Stable carbon isotope (δ¹³C) fractionation is an integral process in soil organic matter (SOM) dynamics, typically resulting in ¹³C-depleted respired CO₂ and ¹³C-enriched residual pools. However, the long-term isotopic trajectory of specific molecular fractions during ecosystem degradation remains poorly understood. We utilized glomalin-related soil protein (GRSP) as a robust SOM proxy to trace these isotopic shifts across a land-use chronosequence, comprising forest (initial), 5-year fallow (intermediate), and 47-year agriculture (late stage), along with their respective one-year laboratory-incubated counterparts. Our results reveal a progressive, stage-dependent ‘isotopic convergence’ as degradation progresses. In undisturbed forests, the soil micro-architecture maintained high isotopic heterogeneity across sequential GRSP fractions (−27.1‰ to −23.7‰), reflecting the sequestration of distinct carbon inputs. This isotopic diversity narrows moderately in the transitional fallow soils before converging completely toward a uniform, ¹³C-enriched signature (−22.8‰) in the long-term agricultural soils. This isotopic terminality reflects a state of functional exhaustion, where the lack of fresh organic inputs and physical breakdown of the soil matrix is consistent with a potential metabolic shift toward the utilization of historical carbon reserves. Our findings also demonstrate that the “labile-stable” continuum of GRSP is not an intrinsic chemical property, but a state-dependent feature of a healthy soil matrix. Ultimately, this study establishes δ¹³C variance across GRSP fractions as a high-resolution fingerprint for tracking bidirectional state transitions between functional carbon sinks and exhausted soils.

Biochar is applied to soils to enhance fertility and sequester carbon, but its impacts on soil fauna remain debated. This work assessed the behavioural responses of collembolans (Folsomia candida) and woodlice (Porcellionides pruinosus) to soils amended with different biochar derived from Ricinus communis and Brassica juncea feedstocks, both pyrolyzed at 400 °C and 600 °C, and tested at 1% and 10% (w/w). Results revealed that F. candida avoided R. communis biochar at high concentrations, suggesting a stronger role of dosage than pyrolysis temperature. In contrast, P. pruinosus was attracted to B. juncea biochar at 400 °C but avoided the sample pyrolyzed at 600 °C, while gregariousness was affected at the highest concentration, highlighting the influence of dose and pyrolysis. Furthermore, we examined whether woodlice presence alters collembolans responses through ecological facilitation–non-trophic interactions that benefit at least one species. Remarkably, collembolans no longer avoided soils previously inhabited by woodlice. Multivariate analysis revealed that responses of soil arthropods to biochar were primarily determined by the type of feedstock, while ecological facilitation was mainly driven by soil conductivity, suggesting that woodlice actively modulate soil properties likely by bioturbation, or faecal deposition. In an ecological perspective, facilitation by woodlice may buffer stress and enhance habitat suitability for other soil fauna, while their high sensitivity positions them as key early indicators of biochar-induced changes in soil ecosystem functioning. It is recommended that ecological sustainable management be adopted, as high soil biodiversity can prevent soil degradation and facilitate natural processes that can mitigate the effects of biochar.

Biogas slurry substitution for chemical fertilizers is a key strategy for reducing fertilizer use and recycling agricultural organic waste. However, the mechanisms underlying its impact on the profile distribution of soil organic carbon (SOC) remain unclear. This study compared the effects of different biogas slurry nitrogen substitution ratios (50% and 75%) and application methods (nitrogen-only substitution vs. combined nutrient substitution) on SOC fractions in paddy soils, aiming to elucidate the transformation pathways and stabilization mechanisms of plant- and microbial-derived carbon in the 0−15 cm layer (topsoil) and 15−30 cm layer (subsoil). Results showed that, in the topsoil, biogas slurry substitution enhanced peroxidase (PER) activity while inhibiting phenol oxidase (POX) activity compared with the chemical fertilizer (CF) treatment. This was accompanied by a significant decrease in lignin phenol content by 30.62%−51.78%, whereas the acid/aldehyde (Ad/Al) ratio remained relatively stable. Additionally, biogas slurry application significantly promoted microbial necromass carbon (MNC) accumulation with increases of 33.50%−109.35%, indicating that MNC became a major contributor to the topsoil organic carbon pool. In the subsoil, anaerobic conditions suppressed extracellular enzyme activity, limiting microbial transformation of plant-derived carbon. The 50% nitrogen substitution treatment significantly increased lignin phenol content by 40.26%−69.44%, but significantly reduced MNC by 54.27%−61.15%. This study reveals the stratified SOC stabilization mechanisms driven by biogas slurry: microbial transformation predominates in the topsoil, while physical and chemical stabilization of plant-derived carbon is central in the subsoil. The 50% substitution rate was identified as the optimal strategy for enhancing SOC sequestration efficiency across the entire soil profile.

