Soil Enzyme Activities Research Articles

The roles of nanoparticle-enriched biochars in improving soil enzyme activities and nutrient uptake by basil plants under arsenic toxicity

Enriched biochar with improved properties and functionality can play a significant role in providing sustainable solutions for mitigating heavy metal contamination in soil. In this experiment, the effects of solid and enriched biochars (potassium-enriched biochar (BC-K), magnesium-enriched biochar (BC-Mg), both individually and combined) were examined on soil microbial and enzyme activities, as well as nutrient uptake by basil plants cultivated in a soil with three levels of arsenic (nontoxic, 50 mg As kg−1 soil, and 100 mg As kg−1 soil). Biochar-related treatments, increased soil organic matter (65–76%), while decreased availability of arsenic (6–55%) in the soil. The microbial biomass carbon (by about 123%) and soil basal respiration (by about 256%), and soil enzymatic activities (β-glucosidase, urease, alkaline phosphatase, and dehydrogenase) were enhanced by enriched biochars under arsenic toxicity. The solid and particularly enriched biochars decreased arsenic content and improved nitrogen and phosphorus contents of roots and shoots, root length, root activity, and root and shoot biomass in basil plants. Therefore, it is conceivable to suggest that enriched biochars are superior treatments for improving nutrient absorption rates and basil growth under arsenic toxicity through decreasing arsenic mobility and increasing soil microbial activities.

Response of soil nitrogen mineralization, nitrification and denitrification to milk vetch (Astragalus sinicus L.) application in a paddy field

We conducted incubation experiments with a paddy soil collected from a long-term field experiment to explore the effect of Chinese milk vetch (Astragalus sinicus L., CMV) application on potential nitrogen (N) denitrification (PDA), nitrification (PNA), mineralization (PNM), soil chemical properties, microbial communities, enzyme activities, yields and nutrient uptake of rice under different fertilization treatments. Five treatments were included: no chemical fertilizers (C0), chemical fertilizers (C100), Chinese milk vetch (M), CMV combined with 100% chemical fertilizers (MC100) and with 80% chemical fertilizers (MC80). Results showed that the M, MC100, and MC80 treatments significantly increased PNM and PNA compared with the C100 treatment (P < 0.05). Meanwhile, the CMV application significantly increased total N, microbial biomass N, and carbon (C) concentrations, the abundances of the bacterial phylum Actinobacteria, and the genera Bradyrhizobium, Mycobacterium, Streptomyces and Reyranella, N-acetyl-glucosaminidase (NAG) activity, yields and N nutrient uptake of rice grain compared with the C100 treatment (P < 0.05). Correlation analyses indicated that grain yield and N uptake of rice, soil total N, microbial biomass C and N, the bacterial phylum Actinobacteria, the genera Bradyrhizobium, Mycobacterium, Streptomyces, Reyranella, and NAG were significantly correlated with PNM under different fertilization regimes, while microbial biomass C and N, Actinobacteria, Bradyrhizobium, and Reyranella were positively related to PNA (P < 0.05). Together, the application of CMV alone or in combination with chemical fertilizers can improve soil properties and rice growth, which may accelerate N mineralization and nitrification in this soil.

Antibacterial Activity of Ocimum Basilicum L. and Thymus Vulgaris L. Extracts against Escherichia coli as a future method for decontamination and deodorization of compost-like mixtures

Ocimum basilicum L. and Thymus vulgaris L. are natural plant sources of antimicrobial activity, which is essential to determine their qualities as biological agents against pathogenic microorganisms. The aim of the study is the analysis of the antibacterial activity of plant extracts of basil and thyme against Escherichia coli for their subsequent application in agricultural practice as additives for decontamination and deodorization of compost-like mixtures. Plant extracts from roots, stems, leaves and whole plants of basil and thyme were obtained by various methods: decoction, tincture, medicinal vinegar, medicinal wine and medicinal oil. Agar diffusion method was used to determine the antimicrobial activity of the extracts against Escherichia coli. The analyzed essential oil cultures increase the microbiological and enzymatic activity of soils. Basil extracts showed stronger antimicrobial activity against Escherichia coli than thyme extracts, differing for individual plant parts - roots variants showed higher antimicrobial activity compared to variants with leaves, stems and whole plant. In general, a lower antimicrobial activity of the plant extracts was found in the medicated wine and tincture variants (except for roots tincture), compared to the decoction, medicated vinegar and medicated oil variants. The antibacterial activity of the stem extracts depended significantly, and that of the root, leaf and whole plant extracts moderately, on the biogenicity of the soils. The analyzed essential oil cultures can be applied for decontamination (against Escherichia coli) and deodorization of compost-like mixtures. The use of basil and thyme extracts decontaminated composts from E. coli content in a repeated 4-month application.

