Soil Microbial Enzyme Activities Research Articles

Unveiling the Impact of Soil Prebiotics on Rhizospheric Microbial Functionality in Zea mays L.

Prebiotics, a subset of biostimulants, have garnered attention for their potential to enhance soil conditions and promote plant growth, offering a promising alternative to conventional agricultural inputs. This study explores how two commercial prebiotics, K1® and NUTRIGEO L® (SPK and SPN), impact soil functions compared to a control (SP). The experiment involved agricultural soil amended with organic wheat straws and cultivated with Zea mays L. Previous research demonstrated substantial effects of these prebiotics on plant biomass, soil parameters, and microbial community ten weeks after application. The present study delves deeper, focusing on soil microbial abundance, enzyme activities, and metabolic diversity. Analysis revealed that SPN notably increased the fungi-to-bacteria ratio, and both prebiotics elevated the activity of several key enzymes. SPN enhanced α-glucosidase and β-galactosidase activities, while SPK increased arylsulfatase, phosphatase, alkaline phosphatase, and urease activities. Enzymatic indexes confirmed the positive impact on soil functional diversity and fertility. Additionally, prebiotic treatments showed distinct metabolic profiles, with SPK degrading eleven carbon sources more rapidly across five groups and SPN accelerating the decomposition rate of four carbon sources from three groups. These findings highlight the ability of prebiotics to shape microbial communities and enhance soil fertility by modulating their functional activity and diversity.

Insight into interaction among soil microbial community, soil metabolomics and enzyme activity after long-term PAH stress

The problem of soil polycyclic aromatic hydrocarbon (PAH) pollution in coking plant sites has been widely studied in recent years, but there is a lack of research on the correlation between soil microorganisms, soil metabolomics, and soil properties. Thus, in this study, the long-term impact of coke combustion on soil microbial community structure, enzyme activities, and metabolic pathways within a former coking plant site was investigated. Soil samples were collected from both the coking production area (CA group) and office area (OLA group), approximately 0 to 20 cm in depth. Compared with OLA group, elevated levels of 16 PAHs in the list of USA EPA were detected by gas chromatography-mass spectrometry in the CA group. Several dominant microorganisms, such as Altererythrobacter, Lysobacter, and Sulfurifustis, were identified by 16 s ribosomal DNA sequencing in the CA group. The fatty acid biosynthesis pathway exhibited specific inhibition, while the phenylalanine metabolic pathway was promoted in response to PAH stress. Long-term PAH exposure led to the inhibition of soil urease activity. The co-occurrence network of microorganisms revealed intricate patterns of co-metabolism and co-adaptation within complex bacterial communities, facilitating their adaptation to and decomposition of soil-borne PAHs. This research could provide valuable insights into the community characteristics and metabolic mechanisms of microorganisms inhabiting PAH-polluted soil within coking plant sites. The findings enhance our understanding of the indigenous soil microbiome and its intricate network dynamics under the persistent stress of PAHs, contributing to a more comprehensive knowledge of soil ecosystems in such environments.

Dynamic interplay between soil microbial communities, enzyme activities, and pear quality across planting years

Few studies have been reported on the effect of planting years on fruit quality and soil of pear trees. In this study, four planting years (T5, T20, T30, and T40) of Cuiguan pears were used to analyze fruit quality, rhizosphere soil enzymes, and microbial diversity of pear trees, and their correlations. The results showed that the content of sucrose, reducing sugar and ascorbic acid in Cuiguan Pear showed a tendency of increasing and then decreasing with the increase of planting years, in which the highest content was found in 20- and 30-year-old fruits, and the highest content of total acid was found in 5-year-old fruits. Rhizosphere soil enzyme activities varied with planting year, with the highest protease activity in 20-year-old soil, phosphatase and urease in 30-year-old soil, polyphenol oxidase in 5-year-old soil, and sucrase in 40-year-old soil. The microbial diversity index and the number of OTUs showed an increasing and decreasing trend with the increase of planting years. Among the top 11 bacteria in pear rhizosphere soil average relative abundance, with Bradyrhizobium decreasing in relative abundance at the peak pear fruiting stages (T20 and T30), while Acidothermus showed an increasing trend in relative abundance with increasing planting years. RDA analysis showed that there were differences in the microbial community structure of pear trees at different planting years, and that both sucrose and reducing sugar contents in pears were positively correlated with T20 and T30, ascorbic acid content was positively correlated with T40, whereas the total acid content was positively correlated with T5, and that T20 was positively correlated with soil protease and phosphate mono esterase activities, and that T30 was positively correlated with polyphenol oxidase and urease activities, whereas T40 was positively correlated with sucrase activity. In summary, with the increase of planting years, changes in soil microbial community structure and soil enzyme activity have a significant impact on pear quality formation, and the results of the study provide a theoretical basis for scientific management of pear orchards.

