Excessive fluorine accumulation poses a significant threat to soil ecology and even human health, yet its impact on soil fauna, especially earthworms, remains poorly understood. This study employed multi-omics and biomarkers to investigate high fluorine-induced biochemical changes that cause tissue damages in Eisenia fetida. The results demonstrated that earthworms exhibited obvious damage with fluorine addition exceeding 200 mg kg(-1), with stress levels escalating as fluorine contents increased. Further analysis of the underlying mechanisms revealed that fluorine could upregulate genes encoding mitochondrial respiratory chain complexes I-III and downregulate those for IV-V, leading to reactive oxygen species (ROS) accumulation despite antioxidant system activation. The resulting ROS interfered with deoxyribonucleoside triphosphate synthesis, prompting homologous recombination as the main DNA repair mechanism. Additionally, fluorine-induced ROS also attacked and disrupted protein and lipid related metabolisms ultimately causing oxidative damages. These cumulative oxidative damages from high fluorine contents subsequently triggered autophagy or apoptosis, resulting in tissue ulceration and epithelial exfoliation. Therefore, high fluorine could threaten earthworms by inducing ROS accumulation and subsequent biomolecule damages.

Soil nitrogen-hydrolyzing enzymes catalyzes a key rate-limiting step in regulating the circulation of soil nutrient elements. The response of soil nitrogen (N)-hydrolyzing enzyme activities to environmental changes has been investigated in different geographic scales or ecosystems. Global warming has increased the frequency of soil freeze-thaw (FT) events, resulting in drastic changes in soil enzyme activities. Clarifying the changes in soil N-hydrolyzing enzymes under freeze-thaw conditions is essential for improving the N cycling and utilization efficiency in soil. However, how soil N-hydrolyzing enzymes respond to FT remains unclear. This study was aimed to analyze the influence of FT on soil N-hydrolyzing enzyme activity in Mollisols. The results showed that soil physicochemical properties and enzyme activities were changed after freeze-thaw events, and freeze-thaw temperature (FTF) had a greater impact on these properties than the number of freeze-thaw cycles (FTC). Correlation analysis showed that total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and pH were the major factors affecting enzyme activities in FT events. Soil N-hydrolyzing enzyme activity was mainly regulated by environmental factors, which can directly and indirectly affect the soil enzyme activity. In the soil ecosystem, pH, TOC, TN and TP were important factors in counteracting damage to enzyme activity from FT effects and a suitable environment and adequate nutrients can limit damage to enzymes from FT events. The findings will better predictions the changing patterns of climate change on soil N-hydrolyzing enzyme activity.

These days, one of the main issues preventing agricultural development is salinized soils. Potassium fulvic acid (PFA) not only regulates plant growth, but also improves the soil nutrient content and physical structure, which makes it a soil conditioner worth promoting. Nevertheless, the research conducted thus far on the subject of PFA with regard to plant growth and inter-root microbial communities remains somewhat limited in scope. In this study, a pot experiment was conducted to simulate both the normal environment and salt stress environment. The objective of this experiment was to verify the effect of PFA on the growth of blueberry (Vaccinium corymbosum L.) as well as its effect on the soil physical and chemical indices and the soil microbial community structure. The findings demonstrated that the implementation of potassium fulvic acids exhibited a minimal impact on the growth of blueberry plants under standard environmental conditions. However, it was observed to exert a substantial effect on enhancing various physiological parameters, including plant height, root activity, and chlorophyll synthesis, particularly in response to salt stress. PFA led to a substantial augmentation in the soil organic matter content, alongside a notable rise in the alkali-hydrolyzable nitrogen (AN) and available potassium (AK) content. Concurrently, PFA caused a notable escalation in the activities of soil urease, sucrase, acid phosphatase, and catalase (p < 0.05) in the salt-stressed environment. PFA increased the abundance of Acidobacteria, Myxococcota, Ascomycota, and Fungi_phy_Incertae_sedis under salt stress, which was mainly related to the decrease in electrical conductivity (EC) values and increase in soil acid phosphatase (S-ACP) activity. It is evident that the implementation of PFA is advantageous in enhancing the saline environment, mitigating the impact of salt damage on blueberries and establishing a foundation for the expansion of cultivated areas and the sustainable cultivation of blueberries.

