Chelate-assisted phytoremediation with biodegradable chelates has been considered to be a promising technique to enhance phytoremediation efficiency, while little information is available on phytostabilization. This study aims to assess NTA-assisted phytostabilization of Pb-contaminated soils by Athyrium wardii (Hook.).
Materials and methodsA pot experiment was carried out to investigate the effects of different application days (1, 3, 5, 7, 10, 14, 21) of nitrilotriacetic acid (NTA) on plant growth, Pb accumulation, and Pb availability in rhizosphere soils of A. wardii grown in soils contaminated with low (200 mg kg?1) and high (800 mg kg?1) concentrations of Pb.
Results and discussionWith the application of NTA, better growth for A. wardii was observed when treated with NTA for 5–14 days for both low and high Pb soils, suggesting potential harvest time. Pb concentrations and Pb accumulation in underground parts of A. wardii grown in low and high Pb soils increased with increasing application time of NTA generally. Similar changes were also found for bioaccumulation coefficients (BCFs) of A. wardii. The greatest remediation factors (RFs) for underground parts and whole plant of A. wardii were observed for NTA application time of 7 and 5 days for low and high Pb soils, suggesting the greatest remediation efficiency. Furthermore, plant growth, BCF, and RF of A. wardii grown in low Pb-contaminated soils were greater than those grown in high Pb-contaminated soils. Pb availability in rhizosphere soils of A. wardii grown in low Pb soils was lower than those in high Pb-contaminated soils.
ConclusionsIt seems to be the optimum for A. wardii to phytostabilize slightly Pb-contaminated soils with the application of NTA for 7 days as taking plant growth, Pb remediation efficiency, and environmental risk into consideration.
相似文献This study assesses the potential of two contrasted fragrant Pelargonium cultivars to induce pH and dissolved organic carbon (DOC) changes in the soil solution, Pb speciation, and their subsequent effects on rhizosphere phytoavailable Pb.
Materials and methodsRooted plantlets were grown in special devices, floating on aerated nutrient solution in PVC tanks. This setup allows roots to be physically separated, through a mesh, from a 3-mm soil matrix layer that can be considered as rhizosphere soil. Two contrasted soils, each spiked with Pb-rich particles, emitted from a battery recycling industry, were used at total burdens of 500 and 1500 mg Pb kg?1 in addition to a control unspiked soil. Soil solution pH, phytoavailable Pb, DOC, Pb adsorption, precipitation on roots, and Pb phases in soil and plant were investigated.
Results and discussionAttar of Roses (Attar) cultivar acidified its rhizosphere by 0.4 pH units in both spiked soils. Concolor Lace (Concolor) was unable to change soil solution pH on soil-1 and increased it by 0.7 units on soil 2. Concentrations of Pb in soil solution from Attar plants were always higher than those of Concolor ones. DOC contents of both unspiked soil-1 and soil-2 without plants were not significantly different. In the case of spiked samples, DOC contents in the rhizosphere soil were increased by three and two times for Attar and Concolor, respectively, compared to the unspiked soil without plant. Both cultivars were able to increase DOC contents, independent of soil type and level of contamination. Accumulation of Pb in shoots and roots was higher in Attar as compared to Concolor due to enhanced available Pb as a result of pH and DOC modifications of the rhizosphere soil. Significant amounts of Pb were adsorbed on roots of both cultivars. X-ray elemental analysis of precipitates on roots revealed the association of Pb with P in cylinder-like structures. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that Pb was present, to a major extent in the inorganic form, mainly as PbSO4 in the soil, whereas it was complexed with organic species within plant tissues. The conversion of Pb into organic species could decrease toxicity, may enhance plant tolerance, and could increase translocation.
ConclusionsPlant-induced changes were responsible for the modification of lead phases within the soil. Immobile forms present in the source leaded particles as well as in the soils were converted into soluble species, ultimately improving the phytoavailable or soil solubilized Pb.
相似文献Decarboxylation of organic anions in crop straw is recognized as one of the mechanisms for increasing pH in acidified soils. However, the effectiveness of specific compounds in alleviating soil acidification from nitrification has not been well determined. This study examined three organic anions commonly found in crop straws and their effect on soil acidity and N transformation processes following urea application to a red soil (Ferralic Cambisol).
