Soil Ecosystem Functioning Research Articles

Straw return was more beneficial to improving saline soil quality and crop productivity than biochar in the short term.

Salinized soil often exhibits high salt content and low nutrient availability, leading to the reduction of soil ecosystem function and crop productivity. Although straw return has profound effects on saline soil improvement, how soil quality index (SQI), soil ecosystem multifunctionality (EMF), and crop yield respond to different organic ameliorants remain unclear. Herein, a field experiment was established to explore the influence of various straw management strategies (no organic ameliorant, CK; corn straw return, CS; and corn straw biochar return; CB) on the saline soil functions and crop productivity. In relation to CK and CB, CS significantly improved SQI by 52% and 35%, respectively. This may be due to the decreased soil salt (especially soluble Na+) and increased available nutrients under corn straw return. Furthermore, CS increased soil EMF than CK by 71% and CB by 39%, which was caused by the increased activities of 1,4-β-glucosidase, β-1,4-N-acetyl-glucosaminidase, and leucine aminopeptidase. The linear model further supported that soil enzyme activities are positively related to available nutrient contents and negatively correlated with salt content. Moreover, the crop yield under CS significantly increased by 22% compared to CK. Also, soil quality positively influenced crop yield, with soil salt and available phosphorus being the primary influencing factors. However, crop yield was not sensitive to soil EMF. In summary, straw return was more beneficial to improving soil quality and crop productivity than biochar in the short term in saline soils.

Thermal Enhanced Electrokinetic Bacterial Transport in Porous Media.

Soil bacterial communities are crucial to various ecosystem services, with significant implications for environmental processes and human health. Delivering functional bacterial strains to target locations enhances the preferred ecological features. However, the delivery process is often constrained by limited bacterial transport through low-permeability soil. Although electrokinetics breaks the bottleneck of bacterial transport in thin porous media, its efficiency remains limited. Here, we tested the hypothesis that thermal effects enhance electrokinetic transport by shifting the net force acting on the bacterium. We found that heating significantly increased electrokinetic transport by 2.75-fold at 1 V cm-1 through porous media. Thermal enhancement mechanisms were interpreted by the heating shift of net force integrating matrix attractive and electrokinetic forces and verified by the Quartz Crystal Microbalance with Dissipation Monitoring (QCMD) observed adhesion rigidity shift. Thermal-dependent parameters liquid viscosity and dielectric constant were the primary contributors to the net force shift. Their variations reduce the attractive force and augment the electrokinetic forces, resulting in lower adhesion rigidity and enhanced bacterial transport. A mechanism-based approach interlinking electric field strength, thermal effect, and collision efficiency was established to facilitate the application of thermally enhanced electrokinetic bacterial transport. These findings provide new prospects for improving bacterial transport, hence optimizing soil ecosystem functions.

Improving spatial prediction of soil organic matter in central Vietnam using Bayesian-enhanced machine learning and environmental covariates

ABSTRACT Soil organic matter (SOM) has a vital role in maintaining soil quality and ecosystem functions. However, predicting its spatial distribution remains a challenging task since it was affected by various environmental covariates. To address this limitation, a novel approach by integrating Bayesian technique into the random forest (RF) algorithm was proposed in this research. A total of 94 surficial soil samples from the top 30 cm and eight key environmental covariates were utilized for training and testing with a 70:30 ratio. According to the results, the enhanced RF model demonstrated a significant improvement in accuracy (RMSE = 0.31%; MAE = 0.25%, R2 = 0.79, Acc = 0.81) compared to the traditional RF model (RMSE = 0.66%; MAE = 0.48%, R2 = 0.10, Acc = 0.61). The four environmental covariates including rainfall, distance to the sea, distance to water bodies, and altitude explained 74.07%, and 75.37% of the variability in SOM content in traditional and enhanced RF models, respectively. Locations with high SOM content were characterized by abundant rainfall, a greater distance from the sea, proximity to rivers, and low elevations. These findings introduce a reliable approach for predicting the spatial distribution of SOM in the context of complex environmental changes.

Global environmental dependences of soil biodiversity and functions are modified by water availability thresholds.