This research investigated the impact of various mixed sowing combinations on soil nutrients and grass yield within the rhizosphere across different seasons. Three varieties of leguminous forages-Medicago sativa 'Gannong No. 3' (GN3), M. sativa 'Gannong No. 9' (GN9), and M. sativa 'Juneng No. 7' (JN7)-as well as three varieties of grasses-Leymus chinensis 'Longmu No. 1' (LC), Agropyron mongolicum 'Mengnong No. 1' (AC), and Bromus inermis 'Yuanye' (BI)-were used as experimental materials for mixed sowing combinations; the monocultures of each material served as controls. We explored the seasonal effects of different legumes and grasses intercropping combinations on rhizosphere soil nutrients and grass yield in the Hexi Corridor region of China. The results indicated that the levels of soil enzyme activity, microbial biomass, and soil nutrients in the rhizosphere across the various treatments followed the following sequence: summer > spring > autumn. The soil enzyme activities and microbial biomass of various mixed sowing combinations were significantly higher than those of the monocultures within the same growing season (p < 0.05). Specifically, the activities of alkaline phosphatase (APA), catalase (CAT), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil microbial biomass phosphorus (SMBP), soil organic matter (SOM), available nitrogen (AN), available phosphorus (AP), and available potassium (AK) within the GN9+BI group were the highest among all treatments. The hay yields of GN3, GN9, and JN7 were markedly greater than those of their respective mixed sowing combinations (p < 0.05). Correlation analysis revealed a positive relationship between enzyme activities, microbial biomass, and soil nutrient levels. This comprehensive evaluation indicated that the mixed sowing combinations of GN9 + BI and GN9 + LC are particularly well suited for widespread adoption in the Hexi Oasis irrigation area.

Salt stress threatens global food security, and although plant growth-promoting rhizobacteria (PGPR) can boost plant resistance and productivity, their field effects are poorly understood. Therefore, this experimental trial explored the mechanisms of PGPR-induced salt stress resistance on ion homeostasis, the photosynthetic system, enzymatic activities, and rhizosphere diversity in rice. The study was conducted in the first week of May 2022, using rice (Tongxi 945) seeds, which were pelleted at the seedling nursery and cultivated in the field under salinity conditions (0.5 and 2.35 g kg- 1) with (+) or without (-) PGPR treatment. Na+/K+ concentrations, photosynthetic, leaf water potential, enzymatic activities, and changes in rhizosphere microorganisms were measured at the heading stage of rice. The findings of this study revealed that salinity stress significantly increased Na+ concentrations in leaves (257.70%), the leaf Na+/K+ ratio (567.96%), and leaf water potential (63.47%) while markedly reducing the net photosynthetic rate (71.72%), stomatal conductance (81.36%), thousand-grain weight (2.22%), and yield (114.15%). However, the application of PGPR mitigated the adverse effects of salinity stress by reducing Na+ concentrations in roots (45.22%) and leaves (26.20%), the root Na+/K+ ratio (64.68%), and leaf water potential (31.39%). PGPR also significantly improved the net photosynthetic rate (29.75%), stomatal conductance (46.89%), transpiration rate (25.56%), and chlorophyll content (11.95%). Applying PGPR significantly enhanced antioxidant enzyme activity, regulated carbon metabolism, increased microbial diversity in rhizosphere soil, and boosted the abundance of dominant fungal genera, alleviating salt stress damage to rice. Overall, PGPR improves microbial diversity, photosynthesis, and enzyme activities, mitigating salt stress effects. Further research is necessary to implement these findings in agriculture and evaluate their long-term impacts on crop productivity and soil health.