Effects of different forest types on soil microbial biomass and enzyme activities in degraded red soil of subtropical region

Effects of different forest types on soil microbial biomass and enzyme activities in degraded red soil of subtropical region

The Impact of Combining Robinia pseudoacacia Leaves and Corn Straw on Soil Carbon Content and Corn Yield in Loess Plateau

In the agroforestry system, the organic matter in the farmland and natural ecosystem enters the farmland soil in a mixed form to improve soil fertility and carbon pool quality. However, it is unclear how soil microbial carbon-degrading enzyme activity responds to carbon dynamics in this process. Therefore, we took farmland in the Loess Plateau as the research object, combining the application of corn straw and Robinia pseudoacacia leaves in a mass ratio of 4:0, 3:1, 2:2, 1:3, and 0:4 for returning to the field. We measured corn grain yield, carbon emission, organic carbon pool component content, and carbon-degrading enzyme activity of the farmland. The results showed that combining corn straw and Robinia pseudoacacia leaves had a significant impact on soil organic carbon components (readily oxidizable organic carbon and recalcitrant organic carbon), carbon-degrading enzymes (polyphenol oxidase, peroxidase, and cellobiohydrolase), and cumulative carbon emissions. The trend of different indicators in different treatments during the corn growth period was similar. We found that soil carbon emissions were closely related to ROC and soil oxidase activity, while soil carbon content was closely related to soil hydrolase activity. Compared to not returning straw to the field, the corn straw and Robinia pseudoacacia leaves returned to the field in a mass ratio of 1:3(Y1C3) can increase corn grain yield by 32.04%. The Y1C3 treatment has the highest soil carbon content and the lowest crop carbon emission efficiency. Soil water content plays a crucial role in the process of carbon pool transformation driven by soil carbon-degrading enzymes. In conclusion, soil carbon dynamics are closely related to the activity of soil carbon-degrading enzymes. Combining the application of corn straw and Robinia pseudoacacia leaves may be a more suitable farming measure for fragile habitats in the Loess Plateau than other solutions.

Mycorrhizosphere bacteria inhibit greenhouse gas emissions from microplastics contaminated soil by regulating soil enzyme activities and microbial community structure

Microplastics (MPs) accumulation in terrestrial ecosystems can affect greenhouse gases (GHGs) production by altering microbial and soil structure. Presently, research on the MPs effect on plants is not consistent, and underlying molecular mechanisms associated with GHGs are yet unknown. For the first time, we conducted a microcosm study to explore the impact of MPs addition (Raw vs. aged) and Trichoderma longibrachiatum and Bacillus subtilis inoculation (Sole vs. combination) on GHGs emission, soil community structure, physiochemical properties, and enzyme activities. Our results indicated that the addition of aged MPs considerably enhanced the GHGs emissions (N2O (+16%) and CO2 (+21%), respectively), C and N cycling gene expression, microbial biomass carbon, and soil physiochemical properties than raw MPs. However, the soil microbial community structure and enzyme activities were enhanced in raw MPs added treatments, irrespective of the MPs type added to soil. However, microbial inoculation significantly reduced GHGs emission by altering the expression of C and N cycling genes in both types of MPs added treatments. The soil microbial community structure, enzymes activities, physiochemical properties and microbial biomass carbon were enhanced in the presence of microbial inoculation in both type of MPs. Among sole and combined inoculation of Trichoderma and Bacillus subtilis, the co-applied Trichoderma and Bacillus subtilis considerably reduced the GHGs emission (N2O (−64%) and CO2 (−61%), respectively) by altering the expression of C and N cycling genes regardless of MPs type used. The combined inoculation also enhanced soil enzyme activities, microbial community structure, physiochemical properties and microbial biomass carbon in both types of MPs treatment. Our findings provide evidence that polyethylene MPs likely pose a high risk of GHGs emission while combined application of Trichoderma and Bacillus subtilis significantly reduced GHGs emission by altering C and N cycling gene expression, soil microbial community structure, and enzyme activities under MPs pollution in a terrestrial ecosystem.