Global soil biodiversity and functions are threatened by water availability thresholds. However, the role of these thresholds in modulating the environmental drivers of soil biodiversity and functions remains poorly understood. Analyzing a global dataset of 383 sites across major terrestrial biomes, we found that water availability threshold (measured by aridity index) reorganizes the relative importance of climate, vegetation, and soil properties in regulating soil biodiversity and functions. In less arid regions, vegetation and soil properties jointly explained the primary patterns of soil biodiversity and functions. Conversely, after crossing such water availability threshold toward more arid conditions, climate became the dominant controlling factor, outpacing other environmental variables. Notably, this water-induced shift in environmental dependence was more pronounced for soil multidiversity than for soil multifunctionality. Our findings highlight the critical role of water availability thresholds in shaping the environmental factors that govern soil biodiversity and ecosystem functions, providing valuable insights into potential ecosystem transformations in the context of on-going global aridification.

A review on the impact of commonly used pesticides on the biology of earthworms

Earthworms are considered important bio-indicators of chemical contamination in the soil ecosystem. Being an important biotic factor of soil ecosystem, earthworms play a vital role in the functioning of soil ecosystems and maintenance of soil fertility. The present review encompasses the diverse effects of chemical contaminants like pesticides on earthworm biology, considering both direct toxicity and indirect impacts on ecosystem functions. Through a comprehensive review of existing literature, we assess the varying impacts of different classes of pesticides on earthworms. Several studies included in this review shed light on how pesticide exposure affects earthworm behaviour, reproduction, regenerative capacity, histology, gut microbial diversity, and nutrient transition, among other adverse effects, which consequently affect the soil ecosystem dynamics. Furthermore, we discuss the implications of these findings for agricultural practices, soil health, and biodiversity conservation. This study discusses the impact of pesticides on different facets of earthworm biology and emphasizes the necessity of sustainable pest management strategies to maintain the productivity and adaptability of ecosystems by enhancing our understanding of the complex interactions that occur between soil organisms, like earthworms, and foreign chemicals, or xenobiotics, like pesticides.

Contrasting responses of soil bacterial and fungal networks to photovoltaic power station.

The rapid expansion of solar photovoltaic (PV) power generation raises concerns regarding its impact on terrestrial ecosystems. Although the influence of PV panels on soil conditions and plant biomass is acknowledged, their effects on the assembly processes and co-occurrence networks of soil microbial communities remain understudied. Clarifying this influence is crucial for understanding the effects of photovoltaic panels on soil ecosystem functions. In this study, we first explored the effects of PV panels on soil properties. Then, using amplicon sequencing, we analyzed the impact of PV panels on soil microbial diversity and function, focusing specifically on the assembly processes and co-occurrence networks of bacterial and fungal communities. Our results indicate that the installation of PV panels improved soil conditions, leading to concurrent effects on microbial community structure and function. This process appears to be deterministic, driven primarily by homogeneous selection. Notably, PV panels increased the complexity of bacterial networks while decreasing their stability. In contrast, PV panels did not affect the complexity of fungal networks despite their stability increased. These findings provide new evidence that soil bacterial networks are more sensitive to PV panels installation than fungal networks, deepening our understanding of land-use change effects on soil ecosystem functions. Moreover, our study demonstrates that higher complexity does not necessarily mean higher stability at least in soil microbial systems, challenging the notion that ecological complexity favors their stability.

Ground cover management enhances soil extracellular enzyme activities across Chinese orchards.

The impacts of ground cover management (GCM) on orchard soil properties have been extensively studied. However, the quantitative assessment of soil extracellular enzyme activities (EEAs) in mulch agriculture remains understudied. In this study, we investigated EEAs related to GCM to assess microbial metabolic activity, soil health, and nutrient status, based on 81 studies focusing on orchards in China. Our findings show that GCM significantly increases carbon acquisition (C-acq, 37%), nitrogen acquisition (N-acq, 34%), phosphorus acquisition (P-acq, 26%), and oxidative decomposition (OX, 14%) enzymes compared to continuous clean tillage. A subgroup analysis and a random forest model were conducted to further identify the effects and potential mechanisms through which soil EEAs respond to GCM in orchards under various moderators. The significant changes in EEAs induced by GCM vary with experimental and environmental factors. Tree age, climate conditions, and soil depth are the primary contributors to the variation in soil EEAs. Overall, our results suggest that the implementation of GCM positively affects EEAs, thereby enhancing microbe-mediated soil ecosystem functions and soil fertility. This meta-analysis provides comprehensive evidence of GCM-induced effects on hydrolase and oxidase activity, improving our understanding of the underlying mechanisms by which orchard mulching impacts soil nutrient cycling.