Perennial planting of kiwifruit can easily lead to soil quality deterioration. To mitigate the negative effects of long-term kiwi cultivation on the soil, spring wheat straw is used to return to the field. The results showed that the longer the duration of straw returning to the field, the more pronounced the effect on soil quality improvement. The contents of SOM, AP, TN, and Alkaline-N were significantly higher in the Y10 plot (10-year-old kiwifruit plot) than in the Y1 plot (1-year-old kiwifruit plot) and the Y6 plot (6-year-old kiwifruit plot). The contents of these nutrients are 189.16%, 110.91%, 98.65% and 41.03% higher than Y1, respectively. Straw returning increased soil nutrients and enzyme activities (S-NP, S-SC and S-CL) and reduced soil acidification. Straw-returning treatment also enriched beneficial microbial groups (Ascomycota, Basidiomycota, Streptophyta, Mucoromycota, etc.) and changed functional groups and cellulolysis related to environmental stress. PLS-PM analysis showed that the years of straw returning to the field affected soil microorganisms' composition and functional adaptability by affecting soil nutrients and enzyme activities. These findings provide a feasible way to solve the problem of soil quality damage caused by long-term planting of kiwifruit.

To comprehensively understand the toxic effects and ecological risks of microplastics on major economic tree species, a pot experiment was conducted using polylactic acid (mPLA) microplastics as the test object to explore the effects of different concentrations (0.1%, 0.5%, 1%, 5%, 10%, w/w, mass fraction) of microplastics on the growth and physiological characteristics of mulberry trees. The study results showed that, compared with the control group, the biomass, total chlorophyll content, and net photosynthetic rate of mulberry trees in the mPLA treatment group were significantly reduced under high concentration (10%) treatment; the activities of SOD and CAT and the MDA content were significantly increased by 50.00%, 47.83%, and 60.87%, respectively, at a 10% concentration. The results indicate that the toxic effects of microplastic addition on mulberry trees are related to the type and concentration of microplastics. High concentrations of mPLA can damage the photosynthetic system of plants, affecting photosynthesis, causing oxidative damage and thus inhibiting the growth of mulberry plants.

Nitrogen fertilizers have a significant impact on the growth of rice. The overuse and inappropriate application of nitrogen fertilizers have resulted in environmental pollution, in addition to subjecting both humans and livestock to negative health hazards. Finding a viable substitute for traditional nitrogen fertilizers is crucial and essential to help improve crop yield and minimize environmental damage. Nano-nitrogen fertilizers offer a possible alternative to traditional fertilizers due to a slow/controlled release of nitrogen. The present work aimed to study the effect of a slow-release urea nanofertilizer on soil ammonical (NH4-N) and nitrate-N (NO3-N) content, culturable soil microflora, and soil enzyme activities in three different soil samples procured from Ludhiana and Patiala districts through a soil column study. Seven treatments, including 0, 50 (75 kg/ha N), 75 (112.5 kg/ha N), and 100% (150 kg/ha N) of the recommended dose (RD) of conventional urea and nano-urea fertilizer were applied. The leachate samples collected from nano-urea treatment exhibited NH4-N for the first two weeks, followed by NO3-N appearance. The higher NH4-N and NO3-N contents in the leachate were recorded for light-textured soil as compared to medium- and heavy-textured soil samples. The soil microbial counts and enzyme activities were recorded to be maximum in light-textured soils. Therefore, this slow-release formulation could be more useful for light-textured soils to decrease applied N-fertilizer losses, as well as for improving the soil microbial viable cell counts and soil enzyme activities. The effect of urea nanofertilizer on the growth and yield of direct-seeded rice (Oryza sativa L.) was also evaluated under field conditions. Both studies were performed independently. Numerically, the highest shoot height, fresh and dry shoot weight, and significantly maximum total chlorophyll, carotenoid, and anthocyanins were recorded in the T2 (100% RDF through nano-urea) treatment. The yield-attributing traits, including the number of filled grains and thousand-grain weight, were also recorded to have increased in T2 treatment. A numerical increase in NPK for plant and grain of rice at 100% RDN through nano-urea was recorded. The soil application of the product exhibited no negative effect on the soil microbial viable cell count on different doses of nano-urea fertilizer. The soil nitrogen fixer viable counts were rather improved in nano-urea treatments. The results reflect that nano-urea fertilizer could be considered as a possible alternative to conventional fertilizer.

