不同土地利用方式下土壤微生物群落水平生理图谱(CLP)与土壤碳、氮有效性之间的相互关系

The goal of this work was to assess soil microbial respiration, determined by the assay of community-level physiological profiling in an oxygen-sensitive microplate (O₂-CLPP), in response to endogenous C and several individual C substrates in the soils with different organic C contents (as a function of soil type and management practice). We also used the O₂-CLPP to determine the respiratory response of these soils to endogenous C and amended C substrates with N addition. A respiratory quotient (RQ) was calculated based on the ratio of the response to endogenous soil C vs. each C-only substrate, and was related to total organic carbon (TOC). For assessing N availability for microbial activity, the effect of N supplementation on soil respiration, expressed as N_ratio, was calculated based on the response of several substrates to N addition relative to the response without N. Soils clustered in 4 groups after a principal component analysis (PCA), based on TOC and their respiratory responses to substrates and endogenous C. These groups reflected differences among soils in their geographic origin, land use and C content. Calculated RQ values were significantly lower in natural forest soils than in managed soils for most C-only substrates. TOC was negatively correlated with RQ (r = - 0.65), indicating that the soils with higher organic matter content increased respiratory efficiency. The N addition in the assay in the absence of C amendment (i.e., only endogenous soil C present) had no effect on microbial respiration in any soil, indicating that these soils were not intrinsically N-limited, but substrate-dependent variation in N_ratio within soil groups was observed.     

Effect of chloropicrin fumigation on microbial communities evaluated by community-level physiological profile and the resistance against fusarium wilt

Different microbial communities characterized by the Biolog pattern were developed in the rhizosphere of radish grown on a rockwool hydroponic system treated with chloropicrinfumigated and non-fumigated soil suspensions although no differences were observed in their viable counts. Different microbial communities also were developed in the rhizosphere and non-rhizosphere. After the development of microbial communities in the rhizosphere, bud cells of Fusarium oxysporum that causes vascular wilt of radish plants were inoculated, and disease symptoms were examined. Treatment with the non-fumigated soil suspension was much more effective than that with the fumigated one in controlling the disease, indicating that the Biolog method might be applicable to characterize microbial communities that control the disease caused by F. oxysporum.     

生物质炭对土壤N2O消耗的影响及其微生物影响机理

生物质炭在温室气体减排方面具有很大的发展前景,它不仅能实现固碳,对于在大气中停留时间长且增温潜势大的N₂O也能发挥积极作用。本研究采用室内厌氧培养试验,按照生物质炭与土壤质量比（0、1%和5%）加入一定量生物质炭,土壤重量含水率控制在20%。利用Robotized Incubation平台实时检测N₂O和N₂浓度变化,通过测定土壤中反硝化功能基因丰度（nirK、nirS、nosZ）分析生物质炭对N₂O消耗的影响及其微生物方面的影响机理。结果表明：经过20 h厌氧培养后,0生物质炭处理的反硝化功能基因丰度（基因拷贝数·g^-1）分别为6.80×10⁷（nirK）、5.59×10⁸（nirS）和1.22×10⁸（nosZ）。与0生物质炭处理相比,1%生物质炭处理的nirS基因丰度由最初的2.65×10⁸基因拷贝数·g^-1升至7.43×10⁸基因拷贝数·g^-1,nosZ基因丰度则提高了一个数量级,由4.82×10⁷基因拷贝数·g^-1升至1.50×10⁸基因拷贝数·g^-1,然而nirK基因丰度并无明显变化;5%生物质炭处理的反硝化功能基因丰度并未发生显著变化。试验结束时,添加生物质炭处理的N₂/（N₂O+N₂）比值也明显高于0生物质炭处理。相关性分析结果表明,nirS基因丰度和nosZ基因丰度均与N₂O浓度在0.01水平上显著相关。试验末期nirS基因丰度和nosZ基因丰度均随着N₂O浓度的降低而升高。因此在本试验中,添加1%生物质炭可显著提高nirS和nosZ基因型反硝化细菌的丰度,增大N₂/（N₂O+N₂）比值,促进N₂O彻底还原成N₂。生物质炭对于N₂O主要影响机理是增大了可以还原氧化亚氮的细菌活性,促进完全反硝化。     

