Soil Fungal Abundance Research Articles

Soil microbial biodiversity supports the delivery of multiple ecosystem functions under elevated CO2 and warming

The contribution of the soil microbes to agroecosystem multifunctionality under global change remains poorly understood. Here, based on data from a field experiment involving elevated carbon dioxide (CO2) and warming in a rice-wheat agroecosystem, we found that soil microbes influence the impact of climate change on agroecosystem functions. The stability of food production during the rice season increased under elevated CO2 but decreased under warming, with no significant changes in the wheat season. The interactive influences of elevated CO2 and warming on agroecosystem multifunctionality were found to be minimal. The abundance of soil fungi and nematode was associated with agroecosystem stability during the rice and wheat seasons, respectively. Soil archaeal diversity and bacterial abundance were linked to agroecosystem multifunctionality in the rice and wheat seasons, respectively. Our work proves the positive effects of soil microbes on agroecosystem functions and highlights the implications of maintaining microbial diversity for agroecosystem health under climate change.

Responses of soil fungal community composition and function to wetland degradation in the Songnen Plain, northeastern China.

Wetlands are ecosystems that have a significant impact on ecological services and are essential for the environment. With the impacts of rapid population growth, wetland reclamation, urbanization, and land use change, wetlands have undergo severe degradation or loss. However, the response of soil fungal communities to wetland degradation remains unknown. It is crucial to comprehend how the diversity and population dynamics of soil fungi respond to varying levels of degradation and ecological progression in the wetlands of the Songnen Plain. In this study, high- throughput sequencing technology to analyze the variety and abundance of soil fungi in the undegraded (UD), light degraded (LD), moderate degraded (MD), and severe degraded (SD) conditions in the Halahai Nature Reserve of Songnen Plain. This study also explored how these fungi are related to the soil's physicochemical properties in wetlands at various degradation levels. The findings indicated that Basidiomycota and Ascomycota were the primary phyla in the Songnen Plain, with Ascomycota increasing and Basidiomycota decreasing as wetland degradation progressed. Significant differences were observed in soil organic carbon (SOC), total nitrogen (TN),and soil total potassium (TK) among the succession degradation stages. With the deterioration of the wetland, there was a pattern of the Shannon and Chao1 indices increasing and then decreasing. Non-metric Multidimensional Scaling (NMDS) analysis indicated that the fungal community structures of UD and LD were quite similar, whereas MD and SD exhibited more distinct differences in their fungal community compositions. Redundancy analysis (RDA) results indicated that Soil Water content (SWC) and total nitrogen (TN) were the primary environmental factors influencing the dominant fungal phylum. According to the FUNGuild prediction, Ectomycorrhizal and plant pathogens gradually declining with wetland degradation. In general, our findings can offer theoretical support develop effective solutions for the preservation and rehabilitation of damaged wetlands.

Warming enhanced the interaction effects of fungi and fungivores and soil potassium mineralization in tropical forest

Potassium (K) cycling in forest systems has received less attention than nitrogen (N) and phosphorus (P) cycles, despite its critical role in maintaining primary production and regulating water economy and use under climate warming. This study conducted a 10-year study in which we translocated dominant tropical forest tree seedlings and underlying soil (i.e., in situ soil) from high-altitude sites (600 m a.s.l.) to lower altitude sites at 300 m a.s.l. (+1.0 °C) and 30 m a.s.l. (+2.1 °C) to simulate climate warming in southern China. We investigated soil microbial and nematode communities, soil and foliar K concentrations at the aggregate level, and tree growth under different altitude sites. Microbial community was characterized by high-throughput sequencing, nematodes were identified to the genus level using microscope. The findings revealed that warming treatments significantly (p < 0.01) increased soil fungal gene abundance (+78 % at 300 m and +62 % at 30 m), fungal/bacterial abundance ratio (+121 % at 300 m and +101 % at 30 m), and soil fungivore abundance (+274 % at 300 m and +233 % at 30 m). These results indicate a shift in the soil decomposition pathway from bacterial to fungal-based channels. In addition, warming amplifies the interactions between fungi and fungivores. Aggregates had few effects on microbial biomass, but had significant effect on nematode abundance. Soil microcosm experiments consistently demonstrated that addition of the dominant fungivore Aphelenchoides significantly (p < 0.05) enhanced soil-exchangeable K by stimulating fungal gene abundance and activity. Furthermore, warming-induced changes in forest communities were observed. At the species-specific tree level, Syzygium rehderianum demonstrated the ability to take advantage of this scenario, exhibiting increased K uptake (−4% at 300 m and +32 % at 30 m). This may be attributed to the species being ectomycorrhizal-forming, where colonizing root surfaces can mobilize interlayer and structural K from the minerals. In contrast, Machilus breviflora exhibited lower foliar K concentrations (−42 % at 300 m and −41 % at 30 m) and reduced growth. However, warming had little effect on Schima superba, Myrsine seguinii, Itea chinensis, and Ardisia lindleyana growth. Warming-induced changes in the plant–soil system K cycle highlight the emergence of a new ecosystem structure with different soil web structures and distinct plant community species composition. Our results prompt further research to understand the microbiome-mediated complexities of understudied nutrient cycles, which are likely to be further altered in the future owing to climate change.