SOC and TN fluctuations determine the variations in microbial enzymatic activities under diverse land use types in the Central Himalaya, India

Soil microbial enzymatic activities, often used as indicators of soil health and fertility, are vulnerable to changes in climate and anthropogenic activities. This study analyses the responses of specific soil enzymatic activities– dehydrogenase (DHA), acid phosphatase (APH), β-glucosidase (BG) and urease (URE)– in Nitosols/Luvisols of the subtropical zone of the Central Himalaya, India. We investigated how these enzymatic activities vary with different land uses: arable land (AL), kitchen garden (KG) and peach orchard (PO), across four villages– Niglat, Kainchidham, Majhera and Syalikhet. Considering associated management practices, we quantified cumulative average soil enzymatic activities for the rabi season (2017–2018). In general, catalytic activity of the selected enzymes was highest in Syalikhet and lowest in Majhera. However, for land use types, enzymatic activities were lower in AL and KG (75.56–90.17% and 39.41–61.72%, respectively) compared to PO values. MANOVA analysis evaluated significant spatial differences (P < 0.001) in enzymatic activities. Soil enzymatic mean values were highest in the surface layer (0–10 cm) and decreased gradually with increasing depth. Parameters such as soil moisture content (SMC) and pH, along with vegetation, management practices, and nutrients such as SOC, TN, K, AP, and N forms (NH4+–N and NO3––N) showed significant and strong correlations with all the soil enzyme activities (r = 0.40–0.97; P < 0.05). TN, SOC, K, SMC, pH, AP, NH4+- N, and clay content were key determining factors of soil enzymatic activities, explaining approximately 59% of the variation. These results suggest that using soil microbial enzymatic activities as soil quality indicators is a feasible approach to assess the impacts of vegetation, management practices, and soil profile depths in soils under different land use types/systems in selected impoverished villages of the fragile Central Himalaya, India.

Exogenous Organic Matter Improves Potato Yield by Regulating the Microbiological Fertility Index

The nutrient availability of carbon (C), nitrogen (N), and phosphorus (P) has been decreasing due to a decline in the biological function of yellow soil, limiting potato yield (PY). Increasing biochar or organic fertilizer input is an effective way to improve soil microbiological fertility. However, indexes to regulate soil microbiological fertility using biochar and organic fertilizer individually or in combination and these indexes’ associations with PY remain unclear. In this study, four fertilization strategies were developed using the nutrient balance method: CK (recommended NPK fertilization), BC (NPK + biochar), OF (NPK + organic fertilizer), and BF (NPK + 1/2 biochar + 1/2 organic fertilizer). Using different fertilization strategies, the eco-stoichiometry characteristics of the soil microbial biomass and enzyme activity; the bioavailability of C, N, and P; and the differences in PY were investigated, and the direct and indirect effects of these factors on PY were determined over a two-year period. The results showed that exogenous organic matter input could considerably affect the stoichiometric ratios of soil microbial biomass; C; N; P; the stoichiometric ratios of C-converting, N-converting, and P-converting enzyme activities (expressed as BG+CBH, NAG+LAP, and AP, respectively); and the integrated enzyme index (IEI). The IEI was the highest in BF, followed by OF, BC, and CK. A significant positive correlation was found between the microbial biomass C, N, and P and their corresponding converting enzyme activities (p &lt; 0.05). The ln(BG+CBH):ln(NAG+LAP), ln(BG+CBH):lnAP, and ln(NAG+LAP):lnAP ratios were all higher than 1:1, but they approached 1:1 in the order of CK-BC-OF-BF. Compared to soil C and N, P-converting enzyme activity was the primary limiting factor for soil nutrient conversion in the study area. BF was less restricted by P and more balanced in its nutrient ratio. The microbial biomass C:N:P could affect PY in eight ways. (1) Microbial biomass C:N directly decreased PY, and microbial biomass C:P indirectly increased PY. (2) It could decrease C-converting enzyme activity, (3) decrease N availability to increase C-converting enzyme activity, (4) decrease P availability, or (5) decrease P availability to decrease the soil C:P-converting enzyme activity ratio. Microbial biomass N:P indirectly increased PY (6) by increasing the soil C:P-converting enzyme activity ratio, (7) by increasing C-converting enzyme activity, or (8) by increasing N availability to increase C-converting enzyme activity. Thus, BF is an effective strategy for regulating the soil microbiological fertility index; enhancing C, N, and P nutrient conversion; and increasing PY. The input of exogenous organic matter can alter the stoichiometric ratios of soil microbial biomass C, N, and P; the stoichiometric ratios of C-converting, N-converting, and P-converting enzyme activities; and nutrient availability, thus regulating PY. Microbial biomass N:P and soil C:P-converting enzyme activity ratios influence PY the most.