Estimation of microbial biomass and activity in soil using microcalorimetry

Relationships between the rate of heat output from soil, the rate of respiration and the soil microbial biomass were investigated for 25 soils from northern Britain. The rate of heat output, measured in a Calvet microcalorimeter at 22°C, correlated well with the rate of carbon dioxide respiration. The average amount of heat evolved per cm³ of gas respired. 21.1 J cm^?3, suggests that the biomass metabolism was largely aerobic. The rate of heat output per unit of total microbial biomass was remarkably uniform over a wide range of soils, but showed differences depending upon whether the soil had been stored or amended. Mineral soils that had been stored at 4°C had the lowest heat output, 12.0 mW g^?1 biomass C, compared with a mean of 20.4 mW g^?1 biomass C for freshly-collected soils. Amendment with glucose (0.5% w/w) caused an immediate increase in respiration and heat output, up to 59.4 mW g^?1 biomass C for stored soils and 188.2 mW g^?1 biomass C for freshly collected soils. There was a consistent relationship between the biomass and the rate of heat output from freshly collected and amended mineral and organic soils which gave a linear fit using log transformed data: y= 0.6970+ 1.025x (r= 0.98, P < 0.001) (y=log₁₀ biomass C, μgC g^?1; x=log₁₀ rate of heat output at 22°C, μW g^?1). The overall relationship between biomass and the rate of heat output for all the amended samples was: 1 g biomass C= 180.05 ± 34.61 mW.     

生物有机肥对土壤微生物活性的影响

通过两次连续温室玉米盆栽试验,研究了施用具有调节微生物功能的生物有机肥对土壤微生物数量与活性的影响,并利用传统平板计数法与BIOLOGECO方法相结合研究生物有机肥对土壤微生物生态的影响。结果表明,与化肥相比,施用生物有机肥可显著提高土壤微生物中3大菌群的数量;AWCD值及微生物对不同碳底物利用水平的测定结果表明,施用生物有机肥可明显提高土壤微生物对碳源的利用率,尤其土壤中的羧酸、胺类和其他类碳源等。表明生物有机肥的施用能增加土壤微生物利用碳源能力,改善微生物营养条件,使微生物保持较高活性,提高土壤微生物多样性。     

The effect of glyphosate on soil microbial activity,microbial community structure,and soil potassium

The herbicide, glyphosate [N-(phosphonomethyl) glycine] is extensively used worldwide. Long-term use of glyphosate can cause micronutrient deficiency but little is known about potassium (K) interactions with glyphosate. The repeated use of glyphosate may create a selection pressure in soil microbial communities that could affect the nutrient dynamics such as K. The objective of this study was to determine the effect of single or repeated glyphosate applications on microbial and K properties of soils. A 54 day incubation study (Exp I) had a 3 × 5 factorial design with 3 soils (silt loam: fine, illitic, mesic Aeric Epiaqualf) of similar physical and chemical characteristics, that varied in long-term glyphosate applications (no, low, and high glyphosate field treatments) and five glyphosate rates (0, 0.5×, 1×, 2×, and 3× recommended field rates applied once at time zero). A second 6 month incubation study (Exp II) had a 3 × 3 factorial design with three soils (as described above) and three rates of glyphosate (0, 1×, and 2× recommended field application rates applied monthly). For each study microbial properties [respiration; community structure measured by ester linked fatty acid methyl ester (EL-FAME) analysis and microbial biomass K] and K fractions (exchangeable and non-exchangeable) were measured periodically. For Exp I, glyphosate significantly increased microbial respiration that was closely related to glyphosate application rate, most notably in soils with a history of receiving glyphosate. For Exp II, there was no significant effect of repeated glyphosate application on soil microbial structure (EL-FAME) or biomass K. We conclude that glyphosate: (1) stimulates microbial respiration particularly on soils with a history of glyphosate application; (2) has no significant effect on functional diversity (EL-FAME) or microbial biomass K; and (3) does not reduce the exchangeable K (putatively available to plants) or affect non-exchangeable K. The respiration response in soils with a long-term glyphosate response would suggest there was a shift in the microbial community that could readily degrade glyphosate but this shift was not detected by EL-FAME.     