Diversity of soil fungi from sacred groves of Kerala, India revealed by comparative metagenomics analysis using illumina sequencing.

The diversity, composition, and abundance of soil fungi from three sacred groves in Kerala, namely Iringole kavu of Ernakulam District, Kollakal Thapovanam of Alappuzha District, and Poyilkavu of Kozhikode District were analysed using Metagenomics analysis and Illumina sequencing. A total of 30,584, 78,323, and 55,640 reads were obtained from these groves, respectively. Ascomycota constitutes over 96% of the total fungi, making it the most abundant phylum, followed by Mortierellomycota, Basidiomycota, Chytridiomycota, and Rozellomycota. These phyla were subdivided into 20 classes, 40 orders, 83 families, 119 genera, and 135 species, while 1269 OTUs remained unidentified at the species level. Eurotiomycetes predominates the class, while the genus Talaromyces from the family Trichomaceae dominates the genera. Neocarmospora falciformis, Trichoderma lixii, and Candida ethanolic are the most abundant fungal species. Diversity analysis shows that Kollakal Thapovanam is rich in fungal species, while Poyilkavu is rich in biodiversity, with a high degree of dominance. Several species were found only in a particular grove and were absent in others and vice-versa, indicating high fungal specificity. Therefore, fungi have to be preserved in their original habitat. The Principal Coordinate Analysis revealed that each grove is distinct highlighting the importance of preserving the unique diversity of each sacred grove. In conclusion, this research provides valuable information about the soil fungal genera in their natural habitat. It emphasizes the need for more systematic research to understand the actual diversity and ecological role of fungi in sacred groves. This study is the first of its kind to analyse and compare soil fungal diversity in sacred groves using the metagenomics approach.

Soil microbial community structure and soil fertility jointly regulate soil microbial residue carbon during the conversion from subtropical primary forest to plantations

Soil microbes mediate soil organic carbon (SOC) storage by affecting microbial residue carbon (C) in terrestrial ecosystems, a main source of SOC. However, how microbial residue C accumulation changes during the conversion of subtropical primary forest to plantations and the role of soil microbial community structure in regulating these changes remain unclear. Here, effects of conversion from forest on microbial residue C accumulation in three plantations, including tea (Camellia sinensis var. assamica), walnut (Juglans regia), and macadamia (Macadamia integrifolia). We assessed amino sugars content and the relative importance of soil microbial community structure, soil fertility, and aboveground biomass in four forest types in southwest Yunnan province, China. Our results show that total microbial residue C accounted for 27.8 % of SOC on average across all forest types, and fungal residue C contributed more to SOC than bacterial residue C across different forest types. Conversion from primary forest decreased fungal, bacterial, and total microbial residue C content in all plantation types except tea. Microbial residue C contents was significantly lower in the macadamia plantation than in the primary forest and the tea plantation. Fungal and total microbial residue C content increased with increasing soil microbial community composition, soil fungal abundance, and soil fertility. Soil fertility regulated fungal, bacterial, and total microbial residue C accumulation, which was major determinant of microbial residue C via its influence on soil fungal and bacterial abundance. Overall, we found that soil fungal abundance contributed more to microbial residue C accumulation than change in soil microbial community composition. We also found that soil bacterial abundance was negatively correlated with fungal and microbial residue C, while soil fungal abundance was positively related to microbial residue C accumulation. Ascomycota was most important phylum regulating microbial residue C. These findings suggest that soil fungal and bacterial abundance and soil fertility are the principal regulators of microbial residue C accumulation during the conversion from primary forest to different plantations.

Does helimulching after severe wildfire affect soil fungal diversity and community composition in a Mediterranean ecosystem?