Soil Enzyme Activities and Microbial Nutrient Limitation of Various Temperate Forest Types in Northeastern China

Soil Enzyme Activities and Microbial Nutrient Limitation of Various Temperate Forest Types in Northeastern China

Assessment of the impact of smoke from thermal destruction of materials of different origins on soil health.

The results of the study of the influence of smoke from the thermal destruction of materials of vegetable and synthetic origin on the enzymatic activity of ordinary chernozem are presented. The decrease of activity of investigated indicators (catalase, peroxidase, polyphenol oxidase, invertase) from thermal destruction of pine sawdust, straw, coniferous and leaf fall, peat, and materials based on polystyrene, rubber, and polyvinyl chloride was revealed. A significant decrease in the activity of soil enzymes after exposure to gaseous products of combustion during 15-60min of soil fumigation was found. Oxidoreductases turned out to be the most sensitive to smoke. Smoke from peat burning has minimal inhibitory effect, activity of catalase after 30min of fumigation decreased only by 15%, and peroxidase and polyphenol oxidase - by 8 and 12%. While the activity of the same enzymes when exposed to smoke from thermal degradation of rubber-based materials decreased by 16-42%, and polyvinyl chloride - by 29-73%, to a lesser extent from polystyrene (decrease by 7-29%). All obtained data on changes in the enzymatic activity of soils are reliable with the level of statistical significance p < 0.05.

How biochar curbs the negative impacts of plastic mulching on soil enzymes and microorganisms while elevating crop yields in ridge-furrow systems

Ridge-furrow tillage is an important tillage and yield enhancement method used in dry farming areas; however, the spatial characteristics of the soil microenvironment under ridge-furrow tillage and the response of crop yields to mulching and biochar addition are not known. In this study, we conducted a three-year field experiment in which mulch and biochar, alone or combined, were introduced into ridge-furrow tillage system to explore their interactive effects on soil enzyme activities, bacterial communities, functional genes, and crop yields. The findings reveal significant spatial differences in soil physicochemical composition, enzyme activity, microbial communities, and functional genes under ridge-furrow tillage, which are further exacerbated by the addition of mulching and biochar. Under the premise of ridge-furrow tillage, both mulching and biochar addition reduce the α diversity of bacterial communities. Mulching simplifies the bacterial network, while biochar addition has the opposite effect. Mulching and biochar addition increase the relative abundance of carbon, nitrogen, and phosphorus functional genes and accelerate nutrient cycling, especially on the ridges. Mulching significantly improves crop yield but is detrimental to alkaline phosphatase activity and the abundance of the gene function. The addition of biochar mitigates the harm of mulching and further increases alfalfa yield. These findings not only provide scientific support for optimizing ridge-furrow tillage but also deepen our comprehensive understanding of the soil biochemical environment after the addition of mulching and biochar, further revealing their positive effects on yield formation.

Long term impact of manuring, fertilization and liming on soil resilience, enzyme activities and productivity under maize-wheat system in an acidic Alfisol

Aim: This study was carried out to evaluate the long-term impact of manuring, fertilization and liming on soil resilience, enzyme activities and system productivity under changing climate scenarios. Methodology: The soil samples were collected from 67 year old long-term experiment going on, at Birsa Agricultural University, Jharkhand during 2022-23 under maize-wheat cropping system from seven treatments, viz. T1: control, T2: 100 % N, T3: 100 % FYM, T4: ½ (N+FYM) + PX/2 + KY/2, T5: 100 % NPK, T6: Lime + NPK, T7: Lime + FYM +P(A-X) + K(B-Y). To assess soil resistance and resilience, surface samples were subjected to with and without heat stress (48±2°C for 80 hrs) and substrate addition (0.02 g glucose g-1 soil). Results: Application of FYM/lime with NPK significantly improved bulk density, pH, SOC and system productivity. The highest enzyme activities and cumulative respiration were observed in lime + FYM + P(A-X) + K(B-Y) treatment. It exhibited the highest resistance index (0.92) and resilience index (0.34). Interpretation: The integrated use of inorganic, organic along with liming proved to be a useful management strategy for maintaining soil quality, resistance and resilience, and crop productivity in acid soil of Jharkhand. Key words: Enzyme, Heat stress, Maize-wheat system, Soil acidification, Substrate induced respiration, Wheat-maize