Assessment of soil microbial diversity and soil enzyme activities under inorganic input sources on maize and rice ecosystems

BackgroundTo increase crop productivity, modern agricultural practices comprises fertilizers, algaecides, herbicides and fungicides. ObjectiveThe purpose of this study was to evaluate the effects of soil microbial population and soil enzyme activity by the use of fertilizer in maize and inorganic input in the rice ecosystem. MethodsA field experiment (2021 to 2023) was carried out using synthetic fertilizer doses with maize crops followed by rice crops using inorganic inputs. Soil microbial population and enzyme activities were examined. ResultsMaize field experiment revealed that the plots treated with 75 % Standardized Dose of Fertilizer (SDF) of NPK had the highest populations of diazotrophs (124 × 105cfu / g), Phosphobacteria (66.33 × 105cfu / g), and Azospirillum (0.409 × 105 MPN / g) than 100 % and 150 % SDF of NPK. The soil enzyme activity was higher in the unfertilized control plot than fertilized plot. These experimental results revealed that a low amount of fertilizer and no fertilizers favour the growth of soil microorganisms and soil enzyme activities, respectively. Followed by the rice field experiment, revealed that the soil microbial population was decreased by the application of inorganic inputs viz., fertilizer, algaecide, herbicide and fungicide. However, the maximum soil microbial population was found in algaecide application followed by herbicide and fungicide. ConclusionThe field experiment concluded that soil microbial population and enzyme activity were affected by inorganic amendments. Less inorganic fertilizers and no fertilizers improve soil microbial activities and soil enzyme activities.

Effect of stand age on soil microbial metabolic limitation and enzyme activities in Robinia pseudoacacia L. plantations in the loess hilly‐gully region, China

AbstractSoil heterotrophic microorganisms play crucial roles in soil biogeochemical cycles by secreting extracellular enzymes, but their metabolism is often limited by resource availability. Identifying major resources that limit soil microbial metabolism could help to create reasonable management practices for the maintenance of ecosystem function. Robinia pseudoacacia plantations perform crucial functions in reconstituting the ecological integrity of disturbed ecosystems; however, soil microbial metabolic limitations in R. pseudoacacia plantations remain poorly understood. Herein, R. pseudoacacia plantations of four age classes (10, 22, 37, and 47 years old) were sampled in the loess hilly‐gully region of northern Shaanxi Province in China. This study analyzed the effects of stand age on soil extracellular enzyme activities and soil microbial metabolic limitation. It also determined the main factor driving soil microbial metabolic limitation and extracellular enzyme activities. The results of ecoenzymatic stoichiometry showed that nitrogen (N) limited soil microbial metabolism in R. pseudoacacia plantations. Soil microbial metabolism at 10 and 22 years old were more carbon (C)‐ and N‐limited than that at 37 and 47 years old. Except for N‐ and phosphorus (P)‐acquiring enzyme activities at 10–20 cm, soil C‐, N‐, and P‐acquiring enzyme activities (in 0–10 and 10–20 cm of soil) at 10 and 22 years old were significantly higher than those at 37 and 47 years old. The enzymatic ratio of C:N:phosphorus(P) acquisition in all R. pseudoacacia plantations, regardless of stand age and soil depth, deviated from 1:1:1. Soil nutrients explained most of the variation (90.80%) in soil extracellular enzyme activities based on variation‐partitioning analysis. The partial least squares path model showed that soil nutrients had the highest total negative effect on microbial C limitation and microbial N/P limitation. Our results confirmed that microbial metabolic limitation was induced by soil resource deficits. The findings provide another visual that increases our understanding of soil microbial metabolic limitation in R. pseudoacacia plantations.

Urbanization-induced soil organic carbon loss and microbial-enzymatic drivers: insights from aggregate size classes in Nanchang city, China.