Straw helimulching was applied to an area with a high soil erosion risk one month after the Navalacruz megafire (Iberian Central System, Ávila, Spain) to mitigate soil erosion and to maintain soil quality. To determine whether the soil fungal community, which is key to soil and vegetation recovery after fire, is altered by straw mulching, we examined the effect of helimulching one year after its application. Three hillside zones were chosen with two treatments in each zone (mulched and non-mulched plots), with three replicates of each treatment. Chemical and genomic DNA analyses of soil samples from mulched and non-mulched plots were performed to assess the soil characteristics and the soil fungal community composition and abundance. The total fungal operational taxonomic unit richness and abundance did not differ between treatments. However, there was an increase in the richness of litter saprotrophs, plant pathogens and wood saprotrophs associated with the application of straw mulch. The total fungal composition of mulched and non-mulched plots differed significantly. Fungal composition at the phylum level correlated with the soil potassium content and marginally with the pH and phosphorus content. The application of mulch promoted the dominance of saprotrophic functional groups. Fungal composition according to guilds was also significantly different between treatments. As conclusion, the application of mulch could mean a faster recovery of saprotrophic functional groups that will be responsible for decomposing the available dead fine fuel.

Effects of different botanical oil meal mixed with cow manure organic fertilizers on soil microbial community and function and tobacco yield and quality.

The continuous application of cow manure in soil for many years leads to the accumulation of heavy metals, pathogenic microorganisms, and antibiotic resistance genes. Therefore, in recent years, cow manure has often been mixed with botanical oil meal as organic fertilizer applied to farmland to improve soil and crop quality. However, the effects of various botanical oil meal and cow manure mixed organic fertilizers on soil microbial composition, community structure, and function, tobacco yield, and quality remain unclear. Therefore, we prepared organic manure via solid fermentation by mixing cow manure with different oil meals (soybean meal, rape meal, peanut bran, sesame meal). Then, we studied its effects on soil microbial community structure and function, physicochemical properties, enzyme activities, tobacco yield and quality; then we analyzed the correlations between these factors. Compared with cow manure alone, the four kinds of mixed botanical oil meal and cow manure improved the yield and quality of flue-cured tobacco to different degrees. Peanut bran, which significantly improved the soil available phosphorus, available potassium, and NO3--N, was the best addition. Compared with cow manure alone, soil fungal diversity was significantly decreased when rape meal or peanut bran was combined with cow manure, while soil bacterial and fungal abundance was significantly increased when rape meal was added compared with soybean meal or peanut bran. The addition of different botanical oil meals significantly enriched the subgroup_7 and Spingomonas bacteria and Chaetomium and Penicillium fungi in the soil. The relative abundances of functional genes of xenobiotics biodegradation and metabolism, soil endophytic fungi, and wood saprotroph functional groups increased. In addition, alkaline phosphatase had the greatest effect on soil microorganisms, while NO3--N had the least effect on soil microorganisms. In conclusion, the mixed application of cow manure and botanical oil meal increased the available phosphorus and potassium contents in soil; enriched beneficial microorganisms; promoted the metabolic function of soil microorganisms; increased the yield and quality of tobacco; and improved the soil microecology.

Ecological safety evaluation of chlorpyrifos on agricultural soil: Effects on soil microbes

The health of farmland soils is directly related to the proper application of pesticides. Chlorpyrifos is a widely used broad-spectrum organophosphorus insecticide, and its ecological security risk to farmland soils requires evaluation. A trial was conducted to study the effects of chlorpyrifos on soil microbes in a wheat–maize rotation field. A 45 % chlorpyrifos emulsion was sprayed at the recommended and dual doses, after which the chlorpyrifos residue, soil microbial content, bacterial community structure, functional microbial abundance, and enzyme activities were measured. The results showed that chlorpyrifos had a half-life of 8.94–9.88 and 2.17–2.18 days in soil for wheat and maize, respectively. Although the final chlorpyrifos residues in the crop grains were lower than the maximum residue limit recommended by the Chinese government, soil fungal abundance was significantly inhibited, and the structure and function of soil bacterial communities were disturbed. Furthermore, the quantities of nitrification-related genera (Acidobacteria GP4 and Acidobacteria GP6) and functional genes (AOB-amoA and AOA-amoA) decreased, whereas those of denitrification-related functional genes (nirS and nirK) and urease activity increased. Gemmatimonas and alkaline phosphatase involved in phosphorus cycling were activated, and the abundance of cbbLR and cbbLG genes involved in carbon fixation decreased. The integrated biomarker response index showed that nirK and β-glucosidase were the most sensitive indicators in wheat and maize stages. The present study provides toxicological data and theoretical guidance for the ecological safety evaluation and rational application of chlorpyrifos in soil.

