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1.
Salinity is the major environmental factor limiting crop production. Alfalfa is a legume with high nutritional value that establishes a symbiosis relation with Ensifer meliloti. Under saline conditions the alfalfa yield decreases and this symbiosis is affected. The aim of this work is to study the effect of the co-inoculation of alfalfa plants with Halomonas maura (a moderately halophile bacterium) and E. meliloti in saline soils to improve their productivity and growth under greenhouse and field conditions. Alfalfa plants were grown in Leonard jar under greenhouse conditions, using a N-free mineral solution to mimic the conditions of an Orthic Solonchak. Then alfalfa plants were grown in the field in the same soil type. Seeds were inoculated with E. meliloti, H. maura, co-inoculated with E. meliloti and H. Maura, or non-inoculated as a control in both experiments. In greenhouse experiments the co-inoculation of alfalfa plants increased significantly the shoot dry weight (0.64 ± 0.02 vs. 0.79 ± 0.02), the leghaemoglobin content (10.17 ± 0.03 vs. 11.25 ± 0.06) and water potential (−3.12 ± 0.02 vs. −2.79 ± 0.02) compared with the single inoculation with E. meliloti. In the field experiments, biomass of co-inoculated plants clearly outyielded those of plants inoculated with any inoculant. The co-inoculation of H. maura and E. meliloti enhances alfalfa productivity in saline soils, thus contributing to the agricultural exploitation of low productive areas. H. maura and E. meliloti could be considered in formulation of bioinoculants to contribute in the reduction of the overuse of chemical fertilizers and their environmental impacts. 相似文献
2.
Arbuscular mycorrhizal fungus (AMF) can enhance plant growth and resistance to toxicity produced by heavy metals (HMs), affect the bioavailability of HMs in soil and the uptake of HMs by plants, and thus has been emerged as the most prominent symbiotic fungus for contribution to phytoremediation. A greenhouse pot experiment was conducted to assess the effect of Glomus versiforme BGC GD01C (Gv) on the growth and Cd accumulation of Cd-hyperaccumulator Solanum nigrum in different Cd-added soils (0, 25, 50, 100 mg Cd kg−1 soil). Mycorrhizal colonization rates were generally high (from 71% to 82%) in Gv-inoculated treatments at all Cd levels. Gv colonization enhanced soil acid phosphatase activity, and hence elevated P acquisition and growth of S. nigrum at all Cd levels. Moreover, the presence of Gv significantly increased DTPA-extractable (phytoavailable) Cd concentrations in 25 and 50 mg Cd kg−1 soils, but did not affect phytoavailable Cd in 100 mg Cd kg−1 soil. Similarly, inoculation with Gv significantly increased Cd concentrations of S. nigrum in 25 and 50 mg Cd kg−1 soils, but decreased Cd concentrations of the plants in 100 mg Cd kg−1 soil. Overall, inoculation with Gv greatly improved the total Cd uptakes in all plant tissues at all Cd levels. The present results indicated that S. nigrum associated with Gv effectively improved the Cd uptake by plant and would be a new strategy in microbe-assisted phytoremediation for Cd-contaminated soils. 相似文献
3.
《Soil biology & biochemistry》2001,33(7-8):913-919
A reliable and simple technique for estimating soil microbial biomass (SMB) is essential if the role of microbes in many soil processes is to be quantified. Conventional techniques are notoriously time-consuming and unreproducible. A technique was investigated that uses the UV absorbance at 280 nm of 0.5 M K2SO4 extracts of fumigated and unfumigated soils to estimate the concentrations of carbon, nitrogen and phosphorus in the SMB. The procedure is based on the fact that compounds released after chloroform fumigation from lysed microbial cells absorb in the near UV region. Using 29 UK permanent grassland soils, with a wide range of organic matter (2.9–8.0%) and clay contents (22–68%), it was demonstrated that the increase in UV absorbance at 280 nm after soil fumigation was strongly correlated with the SMB C (r=0.92), SMB N (r=0.90) and SMB P (r=0.89), as determined by conventional methods. The soils contained a wide range of SMB C (412–3412 μg g−1 dry soil), N (57–346 μg g−1 dry soil) and P (31–239 μg g−1 dry soil) concentrations. It was thus confirmed that the UV absorbance technique described was a rapid, simple, precise and relatively inexpensive method of estimating soil microbial biomass. 相似文献
4.
5.
