Responses of diazotrophic network structure and community diversity to alfalfa-maize intercropping are soil property-dependent.

Introduction: Intercropping and soil properties both affect soil diazotrophic communities. However, the specific effects that alfalfa-maize intercropping has on diazotrophic networks and community diversity under different soil properties remain unclear. Methods: In this study, we investigated the soil diazotrophic communities of two crop systems, alfalfa monoculture (AA) and alfalfa-maize intercropping (A/M), in two sites with similar climates but different soil properties (poor vs. average). Results and discussion: The diazotrophic network complexity and community diversity were higher at the site with poor soil than at the site with average soil (p < 0.05). Community structure also varied significantly between the sites with poor and average soil (p < 0.05). This divergence was mainly due to the differences in soil nitrogen, phosphorus, and organic carbon contents between the two sites. At the site with poor soil, the A/M system had lower diazotrophic diversity, lower network complexity and greater competition between diazotrophs than the AA system (p < 0.05) because intercropping intensified the soil phosphorus limitation under poor soil conditions. However, in the average soil, it was the A/M system that had an altered diazotrophic structure, with an increased abundance of 11 bacterial genera and a decreased abundance of three bacterial genera (p < 0.05). Conclusion: Our results indicated that the effects of alfalfa-maize intercropping on diazotrophic communities were soil property-dependent.

Multifaceted effects of microplastics on soil-plant systems: Exploring the role of particle type and plant species.

Microplastics have emerged as a global environmental concern, yet their impact on terrestrial environments, particularly agricultural soils, remains underexplored. Agricultural soils, due to intensive farming, may serve as significant sinks for microplastics. This study investigated the effects of different types of microplastics-polyester microfibers, polyethylene terephthalate microfragments, and polystyrene microspheres-on soil properties and radish growth, while a complementary experiment examined the impact of polyester microfibers on the growth of lettuce and Chinese cabbage. Through both horizontal and vertical comparisons, this research comprehensively evaluated the interactions between microplastic particles and plant species in soil-plant systems. The results showed that polyester microfibers significantly affected soil bulk density, with effects varying based on planting conditions (p < 0.01). Polyethylene terephthalate microfragments and polystyrene microspheres reduced the proportion of small soil macroaggregates under radish cultivation (p < 0.01). Additionally, polystyrene microspheres significantly altered the total organic carbon stock in radish-growing soil, potentially affecting the microclimate (p < 0.01). Interestingly, polyester microfibers promoted lettuce seed germination and significantly enhanced the root biomass of Chinese cabbage (p < 0.05). Overall, the environmental effects of microplastic exposure varied depending on the type of particle and plant species, suggesting that microplastics are not always harmful to soil-plant systems and may even offer benefits in certain scenarios. Given the crucial role of soil-plant systems in terrestrial ecosystems, and their direct connection to food safety, human health, and global change, further research should explore both the positive and negative impacts of microplastics on agricultural practices.

Effects of short-term nitrogen addition on the recovery of alpine grassland in the Tianshan Mountains of Xinjiang, China.

The restoration of alpine grasslands has garnered significant attention across various sectors. Historically, natural restoration has been the primary approach for grassland recovery, characterized by its prolonged duration. To expedite the recovery of degraded grasslands, it is essential to identify the limiting factors of restoration, enabling efficient and rapid recovery. Appropriate nitrogen (N) addition levels have been considered a potential strategy to enhance the recovery of grassland ecosystems and augment their ecological benefits. However, the effectiveness of N addition in alpine grassland restoration remains debated. This study investigated the impact of five N addition levels (CK: control [0 g/m2]; LN: low N [5 g/m2]; MN: medium N [10 g/m2]; HN: high N [15 g/m2]; SN: severe N [20 g/m2]) and two experimental approaches (N addition once per year [NPY] and three times per year [NTY] at the same dosages) on plant and soil properties and the maximum restoration capacity of alpine meadows. Our findings reveal three key insights: The level of N addition was the primary factor influencing aboveground plant biomass and coverage. Plant diversity decreased under the NTY regime and increased with NPY in the Bayinbruck grassland. N addition significantly altered soil properties, including pH, salinity, soil organic carbon (SOC), soil-available phosphorus (AP), and soil total phosphorus (TP). Notably, soil TP, total nitrogen (TN), and AP substantially impacted plant community structure and diversity. Based on structural equation model (SEM) and analysis of variance (ANOVA), optimal grassland restoration was achieved with the HN (15 g/m2) treatment under NPY and the MN and HN (10 and 15 g/m2) treatments under NTY. Overall, our study offers crucial insights into the conservation, management, and restoration of grassland ecosystems on the Bayinbruck Plateau. It underscores the significance of N addition effects on plant communities, vegetation restoration, and soil properties.