Soil microorganisms and enzymes play crucial roles in soil organic carbon (SOC) sequestration by promoting soil aggregate formation and stability and by participating in SOC cycling and accumulation. However, the effects by which soil microorganisms and enzymes act as mediators driving dynamic changes in SOC during rapid urbanization remain unclear. Therefore, this study selected the built-up area of Nanchang City, China (505 km2), as the study area. Sampling surveys were conducted using 184 sample plots stratified based on the proportion of impermeable surface area to distinguish different urbanization levels. The driving factors of dynamic changes in SOC of different aggregates during the process of urbanization were analyzed using the soil microbial community and enzyme activities. The results demonstrated that with an increase in urbanization intensity, both SOC content and stock exhibited a significant decline (p < 0.05). The highest SOC stock and contribution rate were observed in the 0.25-1 mm aggregates, and they were significantly influenced by urbanization (p < 0.05). In addition, the biomass of gram-positive bacteria (G+) and actinomycetota, and the activities of N-acetylglucosaminidase and acid phosphatase (AP) were significantly higher in low-urbanization areas than in high-urbanization areas (p < 0.05). SOC of each aggregate was positively correlated with fungi, arbuscular mycorrhizal fungi, G+, gram-negative bacteria, actinomycetota, protozoa, β-1,4-glucosidase, N-acetylglucosaminidase, AP, urease, and catalase. Compared to soil enzymes, soil microorganisms exhibited a greater role in SOC sequestration (22.7%). Additionally, a structural equation model indicated that urbanization can directly or indirectly lead to a decrease in SOC of aggregates by altering soil physicochemical properties and affecting microbial and enzyme dynamics. However, the larger vegetation characteristics index mitigate the negative impacts of urbanization on SOC. Overall, urbanization had a negative impact on soil carbon storage. In the future, it is important to consider strategies that focus on improving soil nutrients, maintaining soil structure, protecting existing urban trees, and enhancing plant diversity during the urbanization process. These measures can help increase soil microbial biomass and enzyme activity, thereby improving soil and aggregate-related SOC content. The study could contribute to enhancing carbon sequestration in urban greenspaces.

A comparative analysis of soil physicochemical properties and microbial community structure among four shelterbelt species in the northeast China plain.

The focal point of this study lies in the implementation of a controlled experiment conducted under field conditions. In this experiment, we deliberately selected four shelterbelts within the same field, characterized by identical planting density, and planting year. This deliberate selection effectively mitigated the potential impact of extraneous factors on the three microbiomes, thereby enhancing the reliability and validity of our findings.

Melatonin and 14-hydroxyed brassinosteroid combined promote kiwifruit seedling growth by improving soil microbial distribution, enzyme activity and nutrients uptake.

Kiwifruit, a nutrient-dense fruit, has become increasingly popular with consumers in recent decades. However, kiwifruit trees are prone to stunted growth after a few years of planting, called early tree decline. In this study, melatonin (MT), pollen polysaccharide (SF), 14-hydroxyed brassinosteroid (14-HBR) were applied alone or in combination to investigate their influence on plant growth, nutrition absorption and rhizosphere bacterial abundance in kiwifruit seedlings. The results revealed that MT, SF and 14-HBR alone treatments significantly increased leaf chlorophyll content, photosynthetic capacity and activities of dismutase and catalase compared with the control. Among them, MT treatment significantly increased the dry root biomass by 35.7%, while MT+14-HBR treatment significant enhanced the dry shoot biomass by 36.9%. Furthermore, both MT and MT+14-HBR treatments markedly improved the activities of invertase, urease, protease and phosphatase in soil, as well as the abundance of Proteobacteria and Acidobacteria in rhizosphere microorganisms based on 16S rDNA sequencing. In addition, MT treatment improved the content of available K and organic matter in soil, and increased the uptake of P, K and Fe by seedlings. In summary, 14-HBR and MT combined had the best effect on promoting rhizosphere bacterial distribution, nutrient absorption and plant growth. These findings may provide valuable guidance for solving growth weakness problem in kiwifruit cultivation.

Effects of polyethylene, polylactic acid, and tire particles on the sediment microbiome and metabolome at high and low temperatures.

