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Low ionic concentrations and the chemical stability of the ions involved to water are considered necessary for hydrated ionic solution lubricants. Herein, an ultra-high concentration of chemically active ZnCl2 aqueous solution (up to 20 mol L− 1) is first reported to be used as a liquid superlubricant, with trace amounts of Zn2+ hydrolyzed to generate Zn(OH)2 (i.e., hard clusters) in addition to Zn2+ hydrated with water (i.e., soft clusters), resulting in the formation of heterogeneous phases with a mixture of soft and hard clusters. The coefficient of friction (COF) inversely correlates with the molar concentration of ZnCl2, where the COF of the optimized samples can be as low as 0.006 with a stable macroscopic superlubricated state; the particle size distribution of clusters and their corresponding Spans, however, are positively correlated with the molar concentration, suggesting that asymmetric contact between these unequal-sized soft and hard clusters contributes greatly to the reduction of interfacial shear resistances. This ultra-high-concentration aqueous solution superlubricant not only breaks the convention but also deepens the mechanism of liquid superlubricity from the perspectives of cluster size distribution and interactions between clusters, providing a new insight into the design of advanced water-based ionic solution superlubricants. [ABSTRACT FROM AUTHOR]

Adding additives (e.g., carbon dots, CDs) to liquid lubricants is an effective method for enhancing their load‐bearing capacity and friction reduction. However, it is challenging to simultaneously impart high load‐bearing capacity and superlubricity for them (e.g., ionic liquid analogs, ILAs) through this strategy due to strong Coulombic interactions. With CDs as a competing ligand operon, the cluster size distribution can be expanded, conferring superlubricity with ultrahigh load‐bearing capacity (>705 MPa, the highest value of CDs‐based superlubricious materials thus far) for CDs/ILAs. In particular, methodologies such as Raman, 1H‐NMR, fourier transform infrared spectroscopy, and laser particle size analysis are employed to characterize the evolution of their H‐bonding interactions and particle size distribution. CDs can act as competing ligands and enable CDs/ILAs to form systems with ultra‐low coefficient of friction and wear consisting of a mixture of large and small clusters. The mixed and expanded size clusters facilitate the reduction of the viscosity for CDs/ILAs under shear, thereby reducing the interfacial shear resistance during superlubricity, while the CDs within them efficiently transfer the normal bearing loads. The progress is made from the perspective of cluster particle size distribution rather than individual additive properties, providing a new avenue for designing ILAs‐based superlubricious materials. [ABSTRACT FROM AUTHOR]

Soil fauna plays irreplaceable roles in delivering ecosystem functions in the face of climate change and human activities. Understanding how soil fauna-mediated processes change following environmental stresses is therefore critical to the maintenance of ecosystem services. This study assessed the soil functional capability, as measured by short-term decomposition of plant residues, subjected to simulated copper and heat stress in the presence, or absence, of enchytraeids (Enchytraeus florentinus) in an arable soil. Results showed that enchytraeid density decreased to 37%, 10%, and 5% of the initial density at the end of the experiment in the control, copper, and heat treatments, respectively. Soil functional capability increased in the presence of enchytraeids, but only in the stressed soils and not apparently in the controls. Fungal biomass was increased in the presence of enchytraeids particularly in the control soil. The enchytraeids did not affect water extractable organic C (WEOC) and total extractable N (TEN) in the control; however, they increased TEN in both stressed soils and WEOC in the copper stressed soil. We found that the enchytraeid effects on functional capability were positively related to the proportions of dead enchytraeids throughout the experiment duration. We infer that the contribution of enchytraeids to soil functional capability was mainly due to the after-life effects, most possibly through three potential mechanisms including (1) enhancement of microbial activity with resource contributed from their dead bodies, (2) through microhabitat improvement established before their death, and (3) microbiome composition changes derived from live or dead enchytraeids. We conclude by our case as an example that soil fauna could sustain key ecosystem functions under adverse conditions, highlighting the importance of soil biodiversity conservation in a changing world. [ABSTRACT FROM AUTHOR]

Gut microbiota are determined by both the food ingested and physiological conditions of the host. In soil food webs, detritivore animals occupy various trophic niches, spanning from primary decomposers to predators. However, the relative contribution of food resources and species attributes of consumers to gut microbial communities in soil detritivores has not yet been explored. In this study, we investigated gut bacteria and fungi of oribatid mites (Oribatida, Acari), ubiquitous and diverse soil microarthropods feeding on a variety of food resources, to uncover the contribution of host phylogenetic relatedness and trophic niches to the assemblages of gut microbiota. Abundance and community composition of bacteria and fungi were characterized by qPCR and Illumina sequencing, respectively. Gut bacterial communities were more closely correlated with host phylogenetic affinity, whereas gut fungal communities were more closely correlated with the trophic niches of the host. Community phylogenetic analysis suggests that deterministic processes predominated in the assembly of both bacterial and fungal communities in most of the studied oribatid mite species. Integrating phylogenetic distance and trophic niche distance of hosts resulted in the highest correlation coefficients between host species and their gut microbial communities suggesting that both evolutionary history and current trophic niches shape gut microbial communities. Bacteria in the gut may comprise commensals or mutualists facilitating digestion which potentially coevolved with the host, while the fungal community in the gut reflects the trophic niches of the consumer likely suggesting that they form part of the diet and serve as food resources of soil detritivore microarthropods. [ABSTRACT FROM AUTHOR]

Even though organic fertilization is known to promote soil nitrogen cycling ( N -cycling), it is unclear how this effect is mediated. Here we studied the potential roles of soil physiochemical properties and soil particle-size fraction (PSF) in relation to the diversity and abundance of N -cycling-related prokaryotes by sampling field sites that had been subjected to either mineral or organic fertilization for over 30 years (two independent fields subjected to both fertilization treatments). We found that organic fertilization increased the 63–200 μm sized soil fraction and the abundance of various N -cycling-related prokaryotes including diazotrophs, ammonia-oxidizers and denitrifiers. Moreover, increase in the abundance of different N -cycling-related prokaryotes varied between different size fractions: the abundance of ammonia-oxidizers and nitrate-reducers was the highest in the 63–200 μm size fraction, while the abundance of diazotrophs, ammonifiers and denitrifiers was the highest in the 200–2000 μm, 2–63 μm and 0.1–2 μm size fractions, respectively. According to structural equation modelling (SEM), soil PSF, physiochemical properties and the community structure of N -cycling-related prokaryotes within different PSFs were associated with the abundance of N -cycling-related prokaryotes in non-fractionated bulk soils. In conclusion, these results suggest that organic, but not mineral, fertilization can support the abundance of N -cycling-related prokaryotes and that the strength of the effects depends on their association with specific particle-size fractions. [ABSTRACT FROM AUTHOR]

Sustainable agriculture aims to manage soil and plant health while relying less on chemical inputs. The individual effect of organic amendments or resistant crop cultivars on the suppression of root pests through modulating soil and plant performance is being well documented. However, the interactions between organic amendments and crop cultivars are less well studied. A pot experiment was conducted across two tomato cultivars of distinct resistance to root-knot nematodes (RKNs, Meloidogyne incognita ) with three amendments including inorganic fertilizer (IF), conventional compost (CC) and vermicompost (VC). All treatments were inoculated with second-stage juveniles of M. incognita to simulate the root-knot nematode disease in field condition and to focus on the comparison among different soil amendment effects. Plant growth (shoot height, shoot biomass, root biomass and root C:N ratio), root defense metabolites (phenolics) and their related genes expression, and soil properties including pH, electrical conductivity, available nutrients, 3-indoleacetic acid (IAA), microbial biomass and activity were analyzed at 14 and 30 days post inoculation (dpi). Compared with inorganic fertilizer, vermicompost significantly decreased the numbers of nematode-induced galls on susceptible (Sus) and resistant (Res) cultivar roots by 77% and 42% respectively at 14 dpi, and by 59% and 46% respectively at 30 dpi. Vermicompost also significantly increased root defense metabolite concentrations, defense related gene expression, and improved soil properties ( p < 0.05) except for mineral nitrogen. Multivariate analyses further indicated that soil properties particularly pH, root primary and secondary defense metabolites were negatively associated with root gall. Moreover, soil microbial activity, pH and IAA concentration were the main soil properties positively associated with plant defense metabolites production and biomass for both susceptible and resistant cultivars. Overall, vermicompost could significantly suppress root pests via modulating soil properties as well as plant defenses, particularly for the susceptible plant. [ABSTRACT FROM AUTHOR]

