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[Objective] Soil microorganisms are the most active parts in soil and are sensitive to soil additives. This study aimed to clarify the impacts of the addition of biomass materials (corn straw and biochar) and nitrogen application on the compositions of the soil microbial community in moderately saline soils (salt content was 0.4%). [Method] Indoor constant-temperature cultivation experiments were conducted to study the effects of biomass materials and nitrogen application on the microbial diversity and community structure in moderately saline soils. This experiment had a two-way factorial design, with the biomass materials and nitrogen application rates as the treatments. The biomass materials included no addition of biomass materials as a control (C0), corn straw (C1, 0.64 g/pot), and biochar (C2, 0.85 g/pot), and the nitrogen application rates included 0 g N (N0), 0.015 g N (N1), and 0.03 g N (N2). There were nine treatments, as follows: C0N0, C0N1, C0N2, C1N0, C1N1, C1N2, C2N0, C2N1, and C2N2. [Results] (1) The different biomass materials and nitrogen application levels significantly influenced the α-diversity and composition of the bacterial community. At the initial stage of cultivation, the soil bacterial diversity was relatively high, and it significantly decreased after 35 days of cultivation. Moreover, the improvement of the bacterial community structure by the biochar treatment was better than that of corn straw. After 35 days of cultivation, the relative abundance of Actinobacteria, Bacteroidetes, and Firmicutes in the soil significantly increased, while the relative abundance of Gemmatimonadete, Chloroflexi, Acidobacteria, Planctomycetes, and Patescibacteria significantly decreased. Ammonium nitrogen, nitrate nitrogen, and nitrate reductase were the main environmental factors affecting the bacterial community. (2) The different biomass materials and nitrogen treatments significantly affected the richness of the fungal communities. The fungal richness index significantly increased after adding the corn straw and biochar treatments, and the addition of corn straw promoted an increase in the beneficial bacterial abundance in the moderately saline soil. Soil nitrate reductase and ammonium nitrogen were the main environmental factors affecting the fungal community. [Conclusions] In summary, biomass materials and nitrogen application can effectively increase the diversity of soil microbial communities and optimize the structure of microbial communities, thereby ameliorating the ecosystem health of moderately saline soil. [ABSTRACT FROM AUTHOR]

Microbial fertilizer is an environment-friendly fertilizer that can effectively improve the microecological environment of soil, playing an important role in the remediation of saline–alkali soil and promoting sustainable agricultural development. In this study, we examined the impact of microbial fertilizer application on saline–alkali field improvement over two years. The results indicated that, compared to NS0 and NS2 (the initial sowing period without microbial fertilizer addition), the soil pH and electrical conductivity (EC) levels significantly decreased by 4.1% and 8.49% and 60.56% and 39.66% for NS1 (after the first harvest) and NS3 (after the second harvest), respectively. Compared to NS0, the concentrations of Na+ and Cl−, among the eight major ions in the soil, decreased significantly by 87.23% and 80.91% in the second year, while Ca2+ increased significantly in NS1 and NS3, being 5.27 times and 2.46 times higher than before sowing. Comparing NS3 to NS0, the sodium adsorption ratio decreased by 87.04%. The activities of soil urease, alkaline phosphatase, and invertase in NS3 increased significantly by 90.18%, 45.67%, and 82.31% compared to those in NS0. In contrast, the activity of catalase decreased by 2.79% (p < 0.05). Alpha diversity analysis demonstrated that the Ace, Chao1, and Sobs indices for both bacteria and fungi were significantly higher at NS3 than before sowing, indicating the highest species richness at this stage. The Shannon index exhibited an ascending trend, and the difference in the Simpson index was not significant. After applying microbial fertilizer in the saline–alkali field, the number of bacterial and fungal operational taxonomic units (OTUs) significantly increased. In the bacteria, the proportion of Proteobacteria rose, while Actinobacteriota exhibited a significant reduction. Among fungi, the proportion of Ascomycota decreased and Basidiomycota increased. Principal component analysis (PCA) revealed distinct separation among treatments, indicating significant differences in microbial communities. Redundancy analysis (RDA) identified that the key physicochemical factors influencing bacterial community structure were available phosphorus (AP), electrical conductivity (EC), and pH, whereas for fungi, they were AP, available potassium (AK), and dissolved organic carbon (DOC). This research presents the effects of microbial fertilizer application on the improvement in a saline–alkali field over two years. It provides a scientific basis for the remediation of the saline–alkali field via microbe-induced changes in soil physicochemical properties, enzyme activity, microbial diversity, and community structure at different periods. [ABSTRACT FROM AUTHOR]