Materials and methodsA 35-day incubation experiment was conducted using soil after receiving 26 years of two different nutrient treatments: (1) chemical nitrogen, phosphorus, and potassium fertilization (NPK, pH 4.30) and (2) NPK plus swine manure (NPKM, pH 5.88). Treatments included three rates (0.25, 0.5, and 1.0 g C kg?1) of calcium citrate, 0.5 g C kg?1 calcium oxalate, 0.5 g C kg?1 calcium malate, urea-only (control) soil, and a non-treated soil as a reference. Soil acidity, mineral N species, decarboxylation, and their correlations were determined.
Results and discussionAll three organic anions significantly increased pH in both soils and the effectiveness was positively correlated with application rate. The change in total exchangeable soil acidity was dominated by aluminum concentration in the NPK soil, but by proton concentration in the NPKM soil. At ≥?0.5 g C kg?1, the anions decreased soil exchangeable acidity by 25–68% in NPK soil and by 63–88% in NPKM soil as compared with control. Oxalate was the most effective in increasing soil pH by 0.70 and 1.31 units and reducing exchangeable acidity by 3.79 and 0.33 cmol(+) kg?1 in NPK and NPKM soils, respectively, and also resulted in the highest CO2 production rate. Addition of organic anions led to a lower nitrification rate in NPKM soil relative to the NPK soil.
ConclusionsThese results imply that crop straws rich in organic anions, especially oxalate, would have a higher potential to alleviate soil acidification.
相似文献Elevated CO2 and nitrogen (N) addition both affect soil microbial communities, which significantly influence soil processes and plant growth. Here, we evaluated the combined effects of elevated CO2 and N addition on the soil–microbe–plant system of the Chinese Loess Plateau.
Materials and methodsA pot cultivation experiment with two CO2 treatment levels (400 and 800 μmol mol?1) and three N addition levels (0, 2.5, and 5 g N m?2 year?1) was conducted in climate-controlled chambers to evaluate the effects of elevated CO2 and N addition on microbial community structure in the rhizosphere of Bothriochloa ischaemum using phospholipid fatty acid (PLFA) profiles and associated soil and plant properties. Structural equation modeling (SEM) was used to identify the direct and indirect effects of the experimental treatments on the structure of microbial communities.
Results and discussionElevated CO2 and N addition both increased total and fungal PLFAs. N addition alone increased bacterial, Gram-positive, and Gram-negative PLFAs. However, elevated CO2 interacting with N addition had no significant effects on the microbial community. The SEM indicated that N addition directly affected the soil microbial community structure. Elevated CO2 and N addition both indirectly affected the microbial communities by affecting plant and soil variables. N addition exerted a stronger total effect than elevated CO2.
ConclusionsThe results highlighted the importance of comprehensively studying soil–microbe–plant systems to deeply reveal how characteristics of terrestrial ecosystems may respond under global change.
相似文献There is little knowledge on the organic matter fractions of salt-affected soil aggregates. This study aimed at investigating characteristics of salt-affected soil organic carbon components and the relationships between soil salt concentration and soil organic carbon component content.
Materials and methodsFive typical salt-affected soils in Hetao region China were collected and analyzed for light (LF) and heavy fraction (HF) in different water-stable aggregates. And the soil organic carbon components were measured by Fourier transform infrared (FTIR) and pyrolysis-gas chromatography/mass spectrometer (Py–GC/MS).
Results and discussionThe results showed that the salt-affected soils were dominant in 53–10-μm water-stable aggregates, 61–80% in the bulk soil, and very low in >?250-μm macro-aggregates, less than 7.06% in the bulk soil. The proportions of >?250-μm macro-aggregates and the mean weight diameter (MWD) were negatively correlated to Na+ concentration (p?<?0.05). Furthermore, the macro-aggregates were generally higher in total organic carbon (TOC) and accordingly higher C/N ratio than those in micro-aggregates. Heavy fractions (HF) from both >?53 μm and <?53-μm soil aggregates accounted for 99.30–99.83% of the bulk soil and contained 89.6–98.5% lower TOC and accordingly 49.2–84.8% lower C/N ratio than those in light fractions (LF). The LFs were high in lignin (7.27–34.02% in total pyrolysis products, 19.89% on average) and alkane/alkene-derived compounds (9.51–37.21%, 23.18% on average), but low in N-containing compounds (0–3.64%, 1.71% on average), while HFs were high in both alkane/alkene (4.38–27.46%, 15.06% on average) and N-containing compounds (7.45–26.45%, 13.98% on average), but low in lignin-derived compounds (1.13–8.75%, 3.86% on average).