The combination of nitrogen and Azospirillum can ensure greater nutrient absorption and crop yield in agricultural areas using high technology. Thus, the objective was to evaluate maize response to Azopirillum brasilense (AZ) inoculation and nutrient (macronutrients and micronutrients) application under greenhouse and field conditions in clay and sandy soils of the Brazilian Cerrado. In the greenhouse assays, the following parameters were measured: shoot dry weight (SDW), root dry weight (RDW), and root volume (RV). In the field experiments, the maize yield was determined after drying the grains at 60 °C for 48 h. In clay soil, there was a significant increase in the SDW, RDW and RV in the treatment with AZ concentrated (1011 cells ml−1 of inoculum) when compared with the control treatment and the treatment with AZ diluted (106 cells ml−1 of inoculum). In this soil, adding micronutrients did not affect the maize response under greenhouse conditions. In sandy soil, there was no difference between the AZ treatment and the control, except for treatments where nutrients and AZ were both added leading to a significant increase in the maize response. In both soils, the RV:RDW ratio was higher in the treatment with AZ concentrated compared to that in the treatment with AZ diluted, but the yield response depended on the addition of nutrients. Inoculation with A. brasilense gave comparable yield to the nitrogen treatment. The grain production was increased by 29% in the treatment with A. brasilense and nitrogen compared to nitrogen fertilization alone. In this study, the yield response was affected significantly when maize was inoculated with A. brasilense, but this response was dependent on the soil type under greenhouse conditions. 相似文献
6.
Amynthas agrestis is an exotic, invasive earthworm in North America that has been associated with horticulture settings as well as damage to forest soil. An experiment was conducted to find out whether A. agrestis, an earthworm commonly found in mulches in Vermont, stimulates ligninolytic enzymes in the presence of commercial wood mulches. Mesocosms filled with a sandy loam soil were topped with either spruce, cedar or pine mulch. Half of the mesocosms received juvenile A. agrestis, the other half did not. After 7 weeks soils were analyzed for phenoloxidase and peroxidase activity. Most A. agrestis survived and developed into adults during the incubation period. Significantly greater phenoloxidase activity was detected in soils with A. agrestis than without earthworms. Mean (standard deviation) phenoloxidase activities in the presence of A. agrestis were 0.15 (±0.10), 1.14 (±0.46), 2.71 (±0.98) μmol g−1 h−1 for pine, spruce and cedar respectively, and 0.012 (±0.023), 0.25 (±0.25), 0.78 (±0.45) μmol g−1 h−1 in the absence of A. agrestis. There was significantly greater peroxidase activity for the pine and spruce treatment when earthworms were present. Mean peroxidase activities were 0.47 (±0.21), 0.94 (±0.29), 1.20 (±0.77) μmol h−1 g−1 soil for pine, spruce and cedar, respectively for soils with A. agrestis and 0.15 (±0.10), 0.37 (±0.10), 0.63 (±0.30) μmol h−1 g−1 soil in the absence of earthworms. The increased ligninolytic activity in combination with successful maturation of juveniles into adult A. agrestis suggests that mulch can be habitat for these invasive earthworms. This finding is supported by a survey of master gardeners in Vermont and New Hampshire 20% of whom reported to have seen these earthworms mainly in their gardens and mulched beds. 相似文献
7.
《Soil biology & biochemistry》2001,33(7-8):1103-1111
Biologically active fractions of soil organic matter are important in understanding decomposition potential of organic materials, nutrient cycling dynamics, and biophysical manipulation of soil structure. We evaluated the quantitative relationships among potential C and net N mineralization, soil microbial biomass C (SMBC), and soil organic C (SOC) under four contrasting climatic conditions. Mean SOC values were 28±11 mg g−1 (n=24) in a frigid–dry region (Alberta/British Columbia), 25±5 mg g−1 (n=12) in a frigid–wet region (Maine), 11±4 mg g−1 (n=117) in a thermic–dry region (Texas), and 12±5 mg g−1 (n=131) in a thermic–wet region (Georgia). Higher mean annual temperature resulted in consistently greater basal soil respiration (1.7 vs 0.8 mg CO2–C g−1 SOC d−1 in the thermic compared with the frigid regions, P<0.001), greater net N mineralization (2.8 vs 1.3 mg inorganic N g−1 SOC 24 d−1, P<0.001), and greater SMBC (53 vs 21 mg SMBC g−1 SOC, P<0.001). Specific respiratory activity of SMBC was, however, consistently lower in the thermic than in the frigid regions (29 vs 34 mg CO2–C g−1 SMBC d−1, P<0.01). Higher mean annual precipitation resulted in consistently lower basal soil respiration (1.1 vs 1.3 mg CO2–C g−1 SOC d−1 in the wet compared with the dry regions, P<0.01) and lower SMBC (31 vs 43 mg SMBC g−1 SOC, P<0.001), but had inconsistent effects on net N mineralization that depended upon temperature regime. Specific respiratory activity of SMBC was consistently greater in the wet than the dry regions (≈33 vs 29 mg CO2–C g−1 SMBC d−1, P<0.01). Although the thermic regions were not able to retain as high a level of SOC as the frigid regions, due likely to high annual decomposition rates, biologically active soil fractions were as high per mass of soil and even 2–3-times greater per unit of SOC in the thermic compared with the frigid regions. These results suggest that macroclimate has a large impact on the portion of soil organic matter that is potentially active, but a relatively small impact on the specific respiratory activity of SMBC. 相似文献
8.