Remediation of PBDE-contaminated soil using biochar-based bacterial consortium QY2Y

Biochar-immobilized microbial technologies hold substantial promise for the remediation of environmental contaminants. However, the understanding of remediation efficiency and the operation of microbial consortia in complex soil environments using biochar as a carrier remains limited. In this study, we explored the impacts of biochar combined with bacterial consortium QY2Y (consisting of Chitinophaga sp. MH-1, Achromobacter sp. YH-1, Methylobacterium sp. ZY-1, and Sphingomonas sp. GY-1) on BDE-47 dissipation in contaminated soil, as well as its effects on soil-plant systems. The findings indicated that the immobilization of biochar and QY2Y not only stimulated the biodegradation of BDE-47 (61.50%) but also decreased the bioavailability of BDE-47, subsequently reducing the concentration of BDE-47 in the edible portion of rapeseed (Brassica napus L.) by 82.00%. In addition, the combined treatment notably increased soil pH, enhanced the physicochemical properties and nutrient conditions of the soil, and amplified soil dehydrogenase, catalase, urease, and acid phosphatase activities by 58.72%, 69.25%, 54.24%, and 74.74%, respectively. The application of biochar-based QY2Y improved the soil microbial community structure, bolstered the interspecific symbiotic and cooperative relationships, and restructured the keystone taxa. The key species microbes had direct and significant positive effects on BDE-47 degradation, soil nutrients, and soil enzyme activity. This study deepens our understanding of the potential applications of immobilized microbial consortia in treating PBDE-contaminated soils and offers guidance for the management and remediation of contaminated soils.

Biochemical Parameters of Fallow Light Soil Enriched with Sewage Sludge

One way to manage sewage sludge, which is consistent with the assumptions of the European Green Deal, is to use it in agriculture. The study focused on the possibility of using soil enzyme activity and the GMea index (the geometric mean of enzyme activities) in connection with the total organic carbon (TOC) and the total nitrogen (TN) content to assess the quality of fallow light soil after exogenous organic matter (EOM) fertilization. Exogenous organic matter in the form of stabilized municipal sewage sludge was introduced into the soil. The experiment included five variants: one control site and four sites with 30, 75, 150, and 300 Mg ha−1 of sewage sludge added to the soil. The contents of TOC, TN and heavy metals (Zn, Cu, Pb, Cd) in the soil material were assayed. In addition, the activity of soil enzymes, i.e., neutral phosphatase, urease, protease and dehydrogenase, was examined, and the geometric mean of the enzyme activities (GMea index) was calculated. Fertilization of light soil with sewage sludge resulted in an increase in TOC and TN proportionally to the EOM dose. The addition of sewage sludge increased the content of tested heavy metals in the soil and did not exceed the levels considered acceptable. The introduction of sewage sludge contributed to the stimulation of biological life in the soil. This was evidenced by an intensification of soil enzyme activity. However, individual enzymes showed a different response to EOM fertilization, while GMea showed a significant increase in the quality of the fallowed soils as the EOM rate increased to 150 Mg ha−1.

Effects of different ratios of nitrogen base fertilizer to topdressing on soil nitrogen form and enzyme activity in sugar beet under shallow drip irrigation