Multi-Omics Analysis Reveals Molecular Responses of Alkaloid Content Variations in Lycoris aurea Across Different Locations.

Lycoris aurea, celebrated for its visually striking flowers and significant medicinal value due to the presence of alkaloids such as lycorine and galanthamine, has intricate yet poorly understood regulatory mechanisms. This study provides a detailed examination of the transcriptomic, metabolomic and ecological dynamics of L. aurea, aiming to elucidate the underlying molecular mechanisms of alkaloid biosynthesis. Our comparative analysis across different ecological settings highlighted key genes involved in alkaloid biosynthesis, such as genes encoding aldehyde dehydrogenase and norbelladine 4'-O-methyltransferase, which were distinctively increased in the high alkaloids-producing group. We identified a total of 6871 differentially expressed genes and 915 metabolites involved in pathways like terpenoid backbone biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis. Protein interaction network analysis revealed significant upregulation of photosynthesis, photosystem and photosynthetic membrane pathways in the alkaloids-producing region. Furthermore, our research delineated the interactions among soil microbial communities, genes and plant and soil biochemical properties, noting that bacterial populations correlate with soil properties that favour the activation of metabolic pathways essential for alkaloid production. Collectively, this study advances our understanding of the genetic and metabolic alkaloid biosynthesis pathways in L. aurea, shedding light on the complex interactions that govern alkaloid production.

Altitudinal variation in rhizosphere microbial communities of the endangered plant Lilium tsingtauense and the environmental factors driving this variation.

The rhizosphere soil properties and microbial communities of Lilium tsingtauense, an endangered wild plant, have not been examined in previous studies. Here, we characterized spatial variation in soil properties and microbial communities in the rhizosphere of L. tsingtauense. We measured the abundance of L. tsingtauense at different altitudes and collected rhizosphere and bulk soils at three representative altitudes. The results showed that L. tsingtauense was more abundant, and the rhizosphere soil was richer in nitrogen, phosphorus, potassium, water content, and organic matter and more acidic at high altitudes than at lower altitudes. The diversity and richness of rhizosphere bacteria and fungi increased with altitude and were higher in rhizosphere soil than in bulk soil. In addition, ectomycorrhizal fungi, endophytic fungi, and nitrogen-fixing bacteria were more abundant, and plant-pathogenic fungi were less abundant at high altitudes. Co-occurrence network analysis identified four key phyla (Bacteroidota, Proteobacteria, Ascomycota, and Basidiomycota) in the microbial communities. We identified a series of microbial taxa (Acidobacteriales, Xanthobacteraceae, and Chaetomiaceae) and rhizosphere soil metabolites (phosphatidylcholine and phosphatidylserine) that are crucial for the survival of L. tsingtauense. Correlation analysis and random forest analysis showed that some environmental factors were closely related to the rhizosphere soil microbial community and played an important role in predicting the distribution and growth status of L. tsingtauense. In sum, the results of this study revealed altitudinal variation in the rhizosphere microbial communities of L. tsingtauense and the factors driving this variation. Our findings also have implications for habitat restoration and the conservation of this species. IMPORTANCE: Our study highlighted the importance of the rhizosphere microbial community of the endangered plant L. tsingtauense. We found that soil pH plays an important role in the survival of L. tsingtauense. Our results demonstrated that a series of microbial taxa (Acidobacteriales, Xanthobacteraceae, Aspergillaceae, and Chaetomiaceae) and soil metabolites (phosphatidylcholine and phosphatidylserine) could be essential indicators for L. tsingtauense habitat. We also found that some environmental factors play an important role in shaping rhizosphere microbial community structure. Collectively, these results provided new insights into the altitudinal distribution of L. tsingtauense and highlight the importance of microbial communities in their growth.

Interactive effects of microplastics and cadmium on soil properties, microbial communities and bok choy growth.