Most research on plant–microbe interactions emphasize the effects of micronutrients on the rhizosphere microbial community structure. However, the influence of seed structures, particularly the radicle sheath, on microbial diversity at the seedling root tips under varying temperatures and humidity has been less explored. This study conducted controlled indoor experiments in the northern desert of Xinjiang to assess the radicle sheath's impact on microbial community composition, diversity, and function. The results indicated no significant changes in the Chao1 index for bacteria and fungi, but notable differences were observed in the Shannon and Simpson indices (p < 0.05). Under drought conditions, the radicle sheath significantly reduced bacterial infections without affecting fungi. Genus-level analysis showed an increased abundance of specific dominant bacterial groups when the radicle sheath was retained. NMDS analysis confirmed its significant effect on both bacterial and fungal community structures. LEfSe analysis identified 34 bacterial and 15 fungal biomarkers, highlighting the treatment's impacts on microbial taxonomic composition. Functional predictions using PICRUSt 2 revealed that the radicle sheath facilitated the conversion of CH4 to CH3OH and various nitrogen cycle processes under drought. Overall, the radicle sheath plays a crucial role in maintaining rhizosphere microbial community stability and enhancing the functions of both bacteria and fungi under drought conditions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) pollution in soil has become a huge problem for agricultural production in China and even the world. Passivation and phytoremediation are two important remediation technologies for Cd pollution. In this study, the cadmium-contaminated and phosphorus-poor farmland soil around a mining area in Huainan was taken as the research object, and the remediation effect of biochar and phosphorus-containing materials on soil cadmium pollution was discussed. The results showed that the combined application of biochar and phosphorus-containing materials significantly reduced the pH of non-rhizosphere soil and rhizosphere soil, and increased the content of soil dissolved organic carbon (DOC). The combined application of biochar and phosphorus-containing materials significantly reduced soil pore water Cd and soil available Cd. In addition, both a single application of biochar and synergistic application of biochar and phosphorus-containing materials significantly increased the biomass of aboveground and underground parts of amaranth and soil urease and catalase activities. Phosphorus application reduced the bioavailability of Cd in soil. With the increase in phosphorus application, the content of available Cd in soil decreased significantly, and there was a certain negative correlation between Cd content and phosphorus content in plants. The abundance of beneficial microorganisms such as Ochrobactrum, Anaerolinea, Achromobacter, and Cellvibrio in soil was significantly increased after the synergistic application of biochar and phosphorus-containing materials. [ABSTRACT FROM AUTHOR]

The increasing use of antibiotics in livestock poses environmental risks, leading to contamination of agricultural soils and propagation of microbial antibiotic-resistant genes (ARGs). This study examined the impacts of wood- and manure-derived biochar (BC) on antibiotic residues, ARGs, and microbial communities in sandy loam and clay loam soils amended with manure in Cynodon dactylon pastures. We hypothesized that BC amendments would influence the degradation of antibiotics and the structure of microbial communities based on their physicochemical properties and soil types. Our results demonstrated that wood BC reduced the concentrations of tetracycline and sulfonamides, particularly in sandy loam soil, due to its larger surface area and hydrophobic properties. In contrast, manure BC provided additional nutrients and supported atmospheric nitrogen-fixing microbial groups, especially in clay loam soil, while exhibiting variable efficiency in reducing antibiotic residues due to its lower surface area and higher ash content. These findings underscore the differential impacts of each BC type, emphasizing the need for tailored BC applications based on soil type to effectively mitigate antibiotic contamination and promote sustainable agricultural practices. In conclusion, wood BC was more effective in enhancing soil health by reducing antibiotic residues and improving microbial diversity, particularly in sandy loam soils, while manure BC was beneficial for nutrient cycling in clay loam soils. [ABSTRACT FROM AUTHOR]