Organic amendments not only promote soil quality and plant performance directly but also facilitate the establishment of introduced microbial agents. A field experiment with a fully factorial design was conducted using three levels of vermicompost (without vermicompost, low dose of 15 Mg ha −1 and high dose of 30 Mg ha −1 ), with and without plant growth-promoting rhizobacteria (PGPR) to investigate their effects in a tomato – by spinach rotation system. Our results demonstrated that applying PGPR alone had no effect on soil properties and crop performance. Vermicompost enhanced the beneficial effects of PGPR on both soil and crop, with the extent of promotion depending on the dose of vermicompost and crop types. In the presence of vermicompost, PGPR significantly ( P < 0.05) reduced soil carbon and nitrogen but increased soil microbial biomass carbon and nitrogen. PGPR also significantly increased the yield of tomato and spinach under the low dose of vermicompost, but only significantly increased tomato yield under the high dose of vermicompost. There were strongly synergistic effects between vermicompost and PGPR on crop quality, with crop nitrate concentration being significantly decreased, while the vitamin C in tomato and soluble protein in spinach was significantly increased. Our results revealed the high potential of integrating vermicompost and microbial agents to substitute for regular chemical fertilization practices. [ABSTRACT FROM AUTHOR]

In agricultural ecosystems, most crop cultivars are bred for pest resistance with the aim of resisting aboveground herbivores, but it is unclear if this resistance also affects abundance, composition, and activity of underground pests and content of soil labile pools. A fully factorial greenhouse experiment was carried out, using four rice cultivars with distinct resistance to shoot herbivore brown planthopper, Nilaparvata lugens, with and without rice root nematodes, Hirschmanniella spp., to test two hypotheses: (1) rice cultivars resistant to brown planthopper are more susceptible to rice root nematodes and (2) rice root nematodes of resistant cultivars cause greater modification of labile pools of rhizosphere soil than those of susceptible cultivars by inducing more leakage of plant metabolites. Nematode abundance, soluble sugar and soluble amino acid contents of plant, and microbial biomass C and N, dissolved organic C and N, and soluble sugar and amino acid contents of rhizosphere soil were analyzed. The abundance of rice root nematodes substantially increased under all rice cultivars following root nematode inoculation. Rice cultivar resistance to brown planthopper did not affect the numbers of rice root nematodes but decreased negative effects of nematodes on root growth, shoot soluble sugar and amino acid contents, and labile pools of rhizosphere soil, probably implying that integrated complex mechanisms other than only resource allocation were involved in rice resistance to aboveground and belowground herbivores. Our study will contribute to a better understanding of aboveground-belowground interactions and to the development of integrated pest managements by considering belowground ecosystem responses in crop systems. [ABSTRACT FROM AUTHOR]

A pilot-scale trial of four months was conducted to investigate the responses of heavy metal and nutrient to composting animal manure spiked with mushroom residues with and without earthworms. Results showed that earthworm activities accelerated organic matter mineralization (e.g. reduction in C/N ratio, increase in total concentrations of N, P, K) and humification (e.g. increase in humic acid concentration, humification ratio and humification index). Despite composting increased total heavy metal (i.e. As, Pb, Cu, Zn) concentrations irrespective of earthworm, the availability of heavy metals extracted by DTPA significantly ( P < 0.05) decreased particularly in treatments with earthworms introduced. The shift from available to unavailable fractions of heavy metals was either due to earthworm bioaccumulation, as indicated by total heavy metal concentrations being higher in earthworm tissues, or due to the formation of stable metal-humus complexes as indicated by the promotion of humification. Our results suggest that vermicomposting process could magnify the nutrient quality but relieve the heavy metals risk of agricultural organic wastes. [ABSTRACT FROM AUTHOR]

Background and Aims: The importance of aboveground herbivores for modifying belowground ecosystems has prompted numerous studies; however, studies can be biased by context dependent conditions which lead to extremely inconsistent results. So far, the impacts of herbivory intensity by important rice pests on rice paddy soil ecosystems are lacking. The aim of this study was to test the hypothesis that intermediate herbivory intensity of the brown planthopper ( Nilaparvata lugens Stål) could promote soil labile resources and microbial biomass, while high intensity would show a reverse pattern, by mediating rice plant growth. This study will also help the development of integrative pest management. Methods: Four hopper infestation density treatments (0, 4, 8 and 12 nymphs per rice plant) and two infestation duration treatments (9 and 15 days after N. lugens infestation, DAI 9 and DAI 15) were established in a glasshouse experiment. Soil and plant were sampled destructively from four replicates and analysed for soil labile resources availability, soil microbial biomass and plant performance, respectively. Results: The infestation density significantly affected both shoot and root mass of rice ( P < 0.05), soil dissolved organic carbon (DOC) and nitrogen (DON), and microbial biomass carbon (MBC) and nitrogen (MBN), and the effects were further enhanced by prolonged infestation duration. Compared to the control (CK) without N. lugens, plant dry mass, DOC, DON, MBC and MBN increased under low (LD) and moderate hopper densities (MD) but decreased under high density (HD) on DAI 9. Moreover, the LD treatment exerted the most promotional effects on DAI 15. Rice root to shoot ratio generally increased in treatments subjected to herbivory. The labile resources and microbial biomass showed close relationships with both shoot and root mass across treatments, in particular with root mass on DAI 15. Such a trend indicated that the shift of photosynthate allocation to belowground contributed to changes of soil resource availability and microbial biomass. Conclusions: Intermediate herbivory intensity showed positive effects on rice seedling performance and, further, promoted soil labile resource availability and microbial biomass. The importance of extrapolating temporal and spatial scale, i.e. from the short-term greenhouse experiment to an entire rice growing season in the field, was highlighted. [ABSTRACT FROM AUTHOR]

Abstract: Plant-mediated effects of aboveground herbivory on the belowground ecosystem are well documented, but less attention has been paid to agro-ecosystems and in particular how crop cultivars with different traits (i.e. resistance to pests) shape such interactions. A fully factorial experiment was conducted using four rice cultivars with different insect-resistance, with and without the aboveground herbivore Nilaparvata lugens (brown planthopper), and to test two hypotheses (1) aboveground herbivory affects the soil microbial biomass and nematode community by altering plant performance and soil resource availability and (2) herbivory effects will depend on cultivar resistance traits. Our results suggested that cultivar resistance mediated both herbivory intensity and herbivore effects on plant performance. N. lugens decreased the availability of soil resources (soluble sugars, amino acids, organic acids, dissolved organic carbon and nitrogen), microbial biomass and percentages of bacterivores when feeding on a susceptible cultivar but increased them in a resistant cultivar. However, total nematode abundance and the percentage of plant-parasitic nematodes responded in the opposite way, increasing under a susceptible cultivar and decreasing under a resistant cultivar. The development of plant-parasites under resistant cultivars before aboveground herbivory might contribute to their resistance traits. Our findings provide evidence that N. lugens significantly reversed the pattern of soil resource availability, microbial biomass and nematode community structure (abundance and trophic composition) across cultivars with distinct resistance. In the presence of aboveground pests, the agronomic use of resistant rice cultivars could also control populations of plant-parasites and promote soil resource availability, further extended to higher trophic level of soil food web. [Copyright &y& Elsevier]

Abstract: We grew plants in soil amended with either finely ground (<0.2 mm) or larger pieces (4 × 5 mm2) of maize leaves. Finely ground material will be mineralized faster; hence nitrogen is released faster in the soil. We inoculated the soil with the plant growth inhibiting bacterium Arthrobacter BEM463, a relatively poor food source for bacterial feeders, and the plant growth promoter Sphingopyxis BEM760 which is a good food source. Protozoa and nematodes were introduced separately or in combination. In soil with larger maize leaf pieces (low turnover, slow nitrogen release), bacterial feeders generally increased plant nitrogen uptake and growth. In systems with finely ground material (high turnover, fast nitrogen release), plants hardly benefited from presence of grazers; bacterial mineralization activity alone probably provided enough N for the plants. The harmful Arthrobacter thrived better when grazed by protozoa than when grazed by nematodes, probably because the selective protozoa could avoid it, which resulted in reduced plant performance. We suggest that bacterial feeders generally increase plant performance when nutrients are limited. At high nutrient availability, however, bacterial feeders promote grazer resistant bacteria, and, if these bacteria are harmful to plants, the net effect of bacterial feeders on plant growth can be negative. [Copyright &y& Elsevier]