The simultaneous presence of microplastics (MPs) and cadmium (Cd) in soil environments has raised concerns regarding their potential interactive effects on soil-plant ecosystems. This study explores how polyethylene (PE) at concentrations of 0.5 % (w/w), 1 % (w/w), and 2 % (w/w), and Cd at concentrations of 3 mg kg-1 and 12 mg kg-1, either alone or combined, impact soil physicochemical properties, microbial community structures, and bok choy growth through a 40-day pot experiment. Our findings reveal that the addition of 2 % (w/w) PE significantly increased soil organic carbon (SOC). However, when 2 % PE coexisted with Cd, SOC levels decreased, potentially due to a reduction in enzyme activity (ß-1,4-glucosidase). PE increased the proportion of 1-2 mm soil aggregates, while the coexistence of 2 % PE and Cd significantly increased the content of soil aggregates larger than 2 mm. The coexistence of PE and Cd increased available potassium (AK) in the soil by approximately 13 % to 41 %. Regarding bok choy growth, the aboveground biomass under 2 % PE was approximately 210 % of that under 0.5 % PE, possibly because of the enhancement in soil nutrients. The presence of Cd, however, reduced the chlorophyll content of bok choy by approximately 18 % to 34 %. Notably, the coexistence of high PE concentration (2 % w/w) and low Cd concentration (3 mg kg-1) resulted in the highest aboveground biomass among all coexistence treatments. Furthermore, the addition of PE and Cd significantly altered the structure of soil bacterial and fungal communities, with fungi showing a greater response. Bacteria were significantly associated with soil inorganic N content and plant growth. This study provides new insights into the interactions of microplastics and Cd within microbial-soil-plant systems.

Methane Production Is More Sensitive to Temperature Increase than Aerobic and Anaerobic Methane Oxidation in Chinese Paddy Soils.

Methane emissions from paddy fields can increase under future warming scenarios. Nevertheless, a comprehensive comparison of the temperature sensitivity of methane-related microbial processes remains elusive. Here, we revealed that the temperature sensitivity of methane production (activation energy (Ea) = 0.94 eV; 95% confidence interval (CI), 0.78-1.10 eV) and aerobic (Ea = 0.49 eV; 95% CI, 0.34-0.65 eV) and anaerobic (Ea = 0.46 eV; 95% CI, 0.30-0.62 eV) methane oxidation exhibited notable spatial heterogeneity across 12 Chinese paddy fields spanning 35° longitude and 18° latitude. In addition, the Ea values of aerobic and anaerobic methane oxidation were significantly positively and negatively correlated to the latitude, respectively, while there was no significant correlation between the Ea of methane production and the latitude. Overall, there were no soil factors that had a significant effect on the Ea of methane production. The Ea of aerobic methane oxidation was primarily influenced by the contents of ammonium and clay, whereas the Ea of anaerobic methane oxidation was mainly influenced by the conductivity. Despite the variation, the overall temperature sensitivity of methane production was significantly higher than that of oxidation at a continental scale; therefore, an increase in the emission of methane from paddy fields will be predicted under future warming. Taken together, our study revealed the characteristics of temperature sensitivity of methane production and aerobic and anaerobic methane oxidation simultaneously in Chinese paddy fields, highlighting the potential roles of soil factors in influencing temperature sensitivity.

Towards data-driven tropical forest restoration: Uncovering spatial variation, interactions and historical management effects on nutrients along soil depth gradients.

Data scarcity hinders global conservation initiatives, and there is a pressing demand for spatially detailed soil and species data to restore human-altered tropical forests. We, therefore, aimed to generate foundational soil environment and habitat suitability data and high-resolution soil maps to aid restoration efforts in a critical ecosystem of the threatened Indo-Burma Biodiversity Hotspot region, i.e., Tarap Hill Reserve (THR) in Bangladesh. Using multiple soil depths and vegetation data, we answered three major questions. (QI) How do spatial distribution and the relationships between soil physicochemical properties (i.e., pH, sand, silt, and clay percentages, organic carbon, and nutrients - N, P, K, Ca, Mg, Fe, and Zn) vary from surface to deeper soils (top 1 m)? (QII) How do different forest management interventions, i.e., old-growth forests (OGF), mixed plantations (MXP), and mono-specific plantations (MOP), influence soil properties, nutrients, and carbon in different soil depths? (QIII) Which spatial interpolation methods are best suited for making more accurate soil property predictions at different depths? Our analyses reveal decreasing availability of critical nutrients like N, P, Mg, and Fe from surface to subsurface soils, while pH, soil organic carbon, and clay content increased with depth. Several soil properties showed significant interactions, although the strength of the interactions changed from surface to deeper soils. Besides, forest management interventions significantly influenced soil functionality by having higher nutrient availability and soil organic carbon in OGF than MXP and MOP. Predictive performances of the deterministic and geostatistical interpolation methods varied for different soil properties in different soil depths, and soil maps revealed substantial heterogeneity in the distribution of soil properties across space and along depths. This study represents a pioneering step in data-driven tropical forest restoration, and our novel findings and high-resolution soil maps could guide future studies focusing on species habitat preferences, restoration ecology, and spatial conservation planning in the Indo-Burma Biodiversity Hotspot region and elsewhere in the tropics.