Excess nitrogen (N) is fundamentally reshaping soil microbial communities and the biogeochemical networks that sustain ecosystem functioning. Beyond changes in microbial diversity, increasing evidence suggests that excessive N inputs reorganize microbial interaction networks, with cascading effects on nutrient cycling, plant-microbe relationships, and climate feedbacks. Here, we synthesize emerging insights into how N enrichment alters soil microbial network architecture and the ecological mechanisms underlying these transformations. We propose that microbial network responses to N enrichment are context dependent, governed by nutrient availability, microbial life-history strategies, soil properties, and ecosystem characteristics. Nitrogen-driven shifts in microbial traits, keystone taxa, and interspecific interactions can modify carbon and nitrogen turnover, influence greenhouse gas dynamics, and alter plant health outcomes. However, co-occurrence networks mainly capture statistical associations and require integration with functional, experimental, and process-based approaches to establish causality. Bridging microbial network ecology with biogeochemical theory and sustainable N management will advance our ability to predict ecosystem responses to ongoing global nitrogen perturbations.

Biodiversity-ecosystem function research has increasingly recognized the importance of belowground communities, yet how multidimensional traits of soil nematodes shape ecosystem functions across environmental contexts remains poorly understood. Using data from two large-scale transects on the Mongolian Plateau, we develop an integrative framework to assess how taxonomic diversity, ecological indices, and metabolic traits of nematode community drive ecosystem multifunctionality (EMF) across grassland types spanning a resource gradient. We found that nematode α- and γ-diversity, ecological indices, and metabolic traits increased from desert to meadow steppe, while β-diversity declined. Overall, aboveground, and belowground EMF responded similarly, all peaking in meadow steppe. Aboveground EMF was governed primarily by precipitation, whereas belowground and overall EMF integrated both abiotic drivers and direct positive effects of nematode ecological indices and metabolic traits. Critically, regulatory mechanisms shifted along the gradient: abiotic factors dominated in resource-poor systems (desert, desert steppe), while plant diversity and nematode traits became significant direct drivers and direct abiotic effects weakened in resource-rich systems (typical steppe, meadow steppe). Aboveground EMF remained consistently climate-dominated. Our findings reveal fundamental context dependence in biodiversity–ecosystem functioning relationships, with important implications for predicting grassland responses to global change and informing grassland management.

Woodlice, as one of the key groups, contribute to the decomposition of litter in ecosystems. However, the resource use by woodlice, which likely depends on the body size and developmental stage, remains poorly understood. Understanding ontogenetic shifts in the composition of stable isotopes δ¹³C and δ¹⁵N is essential for assessing the position of woodlice in soil food webs. We applied the stable isotope analysis of carbon and nitrogen to four ontogenetic stages of two synanthropic cosmopolitan woodlice species, Cylisticus convexus and Oniscus asellus, along with their potential food resources in a city park in Moscow, Russia. We compared mancas, juveniles, young adults, and adults. In C. convexus, the δ¹³C values remained constant, while juveniles, young adults and adults were enriched in ¹⁵N compared to mancas. In O. asellus, δ¹³C values remained constant except for the last age (adults), when they were enriched in ¹³C by about 1.5‰, compared to other ages. Young adults of O. asellus were depleted in ¹⁵N compared to other ages. Bayesian mixing models (MixSIAR) indicated leaf litter as the primary dietary resource for both species, with species-specific differences in the contribution of fungi and moss. These results suggest ontogenetic shifts in resource use within woodlice populations. We demonstrate the need to consider the age of woodlice when interpreting isotopic data and assessing their trophic roles in soil ecosystems.