Sugar beets account for 30% of global sugar production each year, and their byproducts are an important source of bioethanol and animal feed. Sugar beet is an important cash crop in Inner Mongolia, China. To achieve high yields and sugar content, it is essential to supply nitrogen fertilizer in accordance with the growth characteristics of sugar beet, thereby enhancing the efficiency of nitrogen fertilizer utilization. A two-year experiment was carried out in the experimental field of the Inner Mongolia Academy of Agricultural &amp; Animal Husbandry Sciences. The impact of varying ratios of nitrogen-based fertilizer to topdressing on nitrate nitrogen and ammonium nitrogen levels in the 20–60 cm soil layer, as well as the activities of protease, urease, catalase, and sucrose in the 20–40 cm soil layer were investigated during the rapid leaf growth period and root and sugar growth period. Results indicated that different ratios of nitrogen-based fertilizer to topdressing significantly influenced the levels of nitrate nitrogen and ammonium nitrogen, and the activities of protease and urease in the 0–20 cm soil layer, with these effects diminishing as soil depth increased. The activities of catalase and sucrose were minimally impacted. Nitrogen was applied at 150 kg/ha during the growth period of sugar beet, according to the growth characteristics of sugar beet to maximize nitrogen utilization efficiency. Topdressing was completed with irrigation at the rapid growth stage. The nitrogen-based fertilizer to topdressing ratio of 6:4 resulted in optimal crop yield and sugar yield of sugar beet under shallow drip irrigation. Additionally, the activities of protease and urease in different soil treatments were significantly different, and the activities of protease and urease in the 0–40 cm soil layer were identified as useful soil physiological indicators for nitrogen utilization in sugar beet.

Faba bean-wheat intercropping controls the occurrence of faba bean Fusarium wilt by improving the microecological environment of rhizosphere soil

BackgroundFusarium wilt is a severe soil-borne disease that affects faba bean production. Faba bean-wheat intercropping is often used to control the occurrence of Fusarium wilt in faba bean. AimsTo evaluate the effects of faba bean-wheat intercropping on the occurrence of faba bean Fusarium wilt and soil microecology. MethodsWe established two planting patterns, faba bean monocropping (M) and faba bean-wheat intercropping (I), to investigate Fusarium wilt occurrence and plant dry weight and assess changes in soil enzyme activities, microbial diversity, and community composition during different stages of disease onset. ResultsIntercropping effectively controlled faba bean Fusarium wilt at the three disease stages and increased the dry weight of faba bean plants. Intercropping promoted the activities of catalase (CAT), urease, sucrase, and acid phosphatase in the rhizosphere soil of faba bean at three disease stages. Bacterial and fungal diversity decreased with disease progression, and intercropping mitigated this trend. Compared with monocropping, intercropping increased the abundance of beneficial bacteria such as Proteobacteria, Actinobacteriota, Gemmatimonadota, Gemmatimonas, Conexibacter, and Sphingomonas, while reducing the abundance of pathogenic fungi such as Alternaria, Cladosporium, and Fusarium. Intercropping also increased the abundance of arbuscular mycorrhiza, soil saprophytes, and undefined saprophytes while decreasing the abundance of plant pathogens. ConclusionFaba bean-wheat intercropping enhanced soil enzyme activities, effective nutrient content, and alpha diversity indices of bacteria and fungi in the rhizosphere soil of faba bean, while promoting the abundance of beneficial bacteria, arbuscular mycorrhizal fungi, as well as both soil and undefined humus. Simultaneously, intercropping reduced the abundance of plant pathogens, facilitated nutrient cycling in the soil, provided sufficient nutrients for crop uptake, and mitigated the toxic effects of hydrogen peroxide on cells. Ultimately, this resulted in a reduced occurrence of Fusarium wilt.

Comparative Remediation of Arsenic and Antimony Co-Contaminated Soil by Iron- and Manganese-Modified Activated Carbon and Biochar.

At present, soil contaminated with arsenic (As) and antimony (Sb) is escalating at an alarming rate, which is harmful to human health. In this study, Fe- and Mn-modified activated carbon (AC) and biochar (BC) were prepared and compared for the remediation of As- and Sb-contaminated soil. The effects on the speciation of As and Sb, soil pH, organic matter (SOM), and enzyme activity with various dosages and remediation times were investigated. The results showed that on the whole, the best stabilization effect of As and Sb was achieved with 3% FeMnBC. Furthermore, with increases in time and dosage, the immobilization effect on As and Sb was more significant. Fe/Mn-modified AC and BC enhanced soil pH, with 3% MnAC being particularly effective; 3% AC and 3% FeMnAC demonstrated the most pronounced enhancement in SOM. The modified carbon materials exhibited a dramatic increase in enzymatic activity. In particular, urease activity showed an increasing trend, and catalase activity first decreased and then increased over 30 days. Among the treatments, 3% MnAC showed the most significant enhancements in catalase and urease activities, whereas 1% FeMnBC had the most pronounced effect on increasing sucrase activity. This study provides theoretical support for the remediation of soil co-contaminated with As and Sb by Fe/Mn-modified AC and BC.