Field inoculation by arbuscular mycorrhizal fungi with contrasting life-history strategies differently affects tomato nutrient uptake and residue decomposition dynamics

PurposePlant microbial biostimulants, such as arbuscular mycorrhizal fungi (AMF), enhance nutrient concentration in fruits, including tomato. However, field studies on tomato AMF inoculation are scarce. AMF species belonging to Gigasporaceae and Glomeraceae families known to vary in life-history strategies may determine differential effects on plant nutrient benefits and residue decomposition. Despite this, the effect of different life-history strategies on nutrient acquisition of tomato fruits has not been investigated yet.MethodsWe studied the effect of inoculation of two tomato varieties with four AMF species belonging to Glomeraceae and Gigasporaceae. Fungal colonization, yield, fruit nutrient concentration, litter decomposition, and bacterial and fungal abundances in soil were assessed in the field under organic agriculture.ResultsOverall Gigasporaceae promoted the concentration of nutrients in tomato fruits compared to Glomeraceae. A variability in AM fungal colonization and fruit nutrient concentration was detected within Glomeraceae. Scutellospora pellucida increased the yield (+ 27%) of var. Rio Grande with respect to Gigaspora gigantea. In var. Rio Grande, inoculation with Funneliformis mosseae did not change litter decomposition as compared to non-inoculated controls, whereas it was lower than in Sclerocystis sinuosa and Gigasporaceae species, which showed the highest decomposition rates. AMF inoculation promoted soil total bacterial and fungal abundance and fungal:bacterial (F:B) ratio compared to controls, and members of Gigasporaceae had the highest F:B ratio.ConclusionThese findings pointed at the inclusion of AM fungal life-history strategy within the selection criteria for the development of biofertilizers able to enhance the nutritional value of vegetables under organic farming systems.

Soil organic carbon regulation from chemistry in top- but microbial community in subsoil in eastern coastal China poplar plantations

Although patterns in the vertical distribution of soil organic carbon (SOC) are key to assessing soil C sequestration potential, they remain poorly understood. We sampled 18 soil profiles at one meter depth at the Dongtai Forest Farm to investigate the vertical distribution of SOC, the stoichiometric relationship between SOC and total nitrogen (TN) and the controlling factors of SOC at different soil depths. We found that SOC content decreased significantly with increasing soil depth. Approximately 67% of SOC was stored in the top 30 cm. The N-C scaling slope (i.e., the slope of the relationship between log-transformed N and C not significantly different from 1.0) revealed significant differences between top- and subsoil with N and C scaled isometrically in topsoil (0–30 cm), but not in subsoil (30–100 cm). SOC content was co-regulated by soil physiochemical and microbial properties at the site level with soil chemical and microbial properties dominant in the top- and subsoil, respectively. Topsoil SOC increased with soil TN, available phosphorus (AP) and fungal abundance. Subsoil SOC increased with the fungal-to-bacterial ratio, fungal abundance and soil dissoluble organic carbon (DOC). Our study highlights the dominance of microbial community in regulating SOC in the subsoil and advances our understanding of the variation in mechanisms regulating SOC along the soil profile.

Effects of Different Topdressing Nitrogen Rates on Soil Fungal Community Structure and Ecological Network in Wheat Field Under Crop Residue Retention