Drought limits wheat production in dryland agroecosystems, yet native rhizosphere bacteria that improve drought tolerance under long-term field management remain insufficiently explored. We integrated high-throughput sequencing, co-occurrence network analysis, and culture-dependent isolation in a 20-year dryland field experiment with different nitrogen (N) addition and wheat genotypes to identify native culturable core bacteria and develop a drought-alleviating synthetic community (SynCom). N addition and wheat genotype altered the abundance of specific bacterial taxa, whereas treatment-driven differences in overall community structure were not detectable at the present replication level. N addition increased network complexity and reshaped bacterial co-occurrence patterns. By integrating 3320 shared ASVs, 597 keystone nodes, and 115 cultured isolates, we identified a culturable core microbiota comprising 9 ASVs. Four compatible strains (Pseudomonas piscicola, Curtobacterium allii, Acinetobacter oryzae, and Peribacillus frigoritolerans) enriched in drought-tolerant wheat were assembled into a SynCom. SynCom inoculation enhanced growth of drought-sensitive wheat seedlings across a simulated drought gradient, increasing root length by 113%−136%, belowground fresh weight by 93%−149%, and total dry weight by 31.75%−45.16%. These results support a microbiome-based strategy for improving wheat drought tolerance under controlled drought-simulation conditions.

Recycling spent mushroom substrate (SMS) to agricultural fields is a widely adopted strategy for organic waste valorization. However, the decomposition characteristics, nutrient release patterns, and microbial succession of SMS under different return rates and nitrogen fertilization regimes remain unclear; we used high-throughput sequencing, enzyme activity assays, and physicochemical analysis to investigate them. In this field experiment, three replicated plots were established per treatment, and destructive sampling was performed at nine time points over 110 days. Overall, the SMS decomposition rate decreased significantly from 5.39 ± 1.42 g d⁻¹ at the early stage to 1.85 ± 0.27 g d⁻¹ at the late stage (P < 0.001, Welch's t-test). Nitrogen fertilization significantly suppressed enzyme activities and decomposition rate, and this effect did not differ significantly among stages (stage × nitrogen, P > 0.05). SMS application rate also significantly affected decomposition, with the lower rate showing a higher decomposition rate overall. The microbial co-occurrence network reached its highest complexity and stability (bacterial AUC = 54.267, fungal AUC = 9.663) at the middle stage, along with the largest niche breadth. Structural equation modeling revealed that the decomposition rate was directly influenced by microbial diversity (Std. β = 0.444, P < 0.001) and residue properties (Std. β = 0.515, P < 0.001), whereas community structure had only indirect effects. This study provides practical guidance for the efficient soil application of SMS under nitrogen fertilization, contributing to the sustainable utilization of agricultural organic wastes.

Oxygen (O₂) availability exerts a primary control on soil greenhouse gas (GHG) emissions, yet its interactions with temperature, depth, and inter-gas coupling remain poorly understood. We conducted controlled incubations to assess how O₂ concentration (21%, 5%, and 0%) regulates soil carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄) emissions and their temperature sensitivities (Q₁₀) across surface (0–10 cm) and subsoil (70–80 cm) layers. The results showed that CO₂ emissions under 0% and 5% O₂ decreased by 22%–30% in the surface soil and by 9%–16% in the subsoil relative to oxic conditions (21% O₂). In contrast, the two anoxic conditions mainly increased N₂O emissions (by up to 672%) in the surface soils. CH₄ fluxes switched from net uptake under oxic conditions to net production under 0% O₂ condition in both soil layers. The temperature sensitivity varied among the three gases as well as among O₂ levels and soil depths. The Q₁₀ of CO₂ emissions was higher in the upper layer (Q₁₀ = 1.5−2.0 in the surface vs 1.0−1.5 in the subsoil), but insensitive to O₂ levels; whereas the Q₁₀ of N₂O and CH₄ was much more sensitive to O₂ levels but similar among depth layers. Pairwise correlation analysis indicated the emission rates of the three gases were generally positively correlated, particularly under anoxia and hypoxia conditions; the correlations of their Q₁₀ was relatively weak. These depth- and O₂-dependent linkages highlight the dynamic trade-offs among carbon oxidation, nitrogen transformation, and methanogenesis across redox transitions. Considering such redox-mediated feedbacks is essential for improving projections of soil GHG emission-climate feedbacks under a warmer climate.

