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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]

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]

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]

Purpose: Prometryne with moderate to low mobility in soil is a ubiquitous environmental pollutant in water and soil. Bioremediation is widely used to remove pollutants from contaminated soil. Bacterial-feeding nematodes have been tested on the decomposition of soil organic matter and the release of nutrients through their interaction with soil microorganisms, but little attention has been paid to their effects on the removal of herbicides in soil. In this study, we investigated the effects of bacterial-feeding nematodes ( Cephalobus Bastian) on the dissipation of prometryne and microbial activity in prometryne contaminated soil. Materials and methods: Cultured with prometryne for a period of 6 months, prometryne-degrading bacteria strains P-1 and P-2 were isolated from sediments obtained from Anhui Huaxing Chemical Industry Co., Ltd. (Anhui Province, China). Bacterial-feeding nematodes were reared on Nematode Growth Medium agar plates (NGM) supplemented with prometryne for 5 months. Gnotobiotic microcosm experiments were conducted by inoculating both nematodes and prometryne-degrading bacteria strains P-1 ( Ochrobactrum sp.) and P-2 ( Bacillus sp.) into the contaminated soil. Soil samples were analyzed for prometryne concentration, the number of bacteria and nematodes, basal soil respiration, and enzyme activities. Results and discussion: The results show that (1) about 50-66% of the prometryne is dissipated in the treatments with nematodes and the dissipation rate is raised by 5-7% compared with the treatments without nematodes. The nematodes have positive effects on the dissipation of prometryne through their interaction with bacteria in soil; (2) the nematode grazing can increase the population size of bacteria; and (3) the introduction of nematodes can enhance basal soil respiration and soil enzyme activities, that is, soil microbial activity. Conclusions: The inoculation of nematodes enhanced microbial activity in contaminated soils and accelerated the dissipation of prometryne, and thus nematodes can be used in restoration of contaminated sites by accelerating pollutants dissipation in the future. [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]

• 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]

Abstract Salinity is one of the main environmental constraints in soil restricting plant growth and agricultural productivity; however, the utilization of salt-affected land brings substantial benefits. This study investigated an in situ remediation method that involved planting Jerusalem artichokes in naturally occurring saline-alkali soils with different salinities (g salt kg−1 soil), specifically, high salinity (H, >4.0), moderate salinity (M, 2.0–4.0) and low salinity (L, 1.0–2.0), in the coastal saline zone of southeast China. We compared these conditions with corresponding soil controls that were not planted. Soil pH and salinity were increased in bulk and unplanted control soils compared to rhizosphere soils. Neutral phosphatase and invertase showed a significant negative correlation with soil salinity, and there was a significant positive correlation between these two enzymes. While catalase activity decreased in the reverse order. The lowest calcite, muscovite and quartz contents as well as the highest chlorite and albite contents were found in the control soils. Planting Jerusalem artichoke also enhanced bacterial microbiota in saline-alkali soils. Bulk soil Operational Taxonomic Units (OTUs) numbers at high (H), moderate (M) and low (L) salinity were 4177, 5325 and 3672, respectively, and they were 1.27, 1.02 and 1.25 times lower than those in rhizosphere soil. This finding demonstrated that the Jerusalem artichoke played a significant role in enhancing soil microbial richness. In conclusion, Jerusalem artichoke could improve the physical and chemical properties of the soil by released root exudates into soil, increased the diversity and richness of soil microbial communities, and so on, so as to achieved the effect of improved the saline-alkali soil in coastal areas of Dafeng, Jiangsu Province, which provided scientific basis for elaborated the salt-tolerant characteristics of Jerusalem artichoke and improved the mechanism of coastal saline soil function. Highlights • The utilization of salt-affected land brings substantial benefits; • Planting JA decreased Soil pH and salinity and optimized soil structure; • Planting JA enhanced phosphatase and invertase activities; • Planting JA enhanced bacterial microbiota • Planting JA could improve saline-alkali soil quality [ABSTRACT FROM AUTHOR]

Rapid urbanization profoundly affects global biodiversity. How urbanization modifies soil biodiversity and perturbs nematodes remains limited. Here, we investigated soil nematodes in four land-use types: Parks, residential areas, natural forests, and maize fields across 12 cities in China. Urban parks and surrounding forests had similar nematode richness exceeding that in urban residential areas and surrounding farmlands. Nematode communities in parks and residential areas were, however, more homogenous than in forests and farmlands. Variations in nematode assemblages in both core urban and urban surroundings were mainly due to taxa replacement, indicating that nematodes were spatially isolated in cities. Urban residential areas were colonized by the lowest number of specialists (i.e., with narrow niche width) and smaller body sizes. Urban parks, conversely, served as hotspots for soil nematodes in cities. Together, our results indicate that urbanization processes reduce nematode diversity, with e.g., 30% loss in residential areas compared to forests, and homogenize soil nematode communities. • Precipitation and temperature determined soil nematode diversity. • Urban soils have low diversity of soil nematodes. • Urbanization homogenized soil nematode community. • Urban parks are hotspots for soil nematodes. [ABSTRACT FROM AUTHOR]