Natural succession and artificial management have different effects on soil microbial ecological patterns in wetland resulting from land-use change

Soil microbiomes play a crucial role in maintaining soil ecosystem functions and are sensitive to environmental changes. Land-use change is one of the important human activities affecting the Earth ecosystem. Understanding microbial community dynamics in land-use change is a key step in assessing and predicting its impact on ecological sustainability. Wetland restoration after land-use change has been widely implemented to help conserve ecological services, but the patterns of microbial dynamics during wetland formation, natural succession and artificial management remain unclear. In this study, taking coal-mining subsidence areas as research areas, soil samples from farmland, newly formed wetlands (1, 6 and 15 years old) following farmland subsidence, and a wetland under artificial management were collected to explore the ecological patterns of soil microbiome in response to land-use change. Results showed that the conversion from farmland to wetland increased microbial α-diversity (4.09 % for bacteria and 12.94 % for fungi), β-diversity (5.95 % for bacteria and 13.89 % for fungi), soil multifunctionality (293.91 %) and co-occurrence network complexity. The relative importance of stochastic processes in the microbial community assembly decreased in the early stage of wetland formation and further increased with wetland succession. Soil multifunctionality significantly decreased by 181.72 % after the artificial management in wetland. Additionally, bacteria and fungi responded differently to artificial management, and bacteria were more sensitive to the land-use change than fungi. Overall, our study broadens the understanding of soil microbial ecological patterns in newly formed wetland after land-use change, while emphasizing the importance of maintaining newly formed wetlands in its natural state.

Influence of human activities on soil microbial diversity, carbon sequestration, and resilience in Central African Forest Ecosystems

While tropical forests serve as critical carbon sinks with high biodiversity, they face increasing threats from deforestation, agriculture, and oil exploitation. This paper explores the relationships between soil bacterial and fungal community structure and diversity, soil properties, and major environmental challenges-including climate change, land degradation, biodiversity loss, and pollution in the mixed-species plantations featuring nitrogen-fixing species. Increased soil carbon storage observed in acacia and eucalyptus plantations may be influenced by the prevalence of Actinobacteria, which plays a critical role in organic matter decomposition. The dominance of Ascomycota within the fungal community appears to support ecosystem stability after environmental disturbances. High sulphur concentrations or hydrogen sulfide (H₂S) emissions promote Actinobacteria growth but, conversely, reduce Ascomycota prevalence. Both acacia and eucalyptus plantations enhance soil resilience to climate and land-use changes through increased carbon storage and other co-benefits. However, oil exploitation activities releasing H₂S emissions may compromise the ability of these mixed-species plantations to withstand environmental stresses, with potential long-term impacts on soil health and ecosystem function. This article underscores the need for sustainable practices to support soil health and ecosystem stability. It also advocates for further interdisciplinary research to understand the broader impacts of anthropogenic disturbances on forest ecosystem functions and resilience.

Agricultural land use modulates responses of soil biota and multifunctionality to increased antibiotic pressures

Antibiotic contamination has been a global agricultural issue due to heavy discharge and undesirable consequences. However, the link between antibiotic pressures and soil multifunctionality in agricultural ecosystems remains unclear. In this study, we investigated the antibiotic levels, soil functions, and their relationships in two land use types (peanut fields vs. maize fields) in a manure-amended agricultural area. The results showed a significant non-linear relationship between antibiotic pressures and soil multifunctionality in agricultural ecosystems. Antibiotics exhibited an inhibitory effect on soil functioning at high concentrations. Specifically, soil bacterial diversity and richness, earthworm abundance, and nitrogen mineralization were significantly suppressed by increasing antibiotic pressures. Increasing antibiotic contamination had peak effects on soil multifunctionality loss at a threshold of 81 %, resulting in a decrease of −1.24 in functions. Land use played a significant role in modulating the effects of antibiotic levels on soil multifunctionality. A significant response of soil function to antibiotics was observed only in peanut fields, not in maize fields. Additionally, differences in antibiotic pressures promoted the functional turnover in agricultural ecosystems. Therefore, controlling antibiotic contamination in soil is crucial for the sustainable provision of soil ecosystem functions, considering the role of land-use modulation in planning and management decisions.