The effect of terroir on volatilome fingerprinting and qualitative attributes of non-irrigated grapes reveals differences on glycosylated aroma compounds.

BACKGROUND: 'Xynisteri' is considered as the reference white grape cultivar in Cyprus with remarkable adaptation to adverse edaphoclimatic conditions and appreciable oenological properties that renders it as an appropriate cultivar for studies within a global context due to climate change. To this aim, two distinct non-irrigated plots with different climatic conditions, soil properties and levels of rainfall were selected; Koilani [KO, altitude 800 m, 76% calcium carbonate (CaCO3) content, pH 7.97, average temperature: 16.5 °C, rainfall: 229 mm] and Kyperounda (KY, altitude 1200 m, CaCO3-free soil, pH 6.47, average temperature: 14.9 °C, rainfall: 658 mm). An array of physiological, biochemical and qualitative indices during successive developmental stages (BBCH 75-89) were determined. During the advanced on-vine developmental stages (BBCH 85-89), the aromatic profile of grapes was assessed with the employment of gas chromatography-mass spectrometry (GC-MS). Such analysis was complemented with non-destructive chemometric analyses. RESULTS: Berry ripening process substantially differed on the examined plots; BBCH 89 stage reached at 267 and 303 Julian days for KO and KY, respectively. Results indicated that berry weight, soluble solids content (SSC) and α-amino nitrogen were higher in KO than in KY, with exception made for ammonium nitrogen content. A total of 75 compounds, including aliphatic alcohols, benzenic compounds, phenols, vanillins, monoterpenes and C13-norisoprenoids were identified and quantified. The variations of mesoclimatic conditions affected the volatile organic compound (VOC) profiles at the fully-ripe stage, showing a considerable rise in glycosylated aroma compounds, especially monoterpenes and benzenic compounds. In particular, the higher amount of glycosylated aroma compounds were obtained in KY berries up to mid-ripe, whereas KO showed higher glycosylated aroma compounds at fully-ripe stage. Results reported herein indicate that aroma profile of 'Xynisteri' grapes varied substantially in the examined terroirs. Interestingly, the limited rainfall in KΟ non-irrigated vine did not compromise qualitative and aromatic properties of berries. CONCLUSIONS: The present study aimed at dissecting the impact of terroir on bush-trained, non-irrigated grapevines of a cultivar appropriate for extreme climate change scenarios. The volatilome fingerprint was highly variable among the examined plots; such results can be further exploited at vinification level towards production of single vineyard premium end products. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of Three Different Types of Biochar on Bioelectricity Generated from Plant Microbial Fuel Cells under Unsaturated Soil Condition.

Plant microbial fuel cell (PMFC) is an emerging technology, showing promise for environmental biosensors and sustainable energy production. Despite its potential, PMFCs struggle with issues like low power output and limited drought resistance. Recent studies proposed that integrating biochar may enhance PMFC performance due to its physicochemical properties. The influence of different biochar types on PMFC efficiency has been minimally explored. This study aims to fill this gap by evaluating the performance of PMFCs integrated with various biochar types under unsaturated soil conditions. The study found that the addition of biochar types─specifically reed straw biochar (RSB), apple wood biochar (AWB), and corn straw biochar (CSB)─significantly influenced the performance of PMFCs. RSB, with its large surface area and porous structure, notably increased the current output by reducing soil resistance and enhancing electron transfer efficiency in microbial reduction reactions, achieving a peak power density of approximately 1608 mW/m2. AWB, despite its less porous structure, leveraged its high cation exchange capacity and hydrophilic functional groups to foster microbial community growth and diversity, thereby also increasing bioelectricity output. Conversely, CSB, with its large surface area, showed the least improvement in PMFC performance due to its layered structure and lower water retention capacity. Additionally, under drought conditions, PMFCs with added RSB and AWB exhibited better drought resistance due to their ability to improve soil moisture characteristics and enhance soil conductivity. The addition of biochar reduced soil resistance, increasing the bioelectric output of PMFCs and maintaining good performance even under low moisture conditions. This study highlights the critical role of biochar's surface area and functional groups in optimizing PMFC performance. It enhances our understanding of PMFC optimization and might offer a novel power generation method for the future, while also presenting a fresh strategy for soil monitoring.