Grazing can alter bacterial communities by influencing soil properties and metabolites. Nevertheless, metabolites in biological soil crusts (BSCs) under grazing disturbance remain poorly understood. Here, we collected BSC samples under three grazing intensities (0 [enclosure, EN], 1.00 [light grazing, LG], and 2.33 [heavy grazing, HG] sheep-units ha⁻¹ year⁻¹) in the arid region of northwestern China to explore the effects of physicochemical properties and metabolites on bacterial communities. Our results indicated that the number of metabolites decreased with increasing grazing intensity, which markedly altered metabolite composition. Nutrients (NO₃⁻-N and NH₄⁺-N) and the metabolite composition of BSCs were closely correlated with bacterial community composition (p < 0.05). A total of 135, 131, and 124 differential metabolites were identified between the EN and LG, EN and HG, and LG and HG groups, among which organic oxygen compounds, phenylpropanoids and polyketides, and lipids and lipid-like molecules were the major classes. Co-occurrence network analysis revealed significant correlations between major differential metabolites and dominant bacteria (Proteobacteria, Actinobacteriota, and Chloroflexi). These results highlight that nutrients and metabolites in BSCs play important roles in regulating bacterial community composition, providing data support for the conservation and restoration of desert grasslands.

Anthropogenic activities have concurrently increased atmospheric nitrogen (N) deposition and altered forest litterfall dynamics, both of which can profoundly influence soil microbial communities. The individual influence of these two factors on soil microorganisms is extensively investigated, whereas their interactive effect remains poorly understood. To address this gap, a 10-year full-factorial experiment with N addition (control and 10 g N m^–2 yr^–1) and litter manipulation (removal, ambient, and addition) was conducted in a Pinus sylvestris var. mongolica plantation. We measured 10 variables related to soil acid-base status and N availability, and assessed soil microbial biomass and community composition using phospholipid fatty acid analyses. Results revealed that chronic N addition reduced soil bacterial and fungal biomass, as well as reshaped microbial communities. These changes in soil microorganisms were associated with N addition-induced soil acidification and increases in soil N availability. Litter manipulation alone had minor effects, but its interaction with N addition markedly influenced soil microbial biomass. Specifically, litter addition mitigated N addition-induced declines in soil bacterial and total microbial biomass. This significant interactive effect was attributed to the role of litter addition in mitigating soil acidification caused by N addition. Overall, these results suggest that litter addition could alleviate N enrichment effects on soil acid-base status and consequently on soil microbial biomass likely owing to the rapid N immobilization and followed by slow N mineralization during litter decomposition, and underscore that litterfall conservation is critical for enhancing soil microbial resistance to N deposition.

Diversified cropping systems incorporating legume pre-crops are widely advocated to enhance cereal performance under low-input conditions, but their benefits may involve mechanisms beyond biological nitrogen (N) fixation and total soil N enrichment. To test this hypothesis, we conducted a greenhouse inoculum-transfer experiment within a plant-soil feedback (PSF) framework. A common sterilized background soil was inoculated with live soils conditioned by rice (Oryza sativa L.), cauliflower (Brassica oleracea var. botrytis L.), or bur clover (Medicago polymorpha L.) and crossed with five fertilization regimes. Rice-conditioned soil induced negative feedback, whereas cauliflower- and bur clover-conditioned soils generated positive feedback, with bur clover showing the strongest stimulatory effect. Soil total N was highest in rice-conditioned soil, indicating decoupling between total N stock and rice performance. Instead, the bur clover legacy reduced bulk density, increased water content, enhanced available N and P, elevated plant P, and shifted plant N:P regulation from plastic or weakly plastic responses toward strict homeostasis. Thus, the rotational advantage of bur clover is driven by coordinated improvements in soil resource availability and strengthened plant stoichiometric regulation rather than total N enrichment alone. These findings reframe the agronomic value of legume pre-crops from an integrated soil-plant nutrient stoichiometry perspective.

Biological soil crusts sustain carbon and nitrogen cycling across dryland surfaces, yet whether their soil multifunctionality is governed by microbial diversity or community composition remains unresolved, and how animal-driven disturbance alters this relationship is poorly known. We examined ant nesting as a natural disturbance gradient across five microhabitats in a revegetation area of the Tengger Desert, from ant hill soil to intact control biocrust. Bacterial and eukaryotic communities were characterized by paired 16S and 18S rRNA gene sequencing and related to a soil multifunctionality index and cumulative CO₂ and N₂O fluxes. Ant nesting restructured community composition most strongly through the photoautotrophic base: cyanobacteria declined from 12.96% in control biocrust to 1.17% in ant hill soil, and oligotrophic actinobacteria were enriched in the disturbed microhabitats. Bacterial and eukaryotic diversity, in contrast, responded asymmetrically and did not follow the gradient. Soil multifunctionality increased monotonically from ant hill soil to control biocrust, and cumulative N₂O flux peaked at both ends of the gradient. Cumulative CO₂ efflux increased steeply with cyanobacterial abundance (r = 0.99), whereas multifunctionality and CO₂ efflux both declined with bacterial diversity (r = −0.89 and −0.95). All co-occurrence network hub genera were bacterial, and labile carbon was coupled to the bacterial community alone, indicating a bacteria-anchored community-function coupling. In this revegetated desert system, soil multifunctionality followed the composition of the photoautotrophic base rather than community diversity. Ant nesting lowered function by dismantling that base.