Response of soil biochemical properties and ecosystem function to microplastics pollution

Microplastics (MPs)-induced changes in soil nutrient cycling and microbial activity may pose a potential risk to soil ecosystem. Although some studies have explored these topics, there is still a large space for exploration and a relative lack of research on the mechanism by which soil health and its functions are affected by these changes. Thus, this study investigated the effects of polyethylene (PE) MPs with two particle sizes (13 μm and 130 μm) at five concentrations (0%, 1%, 3%, 6% and 10%, w/w) on soil biochemical properties and ecosystem function. The findings revealed that the exposure to 13 μm MPs significantly reduced soil respiration (Res) rate, β-glucosidase (Glu) and catalase (CAT) activity, which accompanied with enhanced urease activity and decreased soil pH, available phosphorus (AP), dissolved reactive phosphorus (DRP), dissolved organic carbon (DOC) and available potassium (AK) content in most cases. However, 130 μm MPs exerted negligible influence on the DOC and DRP content, Glu and CAT activity. High concentrations of 130 μm MPs significantly reduced soil pH, total dissolved nitrogen (TDN), AP and AK content, but significantly increased soil Res rate. Overall, soil ecosystem function was significantly reduced by the addition of MPs. The Res rate, soil AP and DRP content and Glu activity were the most important predictors of soil ecosystem function. We found that the risk posed by MPs to soil ecosystem function was dose-dependent and size-dependent. These findings underscore that MPs can alter soil functions related to soil nutrient cycling and provide further insights into MPs behavior in agroecosystems.

Vertical variations in enzymatic activity and C:N:P stoichiometry in forest soils under the influence of different tree species

Abstract Tree species play a crucial role in shaping soil properties, significantly influencing nutrient cycling and ecological dynamics within forest ecosystems. In this comprehensive study, we examined the influence of tree species on soil chemistry especially on C/N/P stoichiometry and enzymatic activities across soil profiles. We analyzed soil samples beneath eight distinct tree species at three vertical horizons of soil: organic (O), humus mineral (A), and mineral enrichment (B) horizons. Our study involved detailed assessment of soil carbon, nitrogen, and phosphorus contents, along with the activities of key enzymes: β-glucosidase, N-acetyl-β-glucosaminidase, and phosphatase. The study revealed pronounced vertical stratification in soil properties, significantly influenced by the tree species. General linear models (GLMs) highlighted differences in C: N:P stoichiometry and enzymatic activity across different soil horizons and among tree species. Enzymatic activity was strongly correlated with C, N and P content. The conducted research confirms the distinctiveness of coniferous and deciduous species in terms of C, N and P stoichiometry and the activity of the tested enzymes involved in the C, N and P circulation. These variations are indicative of the intricate interactions between tree species and soil processes. Our findings underscore the role of diversity of trees in modulating soil nutrient dynamics and enzyme-driven processes, which are crucial for understanding soil ecosystem functions and nutrient cycling. This study provides new insights into the role of tree species in shaping the soil environment, offering implications for forest management and conservation strategies. Taking into account the impact of individual tree species covered by the research on the soil, it is worth considering the cultivation of mixed stands.

Sustainable Land Use Strengthens Microbial and Herbivore Controls in Soil Food Webs in Current and Future Climates.