Intercropping, a well-established agroecological technique designed to bolster ecological stability, has been shown to have a significant impact on soil health. However, the specific effects of tea/Trachelospermum jasminoides intercropping on the physicochemical properties and functional microbial community structure in practical cultivation have not been thoroughly investigated. In this study, we utilized high-throughput sequencing technology on the 16S/ITS rDNA genes to assess the impact of tea intercropping with T. jasminoides on the composition, diversity, and potential functions of the soil microbial community in tea gardens. The results indicated that the tea/T. jasminoides intercropping system significantly increased pH levels, soil organic matter, available nitrogen, phosphorus, potassium, and enzyme activity, ultimately augmenting soil nutrient levels. Furthermore, an in-depth analysis of the bacterial co-occurrence network and topological structure portrayed a more intricate and interconnected soil bacterial community in tea gardens. Remarkably, the abundance of beneficial genera, including Burkholderia, Mesorhizobium, Penicillium, and Trichoderma, underwent a substantial increase, whereas the relative abundance of pathogenic fungi such as Aspergillus, Fusarium, and Curvularia experienced a marked decline. Functional predictions also indicated a notable enhancement in the abundance of microorganisms associated with nitrogen and carbon cycling processes. In summary, the intercropping of tea and T. jasminoides holds the potential to enrich soil nutrient content, reshape the microbial community structure, bolster the abundance of functional microorganisms, and mitigate the prevalence of pathogenic fungi. Consequently, this intercropping system offers a promising solution for sustainable tea garden management, overcoming the limitations of traditional cultivation methods and providing valuable insights for sustainable agriculture practices. [ABSTRACT FROM AUTHOR]

Hydrochar as a carbon-based fertiliser is hypothesised to permanently improve soils by modifying soil carbon quality through the regulation of soil organic carbon dynamics, aggregation properties and microbial diversity. However, the interactions between soil organic carbon (SOC) molecular structure, soil aggregates and soil microbial communities as a result of hydrochar application have not been fully elucidated. In this study, the use of hydrochar derived from duck farm biomass waste for a maize cultivation experiment verified that hydrochar had a promoting effect on maize growth, effectively increasing the nutrient supply to the soil. The application of hydrochar increased the soil organic carbon content by 78 to 253 per cent, which was dominated by CHON-type lignin, carbohydrates and condensed aromatic structural compounds. Meanwhile, hydrochar had a significant effect on both soil aromatic structures and oxygenated functional groups, forming more soil macroaggregates. In addition, hydrochar had a positive effect on soil bacterial abundance. This study suggests that the key mechanism by which hydrochar regulates soil carbon dynamics is mainly through the stabilising effect of hydrochar on macroaggregates while increasing the abundance of carbon-related microscopic bacteria. These results will help to elucidate the potential effects of aqueous carbon on the biogeochemical cycling of carbon in soils. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is an important means to turn agricultural waste into resources and an important way to address the challenges in treating vegetable residues in China. In this study, the co-digestion of dairy manure with tomato residue was investigated to clarify the effect of the total solids (TS) of the digestion substrate on methane's production and mechanism using the self-made anaerobic digestion device. The results showed that all treatments could rapidly ferment methane and that the daily methane production showed a trend of increasing first and then decreasing. The optimal concentrations of the digestion substrate for liquid anaerobic digestion (L-AD), hemi-solid-state anaerobic digestion (HSS-AD), and solid-state anaerobic digestion (SS-AD) were 10%, 18%, and 25%, respectively. Compared with SS-AD and HSS-AD, L-AD gas production peaked 3–6 days earlier. Treatment TS25 had the best cumulative methane production, reaching 117.4 mL/g VS. However, treatment TS6 had acid accumulation and a very unstable system. The cumulative methane production of SS-AD was higher than that of HSS-AD and L-AD. Firmicutes and Bacteroidetes were the dominant flora, and Methanoculleus, Methanosarcina, and Methanobrevibacter were the main archaeal groups. The TS significantly changed the microbial community composition of the digestion system, especially the low TS treatment. The results presented herein indicated that TS significantly changed the bacterial and archaeal community composition of the digestion system, and thus with the increase in TS from 6% to 25%, the methane yield increased. [ABSTRACT FROM AUTHOR]