ConclusionsThe tested salt-affected soils were predominant in 53–10-μm micro-aggregates, which was caused by the Na+ dispersion effect on soil aggregates. Most SOM was stored in HF that contained high N-containing compounds and low C/N ratios. Our results suggested that the components of SOM were mainly controlled by the soil Na+ concentration.
相似文献Being carbon-rich and porous, biochar has the potential to improve soil physical properties, so does conventional farming practice. Here, a field trial was conducted to investigate the combined effects of biochar use and farming practice on the physical properties of a salt-affected compact soil for wheat–maize rotation in the Yellow River Delta region.
Materials and methodsSalix fragilis L. was used as feedstock to produce biochar in the field via aerobic carbonization at an average temperature of 502 °C, terminated by a water mist spray, for use as a soil amendment at 0, 1, 2, and 4 g kg?1 doses (CK, T1, T2, and T3, respectively). Farming practices included rotary tillage/straw returning for wheat sowing, spring irrigation, no-tillage seeding of maize, and autumn irrigation. Both cutting ring and composite samples of the soil were collected at four stages of wheat–maize rotation (22, 238, 321, and 382 d after the benchmark date of land preparation for wheat sowing) for the determination of soil properties by established methods.
Results and discussionRotary tillage/straw returning reduced soil bulk density (BD) from 1.48 to 1.27 g cm?3 (CK) and 1.14 g cm?3 (T3) and increased saturated hydraulic conductivity (Ks) from 0.05?×?10?5 to 0.75?× 10?5 cm s?1 (CK) and 1.25?× 10?5 cm s?1 (T3). This tillage effect on BD and Ks gradually disappeared due to the disturbance from the subsequent farming practice. Biochar use lessened the disturbance. At maize harvest, BD was 1.47 (CK) vs. 1.34 g cm?3 (T3), and Ks was 0.06?×?10?5 (CK) vs. 0.28?×?10?5 cm s?1(T3); in comparison with CK, T3 increased Na+ leaching by 65%, Cl? leaching by 98%, organic carbon content by 40.3%, and water-stable aggregates (0.25–2 mm) by 38%, indicating an improvement in soil properties.
ConclusionsBiochar use and rotary tillage improved soil physical properties (BD, Ks) and favored soil aeration, water filtration, and salt leaching, which further helped the accumulation of soil organic carbon, the formation of water-stable aggregates, and the amelioration of salt-affected compact soil.
相似文献Phosphorus (P) and potassium (K) are two important essential nutrient elements for plant growth and development but their availability is often limited in calcareous soils. The objective of this study was to determine the effects of applying microbial inoculants (MI, containing effective strains of Bacillus megaterium and Bacillus mucilaginous) on the availability of P and K, plant growth, and the bacterial community in calcareous soil.
Materials and methodsA greenhouse experiment was conducted to explore the effects of the addition of MI (control: without MI addition; treatment: with MI addition at the rate of 60 L ha?1) on the concentrations of P and K in soil and plant, soil bacterial community diversity and composition, and chili pepper (Capsicum annuum L.) growth.
Results and discussionThe results showed that MI inoculation significantly increased the fruit yields by 28.5% (p?<?0.01), available P and K in the rhizosphere soil by 32.1% and 28.1% (p?<?0.05), and P and K accumulation in the whole plants by 40.9% and 40.2%, respectively (p?<?0.05). Moreover, high-throughput sequencing revealed that Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, and Gemmatimonadetes were the dominant phyla of soil bacteria. MI application did not significantly impact the diversity and composition of soil bacterial communities, but increased relative abundances of bacterial genera Flavobacterium responsible for promoting root development across growing stages (p?<?0.05), and changed the soil bacterial community structure associated closely with soil properties of available P, K, and pH in soil.
ConclusionsThe application of MI improved the bioavailability of P and K and plant growth due to its impact on the soil bacterial community structure.
相似文献Characterization of tannery sludge (TS) for its plausible use in amelioration and phytoremediation of heavy metal rich TS treated soil by growing economically important plants (Ricinus communis, Brassica juncea and Nerium oleander).