Crop residue retention and fertilizer application are the main sources of soil nutrient input in fields. Crop residue retention combined with appropriate fertilizer application rates could provide necessary nutrients for crop production under the premise of environmentally friendly conditions. The aim of this study was to clarify the influence of different topdressing nitrogen rates on the soil fungal community in a wheat field under crop residue retention and to evaluate the rationality of nitrogen fertilizer management in winter wheat from the perspective of soil ecological function. On the basis of full straw retention and 150 kg·hm-2 basal nitrogen, treatments with five topdressing nitrogen rates (0, 37.5, 75, 112.5, and 150 kg·hm-2) were set up. The abundance, diversity, structure, and ecological network of soil fungal communities were analyzed using real-time fluorescence quantitative PCR and high-throughput sequencing, and the main soil physical and chemical factors driving the change in soil fungal communities were explored. The results showed that, compared with the no topdressing nitrogen and low topdressing nitrogen rate treatments, high topdressing nitrogen rate treatments increased soil total nitrogen and mineral nitrogen and decreased soil pH, total phosphorus, available phosphorus, and available potassium. Compared with the no topdressing nitrogen treatments, the 37.5-150 kg·hm-2 topdressing nitrogen treatments significantly increased soil fungal community abundance (P<0.05), whereas there was no significant difference among different topdressing nitrogen treatments (P>0.05). The Heip index and Shannon index of soil fungal communities decreased gradually with the increase in topdressing nitrogen rate, and the Sobs index, Heip index, and Shannon index of soil fungal communities in the treatment with 150 kg·hm-2 topdressing nitrogen were significantly lower than those of 0-75 kg·hm-2 topdressing nitrogen treatments (P<0.05). Principal component analysis and similarity analysis showed that there were significant differences in soil fungal community structure under different topdressing nitrogen rate treatments (P<0.05). With the increase in topdressing nitrogen rate, the number of network edges and average number of neighbors of soil fungal ecological network increased first and then decreased, and the network complexity of 37.5 kg·hm-2 topdressing nitrogen treatments was the highest. Compared with 0-75 kg·hm-2 topdressing nitrogen treatments, 112.5 kg·hm-2 and 150 kg·hm-2 topdressing nitrogen treatments increased the characteristic path length of the soil fungal ecological network, whereas it decreased the network density. With the increase in topdressing nitrogen rate, the relative abundance of soil saprotrophs gradually increased, and the pathotroph-saprotroph-symbiotroph relative abundance gradually decreased. Redundancy analysis showed that soil pH, total phosphorus, mineral nitrogen, available phosphorus, and available potassium were the main soil physicochemical factors affecting the soil fungal community structure in the wheat field under different topdressing nitrogen rate treatments. In conclusion, on the basis of straw retention and basal nitrogen, topdressing nitrogen at the wheat jointing stage could change the diversity, structure, and species composition of the soil fungal community, in turn affecting the soil fungal ecological network and function, and high topdressing nitrogen rates could reduce soil fungal community diversity, ecological network complexity, and network density.

Moss-dominated biocrust-based biodiversity enhances carbon sequestration via water interception and plant-soil-microbe interactions

We investigated a nature-based solution (NbS) via incorporating biocrust into alfalfa-maize intercropping system to test carbon sequestration in seriously eroded agricultural soils. Field investigation showed that the NbS (moss-dominated biocrust+ intercropping) massively lowered surface soil erosion by 94.5% and soil carbon (C)and nitrogen (N)loss by 94.7 and 96.8% respectively, while promoting rainwater interception by 82.2% relative to bare land (CK). There generally existed positive interactions between biocrust and cropping in the integrated standing biodiversity system. Enhanced plant biomass input into soils substantially promoted soil fungal community diversity and abundance under NbS (p<0.05). This enabled NbS to evidently improve soil macroaggregate proportion and mean weight diameter. Critically, topsoil carbon storage was increased by 2.5 and 10.7%, compared with CK and pure intercropping (p<0.05). Conclusively, the standing diversity under such NbS fostered soil C sequestration via water interception and plant-soil-microbe interactions in degraded agricultural soils.

Long-Read Sequencing Analysis Revealed the Impact of Forest Conversion on Soil Fungal Diversity in Limu Mountain, Hainan.

Soil fungi are essential to soil microorganisms that play an important role in the ecosystem's soil carbon cycle and mineral nutrient transformation. Understanding the structural characteristics and diversity of soil fungal communities helps understand the health of forest ecosystems. The transition from tropical rainforest to artificial forest greatly impacts the composition and diversity of fungal communities. Hainan Limushan tropical rainforest National Park has a large area of artificial forests. Ecologists have conducted in-depth studies on the succession of animals and plants to regenerate tropical rainforests. There are few reports on the diversity of soil fungi and its influencing factors in the succession of tropical rainforests in Limu Mountain. In this study, 44 soil samples from five different stands were collected in the tropical rainforest of Limushan, Hainan. High-throughput sequencing of rDNA in its region was used to analyze fungal communities and study their α and β diversity. Analysis of variance and multiple regression models was used to analyze soil variables and fungal functional groups to determine the effects of interaction between fungi and environmental factors. A total of 273,996 reads and 1290 operational taxonomic units (OTUs) were obtained, belonging to 418 species, 325 genera, 159 families, eight phyla, 30 classes, and 73 orders. The results showed that the composition of soil fungal communities in the five stands was similar, with ascomycetes accounting for 70.5% and basidiomycetes accounting for 14.7%. α and β diversity analysis showed that soil fungi in Limushan tropical rainforest had high abundance and diversity. Multiple regression analysis between soil variables and functional groups showed that organic matter, TN, TP, TK, and AK were excellent predictors for soil fungi. TP was the strongest predictor in all functional groups except soil saprotroph. Organic matter and total nitrogen were the strongest predictors of soil rot. The transformation from tropical rainforest to artificial forest in Limushan did not change the soil fungal community structure, but the richness and diversity of soil fungi changed. The forest transformation did not lead to decreased soil fungal abundance and diversity. Different vegetation types and soil properties affect the diversity of soil fungal communities. We found that Caribbean pine plantations can improve soil fungal diversity, while long-term Eucalyptus spp. plantations may reduce soil fungal diversity.