The use of traditional Chinese medicine (TCM) residue as a crop culture substrate has unique advantages in alleviating the obstacles associated with continuous monocropping, such as increasing production, improving quality and alleviating pests and diseases. However, the effect of TCM residue application on substrates in continuous monocropping practices has not been determined. In this study, the cucumber variety "Jinyou No. 10" was used as the material, and fermented TCM residue, vermiculite and perlite were used as organic substrates (3:1:1). The cucumbers were cultivated on substrates for different durations of continuous monocropping, which were the first cropping cycle (A1), second cropping cycle (A2), third cropping cycle (A3) and fourth cropping cycle (A4). The control (A0) was the substrate sample without any crop planted in it. After the cucumbers were harvested, substrate samples (areas around the cucumber roots) were collected. The physiochemical properties of the cultivated substrates were determined, and the microbial community structures were analyzed through 16S rRNA and ITS sequencing. The physiochemical indices of the substrates with different durations of continuous monocropping (A1–A4) were significantly different than those of the control (A0) substrate. Moreover, the continuous cropping of cucumber had greater effects on fungal communities than on bacterial communities. Bacterial community structure analysis revealed a greater proportion of important bacterial taxa (Proteobacteria, Chloroflexi, and Nitrospirae) in the continuous monocropping substrates than in the A0 substrate. For the fungal community, Ascomycota accounted for the largest percentage of the fungal community in all the samples. The diversity of the microbial community was found to be influenced primarily by electrical conductivity, organic matter content, pH and total potassium content according to the correlation analysis of physicochemical properties and relative abundance of the microbial community. Our study would provide a basis for addressing persistent challenges in continuous cropping and for obtaining the utmost benefit from using TCM organic residue waste. [ABSTRACT FROM AUTHOR]

Continuous cropping is the main form of cultivation in Chinese agriculture. The bacterial community plays an important role in maintaining the healthy growth of plants. However, there are few reports on the composition and dynamics of the bacterial community structure under continuous cropping of Lonicera japonica Thunb. High-throughput sequencing was used to monitor the variation in the soil bacterial community structure of different monocropping years of Lonicera japonica Thunb., as well as the correlation between soil characteristics and bacterial community. Meanwhile, antagonistic bacteria for Fusarium oxysporum pathogens were isolated and functionally verified by culture-dependent techniques and pot experiments. Bacterial community diversity and structure changed significantly with the increase in the years of Lonicera japonica Thunb. succession. However, some beneficial bacteria, such as Bacillus and Nitrosospira, were gradually depleted. The complexity of the bacteria co-occurrence networks decreased with increasing years of cropping. FAPROTAX-based functional prediction showed that the abundance of genes related to carbon, nitrogen, sulfur metabolism and chitinlysis were reduced with the extended crop succession. Furthermore, the three Bacillus strains that were strongly antagonistic toward Fusarium oxysporum and the pot experiment demonstrated they significantly promoted Lonicera japonica Thunb. growth. Our research provides theoretical support for the development of microbial fertilizers that are beneficial to plants. [ABSTRACT FROM AUTHOR]