Effect of organic-complexed superphosphates on microbial biomass and microbial activity of soil

Organic complexed super-phosphates (CSPs) are formed by the complexation of humic acid (HA) with calcium monophosphate. The aim of this study was to determine whether two CSPs, characterized by different HA concentrations, added to a calcareous soil at an agronomic dose, were able to maintain the phosphorus (P) in a soluble form longer than the superphosphate fertilizer. Another important goal was to verify if CSP could positively influence soil microbial biomass and soil microbiological activities. Organic complexed super-phosphates were capable of keeping a large portion of P in a soluble form under different soil water conditions. In particular, the CSP with the highest organic C content was the most effective product, capable of maintaining, in an available form, the 73 % of the initially added P at the end of the experiment. In addition, it was the most effective in increasing C–CO₂ soil emission, microbial biomass carbon (C) and nitrogen (N), fluoresceine diacetate hydrolysis and activities of alkaline phosphomonoesterase, β-glucosidase and urease. The addition of CSPs to soil probably produced a priming effect, increasing several times C–CO₂ release by the treated soil. The significant correlation (p?<?0.05) between C–CO₂ emission and the amount of C added to soil by CSP suggests that the added HA acted as trigger molecules.     

N2O emission mitigation and microbial activity after Biochar and Cao application in a flooded nitrate-rich vegetable soil

Adding easily decomposable organic materials into flooded nitrate-rich soils can effectively decrease the soil nitrate concentration and repair nitrate-rich soil. However, nitrate reduction is usually accompanied with an increase in N₂O emission. This study was conducted to reduce N₂O emission in a nitrate-rich vegetable soil flooded for remediation and amended with biochar. Nitrate-rich vegetable soil was placed in five treatment groups: flooding (F); flooding with rice straw (F?+?RS); flooding with rice straw and 1% biochar (F?+?RS?+?1% biochar); flooding with rice straw and 3% biochar (F?+?RS?+?3% biochar); flooding with rice straw and CaO (F?+?RS?+?CaO). Biochar and CaO reduced the N₂O emission levels relative to the F?+?RS group, with the former being more effective than the latter, achieving reduction of 40.70% (3% biochar) and 17.35% (CaO) of cumulative N₂O emission. The 3% biochar was more effective than the 1% biochar. Regression analysis showed a positive correlation between the abundance of NO reductase gene (norB) and soil N₂O emission flux. In general, biochar and CaO could effectively reduce N₂O emissions from a nitrate-rich vegetable soil during flooding remediation, duo to elevating soil pH and altering denitrifying activity. The norB gene was the most important denitrifying gene driving soil N₂O emission in the remediation.     

Impact of deforestation on soil physicochemical characteristics,microbial biomass and microbial activity of tropical soil

The study dealt with the assessment of the impact of deforestation on tropical soil through a comparative analysis of physicochemical and microbiological parameters of natural forest and a deforested barren site. With significant decline in clay, texturally the soil of the deforested barren site was observed to be different from that of natural forest. Bulk density and porosity data revealed structural deterioration of deforested barren soil. The soil hydrological regime was also adversely affected by the deforestation. Levels of soil organic carbon, total nitrogen, microbial biomass C, N and microfungal biomass also exhibited significant decline in deforested site. Analysis of microbial respiratory quotient (q CO₂) was also observed to be impaired in the deforested site. Copyright © 2001 John Wiley & Sons, Ltd.     