Climate change and land-use intensification are threatening soil communities and ecosystem functions. Understanding the combined effects of climate change and land use is crucial for predicting future impacts on soil biodiversity and ecosystem functioning in agroecosystems. Here, we used a field experiment to quantify the combined effects of climate change (warming and altered precipitation patterns) and land use (agricultural type and management intensity) on soil food webs across nematodes, micro-, and macroarthropods. Specifically, we investigated two types of agricultural systems-croplands and grasslands-under both high- and low-intensity management. We focused on assessing the functioning of soil food webs by investigating changes in energy flux to consumers in the main trophic groups: decomposers, microbivores, herbivores, and predators. While the total energy flux and detritivory, herbivory and predation in the soil food web remained unchanged across treatments, low-intensity land use-compared to high intensity-led to higher microbivory and microbial control under future climate conditions (i.e., warming and summer drought) in croplands and grasslands. At the same time, microbial and herbivore control were higher under low-intensity land use in croplands and grasslands. Overall, our results underscore the potential benefits of less intensive, more sustainable management practices for soil food-web functioning under current and future climate scenarios.

Fertilization shapes microbial life strategies, carbon and nitrogen metabolic functions in Camellia oleifera soil

Mineral and organic fertilizers as well as microbial inoculations are crucial to maintain and to improve soil health and quality, ecosystem functions, and fruit yield in Camellia oleifera plantations. However, how these fertilizers shape the life strategies and functions of microbial communities in soil is unclear. Here, we conducted a one-year field experiment with three types of fertilizers: mineral (NPK), manure (Man), and microbial (MicrF), and analyzed soil properties, bacterial and fungal communities to assess microbial life strategies, functional traits and their determinants. The application of MicrF strongly increased the diversity of both soil bacterial (by 6.4%) and fungal communities (by 23%). Organic matter inputs from Man and MicrF had greater effects on the life strategies of bacteria than fungi: the dominant r-strategy bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria) increased with Man and MicrF, but K-strategists (Acidobacteria) decreased. Conversely, the abundance of r-strategy fungi (Ascomycota) decreased, but that of K-fungi (Basidiomycota) increased. Predictions of the functions indicated that microbial fertilization accelerated the bacterial carbohydrates, carbon and nitrogen metabolism, while also increasing the prevalence of wood saprotrophic fungi. The changes in the taxonomic and functional characteristics of the microbial communities induced priming effects by co-metabolism, which were mainly regulated by contents of soil organic carbon, available phosphorus, and ammonium nitrogen, as well as carbon to nitrogen ratio. The application of MicrF is an effective approach to increase the diversity and multifunctionality of soil microbial communities in Camellia oleifera plantations, including organic matter decomposition, carbon and nitrogen metabolism. These findings provide valuable insights into the fertilizer regimes based on microbial ecological strategies and functional profiles in Camellia oleifera plantations.

Impact of Transition from Natural Grasslands Steppe to Monoculture Artificial Grasslands on Soil Food Webs in the Qinghai–Tibet Plateau

Addressing the imbalance of the livestock–forage–environment system on the Qinghai–Tibet Plateau (QTP), the extensive replacement of natural grasslands with artificial grasslands has been pursued to enhance forage yield and quality. Recognizing their pivotal role in soil ecology, soil nematodes serve as sensitive indicators of the soil ecosystem structure and function. In this context, we embarked on a field investigation aimed at discerning the impact of varying artificial grasslands on soil nematode communities and food webs, with the intent of identifying an optimal forage species through the lens of soil nematode dynamics in the temperate steppe of the QTP. Our findings indicate that artificial grasslands, on the whole, tend to augment the soil nematode diversity—as reflected in the increased Margalef richness—and modify the community structure. Notable enhancements were observed in the abundance of bacterivores and omnivores, the fungivore and omnivore biomass carbon, and the connectance within fungal and bacterial channels. Specific insights reveal that grasslands established with Elymus nutans and Elymus sinosubmuticus notably boost the Margalef richness, omnivore biomass carbon, and both functional and structural metabolic footprints, with E. sinosubmuticus grasslands uniquely elevating the fungal channel connectivity. Elymus sibiricus grasslands, in particular, were associated with increased fungivore biomass carbon and metabolic footprints, as well as increased connectance in fungal and omnivore–predator channels. In summation, E. sibiricus, E. nutans, and E. sinosubmuticus emerge as superior choices for artificial grassland cultivation on the QTP, as suggested by soil nematode indicators. The adoption of mixed-species sowing incorporating these three candidates potentially offers enhanced benefits to the soil food web, although this hypothesis warrants further investigation.