The continuous cropping can restrict the large scale and intensive cultivation of muskmelon, and the use of Trichoderma preparation to alleviate the negative effects is an effective mean. Although the impact on rhizosphere soil microbial communities and metabolites after applying Trichoderma are still unclear. In this study, we applied the fermentation broth of Trichoderma viride T23 to muskmelon under continuous cropping, collected rhizosphere soil samples at 60 days after transplantation, and investigated the changes in the microbial communities and metabolites of muskmelon by using high−throughput sequencing and metabolomic analysis, respectively. The results showed that T. viride T23 could effectively reduce the disease index of muskmelon wilt (65.86 to 18) and significantly increase the soil pH value (6.06 to 6.40). Trichoderma viride T23 induced drastic shifts in the richness, structure, and composition of rhizosphere microbial communities, and Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant bacterial phyla. Bioactive substances such as scopoletin, erythronic acid, and palmitic acid were significantly upregulated in the rhizosphere soil, which enhanced soil activity. Overall, T. viride T23 resolves the continuous cropping limitation in muskmelon by improving soil physicochemical properties, elevating the biomass and diversity of soil microbial communities, and stimulating the production of soil active substances. [ABSTRACT FROM AUTHOR]

Arid and semi-arid ecosystems are categorized as having degraded soils due to the limited availability of water and nutrients. The perennial shrubs in these regions have developed different ecological and physiological adaptations to cope with harsh conditions. The plant species vary in the chemical profile of their root exudates, which can induce variability in the microbial community in the rhizosphere. The present research has been conducted (i) to investigate the variation in composition, diversity, and structure of rhizosphere's bacterial community of desert plants; (ii) to identify plant-specific effects on the rhizosphere microbial community structure; and (iii) to determine the influence of soil moisture on the rhizosphere's microbial community and soil biological properties under stressful conditions. Ten desert plant species from the Cholistan desert were selected as test specimens. Bacterial communities from the rhizosphere of 10 plants of each species were explored. Soil samples were collected during monsoon (June–August) and dry months (March–May). Microbial community structure analyses were carried out through 16S rRNA sequencing by targeting V3 and V4 regions. Among tested plant species, the rhizosphere of Leptadenia pyrotechnica (S6 vs. S16), Aerva javanica (Burm. f.) Juss. ex Schult (S9 vs. S19), and Vachellia jacquemontii (Benth.) (S10 vs. S20) had greater microbial diversity in both seasons. Higher levels of microbial communities were found during monsoon season. Furthermore, Gammaproteobacteria were abundant in the rhizospheres of all studied plants during the monsoon season. In contrast, the rhizosphere was abundant with unidentified_Actinobacteria during the dry season. The rhizospheric soil was further analyzed for biological properties. The maximum microbial biomass carbon (165 mg kg–1) and microbial biomass nitrogen (6.7 mg kg–1) were found in the rhizosphere of Vachellia jacquemontii (Benth.) Benth during monsoon season. However, a minimum of microbial biomass carbon (119 mg kg–1) and microbial biomass nitrogen (4.2 mg kg–1) were found in the rhizosphere of Cleome pallida Kotschy during dry seasons. The diversified microbial community structure and biological properties enable desert plants to cope with adverse climate conditions. [ABSTRACT FROM AUTHOR]