Abstract: Responses of nematode assemblages and soil function (short-term decomposition) in restored and degraded soil following an experimental disturbance (copper, chloroform, heat or drying) were monitored for 65 days. We tested the hypotheses: restoration enhanced the measured soil parameters; stability to disturbance was higher in degraded soil due to induced tolerance; and whether changes of the nematode assemblage were related to soil function. Even after disturbance, greater nematode abundance (>150 vs >10 per 100g soil), nematode richness (D′>1.0 vs >0.4) and function (>1.0 vs >0.05mg CO2 g−1 week−1) were maintained in restored than in degraded soil, respectively. An increase in nematode enrichment index (from 60 to >75) following all disturbances was attributed to the relatively high abundance of tolerant fungivores. The greater stability of the nematode structure index in degraded soil following heat and drying (120% and 125% respectively of the control), than in restored soil (90% and 30% of control) was due to a higher proportion of tolerant omnivores and carnivores. Thus some higher trophic level nematodes, with high c–p values, were tolerant to disturbance. However, stability of function was greater for restored than degraded soil, with a reduction over time in the degraded soil regardless of disturbance type. The differences in the responses of nematodes and soil function to disturbance suggest that nematodes could provide complementary insights into soil stability. [Copyright &y& Elsevier]

Abstract: A field experiment was carried out to investigate the methane emission pattern in a double-rice cropping system under conventional and no tillage in southeast China. The treatments included conventional tillage cultivation in both early rice and late rice (T–T) and conventional tillage in early rice but no-till in late rice (T–NT). The maximum methane emission rate of T–T and T–NT was 21.71mgm−2 h−1 and 24.70mgm−2 h−1 in early rice, respectively; and 18.52mgm−2 h−1 and 7.32mgm−2 h−1 in late rice, respectively. The seasonal amount of methane emission from the T–T and T–NT was not significantly different in early rice, but significant different (P <0.05) in late rice, with the values 6.57gm−2 and 3.04gm−2, respectively. In comparison with early rice, the seasonal amount methane flux of late rice was reduced by 29% and 68% in the T–T and T–NT, respectively. The decrease of methane emission in the T–NT was attributed to lower dissolved organic carbon (DOC) content and higher soil bulk density. In conclusion, no tillage practice conducted in rice cropping season will markedly decrease methane emission for the rice cropping system. [Copyright &y& Elsevier]

Abstract: Understanding the effects of alternative farming on soil quality parameters, such as microbial communities, size, activity and soil nutrient content, is of central importance to concepts of sustainability. Combining organic amendments with chemical fertilizer is a promising approach to develop more sustainable fertilization strategies. We investigated the impacts of quantity, type and application time of organic amendments on temporal dynamics of paddy soil microbial biomass, activity, carbon fractions and nutrient status under a long-term field experiment in a rice–rice cropping system. We established treatments with seven fertilization practices characterized by different quantities and application times of green manure (GM), farmyard manure (FYM) and rice straw (RS) in combination with low amount of chemical fertilizers. We further established one treatment with only recommended amount of chemical fertilizer and an unfertilized control. At all sampling times, organic amendments with low amount of chemical fertilizer enhanced microbial biomass, activity and nutrient availability more than recommended amount of chemical fertilization only and an unfertilized control, with higher quantities of FYM resulting in stronger effects than all other organic amendments. The strongest increase of microbial biomass, activity, carbon and nutrient availability was generally found in the treatment with the most diverse resources and highest amount of organic amendments. Principle component analysis indicated that most soil variables measured were correlated to total soil organic C. Regression analysis indicated that the integrated paddy soil properties were closely related to yearly C input and rice yield. Strong temporal dynamics were demonstrated for all soil variables, indicating that we need multiple time sampling strategies to explore the overall influences of fertilization practices on paddy soil. Our results indicate that the development of effective fertilization practices, especially by manipulating the quantity and type of organic amendments, may improve long-term sustainability of paddy soil ecosystems. [Copyright &y& Elsevier]

Abstract: The effects of management in maintaining high rice yield with less water have received increasing attention in sub-tropical regions where seasonal drought is very severe. To test whether water management affects soil ecological process we compared the soil nematode communities in paddy field soils following water management treatments imposed during late rice cropping. The treatments were continuously flooded rice cultivation (CF), non-continuously flooded rice cultivations without (ZM) and with (M) rice straw mulching. A sequential extraction procedure involving Baermann extraction (Baermann) followed by centrifugal sugar flotation (centrifugation) was used to extract the whole nematode community. Based on the analysis of nematode abundance, genera composition, trophic groups and other ecological indices (Margalef richness index, Shannon index, maturity index, enrichment index and structure index), water management significantly affected the nematode community, with the non-continuously flooded condition, in particular combination with rice straw mulching (M), stimulating nematode development. There was a high abundance, richness, and structure in the nematode community in mulched treatments, indicating improved biodiversity and biological interactions. We hypothesize that soil microclimate and available food resources are affected by water management and directly or indirectly influence the establishment of different nematode communities. We suggested that studies aiming to test natural or anthropogenic influences on nematodes might be distorted by sole use of the Baermann method. Although the Baermann step in a sequential extraction procedure gave valuable information on nematode responses to soil treatments, it was not sufficient to detect effects on the whole nematode community. Our results demonstrate that the sequential extraction procedure is an effective tool to obtain comprehensive information on the whole nematode community, with both steps providing complementary ecologically relevant information, on how the soil ecosystem is affected by human management. [Copyright &y& Elsevier]

Abstract: Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms to operate at low decomposition rates, and that diffusion losses inhibit microbial growth and impede the formation of new microbial colonies. The specialisation of decomposer organisms towards particular microhabitats and substrates gives rise to refuges where organic resources are temporarily not accessed. We derive four stability criteria, by which we classify organic matter pools: passive versus active stabilisation, and partial versus absolute refuge. Two case studies confirm that in temperate soils a dominant quantity of organic material resides in the passive stabilisation/partial refuge status and persists in spite of being accessible and decomposable. We conclude that soil organic matter is stabilised by a complex of mechanisms that constrain decomposition rates, several of which are not based on substrate quality or soil conditions, but on the biology of the decomposing soil organisms. [Copyright &y& Elsevier]

Summary Aboveground and belowground attributes of terrestrial ecosystems interact to shape carbon (C) cycling. However, plants and soil organisms are usually studied separately, leading to a knowledge gap regarding their coordinated contributions to ecosystem C cycling. We explored whether integrated consideration of plant and nematode traits better explained soil organic C (SOC) dynamics than plant or nematode traits considered separately. Our study system was a space‐for‐time natural restoration chronosequence following agricultural abandonment in a subtropical region, with pioneer, early, mid and climax stages. We identified an integrated fast–slow trait spectrum encompassing plants and nematodes, demonstrating coordinated shifts from fast strategies in the pioneer stage to slow strategies in the climax stage, corresponding to enhanced SOC dynamics. Joint consideration of plant and nematode traits explained more variation in SOC than by either group alone. Structural equation modeling revealed that the integrated fast–slow trait spectrum influenced SOC through its regulation of microbial traits, including microbial C use efficiency and microbial biomass. Our findings confirm the pivotal role of plant‐nematode trait coordination in modulating ecosystem C cycling and highlight the value of incorporating belowground traits into biogeochemical cycling under global change scenarios. [ABSTRACT FROM AUTHOR]

Summary Microbiota have co‐evolved with plants over millions of years and are intimately linked to plants, ranging from symbiosis to pathogenesis. However, our understanding of the existence of a shared core microbiota across phylogenetically diverse plants remains limited. A common garden field experiment was conducted to investigate the rhizosphere microbial communities of phylogenetically contrasting herbaceous families. Through a combination of metagenomic sequencing, analysis of plant economic traits, and soil biochemical properties, we aimed to elucidate the eco‐evolutionary role of the core rhizosphere microbiota in light of plant economic strategies. We identified a conserved core microbiota consisting of 278 taxa that was closely associated with the phylogeny of the plants studied. This core microbiota actively participated in multiple nitrogen metabolic processes and showed a strong correlation with the functional potential of rhizosphere nitrogen cycling, thereby serving as an extended trait in the plant nitrogen acquisition. Furthermore, our examination of simulated species loss revealed the crucial role of the core microbiota in maintaining the rhizosphere community's network stability. Our study highlighted that the core microbiota, which exhibited a phylogenetically conserved association with plants, potentially represented an extension of the plant phenotype and played an important role in nitrogen acquisition. These findings held implications for the utilization of microbiota‐mediated plant functions. [ABSTRACT FROM AUTHOR]