The effect of plant mycotrophy and soil disturbance on soil microbial activity

In cropping systems, the choices adopted for the tillage system used and plants cultivated can strongly influence the soil microbial population and its functional profile. Arbuscular mycorrhizal fungi are an important component of soil microbiome and their mutualistic symbiosis with the majority of higher plants grant the latter a wide range of benefits. The extraradical mycelium developed by these fungi expands the volume of soil influenced and harbours a diversity of microbes establishing a distinct environment of complementary interactions. We assessed how growing plants with different levels of mycotrophy modifies the biological activity profile in the soil under Mn toxicity and whether this is modified by soil disturbance. Following mycotrophic plants, soil contained a more active microbiome than after the non-mycotrophic plants, as expressed by higher values of soil basal respiration or dehydrogenase activity. Additionally, the count of phosphorus solubilizes and activity of phosphatase were greater after mycotrophic plants. Even among mycotrophic plants, different profiles of biological activity can be distinguished after growing a legume or grass. ERM disruption by soil disturbance decreased most of the parameters studied and for phosphatase activity and P solubilizers in a more significant way. These results indicate that even under Mn toxicity, the microbiome associated with AMF symbiosis following mycotrophic plants growth presented a higher biological activity and had a differential biological response towards the stress imposed by soil disturbance, when compared with the microbiome associated with non-mycotrophic roots.     

Impact of carbon nanomaterials on microbial activity in soil

In this study, effects of an increase in concentration of fullerene-C_60, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs) or fullerene soot (FS) on overall microbial activity was investigated over a 21 d incubation period. Microbial utilisation of ¹⁴C-glucose and uptake of ¹⁴C-glucose into the microbial biomass was investigated. For CNM-amended soils, greater extents of ¹⁴C-glucose mineralisation were found in the C₆₀-amended soils compared to MWCNT-, SWCNT- or FS-amended soils. In addition, the 100 and 1000 mg kg⁻¹ were consistently found to have higher extents of mineralisation in C₆₀, MWCNT, SWCNT or FS-amended soils, respectively. Further, the incorporation of ¹⁴C-glucose into the microbial biomass declined slightly with an increase in concentration in the amended soils, but no consistent pattern was observed. As a result, the biophysical quotient (BQ) increased significantly (P < 0.05), as concentrations increased from 1 mg kg⁻¹ to 1000 mg kg⁻¹ in all C₆₀-, MWCNT-, SWCNT- and FS-amended soils. The results obtained from this study showed that the addition to carbon nanomaterials had no profound impacts on the overall microbial activity, and the overall influence of CNMs on soil microbial activity does not reveal a specific pattern in the short term.     

Effects of atrazine on microbial activity in semiarid soil

The effect of an atrazine formulation on microbial biomass, microbial respiration, ATP content and dehydrogenase and urease activity in a semiarid soil and the influence of time on the response of soil microbial activity to the herbicide treatment were assessed. The atrazine formulation was added to soil as aqueous solutions of different concentrations of active ingredient to obtain a range of concentrations in the soil from 0.2 to 1000 mg kg⁻¹. Microcosms of soil with the different herbicide concentrations and untreated control soil were incubated for 6 h, 16 and 45 days. In general, an increase in the measured microbiological and biochemical parameters with atrazine concentration in soil was observed. The increase in microbial activity with atrazine pollution was noticeable after lengthy incubation.     

The effect of microbial activity on soil water diffusivity

In this study, we explored the effects of microbial activity on the evaporation of water from cores of a sandy soil under laboratory conditions. We applied treatments to stimulate microbial activity by adding different amounts of synthetic analogue root exudates. For comparison, we used soil samples without synthetic root exudates as control and samples treated with mercuric chloride to suppress microbial activity. Our results suggest that increasing microbial activity reduces the rate of evaporation from soil. Estimated diffusivities in soil with the largest amounts of added root exudates were one third of those estimated in samples where microbial activity was suppressed by adding mercuric chloride. We discuss the effect of our results with respect to water uptake by roots.