Soil aggregates are the key functional units of soil ecosystems which are essential to biogeochemical cycling and plant growth. However, it remains unclear how fertilization regimes influence soil aggregation, associated resources, and microbial distribution among aggregates, as well as the potential subsequent impacts for other abiotic and biotic processes. For this, a long-term maize cropping field experiment was conducted in the subtropical region of China under four fertilization treatments: no fertilizer, chemical fertilization, organic fertilization, and chemical plus organic fertilization. Additionally, we classified soil aggregates into large macro-aggregates (>2 mm), small macro-aggregates (0.25–2 mm), and micro-aggregates (<0.25 mm) and compared soil nutrients, enzyme activities, and microbial communities of each aggregate fraction and bulk soil as well as crop productivity and plant carbon (C), nitrogen (N), and phosphorus (P). Results showed that long-term organic fertilization (1) increased soil C, N, and P contents within macro-aggregates, while increased bacterial and fungal biomass within all three aggregate size fractions, (2) increased N-acquiring enzyme activity, C:P, and N:P enzyme ratios but decreased phosphatase activity and C:N enzyme ratio regardless of aggregate fractions, and (3) promoted crop productivity but decreased plant C:N, C:P, and N:P ratios compared with chemical fertilization. Additionally, the fungi:bacteria ratio and phosphatase activity decreased, but the gram-positive to gram-negative bacterial ratio, C-acquiring enzyme activity, C:N and C:P enzyme ratios increased with decreasing aggregate size. The partial least squares models confirmed that macro-aggregates had strong effects on crop performance while micro-aggregates was the main determinant of microbial community. Taken together, long-term organic fertilization promotes soil functioning and crop productivity via increasing the proportion of soil macro-aggregates. • Aggregates with different sizes played distinct roles in soil functioning. • Organic fertilization increased crop productivity by promoting macro-aggregation. • Macro-aggregates is an important resource of nutrients promoted plant growth. • Resources in micro-aggregate were conducive to microbial utilization. • Microorganisms in micro-aggregates were C-limited. [ABSTRACT FROM AUTHOR]

Salinity is not only a threat to organisms and ecosystems, but also a major factor restricting the development of agricultural production. This study aimed to explore the modification effect of in-situ Jerusalem artichoke (genotype NY-1) cultivation on the rhizosphere micro-ecological environment in the saline-alkali region along the southeast coast of China. We analyzed the change of carbon and nitrogen in the saline soil from a microbial perspective, through the quantification of the area of root channels, rhizosphere secretions and soil microbiome (cbbL , cbbM and nifH). The root channels of NY-1 not only improved the physical structure of saline soil, but also provided a living space for microorganisms, afforded basic conditions for the optimization of the soil micro-ecological environment. In addition, rhizosphere secretions (from roots of NY-1 as well as microorganisms), such as carbohydrates, hydrocarbons, acids, etc., could be considered as a way to improve the saline-alkali soil habitat. NY-1 increased the diversity and abundance of autotrophic and nitrogen-fixing bacteria in saline soil (rhizosphere > bulk soils), which should be a biological way to increase the amount of carbon and nitrogen fixation in soil. Moreover, some of the detected genera (Sideroxydans , Thiobacillus , Sulfuritalea , Desulfuromonas , etc.) participate in the carbon and nitrogen cycles, and in the biogeochemical cycle of other elements. In short, Jerusalem artichoke can improve not only the physical and chemical properties of saline-alkali soil, but also promote material circulation and energy flow in the micro-ecological rhizosphere environment of saline soils. [Display omitted] [ABSTRACT FROM AUTHOR]