Short‐Term Benefits of Tillage and Agronomic Biofortification for Soybean–Wheat Cropping in Central India

ABSTRACTIn a changing climate, conservation tillage and agronomic biofortification are essential for enhancing crop yield, nutritional security, carbon stocks, and soil quality. Consequently, a field study was conducted in central India to assess the short‐term (4 years) effects of crop establishment techniques (CETs) and agronomic biofortification methods (ABMs) on soil health indicators, grain yield, and quality in the soybean–wheat cropping system. The experiment followed a split‐plot design with two CETs in the main plots (permanent broad bed furrow, PBBF, and conventional tillage, CT) and eight ABMs, each with three replications. The results indicated that PBBF and ABMs (seed inoculation with the microbial strains MDSR 14 + MDSR 34, and soil and foliar application of Zn+Fe) improved soil carbon stock (by 49.6% and 52.4%), available nitrogen, phosphorus, potassium, available Zn (by 30.0%), and Fe (by 21.9%) after the fourth year of the study. Similarly, PBBF and microbial inoculation increased soil enzyme activities (dehydrogenase, acid phosphatase, and β‐glucosidase), substrate‐induced respiration, and microbial biomass carbon content. As a result, a higher soybean equivalent yield (5.59% higher in PBBF and 14.2% higher with foliar spray of Zn+Fe) and seed quality attributes (crude protein yield, grain Zn, and Fe) were observed in PBBF and the foliar spray of Zn and Fe treatments compared to CT and control, respectively. Overall, adopting the short‐term PBBF system, microbial inoculation, and soil and foliar application of Zn and Fe improved rhizosphere biochemical properties, yield, and seed quality in the soybean–wheat system.

Enhancement of repeated inoculation strategy with a domesticated bacterial consortium on the biodegradation of high-level crude oil in soil

Repeated inoculation of hydrocarbon degrading microbes should be powerful to improve the survival of inoculant, which is vital to achieve efficient remediation of petroleum contaminated soil. This paper aims to study the repeated inoculation (with different inoculum size and time interval) enhanced bioremediation of high-level petroleum contaminated soil with a domesticated bacterial consortium. The copy number of bacterium and alkB gene, soil enzyme activities and microbial community structure during the remediation were systematically analyzed to preliminarily reveal the mechanism of repeated inoculation affecting remediation for the first time. The results revealed that repeated inoculation remarkably improved the total petroleum hydrocarbon (TPH) removal in soil (86.5 % in HC120) compared with a single inoculation (68.9 % in HA120). The TPH removal of repeated inoculation with high inoculum size (HC) on the 60th day was close to that of once inoculation (HA) on the 120th day, suggesting that repeated inoculation led to faster degradation. Interestingly, the effect of inoculation with low dose and more times (LC120, 78.5 %) was equal to that with high dose and less times (HB120, 78.0 %), even much better than that with high dose and once inoculation (HA120). Treatment HC had a significant impact on the soil bacterial diversity and community structure, and the dominant species in the inoculants, such as Stenotrophomonas and Pseudomonas, which was low abundance in the blank group (CK), still maintained high abundance during the remediation process. The soil catalase activities and the number of alkB gene were the highest in HC. Correlation analysis implied that repeated inoculation of hydrocarbon degrading bacteria did improve the survival of inoculant, soil enzyme activities and maintain the number of degrading bacteria, thus promoting the TPH removal. These findings will facilitate the practical application of bioremediation technology to contaminated environment, which has important environmental and economic benefits.

Herbal materials used as soil amendments alleviate root rot of Panax ginseng

Root rot is a serious soil-borne fungal disease that seriously affects the yield and quality of Panxa ginseng. To develop a sustainable strategy for alleviating ginseng root rot, an herb-based soil amendment is suggested in this study. Mixed powers of medicinal herbs (MP) and corn stalks (CS) were used as soil amendments, respectively, along with a control group (CK) without treatment. The application of MP and CS led to significant relief from ginseng root rot. The disease index (%) represents both the incidence rate and symptom severity of the disease. The disease index of the MP and CS group was 18.52% and 25.93%, respectively, lower than that of CK (40.74%). Correspondingly, three soil enzyme activities improved; the antifungal components in the soil increased; and the relative abundances of root rot pathogens decreased in response to MP Soil enzyme activities were negatively correlated with disease grades. MP group also led to possible interactive changes in the communities of soil fungi and chemical components. In conclusion, our results suggest that the use of herb-based soil amendments has significant potential as an ecological and effective approach to controlling root rot disease of ginseng by the changing rhizosphere fungal community and soil compositions.