The response of root-zone soil bacterial community, metabolites, and soil properties of Sanyeqing medicinal plant varieties to anthracnose disease in reclaimed land, China.

Objectives: To enhance the utilization of reclaimed land, Sanyeqing (SYQ) has been extensively cultivated in Zhejiang province, China. However, the prevalence of anthracnose has significantly hindered SYQ growth, emerging as a primary obstacle to its production. This study aimed to elucidate SYQ's responses to anthracnose in reclaimed land environments by comprehensively analyzing root-zone bacterial community structure, metabolites, and soil properties. Methods: The experiment was conducted on reclaimed land in Chun'an, China. In order to evaluate the responses of SYQ to anthracnose, the fresh and dry weight of SYQ tubes, the soil properties, the high-throughput sequencing, and metabolomics assay were carried out. Results: Significant differences were observed between an anthracnose-resistant variety (A201714) and an anthracnose-susceptibile variety (B201301). Fresh and dry weight increased 131.53 % and 144.82 % for A201714 compared to B201301.Lacibacterium (39.85 %), Gp6 (21.83 %), Gp5 (21.49 %), and Sphingomonas (18.84 %) were more prevalent, whereas Gp3 (22.71 %), WPS-1 (18.88 %), Gp4 (15.60 %), Subdivision3 (14.70 %), Chryseolinea (14.37 %), and Nitrospira (0.76 %) were less prevalent in A201714 than B201301. A total of 24 bacterial biomarkers were detected in all soil samples, while the network suggests a more stable soil bacterial community in A201714 than in B201301. Eight differentially expressed metabolites (DEMs) that belonged to lipids and lipid-like molecules, organic acids and derivatives, benzenoids, nucleosides, nucleotides, and analogues were found between two soil samples, and all these eight DEMs were downregulated in A201714 and had a strong correlation with 12 genera of bacteria. Moreover, the data from the redundancy analysis indicated that the main variables affecting changes in the bacterial communities were pH, available phosphorus (AP), available potassium (AK), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN). Conclusion: This research offers new insights into the SYQ response to anthracnose in reclaimed land and provides valuable recommendations for the high-quality SYQ cultivation and production.

Meta-analysis of GHG emissions stimulated by crop residue return in paddy fields: Strategies for mitigation.

The stimulating impact of crop residue return on greenhouse gas (GHG) emissions from paddy fields have been widely accepted, while the influence of site environmental and human factors on the simulating degree remains unclear. Here, we performed a meta-analysis to assess the GHG emissions affected by residue return, and its mitigation potential combined with key factors in paddy fields. Drawing upon 1047 observation sets of CH4 and N2O emissions from 155 peer-reviewed publications we found that residue return to paddy fields caused an average increase of 73% CH4 emissions and 14% in N2O emissions. Utilizing meta-analytical models, we identified pH as the most significant driver modulating GHG emissions, followed by soil organic matter (SOC) and total nitrogen. In alkaline soils, combining straw return with intermittent irrigation (285.2%) or mid-season drainage (118.9%) significantly reduced CH4 emissions compared to continuous flooding (1201.9%). Additionally, pairing straw return with higher nitrogen inputs (above 150 kg N ha-1) improved soil N2O uptake by -11.5%. In acid and neutral soils, straw carbonization achieved soil CH4 negative emissions (from -2.9% to -39.3%), but the long-term effects remained unclear. Reduced drainage frequency mitigates N2O emissions but may increase CH4 emissions. To efficiently mitigate GHG emissions, we proposed low-carbon schemes for acid or neutral soils based on specific SOC content: For soils with SOC content <10 g kg-1, prioritize nitrogen input control with rates not exceeding 174 kg N ha-1. For soils with SOC content >10 g kg-1, prioritize adjusting the type of straw. Our study underscores the significance of site-specific factors in modulating GHG emissions. Efficient GHG mitigation can be achieved by combining residue return with other agronomic measures tailored to different soil conditions.

Impacts of prescribed fire and mechanical shredding of aboveground vegetation for fire prevention on ecosystem properties, structure, functions and overall multi-functionality of a semi-arid pine forest.