Materials and methodsTreatments were prepared by amalgamation of TS (0, 5, 10, 20, 30, 50, 75, 100 %) with garden soil (GS). All treatments were analysed for chemical properties, total and DTPA (Diethylene triamine pentaacetic acid) extractable heavy metals (Cr, Pb, Cu, and Mn). Seed germination experiment was conducted; unvarying saplings were selected and planted in concerned pots and allowed to grow for 90 days in green house. At harvest, plant samples were washed with distilled water and used for determination of growth parameters (biomass of root, shoot and total biomass on dry weight basis) and metal accumulation in different parts of the plant. Translocation factor (TF) and bioconcentration factor (BCF) have been calculated to check the phytostabilization capability of studied plants.
Results and discussionApplication of TS in fixed quantity as an amendment resulted in significant improvements of GS characteristics (alkaline pH with high electrical conductivity, organic carbon, available NPK and heavy metals) and in treatments. DTPA extractable heavy metal concentrations were found very low and total heavy metal concentrations were also found under allowable range in control and treated soil (T-I to T-VI). The maximum seed germination percentage, plant growth, biomass production for all plant species were observed in T-III treatment (20 % TS + 80 % GS) with majority of the metal accumulation in underground part (BCF >1) and meagre translocation in aerial part (TF <1). From T-IV to T-VII treatment, accumulation of heavy metals in plant parts has generally increased; however, biomass has been tremendously decreased.
ConclusionsTS was found rich in NPK content with significant concentration of heavy metals. Pot growth experiment suggested amelioration of GS with specific quantity of 20 % TS can tremendously enhance the plant growth, help in the utilization of TS and can act as a substitute of synthetic fertilizer. Majority of the metals was accumulated in root part (BCF >1) and meagre translocation (TF <1) in aerial part, concludes R. communis and B. juncea could be suitable plant species to be grown in heavy metal rich TS treated soil, vis-à-vis for phytostabilization of heavy metals. In addition, these oil yielding and medicinal plants can also be used for phytoremediation of moderately contaminated tannery soils.
相似文献Imidacloprid is a widely used seed dressing insecticide in Brazil. However, the effects of this pesticide on non-target organisms such as soil fauna still present some knowledge gaps in tropical soils. This study aimed to assess the toxicity and risk of imidacloprid to earthworms Eisenia andrei and collembolans Folsomia candida in three contrasting Brazilian tropical soils.
Materials and methodsAcute and chronic toxicity assays were performed in the laboratory with both species in a tropical artificial soil (TAS) and in two natural soils (Oxisol and Entisol), at room temperature of 25 °C. The ecological risk was calculated for each species and soil by using the toxicity exposure ratio (TER) and hazard quotient (HQ) approaches.
Results and discussionAcute toxicity for collembolans and earthworms was higher in Entisol (LC50?=?4.68 and 0.55 mg kg?1, respectively) when compared with TAS (LC50?=?10.8 and 9.18 mg kg?1, respectively) and Oxisol (LC50collembolans?=?25.1 mg kg?1). Chronic toxicity for collembolans was similar in TAS and Oxisol (EC50 TAS?=?0.80 mg kg?1; EC50 OXISOL?=?0.83 mg kg?1), whereas higher toxicity was observed in Entisol (EC50?=?0.09 mg kg?1). In chronic assays with earthworms, imidacloprid was also more toxic in Entisol (EC50?=?0.21 mg kg?1) when compared to TAS (EC50?=?1.89 mg kg?1). TER and HQ values indicated a significant risk of exposure of the species to imidacloprid in all soils tested, and the risk in Entisol was at least six times higher than in Oxisol or TAS.
ConclusionsThe toxicity and risk of imidacloprid varied significantly between tropical soils, being the species exposure to this pesticide particularly hazardous in very sandy natural soils such as Entisol.
相似文献Metallic nanomaterials (MNM) like cobalt oxide (nano-Co3O4) are currently attracting enormous interest owing to their unique size and shape-dependent properties and potential applications in various sectors. The aims of this study were to assess the toxicity of nano-Co3O4 and to propose a risk limit through the estimation of a Predicted No Effect Concentration (PNEC) for this MNM to soil biota.