Global warming has led to a high incidence of extreme heat events, and the frequent occurrence of extreme heat events has had extensive and far-reaching impacts on wetland ecosystems. The widespread distribution of plastics in the environment, including polyethylene (PE), polylactic acid (PLA), and tire particles (TPs), has caused various environmental problems. Here, high-throughput sequencing techniques and metabolomics were used for the first time to investigate the effects of three popular microplastic types: PE, PLA, and TP, on the sediment microbiome and the metabolome at both temperatures. The microplastics were incorporated into the sediment at a concentration of 3% by weight of the dry sediment (wt/wt), to reflect environmentally relevant conditions. Sediment enzymatic activity and physicochemical properties were co-regulated by both temperatures and microplastics producing significant differences compared to controls. PE and PLA particles inhibited bacterial diversity at low temperatures and promoted bacterial diversity at high temperatures, and TP particles promoted both at both temperatures. For bacterial richness, only PLA showed inhibition at low temperature; all other treatments showed promotion. PE, PLA, and TP microplastics changed the community structure of sediment bacteria, forming two clusters at low and high temperatures. Furthermore, PE, PLA, and TP changed the sediment metabolic profiles, producing differential metabolites such as lipids and molecules, organic heterocyclic compounds, and organic acids and their derivatives, especially TP had the most significant effect. These findings contribute to a more comprehensive understanding of the potential impact of microplastic contamination.IMPORTANCEIn this study, we added 3% (wt/wt) microplastic particles, including polyethylene, polylactic acid, and tire particles, to natural sediments under simulated laboratory conditions. Subsequently, we simulated the sediment microbial and ecosystem responses under different temperature conditions by incubating them for 60 days at 15°C and 35°C, respectively. After synthesizing these results, our study strongly suggests that the presence of microplastics in sediment ecosystems and exposure under different temperature conditions may have profound effects on soil microbial communities, enzyme activities, and metabolite profiles. This is important for understanding the potential hazards of microplastic contamination on terrestrial ecosystems and for developing relevant environmental management strategies.

Bio-augmentation and bio-stimulation with kenaf core enhanced bacterial enzyme activities during bio-degradation of petroleum hydrocarbon in polluted soil

Indigenous micro-organisms often possess the ability to degrade petroleum hydrocarbon (PHC) in polluted soil. However, this process can be improved by supplementing with nutrients or the addition of more potent microbes. In this study, the ability of kenaf-core to stimulate the PHC degradation capability of microbial isolates from PHC polluted soil samples was evaluated. The standard experimental methods used in this study include: the digestion and analysis of the physico-chemical properties of petroleum hydrocarbon contaminated and non-contaminated soil samples; evaluation of petroleum hydrocarbon biodegradation using bio-augmentation and bio-stimulation (with kenaf-core) treatments; and, determination of soil microbial enzyme activities. Results from this study show that K, Na, total nitrogen, organic carbon, exchangeable cations, and heavy metals were found to be significantly (P < 0.05) higher in the polluted soil than in the non-polluted soil. Also, the polluted samples had pH values ranging from 5.5 to 6.0 while the non-polluted samples had a pH of 7.6. The microbial enzyme activities were comparatively lower in the polluted soils as compared to the non-polluted soil. The percentage degradation in the kenaf-core treated samples (AZ1T2—78.38; BN3T2—70.69; OL1T2—71.06; OT1T2—70.10) were significantly (P < 0.05) higher than those of the untreated (AZ1T1—13.50; BN3T1—12.50; OL1T1—10.55; OT1T1—9.50). The degradation of petroleum hydrocarbon in the bio-augmented and bio-stimulated treatments increased with increasing time of incubation, and were higher than that of the untreated sample. Comparatively, the treatment with a combination of kenaf-core and rhamnolipid exhibited a significantly (P < 0.05) higher degradation rate than that of the treatment with only kenaf core or rhamnolipid. While, the bio-stimulated and bio-augmented treatments had appreciable microbial counts that are higher than that of the untreated. In conclusion, the nutrient-supplement with kenaf-core significantly enhanced microbial growth and activities in the soil, thus improving their ability to biodegrade petroleum hydrocarbons in the polluted soils. Thus, supplementing with Kenaf core to encourage microbiological degradation of petroleum hydrocarbon is recommended.

Indirect influence of soil enzymes and their stoichiometry on soil organic carbon response to warming and nitrogen deposition in the Tibetan Plateau alpine meadow.