Emerging knowledge of plant–soil biotic interactions and the role of soil organisms in shaping the world aboveground is advancing our understanding of ecosystem function. Nematodes are the most abundant animals on Earth. They are morphologically and functionally diverse, and play key roles in ecosystem function, making them ideal for developing a trait-based understanding of adaptation to the environment and for assessing their contributions to ecosystem function. Trait-based approaches allow us to capture the functional attributes of organisms beyond their taxonomic identity, provide insights on evolutionary fitness, and make global comparisons possible. We propose the nematode economics spectrum (NES), analogous to the plant economic spectrum, which describes the tradeoffs among growth, reproduction, and survival, potentially enabling us to predict the impacts of global change on nematode ecological strategies and the associated changes in ecosystem function. Trait-based approaches are being increasingly adopted to understand species' ecological strategies and how organisms influence ecosystem function. Trait-based research on soil organisms, however, remains poorly developed compared with that for plants. The abundant and diverse soil nematodes are prime candidates to advance trait-based approaches belowground, but a unified trait framework to describe nematode ecological strategies and assess their linkages with ecosystem function is lacking. We categorized nematode traits as morphological, physiological, life history, and community clusters, and proposed the nematode economics spectrum (NES) to better understand nematode ecological strategies and their association with ecosystem function. We argue that bridging the NES and the plant economics spectrum will facilitate a more holistic understanding of ecosystem carbon and nutrient cycling under global change. [ABSTRACT FROM AUTHOR]

Abstract The development of soil sustainability is linked to the improved management of soil biota, such as earthworms, and crop residues to improve soil physical structure, enhance microbial activities, and increase nutrient cycling. This study examined the impacts of maize residue (65.8C/N ratio, dry biomass 0.75 kg m−2) incorporation and earthworms (70 g Metaphire guillelmi m−2) on the resistance and resilience of soil C and N cycling to experimentally applied stresses. Field treatments were maize residue incorporation, maize residue incorporation with earthworm addition, and an unamended control. Resistance and resilience of C mineralization, ammonia oxidation, and potential denitrification were investigated over 28 days following a persistent stress of Cu (1 mg Cu soil g−1) or a transient heat stress (50 °C for 16 h). The results indicated that C mineralization was more resistant and resilient than ammonia oxidation and denitrification to either a persistent Cu or a transient heat stress. The application of maize residues significantly increased soil microbial biomass, C mineralization, ammonia oxidation and potential denitrification compared with the unamended control. Maize residues significantly improved the resistance and resilience of N processes to Cu and heat stress. The presence of earthworms significantly increased potential denitrification but had limited positive effect on functional resistance and resilience. This study suggested crop residue incorporation would strongly increase soil functional resistance and resilience to persistent and transient stresses, and thus could be a useful agricultural practice to improve soil ecosystem sustainability. Highlights • C cycling is more resistant and resilient to Cu and heat than N cycling • Resistance and resilience are primarily improved by the addition of crop residues • C and N processes can recover from heat rather than Cu [ABSTRACT FROM AUTHOR]

How biodiversity affects terrestrial productivity is important to the maintenance of ecosystem services under global change. Although the crucial role of plant–soil feedbacks (PSF) in determining diversity–productivity relationship has been increasingly recognized in recent years, its legacy effects on subsequent diversity–productivity relationship are still unclear.We conducted a classic PSF experiment to assess how plant diversity‐conditioned soils influenced subsequent plant diversity–productivity relationships, where three plant diversity levels (1, 4 and 8 species) were planted in soils conditioned at three diversity levels (conditioned by 1, 4 and 8 species for 3 years). In addition, to test the role of soil microbial diversity in mediating the effects of soil conditioning diversity, the three plant diversity levels were planted with low, moderate and high soil biodiversity created by a soil inoculum dilution.The results showed that plant productivities were promoted by mixed‐conditioned soils (4 and 8 species) comparing to mono‐conditioned soils (1 species). Productivity was positively related to planted diversity in mixed‐conditioned soils, while showed no relation with planted diversity in mono‐conditioned soils. Productivity was promoted by soil biodiversity when 4 and 8 species were mixed planted, while did not change when 1 species was planted.Synthesis and applications. Our results highlight that PSF is crucial to strengthen the positive effects of biodiversity on productivity, implying that diversifying cropping systems should be encouraged in agroecosystem management to benefit from positive PSF effects. The importance of soil legacy for optimizing plant productivity is particularly important for conditioning soils with an intermediate number of plant species. [ABSTRACT FROM AUTHOR]

Solid additives can effectively overcome/alleviate the deficiencies of pure liquid lubricants themselves. However, the additive morphology involved in most of the reported solid additive/liquid lubricant systems is mostly irregular. They take more into account species differences and ignore the potential advantages of the sizes of unequal particles for the purpose of superlubricity. Herein, a mixed unequal-diameter sphere additive/ionic liquid analogue (Uneq-SA/ILA) model system is designed from the perspective of asymmetric contact between unequal-diameter spheres. It can easily enter a stable macroscopic superlubricated state (coefficient of friction as low as 0.0046) with negligible wear relative to an equal-diameter sphere additive/ILA system. Such excellent lubrication performance is attributed to the synergy of asymmetric contact between unequal-diameter spheres and low-shear-viscosity ILA; the ILA adsorbed on the sphere additive makes asymmetric slip interface between the spheres mainly concentrated inside the ILA, avoiding direct point-to-surface contact between the spheres. The film thickness of 948 μm implies that unequal-diameter spheres in the ILA have a normal accumulation space during contact, and the lubrication mechanism is dominated by hydrodynamic lubrication. This study deepens the understanding of asymmetric contact function of solid additives and provides new insights for the design of next-generation solid additive/liquid superlubrication systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Intense human activities break the grassland–livestock balance and accelerate grassland degradation. We evaluated the use of native dominant species combined with arbuscular mycorrhizal fungi (AMF) in order to recover grassland and restrain grassland degradation. We conducted a full factorial greenhouse experiment to evaluate the interaction effects of native species of distinct traits grass Lolium perenne (L) and legume Trifolium repens (T) with arbuscular mycorrhizal fungi (AMF) inoculation on grass productivity and soil properties across non-degraded, lightly degraded, and severely degraded soils. The grass–legume mixture was manipulated with five ratios (T:L = 1:0, T:L = 1:1, T:L = 3:1, T:L = 1:3, T:L = 0:1). The results showed that L. perenne significantly increased grassland productivity at different grass–legume ratios, regardless of AMF presence or absence. AMF inoculation increased plant N and P content uptake and improved the productivity of degraded grasslands, especially in severely degraded grasslands. The NO3−-N and available P concentrations increased in soil when the legume component increased from T:L = 0:1 (grass monoculture) to T:L = 1:0 (legume monoculture). This may be because the presence of Lolium perenne (L) can promote nitrogen fixation in legumes. Structural equation modeling indicated that grass–legume mixtures directly affected plant biomass, whereas AMF affected plant biomass via providing plant nutrients. A soil quality index based on minimum datasets indicated a significant positive effect of artificial grassland establishment on soil quality. We conclude that planting T:L = 0:1 and T:L = 1:3 combined with AMF inoculation can be used to recover degraded grassland production, and planting T:L = 1:1 and T:L = 1:3 plus AMF inoculation can be applied for grassland nutrient accumulation and stability maintenance. [ABSTRACT FROM AUTHOR]

A trait-based approach is adopted to understand the responses of the soil nematode food web following cover crops incorporated into the soil, i.e., afterlife effect of plant. We conducted an in situ microcosm experiment with two cover crops including leguminous Astragalus sinicus L. (A. sinicus), characterized by high nutrient content, and gramineous Lolium multiflorum Lam (L. multiflorum), characterized by high C and lignin content, representing the acquisitive and conservative side of the economic spectrum, respectively. Furthermore, two incorporation rates were set to represent low and high biomass production of cover crops that could be incorporated into the soil. Soil main microbial groups, nematode food web, and physicochemical properties were analyzed at weeks 4 and 18 after cover crops incorporated into the soil. Results showed that, regardless of time, cover crops affected the abundance and composition of the soil nematode food web. L. multiflorum supported higher nematode abundance and more complex nematode food web than A. sinicus, charactering with higher fungivore/bacterivore, predator/prey, maturity index, and structure index, particularly under the high incorporation rates. In addition, A. sinicus improved much more resource availability (mineral N and dissolved organic C) than L. multiflorum. Together, the quantity and quality of plant residues jointly drive soil food web structure, and a trait-based framework facilitates the mechanical understanding of afterlife effect of plant on soil ecosystems. [ABSTRACT FROM AUTHOR]