Rising freshwater scarcities pose a serious threat to agricultural production. Reclaimed water (RW) is increasingly utilized as one of the alternative resources for irrigation in agriculture. Microbial communities play crucial roles in the soil microenvironment and can be used as effective indicators to assess the ecological influence of RW irrigation in soil. However, there is a lack of research on the effects of RW with different irrigation techniques on soil attributes and microbial communities. The present experiment was conducted in China to investigate the effect of two kinds of water qualities (RW and clean water (CW)), two kinds of irrigation methods (full irrigation (FI) and alternate partial root-zone irrigation (APRI)), and two kinds of irrigation techniques (furrow irrigation (FUI) and subsurface drip irrigation (SDI)) on soil chemical properties, heavy metal concentrations, and bacterial community structure. The APRI treatments received 70% of the irrigation water volume of FI. The results revealed that electrical conductivity (EC), nitrate nitrogen (NO3−-N), and heavy metal (Cu, Cd, Pb, Zn) concentrations in soil irrigated with RW were significantly higher in comparison to the soil irrigated with CW. SDI significantly decreased the contents of TN by 4.88%, the EC by 13.78%, and the heavy metal Cd concentration by 13.14% in soils than that irrigated with FUI treatment. APRI significantly decreased the heavy metal Cu concentration in soils by 6.26% compared to FI treatment. Proteobacteria, Chloroflexi, Acidobacteria, and Gemmatimonadetes in soil irrigated with RW were more abundant than that irrigated with CW. The irrigation water quality, soil moisture content, heavy metal content, TN, and EC under various irrigation techniques and methods significantly affected the structure of soil bacterial communities. In conclusion, we highlight that the SDI-APRI treatment can be an efficient irrigation practice for reducing the EC, heavy metal pollution, and the security risks of soil irrigated by RW. [ABSTRACT FROM AUTHOR]

Soil microbial communities are an important part of the soil ecosystem in greenhouse vegetable fields, where ammonia-oxidising microorganisms play a key role in nitrogen conversion. The health and stability of the ecological environment of greenhouse vegetable fields are affected by the number of years of continuous cultivation. We used real-time PCR amplification and 16S rRNA gene sequencing to analyse the changes in soil microbial community structure and diversity in different planting years (0, 3, 9, and 13). The content of environmental factors increased with the increase of planting year; the NO3−-N content in the 0–20 cm soil layer showed a cumulative trend, peaking to 1290–1390 mg/kg in year 13. The abundance of operational taxonomic units (OTUs) in the microbial community gradually decreased, and the OTUs of 0–20 cm soil layer in year 13 decreased by 52.2% compared to year 0. The Shannon and Simpson indices indicated a substantial decrease in microbial diversity after year 9. The dominant phyla in the soil microbial community mainly included Firmicutes (23.6%), Actinobacteria (23.2%), Proteobacteria (17.6%), Crenarchaeota (83.4%), and Euryarchaeota (2.7%). Nitrosopumilus and Nitrososphaera in the ammonia-oxidising archaeal (AOA) community and Nitrolancea and Nitrospira in the ammonia-oxidising bacterial (AOB) community dominated the ammonia-oxidising microorganisms. With the increase in planting years in greenhouse vegetable fields, the structure of soil microbial community changed significantly, with soil biomass and diversity significantly decreasing in years 9 and 13. Reasonable fertilization and planting year would improve microbial activity and provide a basis for sustainable utilization and high-quality production in greenhouse vegetable fields. [ABSTRACT FROM AUTHOR]

Intercropping systems can flexibly use resources such as sunlight, heat, water, and nutrients in time and space, improve crop yield and land utilization rates, effectively reduce continuous cropping obstacles and the occurrence of diseases and insect pests, and control the growth of weeds. Thus, intercropping is a safe and efficient ecological planting mode. The legume–cereal intercropping system is the most common planting combination. Legume crops fix nitrogen from the atmosphere through their symbiotic nitrogen fixation abilities, and the fixed nitrogen can be transferred to and utilized by cereal crops in various ways. The symbiotic nitrogen fixation efficiency of legume crops was improved by reducing the inhibition of soil nitrogen on nitrogenase activity through competitive absorption of soil nitrogen. However, the effects of nitrogen transformation and distribution in intercropping systems and microbial community structure characteristics on nitrogen transfer need to be further explored. In this review, (ⅰ) we present the transformation and distribution of nitrogen in the legume–cereal intercropping system; (ⅱ) we describe the soil microbial community characteristics in intercropping systems; and (ⅲ) we discuss the advantages of using modern biological molecular techniques to study soil microorganisms. We conclude that intercropping can increase the diversity of soil microorganisms, and the interaction between different plants has an important impact on the diversity and composition of the bacterial and fungal communities. The extensive application of modern biological molecular techniques in soil microbial research and the great contribution of intercropping systems to sustainable agriculture are particularly emphasized in this review. [ABSTRACT FROM AUTHOR]