《Soil biology & biochemistry》2001,33(4-5):449-455
The influence of several soil properties on soil conduciveness or suppressiveness to disease caused by the soil fungus Fusarium oxysporum f. sp. cubense was studied in seven field plots of banana plantations, situated in Tenerife and Gran Canaria islands (Canary Islands, Spain). In each plot, soil samples were taken in conducive and suppressive areas to Fusarium wilt. Water-stable aggregates (WSA: 200–2000 μm diameter), soil particle size, and selected soil solution characteristics [pH, electric conductivity (EC) and soluble Na] were determined in the samples. Aggregate water-stability was higher in soils of conducive areas than in suppressive areas. The percentage of WSA in the conducive areas ranged from 460 to 330 g kg−1, while in the suppressive areas the maximum value was 285 g kg−1 and the minimum was 150 g kg−1. The soils had high clay content and the EC and soluble Na tended to be higher in suppressive areas than in conducive areas. Soil solution pH was lower in conducive areas (except sites 1 and 9). Our data provide evidence that in different soil areas of the same plot, the structural stability of aggregates, presumably controlled in part by the clay fraction, soluble Na concentration and EC, is of great importance for the conduciveness or suppressiveness to banana wilt caused by Fusarium oxysporum f. sp. cubense of the soils studied. Finally, we hypothesize that a greater stability of the aggregates forming anaerobiosis could partly explain most of the available Fe found in soil areas where the disease was severe, at least in these types of soils. 相似文献
9.
Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two recently discovered processes in the nitrogen cycle that are catalysed by anammox bacteria and n-damo bacteria, respectively. Here, the depth-specific distribution and importance of anammox bacteria and n-damo bacteria were studied in an urban wetland, Xixi Wetland, Zhejiang Province (China). Anammox bacteria related to Candidatus Brocadia, Candidatus Kuenenia and Candidatus Anammoxoglobus, and n-damo bacteria related to “Candidatus Methylomirabilis oxyfera” were present in the collected soil samples. The abundance of anammox bacteria (2.6–8.6 × 106 copies g−1 dry soil) in the shallow soils (0–10 cm and 20–30 cm) was higher than that (2.5–9.8 × 105 copies g−1 dry soil) in the deep soils, whereas the abundance of n-damo bacteria (0.6–1.3 × 107 copies g−1 dry soil) in the deep soils (50–60 cm and 90–100 cm) was higher than that (3.4–4.5 × 106 copies g−1 dry soil) in the shallow soils. Anammox activity was detected at all depths, and higher potential rates (12.1–21.4 nmol N2 g−1 dry soil d−1) were observed at depths of 0–10 cm and 20–30 cm compared with the rates (3.5–8.7 nmol N2 g−1 dry soil d−1) measured at depths of 50–60 and 90–100 cm. In contrast, n-damo was mainly occurred at depths of 50–60 cm and 90–100 cm with potential rates of 0.7–5.0 nmol CO2 g−1 dry soil d−1. This study suggested the niche segregation of the anammox bacteria and n-damo bacteria in wetland soils, with anammox bacteria being active primarily in deep soils and n-damo bacteria being active primarily in shallow soils. 相似文献
10.