Despite extensive research on the impact of warming and nitrogen deposition on soil organic carbon components, the response mechanisms of microbial community composition and enzyme activity to soil organic carbon remain poorly understood. This study investigated the effects of warming and nitrogen deposition on soil organic carbon components in the Tibetan Plateau alpine meadow and elucidated the regulatory mechanisms of microbial characteristics, including soil microbial community, enzyme activity, and stoichiometry, on organic carbon components. Results indicated that both warming and nitrogen deposition significantly increased soil organic carbon, readily oxidizable carbon, dissolved organic carbon, and microbial biomass carbon. The interaction between warming and nitrogen deposition influenced soil carbon components, with soil organic carbon, readily oxidizable carbon, and dissolved organic carbon reaching maximum values in the W0N32 treatment, while microbial biomass carbon peaked in the W3N32 treatment. Warming and nitrogen deposition also significantly increased soil Cellobiohydrolase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase, and alkaline phosphatase. Warming decreased the soil enzyme C: N ratio and C:P ratio but increased the soil enzyme N:P ratio, while nitrogen deposition had the opposite effect. The bacterial Chao1 index and Shannon index increased significantly under warming conditions, particularly in the N32 treatment, whereas there were no significant changes in the fungal Chao1 index and Shannon index with warming and nitrogen addition. Structural equation modeling revealed that soil organic carbon components were directly influenced by the negative impact of warming and the positive impact of nitrogen deposition. Furthermore, warming and nitrogen deposition altered soil bacterial community composition, specifically Gemmatimonadota and Nitrospirota, resulting in a positive impact on soil enzyme activity, particularly soil alkaline phosphatase and β-xylosidase, and enzyme stoichiometry, including N:P and C:P ratios. In summary, changes in soil organic carbon components under warming and nitrogen deposition in the alpine meadows of the Tibetan Plateau primarily depend on the composition of soil bacterial communities, soil enzyme activity, and stoichiometric characteristics.

贵州普定土壤酶活性和氮循环功能基因数据集

The karst ecosystem in southwest China is the most fragile ecological environment in China. To protect the ecological environment, the project of "Grain to Green Program" was initiated in the late 1990s for the vegetation restoration in this region. Changes in soil microbial abundance, community composition and functional activity are closely linked to soil nutrient supply and turnover, which are the critical factors influencing vegetation restoration processes. Soils were sampled from five different vegetation types at Chenqi catchment and Tianlong Mountain, and rhizosphere soils were sampled from the typical tree species at Tianlong Mountain. Through rigorous data quality control processes (including survey sampling, sample analysis, and data accuracy checks), we obtained a dataset of soil microbial enzyme activities and nitrogen cycling functional genes in different vegetation types from the karst ecosystem. This dataset consisted of one excel file with eight different sheets, which contains the data on soil microbial enzyme activities, nitrogen cycling functional gene abundance and nitrogen transformation rate, microbial living biomass, microbial residue carbon, and soil physicochemical properties along soil profile ranging from the surface to bedrock layer in various vegetation types of 2016. Furthermore, the dataset also includes the enzyme activity and physicochemical properties of the rhizosphere soils from typical tree species in the primary forest in 2018. The dataset serves as valuable reference data for better understanding the microbial regulation mechanism of soil nutrient cycling in karst areas, and it is also of great practical significance for soil nutrient management in ecologically fragile regions under the background of "Grain to Green Program" policy.

Unraveling the Impact of Cumin-Centric Cropping Sequences on Cumin Yield, Economic Viability, and Dynamics of Soil Enzymatic Activities in Hot Arid Climatic Conditions

A comprehensive study spanning three kharif and rabi seasons (2018–2019, 2020–2021, and 2021–2022) was conducted to investigate the intricate interactions among different cropping sequences and their impacts on cumin yield, financial outcomes, and soil microbial dynamics. The experiment was designed using a randomized block design, comprising eight distinct treatment combinations, each replicated three times. The results revealed compelling insights into the potential of specific cropping sequences to enhance multiple aspects of agricultural sustainability. The results revealed that the highest cumin yield (averaging 592 kg ha−1 over the three years) was achieved when cumin was cultivated subsequent to pearl millet, showcasing significant increases of 14.28% and 23.07% over the cumin–fallow and cumin–cotton cropping systems, respectively. When it came to cumin equivalent yield, the cumin–cotton cropping sequence (985 kg ha−1) emerged as the most favorable, closely followed by cumin–groundnut (968 kg ha−1). Furthermore, analyzing net realizations and benefit–cost ratios demonstrated that the cumin–pearl millet cropping sequence stood out with the maximum values (₹88,235 ha−1 and 2.7, respectively), followed by the cumin–mung bean cropping system (₹84,164 ha−1 and 2.47, respectively). Among the various cropping sequences studied, cumin–mung bean, cumin–cluster bean, cumin–pearl millet and cumin–groundnut were recorded as statistically similar in terms of soil microbial enzymatic activities viz. fluorescein diacetate (FDA), alkaline phosphatase (ALP), dehydrogenase activity (DHA), and microbial biomass carbon and were at par over the cumin–sorghum, cumin–sesame, cumin–cotton and cumin–fallow cropping systems. These findings emphasize the significance of strategic crop sequencing for sustainable agriculture practices that simultaneously optimize productivity and maintain soil health.