Anthropogenic activities are supposed to reduce global biodiversity and negatively influence the development of diverse groups in the tree of life. Yet how agricultural management shapes the diversity of microscopic organisms and their evolution in the soil, especially at large spatial scale, remains unknown. Here, we investigated how agricultural land-use affected the biodiversity and the underlying evolutionary events of soil nematodes by comparing their communities in natural and agricultural soils covering a latitudinal transect spanning 2500 km across China. In natural habitats, nematode phylogenetic and taxonomic diversity and species richness showed a hump-shaped relationship with latitudes and peaked at 30° N, while in agricultural habitats those community matrices did not change across the studied latitudinal spectrum. Meanwhile, agricultural management reduced both diversity and richness of nematodes with the effect being more pronounced in subtropical zones. However, evolutionary diversification rates were greater in agricultural than in natural habitats across the entire latitudinal range. This was associated with reductions of soil organic carbon and nitrogen as well as shifts of nematode community compositions towards rapidly evolving taxa (r–strategists) in agricultural habitats. Together, our results suggest that the relatively unfavorable environmental status induced by agricultural management could accelerate the community-level speciation rates of nematodes through enriching rapidly evolving taxon. These insights increase our understanding of the systematic impacts of agricultural activities on soil biodiversity that might facilitate conservation and restoration policies for the purpose of sustainable agriculture. • Phylogenetic comparative methods were applied for soil nematode diversity analysis. • Speciation rates was greater in r-strategists. • Community weighted speciation are greater in agricultural habitats. • Speciation rates were related to soil organic carbon and pH. [ABSTRACT FROM AUTHOR]

Earthworms have been perceived as benevolent soil engineers since the time of Charles Darwin, but several recent syntheses link earthworm activities to higher greenhouse gas emissions, less soil biodiversity, and inferior plant defense against pests. Our study provides new field-based evidence of the multiple direct and indirect impacts of earthworms on ecosystem functions within an ecological multifunctionality framework (i.e., aggregated measures of the ability of ecosystems to simultaneously provide multiple ecosystem functions). Data from a 13-year field experiment describing 21 ecosystem functions showed that earthworm presence generally enhanced multifunctionality by indirect rather than direct effects. Specifically, earthworms enhanced multifunctionality by shifting the functional composition toward a soil community favoring the bacterial energy channel and strengthening the biotic associations of soil microbial and microfaunal communities. However, earthworm-mediated changes in soil physical structure, pH, and taxonomic diversity were not related to multifunctionality. We conclude that the coordinated actions of earthworms and their associated soil biota were responsible for the maintenance of multifunctionality at high levels in this rice-wheat cropping system. Management of crop residue inputs and reduction of soil physicochemical disturbances should encourage beneficial earthworm effects and support multiple ecosystem services that are vital to sustainable agriculture., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Coexistence of antibiotics/heavy metals and the overexpression of resistance genes in the vermicompost has become an emerging environmental issue. Little is known about the interaction and correlation between chemical pollutants and biological macromolecular compounds. In this study, three typical vermicompost samples were selected from the Yangtze River Delta region in China to investigate the antibiotic, heavy metal and corresponding antibiotic resistance genes (ARGs) and heavy metal resistance genes (HRGs). The results indicated the prevalence of tetracycline (TC), copper (Cu), zinc (Zn), cadmium (Cd), corresponding TC-resistance genes (tetA, tetC, tetW, tetM, tetO, and tetS) and HRGs (copA, pcoA, cusA, czcA, czcB, and czcR) in the three vermicompost samples. In addition, the ARG level was positively associated with the water-soluble TC fraction in the vermicompost, and it was same between the HRG abundance and exchangeable heavy metal content (p < 0.05). Moreover, a positive correlation was found between ARG and HRG abundance in the vermicompost samples, suggesting a close regulation mechanism involving the expression of both genes. The result obtained here could provide new insight into the controlling risk of heavy metals, TC, and relevant resistance genes mixed contamination in the vermicompost., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Tomocerids are world-widely distributed, but were seldom reported from tropics. In the present paper, three new species of Tomocerus Nicolet are described from Hainan and Yunnan Provinces, tropical zone of China. All three species have compound-type dental spines and belong to Tomocerus ocreatus species-group. Tomocerus tropicus sp. nov. resembles Tomocerus pseudocreatus Yu, but differs from the latter in mesothoracic macrochaetotaxy, manubrial dorsal scales and denticles on the dental spines. Tomocerus nan sp. nov. resembles Tomocerus virgatus Yu, but differs from the latter in colour pattern, cephalic dorsal macrochaetotaxy, manubrial dorsal scales and denticles on the dental spines. Tomocerus nabanensis sp. nov. resembles T. postantennalis Yu, Zhang Deharveng, Tomocerus dong Yu Li and Tomocerus deharvengi Yu Li, but differs from the three species in PAO, cephalic and tergal dorsal macrochaetotaxy and tenent hairs. Our studies including the present work indicate the importance of future survey on Tomocerinae in and near tropics where diversity of this group was historically underestimated.