Biochar is a valuable soil amendment substance. However, no systematic study has investigated the effects of biochar on the microenvironment of saline-sodic soils and maize yield in cold areas of Heilongjiang Province. We investigated variations in soil physicochemical properties, soil bacterial and fungal community structure, maize root formation, plant dry matter accumulation, grain filling rate, and maize yield in saline soils treated with biochar (0, 20, 40, and 80 t/ha). Biochar improved saline soil properties and structure, slightly decreasing bulk density and pH and increasing the water-stable aggregate stabilization rate. Furthermore, the relative abundances of Sphingomonas, Lysobacter, Nitrospira, and Gemmatimonas and the fungal genus Guehomyces were increased, promoting the conversion of soil organic carbon and available nitrogen and phosphorus. Moreover, biochar reduced the relative abundance of some fungal pathogenic genera, including Fusarium, Gibberella, Cladosporium, Alternaria, and Epicoccum. However, shifts in soil bacterial and fungal community structure were indirectly driven by biochar-induced changes in soil physicochemical properties, with organic carbon as the most critical. Biochar promoted maize growth, development, and yield (root length, surface area, volume, dry matter accumulation, grain filling rate, and final weight). Biochar application at 40 t/ha had the greatest effect on soil microenvironment improvement, with the highest maize yield.

Although elevated CO2 (eCO2) in the atmosphere is one of the main factors influencing climate and ecosystem stability, less research on eCO2 in greenhouse soil systems has been conducted, despite their prevalence. In this article, phospholipid fatty acid (PLFA) profiling, 16S rRNA and Internally Transcribed Spacer (ITS) gene sequencing and high-throughput quantity polymerase chain reactions (HT-qPCRs) for 72 biogeochemical cycling-related genes were used to reveal the comprehensive responses of microbes to 23 days eCO2 fumigation in the soil of a tomato greenhouse. Our results indicated that eCO2 significantly increased microbial biomass (p < 0.05). The fungal community was more susceptible to eCO2 than the bacterial community; the fungal alpha diversity indices decreased significantly under eCO2 (p < 0.05) and the abundance of Ascomycota and its lower level taxa also increased significantly (p < 0.01). The absolute abundance of numerous C, N, P, S and methane cycling related genes increased significantly (p < 0.05) under eCO2. Furthermore, the microbial community structure and function were correlated with certain measured plant characteristics. Hence, the microbial ecosystem of the tomato greenhouse soil system was stimulated under eCO2. These results contribute to a greater understanding of how eCO2 in the atmosphere affects terrestrial ecosystem stability.

Examining the soil microbiome structure has great significance in terms of exploring the mechanism behind plant growth changes due to maize (Zea mays L.) and soybean (Glycine max Merr.) crop rotation. This study explored the effects of soil microbial community structure after soybean and maize crop rotation by designing nine treatments combining three crop rotations (continuous cropping maize or soybean; and maize after soybean) with three fertility treatments (organic compound fertilizer, chemical fertilizer, or without fertilizer). Soil was sampled to 30 cm depth the second year at approximately the middle of the growing season, and was analyzed for physical, chemical, and phospholipid fatty acid (PLFA) profiles. Bacteria was found to be the predominant component of soil microorganisms, which mainly contained the PLFAs 16:0. Crop rotation with organic compound fertilizer application reduced the percentage of fungi in the soil by 24% compared to continuous maize and soybean with the same fertilizer application. The combination of crop rotation with organic fertilizer can reduce the percentage of fungi/bacteria to the greatest degree. In addition, the content of soil aggregate and organic matter had great influence on Gram-positive bacteria and actinomyces. In conclusion, soybean and maize crop rotation improve the soil nutrient content primarily by influencing the composition of bacterial community, especially the Gram-positive bacteria.

