss the ionome patterns within gall tissues and their significance for gall development, physiology, structure, and for the nutrition of the gallers. Previous ecological and chemical quantification focused extensively on nitrogen and carbon contents, evoking the carbon-nutrient defence hypothesis as an explanation for establishing the plant-gall interaction. Different elements are involved in cell wall composition dynamics, antioxidant activity, and regulation of plant-gall water dynamics. An overview of the different soil-plant-gall relationships highlights the complexity of the nutritional requirements of gallers, which are strongly influenced by environmental soil traits. Soil and plant chemical profiles interact to determine the outcome of plant-herbivore interactions and need to be addressed by considering not only the soil features and galler nutrition but also the host plant's physiological traits. The quantitative and qualitative results for iron metabolism in gall tissues, as well as the roles of iron as an essential element in the physiology and reproduction of gallers suggest that it may represent a key nutritional resource, aligning with the nutrition hypothesis, and providing an integrative explanation for higher gall diversity in iron-rich soils.

Molecular and Morphological Assessment of the Impact of Gas Flares on the Fungal Abundance and Diversity in soils of Niger Delta Area, Nigeria

Fungal abundance and diversity in soils of three communities flow stations (ID, IR and OB) owned by an unnamed oil exploration firm operating in the Niger Delta area for about five decades were determined using nucleic acid analytical methods. Top soil (0-15 cm) samples were collected from mini pits using sterile bottles at 50, 100 and 150 meters from the flare barrier of each community flow station and soil samples from the control was taken at 2.5 kilometers during the dry and wet seasons. The fungal properties were determined first using the cultural method of serial dilution method which revealed the presence of the following fungi; Aspergillus sp, and penicillium chrysogenum at 50 m away from flare in all the three flow stations during the dry seasons and in the wet season Aspergillus sp, penicillium chrysogenum, Mucor sp., yeast cells, A. niger, and Rhizopus sp. At 100 m away from flare, Mucor sp, A. niger and rhizopus were isolated in all three-flow station in the dry season and in the wet season, Yeast cells, A. niger, Aspegillus sp. and Rhizopus were isolated. P. chrysogenum, Aspergillus sp. and yeast cells were isolated at 150 m away from flare in the dry season and in the same distance, yeast cells, A. niger aggregate, A. niger and P. chrysogenum were isolated. At the control site, during the dry season, A. niger, P. chrysogenum, Aspergillus sp., Rhizopus sp. and Botryodiplodia threobome were isolated in the dry and A. niger, P. chrysogenum and yeast in the wet season. Fungal DNA was extracted using Norgen fungal genomic DNA extraction kits for the molecular analysis to establish the true characteristics and species identity of the isolates earlier identified with cultural methods. This revealed the presence of the following fungi upon sequence blast on NCBI database; Aspergillus fumigatus (Aspergillus fumigatus brown 2 (abr2) gene, complete cds strain), Aspergillus fumigatus (Aspergillus fumigates strain IHM 15988 pigment biosynthesis protein), Fusarium phyllophilum , Fusarium graminearum, Aspergillus oryzae (a strain of Aspergillus niger) Aspergillus oryzae (niger). Findings from this work have shown that molecular technique gave the exact identity of fungal species isolated from study area. All six (6) molecularly identified fungi were isolated from the three-study flow station and in both seasons. The Aspergillus group was dominant as a result of their ability to adapt to the flare environment

Ecological problems of technogenic land pollution in the republic of Кazakhstan

A large territory in Kazakhstan is distinguished by the diversity of soils and the complex structure of the soil cover. Soil contamination with heavy metals, especially in the vicinity of large cities and industrial centers, is one of the environmental problems. Of great scientific and practical interest is the determination of the content of heavy metals in soil, their transformation and entry into food and feed. The accumulation of heavy metals in the soil leads to an increase in their concentration in plants, which affects public health. Therefore, the study and identification of areas with high levels of heavy metals in the soil are of increasing importance. The article summarizes the results of a study of soil and vegetation cover in areas adjacent to mining enterprises factories for the production of non-ferrous and rare metals.

Aridity affects soil organic carbon concentration and chemical stability by different forest types and soil processes across Chinese natural forests

Forest soils play a critical role in carbon (C) reservoirs and climate change mitigation globally. Exploring the driving factors of soil organic carbon (SOC) concentration and stability in forests on a large spatial scale can help us evaluate the role of forest soils in regulating C sequestration. Based on SOC quantification and solid-state 13C nuclear magnetic resonance spectroscopy, we investigated the SOC concentration and SOC chemical stability (indicated by alkyl-to-O-alkyl ratio and hydrophobic-to-hydrophilic ratio) in top 0–5 and 5–10 cm soils from 65 Chinese natural forest sites and explored their driving factors. Results showed that SOC concentration in 0–5 cm soils were highest in mixed forests but SOC chemical stability in 0–5 cm soils were highest in coniferous forests, while SOC concentration and chemical stability in 5–10 cm soil layers did not differ across forest types. SOC concentration in 0–5 cm was directly related to soil pH and soil bacterial diversity. Structural equation models showed that aridity indirectly affected SOC concentration in 0–5 cm by directly affecting soil pH. While SOC chemical stability in 0–5 cm soils was higher with increased aridity. According to the correlations, the potential mechanisms could be attributed to higher proportion of coniferous forests in more arid forest sites, lower relative abundance of O-alkyl C, higher MgO and CaO contents, and higher bacterial diversity in soils from more arid forest sites. Our study reveals the important role of aridity in mediating SOC concentration and chemical stability in top 0–5 cm soils in Chinese natural forests on a large-scale field investigation. These results will help us better understand the different mechanisms underlying SOC concentration and stability in forests and assess the feedback of forest SOC to future climate change.

Nitrogenous fertilizer plays a more important role than cultivars in shaping sorghum-associated microbiomes

The plant microbiome plays a crucial role in facilitating plant growth through enhancing nutrient cycling, acquisition and transport, as well as alleviating stresses induced by nutrient limitations. Despite its significance, the relative importance of common agronomic practices, such as nitrogenous fertilizer, in shaping the plant microbiome across different cultivars remains unclear. This study investigated the dynamics of bacterial and fungal communities in leaf, root, rhizosphere, and bulk soil in response to nitrogenous fertilizer across ten sorghum varieties, using 16S rRNA and ITS gene amplicon sequencing, respectively. Our results revealed that nitrogen addition had a greater impact on sorghum-associated microbial communities compared to cultivar. Nitrogen addition significantly reduced bacterial diversity in all compartments except for the root endophytes. However, N addition significantly increased fungal diversity in both rhizosphere and bulk soils, while significantly reducing fungal diversity in the root endophytes. Furthermore, N addition significantly altered the community composition of bacteria and fungi in all four compartments, while cultivars only affected the community composition of root endosphere bacteria and fungi. Network analysis revealed that fertilization significantly reduced microbial network complexity and increased fungal-related network complexity. Collectively, this study provides empirical evidence that sorghum-associated microbiomes are predominantly shaped by nitrogenous fertilizer rather than by cultivars, suggesting that consistent application of nitrogenous fertilizer will ultimately alter plant-associated microbiomes regardless of cultivar selection.

Environmental driving factors of diazotrophic community diversity and activity in Chinese paddy soils

Environmental driving factors of diazotrophic community diversity and activity in Chinese paddy soils