Materials and methodsFor this purpose, a battery of sub-lethal ecotoxicological tests was performed to assess the influence of this MNM on four plant species (endpoints: germination and growth) and two invertebrate species (endpoints: avoidance and reproduction) following standard protocols. Further, biochemical endpoints (acetylcholinesterase [AChE], catalase [CAT], glutathione-S-transferase [GST] activity, and lipid peroxidation [LPO]) were also assessed in Eisenia andrei, one of the invertebrate species tested, in order to contribute for refining the PNEC value.
Results and discussionThe recorded data showed a significant inhibition in the germination of L. lycopersicum and in the growth of Z. mays, even at the lowest concentration tested (269.3 mg kg?1 soildw of nano-Co3O4). Concerning the soil invertebrates, the results showed only significant avoidance (p?<?0.05) by E. andrei in the soil contaminated with the highest concentration tested (1000 mg kg?1 soildw of nano-Co3O4), while no significant ecotoxicological effect on reproductive outputs of both species was recorded. However, the data reported for AChE, CAT, GST, and LPO showed significant effects at the range of concentrations tested in E. andrei. Thus, we recorded, the occurrence of oxidative stress and the enhancement of lipid peroxidation, on this invertebrate species.
ConclusionsThe data obtained in this study supports the proposal of a PNEC value of 9.1 mg kg?1 soildw for nano-Co3O4 in soil. The integration of data from biochemical endpoints allowed the refinement of the PNEC value and to obtain a more protective threshold.
相似文献The iron redox cycle is closely tied to the fate of carbon in terrestrial ecosystems, especially paddy soils. Varies diurnally and seasonally, light—the crucial environmental factor—may be a fundamental factor elucidating temporal and spatial variabilities of carbon-containing gases emission. The role of sunlight in the iron-mediated carbon cycle, however, has not been fully elucidated. We conduct this study to test the role of light in the iron-mediated carbon cycling.
Materials and methodsIn this study, we conducted anaerobic incubation experiments of a calcareous paddy soil in serum vials under alternating dark and light conditions. The dynamic evolution of the carbon and iron contents was evaluated by measuring the CO2, CH4, and O2 concentrations in the headspace of the vials, as well as the water-soluble inorganic carbon, microbial biomass carbon, and HCl-extractable ferrous iron contents in soil slurries. We also analyzed the soil microbial community structure by high-throughput 16S rRNA gene sequencing.
Results and discussionThe results highlighted the positive correlation between carbon mineralization and ferric iron reduction under dark conditions. Under light conditions, however, ferrous iron was oxidized by the O2 generated via oxygenic photosynthesis of phototrophic bacteria such as Cyanobacteria, along with a decreased production of CO2, CH4, and water-soluble inorganic carbon. The abundance of Cyanobacteria positively correlated to O2 levels and MBC content significantly. Light-induced periodic variations in the redox conditions facilitated carbon fixation in microbial biomass and up to 31.79 μmol g?1 carbon was sequestrated during 30 days light incubation.
ConclusionsThese results indicate that light inhibits the emission of carbon-containing greenhouse gases associated with the iron redox cycle in calcareous paddy soil. Assimilation of inorganic carbon by phototrophs may responsible for the inhibition of carbon mineralization. Our study suggests that procedures allowing more light to reach the soil surface, for instance, reducing the planting density, may mitigate greenhouse gas emissions and promote carbon sequestration in paddy soils.
相似文献Prescribed burning is a forest management practice which can lead to nitrogen (N)-limited conditions. This study aimed to explore whether biological N2 fixation (BNF) remained the main source of N acquisition for two understorey Acacia species in a Eucalyptus-dominated suburban forest of subtropical Australia, 3 to 6 years after prescribed burning. Root-nodule bacteria associated with these acacias were also characterised to unravel the differences in rhizobial communities between sites and species.
Material and methodsTwo sites, burned 3 and 6 years before sample collection, were selected within a dry subtropical forest of south-east Queensland, Australia. Leaves were collected from individuals of Acacia disparrima and A. leiocalyx at each site to determine leaf total carbon (C) and N content, C and N isotope composition (δ13C and δ15N) and the percentage of N derived from atmospheric N2. Nodules were harvested from both acacia species at each site to isolate root nodule bacteria. Bacterial isolates were processed for 16S rDNA gene sequencing.