Exploring Global Data Sets to Detect Changes in Soil Microbial Carbon and Nitrogen Over Three Decades

AbstractUnderstanding the temporal dynamics of soil microbial biomass is crucial for assessing soil ecosystem functions and services, yet these dynamics are globally uncertain. Here, we compiled a data set of soil microbial biomass carbon (MBC) and nitrogen (MBN) from 1493 studies between 1988 and 2019 to elucidate their temporal trends and potential drivers. Results showed that global MBC and MBN significantly decreased by 0.033 Mg C ha−1 yr−1 and 0.007 Mg N ha−1 yr−1 at 0–30 cm soil depth, between 1988 and 2019, respectively, which might be primarily attributed to the warming of the climate, the increase in global precipitation, and reduction of soil organic carbon (SOC) stock. The rate of decline in MBC and MBN showed a non‐linear trend: following a decline from 1988 to 1999, it slowed down until 2014, likely due to the global warming hiatus. Afterward, the pace of decline increased again from 2015 to 2019. Boreal biomes experienced the largest decrease in soil microbial biomass with the reduction rate of MBC being 4.3 times higher than in temperate biomes, showing a higher sensitivity in boreal biomes to climate change. Grassland ecosystems also exhibited greater reductions, possibly driven by their degradation. These findings shed valuable insights on the long‐term dynamics of soil microbial biomass on a global scale over the last three decades. Furthermore, this study underscores the importance of preserving soil microbial biomass as a key strategy to mitigate the adverse effects of future climate change, thereby sustaining ecosystem health and resilience.

Regenerative soil management practices no‐till and sheep grazing induce significant but contrasting short‐term changes in the vineyard soil microbiome

Societal Impact StatementWinegrape production is an essential cultural heritage and economic engine of many regions of the world. Regenerative management, which is gaining traction with industry and consumers alike, relies on soil biodiversity for agroecosystem function, reducing external inputs and increasing ecosystem resilience to climate change. We evaluated the effects of no‐till and sheep integration on vineyard soil biodiversity and soil ecosystem function. No‐till had stronger effects on microbial diversity, while sheep grazing stimulated microbial functioning. By providing a better understanding of the practices, we provide fundamental information for growers that want to embrace regenerative principles, ultimately contributing to the sustainability and resilience of the winegrape industry.Summary Regenerative management aims to optimize soil microbial function and diversity for enhanced agroecosystem functionality. Understanding the effects of management practices on soil microorganisms is crucial in the context of growing societal interest in this type of management. This study evaluated the short‐term effects of two soil conservation practices: sheep grazing and no‐till, on abundance, diversity, activity, and network complexity of prokaryotes and fungi in a vineyard soil. Four treatments were applied for 3 years: (1) grazed and tilled, (2) grazed and non‐tilled, (3) non‐grazed and tilled, and (4) non‐grazed and non‐tilled. We hypothesized that stacking of conservation practices (grazing and no‐till) would increase microbial diversity, function, and network complexity. Grazing had strong effects on microbial function, increasing the α‐glucosidase, β‐glucosidase, cellulase, phosphatase, and β‐xylosidase enzymatic activity by 82%, 48%, 61%, 39%, and 55%, respectively, compared to non‐grazed soils, while not causing significant changes in soil microbial diversity. Tillage had strong effects on soil prokaryotic and fungal diversity. For prokaryotes, significant interactions in alpha diversity were found between tillage and grazing, and between tillage and sampling location (tractor row and under vine). Fungal Shannon diversity index was higher in the subsoil (15–30 cm) while a significant interaction between depth, location, tillage, and grazing was found for the Chao‐1 index. Microbial network properties were only significantly affected by sampling depth. This study shows that the lack of disturbance in non‐tilled and non‐grazed soils resulted in a more diverse soil community, while grazing stimulated microbial function, thus showing a decoupling between diversity and function in vineyard soil ecosystems.