Plants act as ecosystem engineers playing fundamental roles in steering their surroundings, including soil abiotic and biotic conditions, soil organisms, and the complex soil food web they comprise. Trait‐based approaches have been considered a 'Holy Grail' in linking plants to ecosystem functions, but the mechanistic relationship between plant traits and the soil food web as an indicator of soil health remains poorly understood.We examined this relationship for 16 cover crop species differing in leaf and root traits in a field experiment where corn, Zea mays was the main crop. Based on functional traits, the cover crop species were categorized into two ecological strategies at either end of the resource acquisitive‐conservative spectrum. We investigated the effects of cover crop ecological strategies on corn productivity and soil health. We used soil nematodes as an indicator of soil health and analysed soil physico‐chemical properties and microbial community activities.We found that acquisitive cover crops supported higher soil resource availability, bacterial energy channels in the soil food web, and greater corn productivity than conservative cover crops. In contrast, conservative cover crops supported higher abundances of fungivores and omni‐carnivores than acquisitive cover crop, which reflected a more structured and complex soil food web, implying a healthier soil ecosystem. Conservative cover crops also increased corn productivity compared to the no cover crop control treatment.Synthesis and applications. Collectively, this work shows that cover crops with distinct ecological strategies had their own strengths to enhance ecosystem functions: acquisitive and conservative cover crops improved crop productivity and soil health, respectively. These results indicates that farmers and policy makers can make trait‐based choices in selecting cover crop best serving the local needs. This points to a win‐win solution for food production and ecosystem sustainability. [ABSTRACT FROM AUTHOR]

Anthropogenic land use is threatening global biodiversity. As one of the most abundant animals on Earth, nematodes occupy several key positions in belowground food webs and contribute to many ecosystem functions and services. However, the effects of land use on nematode abundance and its determinants remain poorly understood at a global scale.To characterize nematodes' responses to land use across trophic groups, we used a dataset of 6,825 soil samples globally to assess how nematode abundance varies among regional land‐use types (i.e. primary vegetation, secondary vegetation, pasture, cropland and urban) and local land‐use intensities (i.e. human‐managed or not). We also quantified the interactive effects of land use and environmental predictors (i.e. mean annual temperature, annual precipitation, soil organic carbon, soil pH, global vegetation biomass and global vegetation productivity) on nematode abundance.We found that total nematode abundance and the abundance of bacterivores, fungivores, herbivores, omnivores and predators generally increased or were not affected under management across land‐use types. Specifically, the most numerically abundant bacterivores were higher in managed than in unmanaged secondary vegetation habitats and urban areas, and herbivores were more abundant in managed than in unmanaged primary and secondary vegetation habitats. Furthermore, the numbers of significant environmental predictors of nematode abundance were reduced and the magnitude and the direction of the predictors were changed under management. We also found that nematode abundance was more variable and less determined by environmental factors in urban than in other land‐use types.These findings challenge the view that human land use decreases animal abundance across trophic groups, but highlight that land use is altering the trophic composition of soil nematodes and its relationships with the environment at the global scale. [ABSTRACT FROM AUTHOR]

Soil has become a major hotspot of biodiversity studies, yet the pattern and timing of the evolution of soil organisms are poorly known because of the scarcity of paleontological data. To overcome this limitation, we conducted a genome-based macroevolutionary study of an ancient, diversified, and widespread lineage of soil fauna, the elongate-bodied springtails (class Collembola, order Entomobryomorpha). To build the first robust backbone phylogeny of this previously refractory group, we sampled representatives of major higher taxa (6 out of 8 families, 11 out of 16 subfamilies) of the order with an emphasis on the most problematic superfamily Tomoceroidea, applied whole-genome sequencing methods, and compared the performance of different combinations of data sets (universal single-copy orthologs [USCO] vs. ultraconserved elements]) and modeling schemes. The fossil-calibrated timetree was used to reconstruct the evolution of body size, sensory organs, and pigmentation to establish a time frame of the ecomorphological divergences. The resultant trees based on different analyses were congruent in most nodes. Several discordant nodes were carefully evaluated by considering method fitness, morphological information, and topology test. The evaluation favored the well-resolved topology from analyses using USCO amino acid matrices and complex site-heterogeneous models (CAT |$+$| GTR and LG |$+$| PMSF (C60)). The preferred topology supports the monophyletic superfamily Tomoceroidea as an early-diverging lineage and a sister relationship between Entomobryoidea and Isotomoidea. The family Tomoceridae was recovered as monophyletic, whereas Oncopoduridae was recovered as paraphyletic, with Harlomillsia as a sister to Tomoceridae and hence deserving a separate family status as Harlomillsiidae Yu and Zhang fam. n. Ancestral Entomobryomorpha were reconstructed as surface-living, supporting independent origins of soil-living groups across the Paleozoic–Mesozoic, and highlighting the ancient evolutionary interaction between aboveground and belowground fauna. [Collembola; phylogenomics; soil-living adaptation; whole-genome sequencing.] [ABSTRACT FROM AUTHOR]

Purpose: Roots bridge aboveground and belowground systems, and play a pivotal role in structuring root-associated organisms via influencing food resources and habitat conditions. Most studies focused on the relationships between plant identity and root-associated organisms, however, little is known about how root traits affect nematode communities within the rhizosphere. Methods: We investigated the relationships between root traits of four plant species and nematode abundance, community structure and trophic complexity in an ex-arable field. Results: While the relative abundance of herbivores was negatively associated with specific root length (SRL), specific root area (SRA), root length density (RLD) and root C: N ratio, free-living nematodes were positively affected by these traits, implying a multifaceted effect of root traits on root-associated organisms. Importantly, we found that finer root systems promoted the complexity of rhizosphere nematode community, by increasing the relative abundance of high trophic-level nematodes (i.e., omnivores and predators) and enhancing nematode diversity. Conclusions: Our findings suggest that root traits could comprehensively shape soil community structure and interactions, and provide new insights into soil biodiversity conservation and functional maintenance. [ABSTRACT FROM AUTHOR]

The extent to which individuals experience interspecific and intraspecific interactions through their spatial arrangements within diverse plant communities, whether because of confounding effects of species richness, evenness or direct changes in species patch sizes on their neighbourhood relationships, could affect grassland biomass production and its stability at community scales. Elucidating the ways in which neighbourhood effects and species richness contribute to such community responses has important implications for how practitioners establish grasslands to meet forage production and conservation goals.We assessed the effects of altering plant species richness (3 levels: 2, 4 or 8 forage species per plot) and seed arrangements (4 levels: species mixed and seeded or seeded in 0.0625, 0.25 or 1.0 m2 single‐species patches while maintaining plot‐scale species evenness) on above‐ground biomass production and its temporal stability in developing grasslands seeded with a suite of globally common forage species (three legumes, three cool‐season grasses and two warm‐season grasses).Communities seeded with more species and those with their seeds arranged into smaller conspecific patches produced more biomass and were more temporally stable than those seeded with fewer species and larger conspecific patches. The effect of manipulating species arrangements is attributable to greater neighbourhood‐scale interspecific interactions and stronger complementary effects. Furthermore, seeding species into conspecific patches resulted in communities that were 34% more productive, that were just as temporally stable, and that had similar diversity effects as those seeded with a species mixture, as is common in grassland reconstruction efforts.Synthesis. In comparison with conventional mixed‐seeding methods, seeding grasslands with high species richness and small, single‐species patches may promote grassland reconstruction through increased biomass production, temporal stability and complementarity effects. Our study highlights the importance of regulating intraspecific interactions within diverse communities for improving grassland biomass production and suggests that efforts to re‐evaluate methods used to establish forage and conservation grasslands could result in greater biomass production and stability in these systems. [ABSTRACT FROM AUTHOR]

Nitrogen (N) enrichment shapes litter chemistry, subsequently influencing soil invertebrates and litter decomposition. However, there has been a lack of attention to how soil invertebrates respond to changes in litter chemistry and then drive litter decomposition under N enrichment. Here, trait-based approaches were adopted to explore functional responses of Collembola, a crucial and functional group of invertebrates. We conducted reciprocal transplantation of plant litter between ambient N levels (0 kg N ha−1 yr−1) and N enrichment (90 kg N ha−1 yr−1) plots in a field experiment, quantifying Collembola traits and litter mass loss during litter decomposition process. Results showed that N enrichment-derived litter recruited Collembola with long antenna, legs, and strong mandibles in enrichment environment, while Collembola with same traits were recruited by ambient-derived litter in ambient environment. Collembola traits, including antenna to body ratio, leg to body ratio, and mandible width to length ratio, coincided with high litter decomposition rates under N enrichment. Overall, the results provide evidence that Collembola with strong resource acquisition abilities responded to changes in litter chemistry, and such shifts further accelerate litter decomposition under N enrichment. Our findings demonstrate that adopting trait-based approaches to link litter and invertebrates would advance the understanding of ecosystem processes governed by biological regulation under global change. • Litter structure traits positively link to Collembola resource-acquisition traits. • Collembola traits are more strongly related to decomposition than taxonomic characteristics. • Litter decomposition was promoted by Collembola resource-acquisition traits. • Collembola traits response to litter traits drive decomposition under N enrichment. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first phylogenomic backbone of Collembola was reconstructed. • A wide range of phylogenomic methods were employed and compared. • Arthropleona and Symphypleona s.l. were refuted. • Entomobryomorpha was supported to be the basal branch. • Parallel evolution of body shape and pronotum across orders was supported. Springtails (Collembola) stand as one of the most abundant, widespread, and ancient terrestrial arthropods on earth. However, their evolutionary history and deep phylogenetic relationships remain elusive. In this study, we employed phylogenomic approaches to elucidate the basal relationships among Collembola. We sampled whole-genome data representing all major collembolan lineages in proportion to their known diversity. To account for potential phylogenomic biases, we implemented various data extraction, locus sampling, and signal filtering strategies to generate matrices. Subsequently, we applied a diverse array of tree-searching and rate-modelling methods to reconstruct the phylogeny. Our analyses, utilizing different matrices and methods, converged on the same unrooted relationships among collembolan ingroups, supporting the current ordinal classification and challenging the monophyly of Arthropleona and Symphypleona s.l. However, discrepancies across analyses existed in the root of Collembola. Among various root positions, those based on more informative matrices and biologically realistic models, favoring a basal topology of Entomobryomorpha + (Symphypleona s.s. + (Neelipleona + Poduromorpha)), were supported by subsequent methodological assessment, topology tests, and rooting analyses. This optimal topology suggests multiple independent reduction of the pronotum in non-poduromorph orders and aligns with the plesiomorphic status of neuroendocrine organs and epicuticular structure of Entomobryomorpha. Fossil-calibrated dating analyses based on the optimal topology indicated late-Paleozoic to mid-Mesozoic origins of the crown Collembola and four orders. In addition, our results questioned the monophyly of Isotomidae and Neanuridae, underscoring the need for further attention to the systematics of these families. Overall, this study provides novel insights into the phylogenetic backbone of Collembola, which will inform future studies on the systematics, ecology, and evolution of this significant arthropod lineage. [ABSTRACT FROM AUTHOR]