Results and discussionGenerally, no differences were found in plant physiological variables between the two acacia species. Six years after the fire, both species still depended upon BNF for their N supply, with a higher dependence in winter than in summer. Fire, although of low intensity, was likely to have created a N-limited environment which induced the reliance of legumes on BNF. Root nodule bacteria were dominated by non-rhizobial endophytes, mainly from the Firmicutes phylum. No difference in nodule bacterial diversity was found between sites. The relative abundance of rhizobial genera varied amongst plant species and sites, with a shift in dominance from Bradyrhizobium to Rhizobium species between sites 1 and 2.
ConclusionsOur results show that even 6 years after burning, ecosystem remained under N stress and BNF was still the main mechanism for N acquisition by the understorey legumes.
相似文献Without precaution to deal with gas emissions and leachate generation, dumpsites have become a severe environmental problem in many developing countries. The objectives of this study were to investigate the pollution status of polycyclic aromatic hydrocarbons (PAHs) in dumpsite soil in rural areas of China and to verify phytoremediation effectiveness with Sedum alfredii Hance and alfalfa (Medicago sativa L.) under complex pollution conditions in PAH-contaminated soil.
Materials and methodsIn this study, we collected soil cores from four dumpsites in rural areas of North China (Hebei Province) for analysis, and correspondingly conducted an in situ phytoremediation experiment using Sedum alfredii Hance and alfalfa (Medicago sativa L.) at one of these sites, monitoring the total PAH concentration in soil.
Results and discussionResults showed generally moderate pollution by PAHs in soil samples from dumpsites with pockets of heavy pollution. PAH concentrations in dumpsite soil ranged from 827 to 1101 ng/g (dry weight). High-molecular-weight PAHs were present in higher proportions at oldest dumpsite in operation. Certain molecular ratios of PAHs can be used to diagnose the source of PAHs in soil, and it indicated that the main sources were combustion of domestic coal and biomass, as well as the automobile exhaust and kitchen exhaust. A 17-month in situ phytoremediation experiment resulted in the effective removal of PAHs in the Sedum alfredii and alfalfa plots, with total PAH concentrations decreasing by 82.4% and 81.3%, respectively. Furthermore, PAH concentrations in plants correlated to plant growth conditions.
ConclusionsThis study indicated that the soils of the dumpsites were generally moderately polluted by PAHs, and some parts of the area were heavily polluted. Both Sedum alfredii and alfalfa absorbed PAHs from soil, and PAH concentrations in these two plants correlated to the growth conditions of the plants. Phytoremediation can effectively be used for PAH removal in open dumpsites.
相似文献Many studies have shown the simulated effects of nitrogen (N) deposition on soil microbial community composition by adding N directly to the forest floor but have ignored the N retention process by the canopy. This study was conducted to compare the responses of soil microbial biomass and community composition between soil application of N (SAN) and foliage application of N (FAN).
Materials and methodsA pot experiment was designed with (1) two N application methods (SAN and FAN), (2) three N application levels (5.6, 15.6 and 20.6 g N m?2 year?1), and (3) two tree species (Schima superba Gardn. et Champ. and Pinus massoniana Lamb.) following a nested factorial design. Soil microbial biomass and community composition were determined using phospholipid fatty acids (PLFAs) techniques after 1 and 1.5 years of treatments.
Results and discussionNitrogen addition increased (P?<?0.05) soil NH4+-N content and soil NO3?-N content and decreased (P?<?0.05) soil pH and soil microbial (bacterial, fungal, and actinomycete) biomass for both N application methods. Compared with the SAN treatment, the FAN treatment had higher (P?<?0.05) pH and lower (P?<?0.05) contents of soil NH4+-N and soil NO3?-N. Soil microbial biomass and community composition were significantly different between the different N addition levels under the SAN treatment, but they showed no significant difference (P?<?0.05) between the different N addition levels under the FAN treatment. The soil microbial biomass in the S. superba soil was higher (P?<?0.05) than that in the P. massoniana soil for the FAN treatment, with the opposite trend observed under the SAN treatment. Moreover, redundancy analysis showed that soil microorganisms were significantly correlated with soil pH, soil water content, NH4+-N, and NO3?-N.
ConclusionsThe results showed that N addition affected soil properties, microbial biomass, and the composition of microbial communities; however, the FAN treatment had less influence on soil properties and soil microorganisms than did the SAN treatment over short time scales, and the extent of this effect was different between coniferous and broadleaf trees.
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