Highlights

• We explored effects of microbial activity on the evaporation of water from cores of a sandy soil.
• We found the effect of microbial activity on water release characteristic was small.
• Increasing microbial activity reduced evaporation from soil, while microbial suppression increased it.
• Effect of microbial activity on root water uptake was estimated to be equivalent to a change in soil structure.

     

重金属对土壤微生物酶活性的影响

本文通过含有不同浓度的铜、铅、砷、镉 4种重金属的大豆、小麦盆栽试验 ,采用气相色谱方法测定土壤微生物酶活性 .结果表明 :低浓度的重金属能够提高固氮酶和反硝化酶的活性 ,而高浓度的重金属对上述二种酶有强烈的抑制作用     

Effect of some herbicides on microbial activity in soil

The effect of 25 herbicides and herbicide combinations, in amounts comparable to those used in agriculture, on microbial activity in two soil types was determined in the laboratory. Herbicides did not affect respiration, assayed by CO₂ evolution and dehydrogenase activity, in either silty clay loam or loamy sand. Organic matter decomposition, determined by the amount of CO₂ evolved and inorganic N formed from decomposing alfalfa tissue, was also not affected. Alteration in soil pH or moisture content did not affect herbicide action. Addition of herbicides 3 weeks before amendment, or fertilizer application, also did not influence herbicide activity. Selected herbicides (trifluralin, linuron, dinoseb) at concentrations 100-fold higher than the recommended rates did not affect alfalfa decomposition. Solubilization of Ca₃(PO₄)₂ in soil was not affected by herbicides. S oxidation to SO^2?₄ in soil, however, was increased by most herbicides. In silty clay loam, 18 of the 25 herbicides and herbicide combinations increased S oxidation almost up to 3-fold. Results in loamy sand were similar. Dinoseb effectively reduced the algal population in loamy sand by more than 90%. Trifluralin, linuron, and metribuzin did not inhibit algal populations.     

Effect of biochar amendment on soil carbon balance and soil microbial activity

We investigated the behavior of biochars in arable and forest soil in a greenhouse experiment in order to prove that these amendments can increase carbon storage in soils. Two qualities of biochar were produced by hydrothermal pyrolysis from ¹³C labeled glucose (0% N) and yeast (5% N), respectively. We quantified respiratory losses of soil and biochar carbon and calculated mean residence times of the biochars using the isotopic label. Extraction of phospholipid fatty acids from soil at the beginning and after 4 months of incubation was used to quantify changes in microbial biomass and to identify microbial groups utilizing the biochars. Mean residence times varied between 4 and 29 years, depending on soil type and quality of biochar. Yeast-derived biochar promoted fungi in the soil, while glucose-derived biochar was utilized by Gram-negative bacteria. Our results suggest that residence times of biochar in soils can be manipulated with the aim to “design” the best possible biochar for a given soil type.     

聚丙烯酸盐类土壤改良剂对燕麦土壤微生物量氮及酶活性的影响

以燕麦田土壤为研究对象,探讨了聚丙烯酸盐类土壤改良剂及其复配(聚丙烯酸钾、聚丙烯酰胺、腐植酸钾、聚丙烯酸钾+腐植酸钾、聚丙烯酰胺+腐植酸钾)对燕麦田土壤微生物量氮及土壤酶活性的影响。结果表明,不同土壤改良剂均能提高土壤有机质、碱解氮、速效磷和速效钾的含量,各指标分别比对照增加了8.24%～30.22%、7.60%～19.29%、5.15%～29.45%和27.86%～68.86%;土壤改良剂能促使燕麦全生育期内0～10、10～20和20～40 cm各土层的土壤微生物量氮含量显著提高,聚丙烯酸钾+腐植酸钾和聚丙烯酰胺+腐植酸钾复配处理较其各单施效果显著,随土壤深度的增加土壤微生物量氮逐层递减;与对照相比,土壤改良剂能显著提高燕麦全生育期各土层过氧化氢酶活性,在抽穗期活性最高,且以聚丙烯酸钾+腐植酸钾较高;但对于脲酶,聚丙烯酸钾+腐植酸钾、聚丙烯酰胺+腐植酸钾和腐植酸钾3个处理在苗期显著低于对照,在抽穗期和成熟期高于对照,两种酶活性均随土壤深度的增加逐渐降低。     