Ecosystem multi-functionality is a key concept when measured to protect forests from natural and anthropogenic disturbances, such as fire prevention techniques, must be adopted. Despite this importance, scarce studies have analysed the impacts of prescribed burning and aboveground vegetation management on ecosystem functions and overall multi-functionality. To fill this gap, this study has evaluated the changes in some ecosystem properties and structure (associated with soil characteristics and plant diversity, respectively), in important forest functions, and the overall ecosystem multi-functionality in a Mediterranean pine forest of Castilla La Mancha (Central Eastern Spain) under three site conditions: (i) undisturbed ecosystem; (ii) forest subjected to mechanical shredding of aboveground vegetation (hereafter "AVMS"); and (iii) forest treated as above and then with prescribed fire ("AVMS + PF"). The results of the study have shown that neither the PF nor AVMS have significantly modified the structure, properties and functions as well as the overall multi-functionality of the forest ecosystem. These slight impacts of the treatments are due to the low fire severity of the prescribed burning and the long time elapsed from the vegetation management. Among the studied ecosystem functions, organic matter decomposition (driven by the enzymatic activities and soil basal respiration), water cycle (influenced by soil water content and water infiltration), carbon stock (linked to soil organic matter) and biomass production decreased, when species richness and plant diversity increased. The study is useful to indicate the feasibility of forest management actions for fire prevention in delicate forest ecosystems of the Mediterranean environments.

Feasibility assessment of biochar amendment for mitigating phytotoxicity of polyvinyl chloride micro/nano-plastics: A study based on lettuce pot experiments.

Micro/nano-plastics (M/NPs) are pervasive in agricultural soils, and their detrimental effects on crops are increasingly evident. This ultimately results in reduced crop yields and quality, posing a great threat to global food security. Therefore, the urgent need to mitigate the phytotoxicity of M/NPs has become apparent. Biochar (BC), as an environmentally friendly soil amendment, plays a crucial role in modifying soil properties and boosting agricultural production levels. Its strong adsorption capacity enables it to effectively passivate soil pollutants and reduce their phytotoxicity. However, the effect of BC on the phytotoxicity of M/NPs in soil remains unknown. In this study, the feasibility of BC amendment for mitigating phytotoxicity of polyvinyl chloride M/NPs (PVC-M/NPs) was evaluated by conducting pot experiments. The results show that the application of 0.1% (w/w) PVC-M/NPs resulted in a 48.60% reduction in lettuce yield. This reduction can be attributed to the decreased soil microbial activity and soil cation exchange capacity (CEC), as well as the direct physical damage to lettuce roots caused by PVC-M/NPs. BC amendment improved soil quality, but had insignificant effect on lettuce biomass compared to the control (p > 0.05). In contrast, BC amendment at an appropriate concentration (0.5% and 2.5%, w/w) to soils contaminated with PVC-M/NPs resulted in a significant increase in lettuce yield (p < 0.01). Furthermore, BC was found to mitigate the oxidative stress of PVC-M/NPs on lettuce roots. This indicates that the BC amendment has the potential to mitigate the toxicity of PVC-M/NPs to lettuce. Improving soil quality and enhancing PVC-M/NPs adsorption are perceived as the influencing mechanisms of BC on the phytotoxicity of PVC-M/NPs. The findings suggest that it is feasible to mitigate the phytotoxicity of M/NPs through BC amendments.

Vegetation restoration enhancing soil carbon sequestration in karst rocky desertification ecosystems: A meta-analysis.

Vegetation restoration measures have been increasingly employed to alleviate rocky desertification in karst ecosystems. However, the comprehensive effects of these interventions on soil properties and soil organic carbon (SOC) remain poorly understood. Herein, we gathered 644 paired observations from 68 studies and conducted a meta-analysis to quantify the performance of different vegetation restoration measures including moss (MS), grassland (GL), cash crop (CP), shrub (SH), and secondary forest (SF) through soil properties and SOC. Our results demonstrated significant effects of MS, GL, CP, SH, and SF on soil biotic and abiotic factors, each with distinct response characteristics. Particularly, MS significantly enhanced all soil properties (excluding a slight decrease in soil pH by 10.8%). Moreover, MS, GL, CP, SH, and SF could elevate SOC by 32.1%, 17.6%, 24.9%, 59.2%, and 48.7% respectively. Utilizing random forest and linear regression models, we identified primary drivers for SOC in MS, GL, CP, SH, and SF as soil moisture content, arbuscular mycorrhizal fungi, soil microbial phosphorus, total nitrogen, and ß-1,4-glucosidase, respectively. This meta-analysis underlined the varied effects of vegetation restoration measures on soil properties and advocates for restoration measures that prioritize plant productivity and reduce soil temperature during the karst rocky desertification restoration process. Additionally, this study underscores the pivotal role of vegetation rehabilitation in environmental conservation and carbon sequestration of ecologically vulnerable regions.

Bank erosion under the impacts of fluvial erosion, frost heaving/freeze-thaw process of rivers in seasonal frozen regions.