Biodiversity can enhance soil multifunctionality through strengthening biotic interactions in soil food webs, but largely unknown in agroecosystems. We therefore predicted that vermicompost, serving as an organic amendment and soil health conditioner, could enhance trophic interactions among bacteria, fungi and nematodes and mediate synergies and trade-offs among soil functions, especially when substituting synthetic fertilizer was applied to soils. Soil multifunctionality was assessed from plant growth and product quality, carbon and nutrient cycling, water and climate regulation in an intensive cropping system. Pepper, tomato and spinach were cultivated in rotation annually, with substituting vermicompost as a nutrient replacement for synthetic fertilizer for 5 years. Results showed that substituting a moderate dose of vermicompost for synthetic fertilizer offered the highest soil multifunctionality by enhancing synergies among multiple functions. The vermicompost-stimulated multifunctionality was primarily attributed to the cascading effects of the complex food web structure induced by omnivorous nematode. These effects were regulated by the physicochemical environment of the vermicompost-amended soil. Notably, the multifunctional benefits degraded when higher rates of vermicompost were applied, suggesting that over-use of vermicompost combined with an inadequate amount of synthetic fertilizer could simplify soil food web structure and decrease soil functions, mainly due to the nutrient limitation and increasing harmful substances as indicated by C:N stoichiometry, heavy metals and antibiotic resistance genes. In intensive agricultural systems, finding an optimal balance of organic amendments and synthetic fertilizer that supports complex soil food web interactions is therefore crucial for promoting multiple soil functions and particularly sustaining the production of high-quality food crops. • The highest soil multifunctionality was observed in moderate vermicompost substitution. • Moderate vermicompost addition enhanced synergies among multiple functions. • Soil food web structure coordinated by omnivores was associated with multifunctionality. • Vermicompost supported multifunctionality of ecologically intensive agriculture. [ABSTRACT FROM AUTHOR]

Although straw-decomposing microbial inoculants (SDMI) are capable to generally promote the fertility of straw-amended soils, their impact on the release of individual soil major nutrients remains controversial. Additionally, the combined effects of SDMI and environment/management on various forms of nutrients remain poorly documented. To fill these research gaps, we conducted a meta-analysis study using 1214 paired observations from 132 field trials in China. Our results showed that SDMI significantly increases the total and available concentrations of nitrogen, phosphorus, and potassium in soil (p < 0.05), although increases in nutrients varied with different conditions. Moreover, mean annual precipitation (MAP) had significant correlations with the effects of SDMI-amended straw on soil total nitrogen (p = 0.008) and available nitrogen (p = 0.0006). The effect of SDMI-amended straw on soil total phosphorus and soil available potassium was mainly correlated with soil organic matter (p = 0.032) and MAP (p = 0.049), respectively. Our findings indicate that SDMI-amended straw can have a measurable impact on the status of soil major nutrients. In particular, the application of SDMI-amended rice straw with an initial C/N ratio of ≤15 to neutral soils in temperate and subtropical monsoon climates is a promising strategy. [ABSTRACT FROM AUTHOR]

Abstract: The influence of earthworms on nematodes and protozoan communities was determined during the wheat phase of a six year rice–wheat rotation agro-ecosystem. Experimental plots in the rotation had five treatments, i.e. incorporation or mulching of maize residues with or without added earthworms and a control. The addition of maize residues to soil strongly affected the abundance and community structure of nematodes and protozoa in the absence of earthworms. The presence of earthworms gave significantly lower total nematode numbers at all soil depths following maize residue incorporation than the same treatment without earthworms, and also gave lower (although not significantly) total nematode numbers in the upper soil layer following maize residue mulching than the same treatment without earthworms. This was mainly due to a significant decrease in bacterial-feeding nematode numbers. Earthworms also strongly affected the distribution of the number of total nematodes and two trophic groups (bacterial and plant feeders) with soil depth. In the presence of earthworms, total protozoan and flagellate numbers significantly increased at all soil depths following both incorporation and mulching of maize residues, while numbers of amoebae increased only when maize residues were mulched. Additionally, in earthworm casts total nematode numbers (mainly bacterial and fungal feeders) were significantly higher, whereas total protozoa numbers (mainly flagellates and amoebae) were significantly lower than that in soil from 0 to 5cm layer. These results indicated that earthworm activity could affect the abundance and community structure of microfauna, and change their distribution between soil layers and cast material, depending on the mode of application of organic residues. [Copyright &y& Elsevier]

Nitrogen (N) enrichment has been shown to increase, decrease or have no effect on soil carbon dioxide (CO 2) emissions via changing microbial activity and community composition. Earthworms are known to substantially influence soil microbes, and to thus CO 2 emissions, potentially fueling an interactive effect with N enrichment. Yet, we have a limited understanding of how earthworms interact with N enrichment to influence CO 2 emissions from arable soil. Here, we investigated how manipulations of N enrichment and earthworms influenced CO 2 emissions over 91 days by using a mesocosm experiment. Our results showed that N enrichment gradient changed the effects of earthworms on soil CO 2 emissions. Specifically, earthworms did not influence soil CO 2 emissions under lower N addition rates, however, earthworm presence did increase soil CO 2 emissions at levels of 240 kg N ha−1 and higher, mainly by their top-down controls on microbes, i.e., reducing fungi:bacteria ratio, and enhancing microbial C-acquiring activities, as evidenced by a positive relationship between soil CO 2 emissions and glycosidase activity. Together, we suggest that N enrichment and key soil fauna-microbe interactions can determine the degree to which microorganisms regulate soil C dynamics. Furthermore, our findings potentially advocate for the specific soil fauna effects on soil CO 2 emissions mediated by N enrichment as a mean to reduce the unexplained variation in large-scale biogeochemical models. [Display omitted] • Earthworms increased soil CO 2 emissions at higher N addition levels. • Earthworms reduced fungi and increased bacteria at higher N addition levels. • Changed microbial community contributed to reduce microbial metabolic efficiency. • Earthworm presence induced higher microbial C-acquiring activity. • Soil fauna-microbe interaction is needed in predicting soil C dynamics in the future. [ABSTRACT FROM AUTHOR]

Global change in organismal stoichiometry and biodiversity is often correlated with energy dynamics in ecological networks that underpin the functioning of terrestrial ecosystems and services. However, we know little about which facets of biodiversity, such as taxonomic, functional, and phylogenetic diversity, account for most of the variation in the energy dynamics of ecological networks along litter stoichiometry gradients. Here, we quantified how multiple facets of biodiversity impact energy fluxes of soil food webs through time in agricultural fields incorporating litter from six plant species of varying C:N stoichiometry. We found that community biomass and energy flux in soil food webs decreased while community maintenance cost (i.e. energy flux to biomass ratio) increased with increasing litter C:N ratio. Taxonomic, functional, and phylogenetic diversity of soil nematodes declined along increasing litter C:N stoichiometry, and together explained 73 % and 51.3 % of variation in community biomass, 71.6 % and 49.2 % of variation in energy flux, and 59.8 % and 37.4 % of variation in community maintenance cost in early and later decomposition stages, respectively. Functional and taxonomic diversity were highly associated with energy dynamics in early decomposition stages, while phylogenetic diversity emerged as the central predictor in later decomposition stages. By identifying the crucial role of multi-faceted biodiversity conservation facilitated by low C:N litter in driving the energy dynamics of food webs, these findings shed new light on the applicability of energy dynamics for linking biodiversity and ecosystem functioning under global change scenarios. • Energy storage, flux and use efficiency decrease with increasing litter C:N ratio. • Multi-faceted biodiversity correlates with energy storage, flux and use efficiency. • The importance of biodiversity facets to energy dynamics differs over time. • Energy dynamics underpins biodiversity-ecosystem functional relationships. [ABSTRACT FROM AUTHOR]