Influence of cold storage on soil microbial community level physiological profiles and implications for soil quality monitoring

Following collection of soil, storage prior to analyses is often required where the microbial community is unlikely to remain stable. We assessed the change in microbial community level physiological profiles (CLPP) during cold storage at 4 °C between 3 and 101 days. We hypothesized that the microbial community in soils containing less carbon would be affected more rapidly by storage. In particular we wanted to ascertain whether variability in CLPP through time masked inherent differences between soils derived from different ecosystems. Results illustrated that whilst total CO₂ evolution did vary with incubation time, significant differences in microbial community structure were detected between ecosystems for all times. Thus storage time did not mask intrinsic differences in microbial community structure between ecosystems.     

大气CO2和O3升高对菜地土壤酶活性和微生物量的影响

利用OTC平台和青菜盆栽实验,探索[CO2]、[O3]或[CO2+O3]升高条件下,土壤理化性质、微生物量和土壤酶活性的变化,以期获得未来大气CO2或/和O3升高对土壤微生态系统的风险性。结果表明,[CO2]升高不同程度地提高了土壤的可溶性有机碳（DOC）、可溶性有机氮（DON）、总磷（TP）、总碳（TC）、铵态氮（AN）、硝态氮（NN）含量和含水量（SWC）,进而不同程度地提高了土壤微生物量碳（MBC）、微生物量氮（MBN）含量以及土壤蛋白酶（PRA）、蔗糖酶（SA）、脲酶（UA）、多酚氧化酶（POA）、酸性磷酸酶（APA）和中性磷酸酶（NPA）活性。相反,[O3]升高不同程度降低了土壤DOC、TP、TK、TC、TN、AN、NN、SWC、MBC和MBN含量,提高了MBC/MBN比值,在不同程度上降低了土壤PRA、SA、UA、POA、APA和NPA酶活性。而[CO2+O3]在一定程度上消减了[O3]对土壤微生物量和酶活性的抑制作用,也降低了[CO2]升高对土壤微生物量和酶活性的刺激效应。因此,土壤微生物量和土壤酶活性的变化可用于评价未来大气CO2或/和O3升高对菜地土壤微生态环境的影响。     

Effects of nonylphenols on soil microbial activity and water retention

The main aim of this study is to analyze the influence of 4-nonylphenol (NP) on soil water retention and biological activity. Two doses of 4-nonylphenol (25 and 50 mg kg⁻¹) were tested in a loam soil with and without peat amendment. In general, one week after the start of the experiment, the soil water content retained at −0.75 MPa of soil suction was 18% higher in the soil amended and its basal respiration (BR) was 15% higher than soil without peat. In contrast, the microbial activity indices (CM: coefficient of mineralization or BR:total organic carbon (TOC) ratio; Cmic:Corg: microbial biomass carbon (MBC):TOC ratio; qCO₂: metabolic quotient or BR:MBC ratio) were higher in the soil without peat, compared to the soil amended with peat. On the other hand, the addition of NP to soil was able to modify soil biological but not physical (water retention, desorption) properties. When soil was amended with peat, MBC was reduced one week after applying NP. In contrast, no effects of NP on MBC were observed in the soil without peat. BR was reduced by 16% one week after applying 50 mg kg⁻¹ of NP to soil with peat, and was increased by 46% one week after applying 25 mg kg⁻¹ of NP to soil without peat. The effects of NP on MBC and BR could be associated more with the adsorption of NP by soil organic matter, while changes in CM or Cmic:Corg ratio were more closely related to changes in soil water retention. The potential toxic effects of NP (high qCO₂ values) were only observed in the absence of peat amendments. Peat addition reduced NP toxic effects on microorganisms.