Effect of Aerated Irrigation on the Growth and Rhizosphere Soil Fungal Community Structure of Greenhouse Grape Seedlings

Conventional irrigation methods decrease greenhouse soil aeration, which leads to restricted root growth and reduced soil fungal abundance in greenhouse grapes. In this study, aerated irrigation equipment was used to investigate the effects of aerated irrigation on the biomass accumulation, root growth, and soil fungal community structure of grape seedlings. The results show that aerated irrigation significantly increased the root length, root surface area, root volume, and number of root tips by 38.5%, 32.1%, 62.1%, and 23.4%, respectively, at a soil depth of 20–40 cm (p ≤ 0.05). The chao1 index and ACE index of fungi at different soil depths under aerated irrigation were higher than those without aerated treatment; aerated irrigation changed the relative abundance of dominant fungi in rhizosphere soil. At a soil depth of 20–40 cm, aerated irrigation increased the abundance of Fusarium by 42.2%. Aerated irrigation also contributed to the abundance of the beneficial fungal genera Mortierella, Cladosporium, and Glomus. At a soil depth of 0–20 cm, the abundance of Mortierella in the soil that received aerated treatment was 180.6% higher than in the control treatment. These findings suggest that aerated irrigation is a promising strategy for the promotion of grape root growth and biomass accumulation, and it can also increase the abundance of some beneficial fungi.

Short-term application of chicken manure under different nitrogen rates alters structure and co-occurrence pattern but not diversity of soil microbial community in wheat field.

Manure application is an effective way to improve the utilization efficiency of organic resources and alleviate the adverse effects of long-term application of chemical fertilizers. However, the impact of applying manure under different nitrogen rates on soil microbial community in wheat field remains unclear. Treatments with and without chicken manure application under three nitrogen rates (N 135, 180 and 225 kg⋅hm–2) were set in wheat field. Soil organic carbon, available nutrients, and abundance, diversity, structure and co-occurrence pattern of soil microbial community at wheat maturity were investigated. Compared with no manure application, chicken manure application increased the soil organic carbon and available phosphorus, while the effects on soil mineral nitrogen and available potassium varied with different nitrogen rates. Chicken manure application significantly increased soil bacterial abundance under the nitrogen fertilization of 135 and 225 kg⋅hm–2, increased soil fungal abundance under the nitrogen fertilization of 135 kg⋅hm–2, but decreased soil fungal abundance under the nitrogen fertilization of 180 and 225 kg⋅hm–2 (P < 0.05). There was no significant difference in alpha diversity indices of soil microbial communities between treatments with and without chicken manure application under different nitrogen rates (P > 0.05). Chicken manure application and its interaction with nitrogen rate significantly changed soil bacterial and fungal community structures (P < 0.05). There were significantly different taxa of soil microbial communities between treatments with and without chicken manure application. Chicken manure application reduced the ecological network complexity of soil bacterial community and increased that of soil fungal community. In summary, the responses of soil available nutrients and microbial abundance to applying chicken manure varied with different nitrogen rates. One growing season application of chicken manure was sufficient to alter the soil microbial community structure, composition and co-occurrence pattern, whereas not significantly affected soil microbial community diversity.

Responses of soil fungal communities and functional guilds to ~160 years of natural revegetation in the Loess Plateau of China.