Urbanization is threatening terrestrial biodiversity and ecosystem functions. Nematodes, as one of the most abundant animals on Earth, play diverse roles within soil food webs and contribute to vital ecosystem services. However, the effects of urbanization on soil nematode functional groups, and the ecological functions and services they provide remain poorly understood. Here, we investigated functional groups of soil nematodes across 12 cities in China and validated the results by using a global nematode dataset. Specifically, we found the proportions of omnivores (by 45∼60%) and predators (by 40∼50%) as well as temporal ecosystem stability (by 10∼20%), as indicated by the normalized difference vegetation index, were reduced in urban ecosystems, while the proportions of fungivores and bacterivores increased (30–60% and 10–20%, respectively). We identified total soil phosphorus and nitrogen as the main drivers influencing soil nematode feeding groups in urban ecosystems. Soil pH, mean annual precipitation, and mean annual temperature were predominant factors in non-urban ecosystems. We further demonstrated that nematode functional guilds contributed to ecosystem stability in urban ecosystems, but this was not true in non-urban ecosystems. Our findings evidence the homogenization effects of urbanization on key functional guilds of soil nematodes and their roles in maintaining ecosystem stability. The fact that ecosystem stability and the abundance of nematode functional guilds are closely related and driven by climatic, edaphic, and anthropogenic factors may help in setting priorities for urban soil management. • Temporal stability was reduced in urban soils. • Omnivores and predators were decreased in urban soils. • Total soil phosphorus and nitrogen were the main drivers of urban nematodes. • Soil nematodes contributed to ecosystem stability in urban ecosystems. [ABSTRACT FROM AUTHOR]

Herbivore grazing has long-lasting effects on the structure and functions of grassland ecosystems, even after the grazing pressure has ceased. These lasting effects are known as grazing legacy effects and significantly affect plant productivity and biodiversity, with the magnitude increased with grazing intensity and further led to grassland degradation. Fencing is a common approach used for restoring degraded grasslands by excluding grazing. Moderate grazing representing a controlled level of grazing intensity is believed to be a useful way to restore ecological functions and thus mitigate grazing legacies. However, how fencing and ongoing moderate grazing affect grazing legacy effects remain unclear and rarely tested with field experiments, particularly with different grazing histories. Here, we investigated aboveground net primary productivity (ANPP), species richness, litter, soil organic carbon (SOC), soil dissolved nitrogen (DON) and hyphal length density (HLD) in 2015 (fencing for 1 year) and 2018 (fencing vs moderate grazing for the subsequent 3 years) after 0, 2, 5, 7 and 12 years of free grazing in a meadow steppe to explore how moderate grazing and fencing affect grazing legacy effects with different histories. We observed a decline in ANPP and species richness with increasing grazing histories, and the magnitude of grazing legacy effects increased accordingly. In most grazing histories, moderate grazing had a greater impact than fencing in reducing the grazing legacy effects on ANPP and species richness. However, with a grazing history of 12 years, moderate grazing led to a smaller increase in ANPP compared to fencing. Additionally, the grazing legacy effects on ANPP and species richness weakened with longer fencing duration for excluding grazing. Litter, SOC, DON and HLD exhibited consistent patterns with the dynamics of ANPP and species richness. Our results indicate that grazing legacy effects on ANPP and species richness intensify with prolonged grazing histories, suggesting that grazing history have stronger impacts on grassland ecosystem functions and structure. The study implies that moderate grazing is an effective strategy for restoring degraded grasslands, particularly for species richness and with short-term grazing histories, instead of relying solely on fencing. The changes of soil variables underlie the grazing legacy effects and the interactions with fencing and moderate grazing. • The legacy effects of grazing history have less been studied. • This study is the first that explore the grazing legacy effects of grazing history on ANPP and species richness. • Our findings underscore the importance of grazing legacy effects in land management and conservation planning. [ABSTRACT FROM AUTHOR]

Two greenhouse experiments using soils from long-term field plots were carried out to test whether and how soil factors modulated by organic amendments feed back to rice plant growth and defense against an aboveground herbivore, the planthopper Nilaparvata lugens. Using factorial combinations of sterilized soil and soil inocula obtained from chemically amended plots (i.e., control treatment) or chemically plus organically amended plots (i.e., organic treatment), we disentangled the effects of biotic and abiotic soil properties on plant and planthopper performance. We found that, compared with abiotic soil properties, soil biological factors were the main drivers in regulating plant growth performance. Specifically, soil biota that are shaped by the organic treatment had high microbial abundance and diversity and enhanced rice plant tolerance (i.e., increasing plant total biomass) and resistance (i.e., decreasing amino acid and sugar concentrations) to planthoppers. Moreover, the organic treatment simultaneously increased plant growth and defense against planthoppers, which could be explained by high soil nutrient availability driven by soil biota. Our results demonstrate the importance of synergistic effects of soil biota and soil abiotic factors on plant growth and resistance to herbivory. These findings are important for better understanding the mechanisms and impacts of ecological intensification as well as the potential of steering soil communities to reduce the use of chemical fertilizers and pesticides and further optimize crop production. [ABSTRACT FROM AUTHOR]

Both contemporary and historical factors are documented to be crucial in regulating species diversity and distribution. Soil fauna contribute substantially to global biodiversity and ecosystem functioning, while it is unclear whether and to what extent historical factors shape their diversity patterns. Here, we used soil nematodes as a model organism to test historical effects on soil fauna and to investigate the relative importance of climatic, soil, and historical factors. Based on nematode distribution data in 16 natural sites at a large scale (ranging from 22 to 40°N) in mainland China, we conducted elastic net regression model to test the effects of climatic (e.g., mean and seasonality of temperature/precipitation), soil (e.g., soil carbon, nitrogen, and pH), and historical (e.g., temperature/precipitation anomaly and the velocity of the change since the Last Glacial Maximum) variables on nematode genus richness and Shannon's diversity. Additionally, variation partitioning was used to determine the contribution of the three predictor sets to the explanation of both Jaccard and Bray–Curtis community dissimilarity. We found that climate generally explained more variations in both diversity and composition than soil and historical predictors in our samples. We also showed that although historical factors (e.g., temperature change velocity) were correlated with nematode diversity and composition, the pure effects of these historical factors were negligible. In other words, the historical effects were commonly represented by their interactions with current climatic and soil factors within our selected sites. Our results indicated that contemporary factors, especially climate, may outperform historical factors in regulating soil nematode diversity patterns at large scales. [ABSTRACT FROM AUTHOR]

Biochar application is perceived as a promising agricultural technology, but risk evaluation on the soil ecosystem has focused exclusively on soil microbes, whether microfood-web is likewise influenced by biochar remains unclear. We carried out a pot experiment planted with rapeseed for 2 years to test how biochar application (0, 20, 60 t ha−1), with or without nitrogen (N) fertilizer (0, 60, 120 t ha−1), affected soil microbes and microfauna (protists and nematodes). We observed that a high amount of biochar (60 t ha−1) increased crop productivity, microbial activity, and biomass carbon (C) and N, as well as the abundance of flagellates (protists), but decreased the abundances of bacterivorous, fungivorous, and herbivorous nematodes as well as the abundance of amoebae (protists). High biochar addition rates also shifted nematode community composition toward a fungivore dominance, and favored herbivores by decreasing the ratio of microbivorous to herbivorous nematodes. However, N fertilizer and its interaction with biochar generally had no effect on microbial activity and biomass as well as the abundance of protist and nematode. A structural equation model revealed that the effects of biochar on soil biota were largely direct, which might depend on biochar properties (e.g., pore size and alkalinity), whereas indirect effects, mediated by crop, soil pH, soil moisture, and polycyclic aromatic hydrocarbon (PAH) concentration, generally had no effect on soil biota. We conclude that biochar is a suitable soil amendment for increasing crop growth, but its detrimental effect on multitrophic levels of soil fauna calls for an identification of the optimal application rate and size fraction that could minimize potential negative effects on certain soil communities. [ABSTRACT FROM AUTHOR]