Effects of nanocarbon and nano‐calcium carbonate on soil enzyme activities and soil microbial community in wheat (Triticum aestivum L.) rhizosphere soil

AbstractBackgroundNanofertilisers can enhance the efficiency of nutrient utilization in crop production. Nevertheless, it is unclear how soil microbial and enzyme activities are affected by the application of nanofertilisers to wheat inter‐root soil.AimsThe study aims to investigate the influences of nanocarbon (NC) and nano‐calcium carbonate (NCC) on soil enzyme activities and microbial community in the open field setting.MethodsThe effects of nanofertilisers on soil wheat rhizosphere soil were studied through the evaluation of soil microbial quantity, enzyme activity, and microbial diversity.ResultsThe findings revealed that the combined utilization of nanofertilizers and compound fertilizers (CF) led to an augmentation in the diversity of the soil microbial community. When comparing the effects of 100% composite nanofertilizers (100% CF + 50% NC + 50% NCC) with the control (CK) (100% CF), it was observed that the activities of urease (EC 3.5.1.5), catalase (EC 1.11.1.6), alkaline phosphatase (EC 3.1.3.1), sucrase (EC.3.2.1.26), as well as the number of fungi, actinomycetes, and bacteria, increased by 22.4%, 7.7%, 17.8%, 9.3%, 35.9%, 27.7%, and 26.0%, respectively. Similarly, the employment of 70% composite nanofertilizers (70% CF + 35% NC + 35% NCC) also resulted in an enhancement of these aforementioned indicators. The magnitude of increase over the 100% CF was 19.0%, 6.6%, 13.6%, 6.2%, 26.8%, 21.3%, and 23.5%, respectively. Notably, there was no significant difference observed between 100% CF + 50% NC + 50 % NCC and 70% CF + 35% NC + 35% NCC within the 0–35 d after anthesis. Furthermore, both 100% CF + 50% NC + 50% NCC and 70% CF + 35% NC + 35% NCC contributed to an improvement in the species uniformity and operational taxonomic unit abundance of wheat rhizosphere microorganisms, while also increasing the abundance of Proteobacteria and Actinobacteria compared to the CK. The relative abundance of Bacteroidetes and Actinobacteria was found to be elevated in the nanomaterials‐treated groups, both at 0–7 d and 14–21 d after anthesis, and positively correlated with soil enzyme activities and soil microbial populations.ConclusionsThese results indicate that the application of composite nanofertilizers can enhance the soil microenvironment in wheat fields, particularly under reduced fertilization conditions.

Mechanism of polyethylene and biodegradable microplastic aging effects on soil organic carbon fractions in different land-use types

Microplastics (MPs) are widely present in terrestrial ecosystems, but knowledge about the aging characteristics of MPs in different land-use types and their impact on soil organic carbon fractions is still limited. Polyethylene (PE) and biodegradable MPs (Poly propylene carbonate and Polybutylene adipate terephthalate synthetic material (PPC + PBAT, Bio)), at 0 %, 0.03 %, and 0.3 % (w/w) dosages, were added to grassland, farmland, and facility soils for eight-week incubation. The aging degree of MPs was explored by quantifying the carbonyl index (CI). Soil organic C fractions such as SOC, particulate organic carbon (POC), mineral-associated organic carbon (MAOC), and microbial-derived C were analyzed. MPs underwent rapid aging after incubation, and the CI value for 0.03 % PE-MPs increased from 0.05 to 0.27 (farmland) and 0.26 (facility) (p < 0.05). The aging degree of 0.03 % and 0.3 % Bio-MPs was most significant in grassland, with CI decreasing by 46.6 % and 69.0 %, respectively. The CI of MPs were negatively correlated with their dosage. The 0.03 % and 0.3 % PE-MPs decreased soil organic carbon (SOC) content by 7.4 % and 8.2 % in grassland, and 3.0 % and 6.0 % in the facility (p < 0.05). POC content of farmland and facility soil was negatively correlated with PE-MPs' CI (p < 0.05). The 0.03 % PE and Bio-MPs decreased fungal necromass C (FNC) by 0.40 and 0.05 g kg−1 in grassland and 0.48 and 0.21 g kg−1 in farmland. Besides, the dosage of MPs regulated FNC content through soil pH, nutrients, and extracellular enzyme activity, either directly or indirectly, ultimately affecting the soil C pool. Therefore, this study demonstrates that MPs strongly affect SOC dynamics by influencing soil microbial enzyme activity and fungal necromass.