Natural revegetation has been widely confirmed to be an effective strategy for the restoration of degraded lands, particularly in terms of rehabilitating ecosystem productivity and soil nutrients. Yet the mechanisms of how natural revegetation influences the variabilities and drivers of soil residing fungal communities, and its downstream effects on ecosystem nutrient cycling are not well understood. For this study, we investigated changes in soil fungal communities along with ~160 years of natural revegetation in the Loess Plateau of China, employing Illumina MiSeq DNA sequencing analyses. Our results revealed that the soil fungal abundance was greatly enhanced during the later stages of revegetation. As revegetation progresses, soil fungal richness appeared first to rise and then decline at the climax Quercus liaotungensis forest stage. The fungal Shannon and Simpson diversity indexes were the lowest and highest at the climax forest stage among revegetation stages, respectively. Principal component analysis, Bray–Curtis similarity indices, and FUNGuild function prediction suggested that the composition, trophic modes, and functional groups for soil fungal communities gradually shifted along with natural revegetation. Specifically, the relative abundances of Basidiomycota, Agaricomycetes, Eurotiomycetes, and ectomycorrhizal fungi progressively increased, while that of Ascomycota, Sordariomycetes, Dothideomycetes, Tremellomycetes, saprotrophic, pathotrophic, arbuscular mycorrhizal fungi, and endophyte fungi gradually decreased along with natural revegetation, respectively. The most enriched members of Basidiomycota (e.g., Agaricomycetes, Agaricales, Cortinariaceae, Cortinarius, Sebacinales, Sebacinaceae, Tricholomataceae, Tricholoma, Russulales, and Russulaceae) were found at the climax forest stage. As important carbon (C) sources, the most enriched symbiotic fungi (particularly ectomycorrhizal fungi containing more recalcitrant compounds) can promote organic C and nitrogen (N) accumulation in soils of climax forest. However, the most abundant of saprotrophic fungi in the early stages of revegetation decreased soil organic C and N accumulation by expediting the decomposition of soil organic matter. Our results suggest that natural revegetation can effectively restore soil fungal abundance, and modify soil fungal diversity, community composition, trophic modes, and functional groups by altering plant properties (e.g., plant species richness, diversity, evenness, litter quantity and quality), quantity and quality of soil nutrient substrates, soil moisture and pH. These changes in soil fungal communities, particularly their trophic modes and functional groups along with natural revegetation, impact the accumulation and decomposition of soil C and N and potentially affect ecosystem C and N cycling in the Loess Plateau of China.

Microbial Fertilization Improves Soil Health When Compared to Chemical Fumigation in Sweet Lily.

Lanzhou Lily(Lilium davidii) var. unicolor, which is also known as sweet lily in China, is used as a type of food. This lily is distributed in narrow regions, propagates asexually, cultivates perennially, and cultivates commonly in serious consecutive replant problems (CRPs). Soil fumigation is commonly used to control soil-borne disease to alleviate crops’ consecutive replant problems (CRPs). However, due to the improper fumigation application, it is common to cause chemical hazard to crops. In this study, we designed a two-factor experiment to explore the bacterial and fungal community structure and some specific microbial groups in the lily rhizosphere soil after chemical versus bacterial fertilizer treatments, by using a metagenomic analysis of the treated soils. The results showed that metham-sodium soil fumigation (SMF treatment) significantly decreased plant growth, as well as it significantly decreased both soil fungal diversity and abundance at the OTUs levels, while Special 8™ microbial fertilizer supplement (MF treatment) significantly improved plant growth and increased fungal diversity and abundance. Under FM treatment, Chao1 richness and Shannon’s diversity increased by 6.70% and 35.09% compared to CK (no treatment). However, the bacterial diversity and abundance were not significantly changed among these treatments. The fungal and bacterial community structure were different in all treatments. In SMF treatment, the pathogenic fungal species Fusarium oxysporum increased compared to CK, but it significantly decreased in MF treatment; in MF and MMF treatments, some beneficial bacteria groups such as the bacterial phylum Proteobacteria and its member genus Sphingomonas, as well as the fungal genus Mortierella, increased compared to CK and SFM treatments, but the harmful bacterial genera Gemmatimona was decreased, as well as the harmful fungal genus Cryptococcus. Thus, we concluded that under chemical fumigation conditions, both fungal diversity loss and overall microorganism reduction, which impair multiple ecosystem function, in conjunction with the increase of harmful fungal species such as Fusarium oxysporum, are causes for soil degradation. On the other hand, under microbial fertilizer supplement, it was the fungal diversity increase, as well as these beneficial microorganisms groups’ accumulation, together with those harmful groups’ depletion, played important roles in restoring and improving soil health that suffered from the chemical fumigant hazard. In addition, the bacterial phylum Proteobacteria and its member genus Sphingomonas are involved in soil health recovery and promotion. The results also emphasized that whether soil is chemically fumigated or not, beneficial microorganism supplementary is effective in ensuring soil productivity.