Bank erosion is a key feature of channel evolution in alluvial rivers, and will occur under the combined effect of hydraulic erosion and frost heave/freeze-thaw process of rivers in seasonal frozen regions. However, most research on bank erosion modeling has seldom considered the impact of the frost heave/freeze-thaw process. Therefore, the variation in the mechanical characteristics of riverbank soil under the freeze-thaw cycle was investigated firstly in the current research and then used in the modeling of bank erosion processes at typical sections of the Songhua River. Additionally, a sensitivity analysis of riverbank stability was conducted using orthogonal experiments. The results indicate that after 7 freeze-thaw cycles, the soil cohesion and internal friction angle of bank soil decreased by about 10%-47 % and 9%-19 %, respectively. Unlike lowland rivers, bank erosion of rivers in seasonal frozen regions is more likely to occur during the rising water period. The frost heaving/freeze-thaw process will make the bank stability safety coefficient Fs more quickly decrease to the unstable critical value. As compared with the case without considering the frost heaving/freeze-thaw process, the mass failure occurred in advance when the frost heaving/freeze-thaw process was considered, and the calculated bank erosion volume was increased by 11%-51 %, agreeing better with the measured value. The sensitivity ranking of the four influencing factors on riverbank stability under freezing-thawing conditions is as follows: river stage > groundwater level > cohesion > internal friction angle. The current study can provide a reference for research on bank erosion and channel evolution of rivers in seasonal frozen regions.

Biochar improves the nutrient cycle in sandy-textured soils and increases crop yield: a systematic review.

BACKGROUND: Biochar is a relatively new development in sustainable agricultural management that can be applied to ameliorate degraded and less fertile soils, especially sandy-textured ones, to improve their productivity with respect to crop production through improved nutrient availability. However, as the literature has shown, the response of sandy-textured soils to biochar varies in terms of effect size and direction. Therefore, the present study systematically reviewed the available evidence to synthesize the impact of biochar amendments on aspects of the nutrient cycle of sandy-textured soils. METHODS: Both peer-reviewed and gray literature were searched in English in bibliographic databases, organizational web pages, and Internet search engines. Articles underwent a two-stage screening (title and abstract, and full-text) based on predefined criteria, with consistency checks. Validity assessments were conducted, utilizing specifically designed tools for study validity. Data extraction involved categorizing the various properties of the nutrient cycle into nine main Soil and Plant Properties (SPPs), each of which was studied independently. Nine meta-analyses were performed using a total of 1609 observations derived from 92 articles. Comparing meta-averages with and without correction for publication bias suggests that publication bias plays a minor role in the literature, while some indication for publication bias is found when accounting for heterogeneity by means of meta-regressions. REVIEW FINDINGS: According to the results, soil total and available nitrogen [N], phosphorous [P] and potassium [K], plant nutrient level, and potential cation exchange capacity (CEC) increased by 36% (CI [23%, 50%]), 34% (CI [15%, 57%]), 15% (CI [1%, 31%]), and 18% (CI [3%, 36%), respectively, and N2O emission and mineral nutrient leaching decreased by 29% (CI [- 48%, - 3%]) and 38% (CI [- 56%, - 13%). On average, however, biochar had no effect on soil mineral nitrogen and nutrient use efficiency. Publication bias was identified in the response of effective CEC. After corrections for publication bias, the response shifted from 36% to a negative value of - 34% (CI [- 50%, - 14%]). Meta-regression found that the effect modifiers experimental continent, biochar application rate, and soil pH, explain result heterogeneity. Stronger responses came from the continent of South America, higher application rates, and higher pH soils. Overall, biochar is found useful for many SPPs of nutrient cycling of sandy-textured soils, thereby contributing to increased crop yields in such soils.

Diversity of Microbial Functional Genes Promotes Soil Nitrogen Mineralization in Boreal Forests.