Mechanistic insight into interactive effect of microplastics and arsenic on growth of rice (Oryza sativa L.) and soil health indicators

Microplastics (MPs) pollution has recently become a major concern for agroecosystems. The interplay between MPs, and heavy metal(loid)s in the soil can intensify the risks to plant growth and human health. The current study investigated the interactive effects of arsenic (As) and biodegradable and petroleum-based conventional MPs on rice growth, As bioavailability, soil bacterial communities, and soil enzyme activities. As-contaminated soil (5 mg kg−1) was treated with conventional MPs i.e., polystyrene (PS) and polyethylene (PE) and biodegradable MPs i.e., polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) at 0.1 % and 1 % rates. In a pot experiment, rice plants were cultivated in soil co-contaminated with As and MPs. PLA-MPs exhibited significant interactions with As, increasing its bioavailability and impairing rice plant growth by enhancing plant oxidative stress. The results illustrated that T2 treatment (PLA-MPs @ 1 % + As 5 mg kg−1) significantly decreased the root and shoot lengths, root and shoot dry weights as well as the rates of photosynthesis, transpiration, intercellular CO2, and stomatal conductance in rice plants. Biodegradable PLA-MPs @ 1 % resulted in increased uptake of As in rice roots, stems, and leaves by 13.4 %, 38.9 %, and 20.6 %, respectively. In contrast, conventional PE-MPs @ 1 % showed contradictory results with As uptake declined by 2.2 %, 5.1 %, and 9.9 % in rice roots, stem and leaves. Soil enzyme kinetics showed that biodegradable MPs increased the activities of soil catalase, dehydrogenase, and phytase enzymes, whereas both conventional PS and PE-MPs decreased their activities. Moreover, As and PLA-MPs combined stress altered soil bacterial communities by increasing the relative abundance of Protobacteria, Acidobacteria, Chloroflexi, and Firmicutes phyla by 49 %, 29 %, 82 %, and 57 %, respectively. This study provides new insights into MPs-As interactions in soil-plant system and ecological risks associated with their coexistence.

Eucalyptus and Native Broadleaf Mixed Cultures Boost Soil Multifunctionality by Regulating Soil Fertility and Fungal Community Dynamics.

The growing recognition of mixed Eucalyptus and native broadleaf plantations as a means of offsetting the detrimental impacts of pure Eucalyptus plantations on soil fertility and the wider ecological environment is accompanied by a clear and undeniable positive impact on forest ecosystem functions. Nevertheless, the question of how mixed Eucalyptus and native broadleaf plantations enhance soil multifunctionality (SMF) and the mechanisms driving soil fungal communities remains unanswered. In this study, three types of mixed Eucalyptus and native broadleaf plantations were selected and compared with neighboring evergreen broadleaf forests and pure Eucalyptus plantations. SMF was quantified using 20 parameters related to soil nutrient cycling. Partial least squares path modeling (PLS-PM) was employed to identify the key drivers regulating SMF. The findings of this study indicate that mixed Eucalyptus and native broadleaf plantations significantly enhance SMF. Mixed Eucalyptus and native broadleaf plantations led to improvements in soil properties (7.60-52.22%), enzyme activities (10.13-275.51%), and fungal community diversity (1.54-29.5%) to varying degrees compared with pure Eucalyptus plantations. Additionally, the mixed plantations exhibit enhanced connectivity and complexity in fungal co-occurrence networks. The PLS-PM results reveal that soil properties, fungal diversity, and co-occurrence network complexity directly and positively drive changes in SMF. Furthermore, soil properties exert an indirect influence on SMF through their impact on fungal diversity, species composition, and network complexity. The findings of this study highlight the significant role of mixed Eucalyptus and native broadleaf plantations in enhancing SMF through improved soil properties, fungal diversity, and co-occurrence network complexity. This indicates that incorporating native broadleaf species into Eucalyptus plantations can effectively mitigate the negative impacts of monoculture plantations on soil health and ecosystem functionality. In conclusion, our study contributes to the understanding of how mixed plantations influence SMF, offering new insights into the optimization of forest management and ecological restoration strategies in artificial forest ecosystems.