Risk assessment and ecological effects are a concern of transgenic rice. In this study, the effects of three lines of Bt rice expressing single Cry1Ab protein (Kemingdao: cv. KMD) and fused Cry1Ab/Cry1Ac proteins (Huahui 1: cv. HH1; Bt Shanyou 63: cv. Bt-SY63) on soil mite community were investigated under field conditions. Transgenic treatment (cv. Bt-rice vs. non-Bt rice) significantly decreased the community index of Margalef's richness (SR) of soil mite in KMD, and significantly increased the abundance and the community indexes of Shannon diversity (H'), Pielou's evenness (J) and SR of soil mite in Bt-SY63 (p < 0.05). Transgene type (cv. KMD vs. HH1) did not significantly affect the composition, abundance and the community index (p > 0.05). Breeding type (cv. HH1 vs. Bt-SY63) significantly changed the composition and markedly improved the abundance and the J value in Bt-SY63 (p < 0.05). However, seasonal and inter-annual changes were apparent, and the Bt effects were not consistent at all for the different plant backgrounds over a 2-year period. These results suggested that the cultivation of Bt rice has a significant but transient effect on soil mite community. [ABSTRACT FROM AUTHOR]

Summary: Soil organic carbon (SOC) sequestration under elevated CO2 concentration (eCO2) is a function of carbon (C) input and C retention. Nitrogen (N) limitation in natural ecosystems can constrain plant responses to eCO2 and their subsequent effects on SOC, but the effect of eCO2 on SOC in N‐enriched agroecosystems with cultivars highly responsive to eCO2 is largely unknown.We reported results of SOC dynamics from a field free‐air CO2 enrichment experiment with two rice cultivars having distinct photosynthetic capacities under eCO2. A reciprocal incubation experiment was further conducted to disentangle the effect of changes in litter quality and soil microbial community on litter‐derived C dynamics.eCO2 significantly increased total SOC content, dissolved organic C and particulate organic C under the strongly responsive cultivar, likely due to enhanced organic C inputs originated from CO2 stimulation of shoot and root biomass. Increases in the residue C : N ratio and fungal abundance induced by eCO2 under the strongly responsive cultivar reduced C losses from decomposition, possibly through increasing microbial C use efficiency.Our findings suggest that applications of high‐yielding cultivars may substantially enhance soil C sequestration in rice paddies under future CO2 scenarios. [ABSTRACT FROM AUTHOR]

Anthropogenic conversion of natural to agricultural land reduces aboveground biodiversity. Yet, the overall consequences of land‐use changes on belowground biodiversity at large scales remain insufficiently explored. Furthermore, the effects of conversion on different organism groups are usually determined at the taxonomic level, while an integrated investigation that includes functional and phylogenetic levels is rare and absent for belowground organisms. Here, we studied the Earth's most abundant metazoa—nematodes—to examine the effects of conversion from natural to agricultural habitats on soil biodiversity across a large spatial scale. To this aim, we investigated the diversity and composition of nematode communities at the taxonomic, functional, and phylogenetic level in 16 assemblage pairs (32 sites in total with 16 in each habitat type) in mainland China. While the overall alpha and beta diversity did not differ between natural and agricultural systems, all three alpha diversity facets decreased with latitude in natural habitats. Both alpha and beta diversity levels were driven by climatic differences in natural habitats, while none of the diversity levels changed in agricultural systems. This indicates that land conversion affects soil biodiversity in a geographically dependent manner and that agriculture could erase climatic constraints on soil biodiversity at such a scale. Additionally, the functional composition of nematode communities was more dissimilar in agricultural than in natural habitats, while the phylogenetic composition was more similar, indicating that changes among different biodiversity facets are asynchronous. Our study deepens the understanding of land‐use effects on soil nematode diversity across large spatial scales. Moreover, the detected asynchrony of taxonomic, functional, and phylogenetic diversity highlights the necessity to monitor multiple facets of soil biodiversity in ecological studies such as those investigating environmental changes. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterize stage of ecosystem development in spontaneously developing catchment (Morning glory) and compare them with reference experimental catchment (Hydrohill). Both of these experimental catchments were constructed side by side near Nanjing (China) in 1978, consisting from vadose zone on impermeable surface, which offer unique opportunity to measure total runoff including subsurface runoff. In Hydrohill, the soil profile was reconstructed by importing 80-100cm of soil, grassy vegetation was established and kept by mowing. In Morning glory, no soil was added and initial surface was formed by solid rock covered by rock debris which gradually weather and form soil on which spontaneous vegetation developed by primary succession. Here we benefit from existence historical data describing rainfall-runoff including chemistry and isotopic composition of both catchments measured in 1989, which can be compared to situation in 2018. Soil data show that most of measured soil parameters including water field capacity and soil microbial biomass in Morning glory were comparable with soil in Hydrohill, however average depth of soil profile was significantly lower and plant biomass both above and below ground significantly higher in Morning glory catchment. As concern runoff parameters in many of them such as pH, 18O, Morning glory become similar to Hydrohil in 2018 than in 1989 but some differences remain such as F content in runoff. Interesting is comparison in nitrates which were absent in Morning glory in 1989 and higher than Hydrohill in 2018 apparently due to N fixing plants and organic matter accumulation in Morning glory soil. To conclude after 50 years of development by primary succession soil had much lower depth but parameters of topsoil are comparable with reference, which is reflected in runoff characteristics. [ABSTRACT FROM AUTHOR]

As ubiquitous ecosystem engineers, earthworms play an important role in shaping the architecture and functioning of soil systems. However, there is limited knowledge on how earthworms modify the soil microbiome in relation to soil biogenic aggregates, hot-spots formed by earthworms, especially in agricultural systems. We investigated microbial communities in physical fractions and bulk soil from an arable field with consecutive rice - wheat cropping after manipulating earthworms and organic amendments for 13 years. Earthworms significantly enhanced soil aggregation by 33.4% across two consecutive cropping seasons. The assemblage of bacterial communities varied strongly between soil aggregate fractions and with earthworm presence, while the assemblage of fungal communities varied most with organic amendments and less between aggregate fractions. Structural equation modelling (SEM) suggests that besides direct effects on bacteria and fungi, earthworms affected bacteria indirectly via increasing soil aggregation (MWD), but mediated fungi via lowering pH, indicating that the role of soil aggregates in structuring soil bacterial communities override that of resource availability. In conclusion, results of our over-decade field experiment suggest that earthworms modify soil microbial communities primarily through mediating soil habitat architecture and affecting resource supply. • A long-term study explored earthworm impacts on aggregate-associated microbiome. • Earthworms increase soil macro-aggregates (>2 mm) formation. • Earthworms modify soil bacterial community mainly via stimulating soil aggregation. • Earthworms modify soil fungal community mainly via changing chemical properties. [ABSTRACT FROM AUTHOR]

• Minimum data set includes four factors, which reflect the integrated soil function. • Significant differences in soil quality between different productivity. • The significant positive correlation between SQI and wheat yield. • Available N, SOM and microbial biomass N to total N ratio were limiting factors. The double-cropping of winter wheat and summer maize is a major grain production system in China which occupies more than half the double-cropping systems of the country's dryland area. This cropping system has experienced a decreased crop yield and soil quality and the limiting factors are poorly known. The goal of this study was to conduct a systematic evaluation of wheat yield and soil quality from 132 fields along a regional scale in China. The specific objectives were (i) to establish a minimum data set (MDS) in wheat phase under the wheat-maize cropping system (ii) to evaluate soil quality of the wheat field and determine the factors limiting wheat productivity. The wheat-maize cropping system was partitioned into three productivity levels (high, medium and low) according to the wheat yield. Twenty-six soil indicators, including soil microbiological, chemical and physical factors were measured and analyzed. Using Pearson correlation analysis we identified eight key soil indicators that determine wheat yield. We then used principal component analysis to determine an MDS, which included soil organic matter, alkali-hydrolyzable nitrogen, the ratio of microbial biomass nitrogen to total nitrogen, and available zinc. One-way analysis of variance based on the individual contribution of each MDS indicators under three productivity, revealed available nitrogen, soil organic matter and the ratio of microbial biomass nitrogen to total nitrogen was the most important indicators on limiting wheat yield. A soil quality index (SQI) based on scoring and weighting of MDS indicators was integrated as a tool for assessing farmland soil quality. Based on the MDS, high (HP), medium (MP) and low (LP) productivity received mean SQI of 0.55, 0.48 and 0.39, respectively. The significant positive correlation between SQI and wheat yield suggests that this is a good representative of the MDS for the wheat-maize cropping system in China. We conclude that our SQI may be an effective and practical tool to guide a strategic, regional goal with respect to sustainable high yields. [ABSTRACT FROM AUTHOR]