Soil nitrogen (N) mineralization typically governs the availability and movement of soil N. Understanding how factors, especially functional genes, affect N transformations is essential for the protection and restoration of forest ecosystems. To uncover the underlying mechanisms driving soil N mineralization, this study investigated the effects of edaphic environments, substrates, and soil microbial assemblages on net soil N mineralization in boreal forests. Field studies were conducted in five representative forests: Larix principis-rupprechtii forest (LF), Betula platyphylla forest (BF), mixed forest of Larix principis-rupprechtii and Betula platyphylla (MF), Picea asperata forest (SF), and Pinus sylvestris var. mongolica forest (MPF). Results showed that soil N mineralization rates (Rmin) differed significantly among forests, with the highest rate in BF (p < 0.05). Soil properties and microbial assemblages accounted for over 50% of the variability in N mineralization. This study indicated that soil environmental factors influenced N mineralization through their regulatory impact on microbial assemblages. Compared with microbial community assemblages (α-diversity, Shannon and Richness), functional genes assemblages were the most important indexes to regulate N mineralization. It was thus determined that microbial functional genes controlled N mineralization in boreal forests. This study clarified the mechanisms of N mineralization and provided a mechanistic understanding to enhance biogeochemical models for forecasting soil N availability, alongside aiding species diversity conservation and fragile ecosystem revitalization in boreal forests.

Impact of Intercropping Five Medicinal Plants on Soil Nutrients, Enzyme Activity, and Microbial Community Structure in Camellia oleifera Plantations.

Intercropping medicinal plants plays an important role in agroforestry that can improve the physical, chemical, and biological fertility of soil. However, the influence of intercropping medicinal plants on the Camellia oleifera soil properties and bacterial communities remains elusive. In this study, five intercropping treatment groups were set as follows: Curcuma zedoaria/C. oleifera (EZ), Curcuma longa/C. oleifera (JH), Clinacanthus nutans/C. oleifera (YDC), Fructus Galangae/C. oleifera (HDK), and Ficus simplicissima/C. oleifera (WZMT). The soil chemical properties, enzyme activities, and bacterial communities were measured and analyzed to evaluate the effects of different intercropping systems. The results indicated that, compared to the C. oleifera monoculture group, YDC and EZ showed noticeable impacts on the soil chemical properties with a significant increase in total nitrogen (TN), nitrate nitrogen (NN), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). Among them, the content of TN and AK in the rhizosphere soil of Camellia oleifera in the YDC intercropping system was the highest, which was 7.82 g/kg and 21.94 mg/kg higher than CK. Similarly, in the EZ intercropping system, the content of NN and OM in the rhizosphere soil of Camellia oleifera was the highest, which was higher than that of CK at 722.33 mg/kg and 2.36 g/kg, respectively. Curcuma longa/C. oleifera (JH) and Clinacanthus nutans/C. oleifera (YDC) had the most effect on soil enzyme activities. Furthermore, YDC extensively increased the activities of hydrogen peroxide and acid phosphatase enzymes; the increase was 2.27 mg/g and 3.21 mg/g, respectively. While JH obviously increased the urease activity, the diversity of bacterial populations in the rhizosphere soil of the intercropping plants decreased, especially the Shannon index of YDC and HDK. Compared with the monoculture group, the bacterial community abundance and structure of JH and YDC were quite different. The relative abundance of Actinobacteriota and Firmicutes was increased in YDC, and that of Acidobacteriota and Myxococcota was increased in JH. According to the redundancy analysis (RDA), pH, total potassium, and soil catalase activity were identified as the main factors influencing the microbial community structure of the intercropping systems. In conclusion, intercropping with JH and YDC increased the relative abundance of the dominant bacterial communities, improved the microbial community structure, and enhanced the soil nutrients and enzyme activities. Therefore, in the future, these two medicinal plants can be used for intercropping with C. oleifera.

Effect of Organic Manure on Crop Yield, Soil Properties, and Economic Benefit in Wheat-Maize-Sunflower Rotation System, Hetao Irrigation District.

The combined application of manure and mineral fertilizer represents an effective strategy for enhancing crop yield. However, the relationship between soil fertility and crop yield remains unclear in saline-alkaline soil. Here, a 9-year field experiment (2015-2023) was conducted to investigate the effects of manure application and crop rotations on crop yield and economic efficiency as well as potential associated mechanisms in the Hetao Irrigation District. The results showed that in the third cropping rotation cycle, combined application of manure and mineral fertilizers (NPKO) caused a 6.2%, 38.9%, 65.3%, and 132.2% increase in wheat, sunflower, wheat equivalent yield, and the economic income of sunflower, respectively. The average grain yield had a positive correlation with soil organic matter and nutrient supply. This suggested that the soil organic matter had a positive effect on the crop yield due to its impact on nutrient supply. Simultaneously, the sunflower seed setting rate increased by 65.2% under NPKO. The linear regression model revealed that each additional input of 20 Mg ha-1 of manure resulted in an increase of 3.56 kg ha-1 in crop phosphorus harvest and a 0.05 Kg ha-1 increase in wheat equivalent yield compared to NPK. In conclusion, our results highlighted that manure application promotes soil properties and improves crop yield.