From the perspective of global agricultural civilizations, traditional Chinese agriculture maintained high and stable yields for several thousand years without exhausting soil fertility. This achievement was supported by a long tradition of soil management. This paper traces the tradition through a circular process of “theory–practice–theory.” It first examines land suitability and soil veins within the framework of the Three Realms as the theoretical basis of ancient Chinese soil management. These ideas show that soil was understood as a living and dynamic system closely connected with climate, landforms, crops, and human activity. The paper then discusses treating manure as medicine, a principle first proposed by Chen Fu in the Southern Song Dynasty. The principle applied the view of soil as a living body to fertilization practice. It required farmers to select and apply fertilizers according to soil conditions, fertilizer properties, and farming seasons, thereby helping to systematize traditional fertilization techniques. Finally, the paper explains how long-term fertilization practice gave rise to the theory of renewed and sustained soil fertility. By recycling nutrients and returning organic matter to the soil, ancient Chinese practices sustained long-term soil fertility, contrasting with the classical Western doctrine of diminishing returns in agriculture. The study shows that ancient Chinese soil management linked ecological understanding, farming practice, and theoretical reflection, and offers useful historical experience for addressing soil degradation and developing sustainable agriculture today.

Soil, as the largest terrestrial carbon (C) reservoir, plays a pivotal role in the global C cycle. However, predicting how warming affects soil organic C (SOC) remains challenging, partly due to the diverse vulnerabilities of its constituent pools. To address this gap, we conducted a global meta-analysis based on 155 peer-reviewed studies, systematically assessing the responses of key SOC pools to field warming and their underlying drivers. Our results showed that, warming did not significantly change the contents of bulk SOC, particulate organic C (POC), or mineral-associated organic C (MAOC). However, responses of dissolved organic C (DOC) and microbial biomass C (MBC) depended on warming duration, magnitude, method, and ecosystem type. Under long-term warming (⩾5 years), both DOC and MBC increased significantly, while infrared heating produced stronger positive responses than other methods. Subgroup analyses further revealed that warming increased MBC by 6.1% in croplands and DOC by 4.7% in grasslands. The responses of DOC and MBC intensified with increasing soil pH. Overall, these findings reveal divergent sensitivities among SOC pools, with physical SOC fractions remaining largely unchanged, whereas biological active SOC pools exhibited context-dependent responses to warming. Distinguishing among SOC pools is therefore important for evaluating soil C–climate feedbacks.

Antibiotic-contaminated wastewater has become a significant environmental challenge driving the dissemination of antibiotic resistance genes (ARGs) and disrupting soil microbial ecology in agroecosystems. Wastewater from hospitals, livestock production systems, slaughterhouses, and wastewater irrigation introduces antibiotic residues, antibiotic-resistant bacteria (ARB), and mobile genetic elements (MGEs) into agricultural soils, accelerating selective pressure and horizontal gene transfer (HGT) within microbial communities. This review examines the major sources and environmental fate of antibiotics in soil systems and discusses their impacts on microbiome-resistome interactions, nutrient cycling, soil fertility, agroecosystem resilience, and food safety. We also explore how antibiotic exposure alters microbial community structure and promotes the persistence of resistant pathogens in agricultural environments. Advanced mitigation strategies, including membrane technologies, membrane bioreactors, advanced oxidation processes, constructed wetlands, and biochar-based remediation, are evaluated for reducing antibiotic and ARG dissemination. In addition, emerging CRISPR-based engineering and bacteriophage-mediated approaches are discussed as precision tools for targeted resistome suppression and soil microbiome restoration. Finally, an integrated One Health framework linking wastewater regulation, antimicrobial stewardship at farm level, sustainable manure management, and soil microbiome surveillance is proposed to support sustainable agriculture and mitigate environmental antimicrobial resistance.