Multiple anthropogenic pressures eliminate the effects of soil microbial diversity on ecosystem functions in experimental microcosms

Biodiversity is crucial for the provision of ecosystem functions. However, ecosystems are now exposed to a rapidly growing number of anthropogenic pressures, and it remains unknown whether biodiversity can still promote ecosystem functions under multifaceted pressures. Here we investigated the effects of soil microbial diversity on soil functions and properties when faced with an increasing number of simultaneous global change factors in experimental microcosms. Higher soil microbial diversity had a positive effect on soil functions and properties when no or few (i.e., 1–4) global change factors were applied, but this positive effect was eliminated by the co-occurrence of numerous global change factors. This was attributable to the reduction of soil fungal abundance and the relative abundance of an ecological cluster of coexisting soil bacterial and fungal taxa. Our study indicates that reducing the number of anthropogenic pressures should be a goal in ecosystem management, in addition to biodiversity conservation.

Concentration‐dependent response of soil parameters and functions to trifluoroacetic acid

AbstractDespite growing environmental concerns about perfluoroalkyl and polyfluoroalkyl substances (PFAS) worldwide, the ultra‐short‐chain PFAS, for example, trifluoroacetic acid (TFA), have been largely neglected in the context of soil pollution. Given the persistence and increasing occurrence of TFA in the soil environment, accumulated TFA could impact soil properties and functions. Therefore, we investigated the effects of a wide range of concentrations of TFA (0.001–100 μg g−1) on chemical, physical and biological indicators of soil health, using a six‐week microcosm experiment. Our results showed that TFA treatments decreased soil pH, sulphate content, soil respiration, litter decomposition and bacterial abundance, and increased phosphate content (p &lt; 0.05). These effects were observed for TFA concentrations ≥1 μg g−1. As expected, because of its strong acidity, TFA decreased soil pH, and this change likely contributed to effects on other soil parameters and functions, for example, reducing bacterial abundance and soluble nutrients. However, importantly, TFA clearly also affected soil parameters at concentrations at which soil pH was not changed. Soil aggregation, fungal abundance, and enzyme activities were not affected by TFA in this study. Considering the current reported environmental levels of TFA of &lt;2.4 μg g−1, only litter decomposition would be affected under current field conditions. Our data also show that future accumulation of higher concentrations, or hotspots of TFA, will likely negatively affect soils with similar properties as our test soil. Thus, we demonstrated that microbial processes can be impacted by the accumulation of the ‘forever chemical’ TFA in the tested sandy, low organic matter soil.Highlights Trifluoroacetic acid (TFA) decreased soil pH, respiration, litter decomposition and bacterial abundance. TFA affected soil soluble nutrients. TFA affected litter decomposition at 1 μg g−1 with no change in soil pH. Effects of TFA on soil enzyme activity and aggregation and fungal abundance were negligible.

Effects of perfluoroalkyl and polyfluoroalkyl substances (PFAS) on soil structure and function

Soils are impacted globally by several anthropogenic factors, including chemical pollutants. Among those, perfluoroalkyl and polyfluoroalkyl substances (PFAS) are of concern due to their high environmental persistence, and as they might affect soil structure and function. However, data on impacts of PFAS on soil structure and microbially-driven processes are currently lacking. This study explored the effects of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutanesulfonic acid (PFBS) at environmental-relevant concentrations on soil health, using a 6-week microcosm experiment. PFAS (even at 0.5 ng g−1 for PFBS) significantly increased litter decomposition, associated with positive effects on β-glucosidase activities. This effect increased with PFAS concentrations. Soil pH was significantly increased, likely as a direct consequence of increased litter decomposition affected by PFAS. Soil respiration was significantly inhibited by PFAS in week 3, while this effect was more variable in week 6. Water-stable aggregates were negatively affected by PFOS, possibly related to microbial shifts. PFAS affected soil bacterial and fungal abundance, but not microbial and certain enzyme activities. Our work highlights the potential effects of PFAS on soil health, and we argue that this substance class could be a factor of environmental change of potentially broad relevance in terrestrial ecosystem functioning.