Chromium contamination affects the fungal community and increases the complexity and stability of the network in long-term contaminated soils

Chromium (Cr) contamination can adversely affect soil ecology, yet our knowledge of how fungi respond to Cr contamination at heavily contaminated field sites remains relatively limited. This study employed high-throughput sequencing technology to analyze fungal community characteristics in soils with varying Cr concentrations. The results showed that Cr contamination significantly influenced soil fungi's relative abundance and structure. Mantel test analysis identified hexavalent chromium (Cr(VI)) as the primary factor affecting the structure of the soil fungal community. In addition, FUNGuild functional prediction analysis exhibited that Cr contamination reduced the relative abundance of Pathotroph and Symbiotroph trophic types. High concentrations of Cr may lead to a drop in the relative abundance of Animal Pathogens. Molecular ecological network analysis showed that Cr contamination increased interactions among soil fungi, thereby enhancing the stability and complexity of the network. Within these networks, specific keystone taxa, such as the genus Phanerochaete, exhibited properties capable of removing or reducing the toxicity of heavy metals. Our studies suggest that Cr contamination can alter indigenous fungal communities in soil systems, potentially impacting soil ecosystem function.

Modelling soil prokaryotic traits across environments with the trait sequence database ampliconTraits and the R package MicEnvMod

We present a comprehensive, customizable workflow for inferring prokaryotic phenotypic traits from marker gene sequences and modelling the relationships between these traits and environmental factors, thus overcoming the limited ecological interpretability of marker gene sequencing data. We created the trait sequence database ampliconTraits, constructed by cross-mapping species from a phenotypic trait database to the SILVA sequence database and formatted to enable seamless classification of environmental sequences using the SINAPS algorithm. The R package MicEnvMod enables modelling of trait – environment relationships, combining the strengths of different model types and integrating an approach to evaluate the models' predictive performance in a single framework. Traits could be accurately predicted even for sequences with low sequence identity (80 %) with the reference sequences, indicating that our approach is suitable to classify a wide range of environmental sequences. Validating our approach in a large trans-continental soil dataset, we showed that trait distributions were robust to classification settings such as the bootstrap cutoff for classification and the number of discrete intervals for continuous traits. Using functions from MicEnvMod, we revealed precipitation seasonality and land cover as the most important predictors of genome size. We found Pearson correlation coefficients between observed and predicted values up to 0.70 using repeated split sampling cross validation, corroborating the predictive ability of our models beyond the training data. Predicting genome size across the Iberian Peninsula, we found the largest genomes in the northern part. Potential limitations of our trait inference approach include dependence on the phylogenetic conservation of traits and limited database coverage of environmental prokaryotes. Overall, our approach enables robust inference of ecologically interpretable traits combined with environmental modelling allowing to harness traits as bioindicators of soil ecosystem functioning.

Microplastics and nanoplastics in soil: Sources, impacts, and solutions for soil health and environmental sustainability.

The present review discusses the growing concern of microplastics (MPs) and nanoplastics (NPs) in soil, together with their sources, concentration, distribution, and impact on soil microorganisms, human health, and ecosystems. MPs and NPs can enter the soil through various pathways, such as agricultural activities, sewage sludge application, and atmospheric deposition. Once in the soil, they can accumulate in the upper layers and affect soil structure, water retention, and nutrient availability. The presence of MPs and NPs in soil can also have ecological consequences, acting as carriers for pollutants and contaminants, such as heavy metals and persistent organic pollutants. Additionally, the leaching of chemicals and additives from MPs and NPs can pose public health risks through the food web and groundwater contamination. The detection and analyses of MPs and NPs in soil can be challenging, and methods involve spectroscopic and microscopy techniques, such as Fourier-transform infrared spectroscopy and scanning electron microscopy. To mitigate the presence and effects of MPs and NPs in soil, it is essential to reduce plastic waste production, improve waste management practices, and adopt sustainable agricultural practices. Effective mitigation measures include implementing stricter regulations on plastic use, promoting biodegradable alternatives, and enhancing recycling infrastructure. Additionally, soil amendments, such as biochar and compost, can help immobilize MPs and NPs, reducing their mobility and bioavailability. This review article aims to provide a comprehensive understanding of these emerging environmental issues and identify potential solutions to alleviate their impact on soil health, ecosystem functioning, and community health.