The manual addition of lime to soil, in addition to tree planting and fertilization have been the dominant strategy described in restoration protocols for ecosystems damaged by acid rain and metal contamination. Investigations on aerial-limed soils in inaccessible lands are limited. The objective of this study was to assess the effects of aerial liming on soil pH, organic matter, microbial biomass, and enzymatic activities, and aboveground plant population quality in metal-contaminated lands in northern Ontario, Canada. Soil samples were collected from three sites around the City of Greater Sudbury with each pair being composed of a reclaimed (areal-limed) site and an adjacent undisturbed (unlimed) area. Soil physico-chemistry, microbial biomass (assessed by Phospholipid fatty acid analysis) and enzymatic activities were analyzed. Soil pH was higher in limed sites compared to unlimed at recently restored sites (Baby Lake and Wahnapitae) but not at the oldest reclaimed site (HWY 80 N). Organic matter was higher in limed areas compared to the unlimed reference site only at most recently reclaimed site at Baby Lake. Aboveground plant population health was visibly improved in limed sites compared to unlimed areas. Metal concentrations of iron (Fe) and arsenic (As), total microbial biomasses, gram-negative bacterial, fungal, and eukaryotic biomasses were all significantly increased in the limed soils compared to the unlimed samples. The same trend was observed for the activities of three of the enzymes tested, beta-N-acetylglucosaminidase (BG), aryl sulfatase (AS), and glycine aminopeptidase (GAP). Interestingly, strong positive correlations between the levels of soil organic matter, microbial biomasses, and NAGase and ALP activities were observed. Although expensive, aerial liming is effective in restoring inaccessible sites impacted by smelting operations where other methods cannot easily be used.

Nitrogen deposition and drought significantly influence plant growth and soil physicochemical properties. This study investigates the effects of nitrogen deposition and water stress on the growth and physiological responses of Quercus dentata, and how these factors interact to influence the overall productivity. Two-year-old potted seedlings were selected to simulate nitrogen deposition and water stress. Nitrogen was applied at rates of 0 kgha-1year-1 (N0) and 150 kgha-1year-1 (N150). The levels of water stress corresponded to 80% (W80), 50% (W50), and 20% (W20) of soil saturation moisture content. High nitrogen (N150) significantly increased stem elongation and stem diameter by enhancing photosynthetic parameters, including P n (W80) and G s (W50), and maintained higher water use efficiency. Under drought conditions, nitrogen enhanced leaf water content, stabilized electrical conductivity, regulated antioxidant enzyme activity, and increased the accumulation of proline. However, under severe drought, nitrogen did not significantly improve biomass, highlighting the critical role of water availability. Additionally, increased nitrogen levels enhanced soil enzyme activity, facilitated the uptake of crucial nutrients like K and Zn. Mantel tests indicated significant correlations between soil enzyme activity, water use efficiency, and leaf Fe content, suggesting that nitrogen deposition altered nutrient uptake strategies in Q. dentata to sustain normal photosynthetic capacity under water stress. This study demonstrates that nitrogen deposition substantially enhances the growth and physiological resilience of Q. dentata under W50 by optimizing photosynthetic efficiency, water use efficiency, and nutrient uptake. However, the efficacy of nitrogen is highly dependent on water availability, highlighting the necessity of integrated nutrient and water management for plant growth.