Understanding the interaction between soil ORP and enzyme activity: How does wetland type affect constructed wetland performance for the advanced treatment of swine wastewater?

Constructed wetlands (CWs) are widely used for the advanced treatment of swine wastewater. Wetland type is the most critical parameter for engineering applications; therefore, the performance of horizontal/vertical subsurface flow CWs (HSFCWs and VSFCWs) was explored over one year of operation. The effects of five antibiotics (40 μg/L each), copper (Cu, 1.0 mg/L), and their combination on CW performance and soil oxidation–reduction potential (ORP) and enzyme activity were investigated. The annual removal efficiencies of HSFCWs and VSFCWs for total organic carbon (TOC), nitrogen, and phosphorus were 72.03 %–84.49 % and 87.15 %–90.72 %, for antibiotics were 91.35 %–99.52 % and 87.33 %–99.57 %, and for Cu were 97.37 %–97.44 % and 95.52 %–96.85 %, respectively. The CWs removed antibiotics through substrate adsorption, plant absorption, and biodegradation. Total antibiotic residues in HSFCW and VSFCW soils ranged from 6.29 to 17.31 and 24.57 to 589.07 μg/kg, respectively, and enrofloxacin and roxithromycin posed medium and high risks in VSFCW non-rhizosphere soil. The amount of residual antibiotics in Phragmites australis parts was in the order of fibrous roots > rhizomes > aboveground. ORP and enzyme activities were greater in rhizosphere soil than in non-rhizosphere soil and greater in the VSFCWs than in the HSFCWs. CW performance and soil enzyme activities decreased under the stress of antibiotics and coexistence of antibiotics and Cu. These findings advance our knowledge of CW design, elucidate the unique advantages of CWs, and offer efficient operation strategies for swine wastewater advanced treatment, helping researchers recognize the adverse effects of antibiotics on CWs.

Global perspective of ecological risk of plastic pollution on soil microbial communities.

The impacts of plastic pollution on soil ecosystems have emerged as a significant global environmental concern. The progress in understanding how plastic pollution affects soil microbial communities and ecological functions is essential for addressing this issue effectively. A bibliometric analysis was conducted on the literature from the Web of Science Core Collection database to offer valuable insights into the dynamics and trends in this field. To date, the effects of plastic residues on soil enzymatic activities, microbial biomass, respiration rate, community diversity and functions have been examined, whereas the effects of plastic pollution on soil microbes are still controversial. To include a comprehensive examination of the combined effects of plastic residue properties (Type, element composition, size and age), soil properties (soil texture, pH) at environmentally relevant concentrations with various exposure durations under field conditions in future studies is crucial for a holistic understanding of the impact of plastic pollution on soil ecosystems. Risk assessment of plastic pollution, particularly for nanoplasctics, from the perspective of soil food web and ecosystem multifunctioning is also needed. By addressing critical knowledge gaps, scholars can play a pivotal role in developing strategies to mitigate the ecological risks posed by plastic pollution on soil microorganisms.

Phosphogypsum with Rice Cultivation Driven Saline-Alkali Soil Remediation Alters the Microbial Community Structure.

The improvement of saline-alkali land plays a key role in ensuring food security and promoting agricultural development. Saline soils modifies the response of the soil microbial community, but research is still limited. The effects of applying phosphogypsum with rice cultivation (PRC) on soil physicochemical properties and bacterial community in soda saline-alkali paddy fields in Songnen Plain, China were studied. The results showed that the PRC significantly improved the physicochemical properties of soil, significantly reduced the salinity, increased the utilization efficiency of carbon, nitrogen, and phosphorus, and significantly increased the activities of urease and phosphatase. The activities of urease and phosphatase were significantly correlated with the contents of total organic carbon and total carbon. A redundancy analysis showed that pH, AP, ESP, HCO3-, and Na+ were dominant factors in determining the bacterial community structure. The results showed that PRC could improve soil quality and enhance the ecosystem functionality of soda saline-alkali paddy fields by increasing nutrient content, stimulating soil enzyme activity, and regulating bacterial community improvement. After many years of PRC, the soda-alkali soil paddy field still develops continuously and healthily, which will provide a new idea for sustainable land use management and agricultural development.