Although elevated CO2 (eCO2) in the atmosphere is one of the main factors influencing climate and ecosystem stability, less research on eCO2 in greenhouse soil systems has been conducted, despite their prevalence. In this article, phospholipid fatty acid (PLFA) profiling, 16S rRNA and Internally Transcribed Spacer (ITS) gene sequencing and high-throughput quantity polymerase chain reactions (HT-qPCRs) for 72 biogeochemical cycling-related genes were used to reveal the comprehensive responses of microbes to 23 days eCO2 fumigation in the soil of a tomato greenhouse. Our results indicated that eCO2 significantly increased microbial biomass (p < 0.05). The fungal community was more susceptible to eCO2 than the bacterial community; the fungal alpha diversity indices decreased significantly under eCO2 (p < 0.05) and the abundance of Ascomycota and its lower level taxa also increased significantly (p < 0.01). The absolute abundance of numerous C, N, P, S and methane cycling related genes increased significantly (p < 0.05) under eCO2. Furthermore, the microbial community structure and function were correlated with certain measured plant characteristics. Hence, the microbial ecosystem of the tomato greenhouse soil system was stimulated under eCO2. These results contribute to a greater understanding of how eCO2 in the atmosphere affects terrestrial ecosystem stability. [ABSTRACT FROM AUTHOR]

Fertilization is a worldwide agricultural practice used in agronomy to increase crop yields. Fertilizer application influences overall soil characteristics, including soil microbial community composition and metabolic processes mediated by microbial enzymatic activity. Changes in the structure of microbial communities and their metabolic activity after long-term fertilization were studied in this research. We hypothesized that the different types of fertilization regimes affect nutrient levels in the soil which subsequently influence the metabolic processes and microbial diversity and community structure. Manure (MF; 330 kg N/ha), sewage sludge at two application doses (SF; 330 kg N/ha and SF3x; 990 kg N/ha) and chemical (NPK; N-P-K nutrients in concentrations of 330-90-300 kg/ha) fertilizers have been applied regularly to an experimental field since 1996. The microbial diversity increased in all soils amended with both organic (MF, SF, SF3x) and chemical (NPK) fertilizers. The shifts in microbial communities were observed, which were mainly caused by less abundant genera that were mostly associated with one or more fertilization treatment(s). Fertilization also influenced soil chemistry and the activity of β-xylosidase, β-N-acetylglucosaminidase (NAG), acid phosphatase and FDA-hydrolases. Specifically, all fertilization treatments were associated with a higher activity of β xylosidase and lower NAG activity. Only the NPK treatment was associated with a higher activity of acid phosphatase. [ABSTRACT FROM AUTHOR]

Examining the soil microbiome structure has great significance in terms of exploring the mechanism behind plant growth changes due to maize (Zea mays L.) and soybean (Glycine max Merr.) crop rotation. This study explored the effects of soil microbial community structure after soybean and maize crop rotation by designing nine treatments combining three crop rotations (continuous cropping maize or soybean; and maize after soybean) with three fertility treatments (organic compound fertilizer, chemical fertilizer, or without fertilizer). Soil was sampled to 30 cm depth the second year at approximately the middle of the growing season, and was analyzed for physical, chemical, and phospholipid fatty acid (PLFA) profiles. Bacteria was found to be the predominant component of soil microorganisms, which mainly contained the PLFAs 16:0. Crop rotation with organic compound fertilizer application reduced the percentage of fungi in the soil by 24% compared to continuous maize and soybean with the same fertilizer application. The combination of crop rotation with organic fertilizer can reduce the percentage of fungi/bacteria to the greatest degree. In addition, the content of soil aggregate and organic matter had great influence on Gram-positive bacteria and actinomyces. In conclusion, soybean and maize crop rotation improve the soil nutrient content primarily by influencing the composition of bacterial community, especially the Gram-positive bacteria. [ABSTRACT FROM AUTHOR]