《European Journal of Soil Biology》2008,44(2):158-165
Addition of organic manure over thousands of years has resulted in the development of very fertile soils in parts of the Loess Plateau in Northwest China. This region also suffers from serious soil erosion. For that reason, afforestation of arable soils has taken place. The dynamics of soil organic matter in these soils affected by a very specific management and by land use changes is largely unknown. Therefore, we measured C mineralization in a 35-days incubation experiment and analyzed amounts and properties of water-extractable organic carbon (WEOC) in 12 topsoils of this region. The soils differed in land use (arable vs. forest) and in amounts of added organic manure. Afforestation of arable soils resulted in a distinct stabilization of organic C as indicated by the smallest C mineralization (0.48 mg C g−1 C d−1) and the highest C content (2.3%) of the studied soils. In the soils exposed to intensive crop production without regular addition of organic manure we found the largest C mineralization (0.85 mg C g−1 C d−1) and the lowest contents of organic C (0.9%). Addition of organic manure over a time scale of millennia resulted in high organic C contents (1.8%) and small C mineralization (0.55 mg C g−1 C d−1). The content of WEOC reflected differences in C mineralization between the soils quite well and the two variables correlated significantly. Water-extractable organic C decreased during C mineralization from the soil illustrating its mainly labile character. Carbon mineralization from soils was particularly large in soils with small specific UV absorbance of WEOC. We conclude that amounts and properties of WEOC reflected differences in the stability of soil organic C. Both afforestation of arable land and the long-term addition of organic manure may contribute to C accumulation and stabilization in these soils. 相似文献
11.
《Soil biology & biochemistry》2001,33(12-13):1581-1589
The activity and biomass of soil microorganisms were measured in soils from 25 different arable sites in the Pacific region of Nicaragua with the objective of elucidating their interrelationship with soil textural and soil chemical properties. All soils developed from recent volcanic deposits but differ in their particle size distribution. Short-term phosphorus fixation capacity varied widely and was, on average, 11% of added P. In contrast, long-term P fixation capacity varied within a small range of around 55%. Mean basal respiration was 8.6 μg CO2–C d−1 g−1 soil, average contents of biomass C, biomass P, and ergosterol as an indicator of fungal biomass were 116, 1.95, and 0.34 μg g−1 soil, respectively. They were all, except biomass P, significantly lower in the sandy than in the loamy soils. The mean biomass C-to-soil C ratio was 0.69%, the mean metabolic quotient 95 mg CO2–C d−1 g−1 biomass C, the mean ergosterol-to-biomass C ratio 0.31% and the mean biomass C-to-P ratio 107. The very low ergosterol-to-biomass C ratio indicates that fungi contribute only a relatively small percentage to the microbial biomass. The biomass C-to-P ratio exceeded considerably the soil C-to-total P ratio. Metabolic quotient qCO2 and ergosterol-to-biomass C were both negatively correlated with biomass C-to-soil C ratio and clay content, indicating positive correlations between qCO2 and ergosterol-to-biomass C ratio and between biomass C-to-soil C ratio and clay content. Key problems of soil fertility and soil quality in Nicaragua are low availability of soil organic matter and phosphorus to soil microorganisms, which are magnified by a low percentage of fungi, probably reducing the ability of soil to provide nutrients for plant growth. 相似文献
12.
《Applied soil ecology》2009,42(3):269-276
Earthworms can be used to remove polycyclic aromatic hydrocarbons (PAHs) from soil, but this might affect their survival and they might accumulate the contaminants. Sterilized and unsterilized soil was contaminated with phenanthrene (Phen), anthracene (Anth) and benzo(a)pyrene (BaP), added with or without Eisenia fetida, sewage sludge or vermicompost. Survival, growth, cocoon formation and concentrations of PAHs in the earthworms were monitored for 70 days. Addition of sewage sludge to sterilized or unsterilized soil maintained the number of earthworms and their survival was 94%. The addition of sludge significantly increased the weight of earthworms 1.3 times compared to those kept in the unamended soil or in soil amended with vermicompost. The weight of earthworms was significantly lower in sterilized than in unsterilized soil. Cocoons were only detected when sewage sludge was added to unsterilized soil. A maximum concentration of 62.3 μg Phen kg−1 was found in the earthworms kept in sterilized soil amended with vermicompost after 7 days and 22.3 μg Phen kg−1 when kept in the unamended unsterilized soil after 14 days. Concentrations of Phen in the earthworms decreased thereafter and ≤2 μg kg−1 after 28 days. A maximum Anth concentration of 82.5 μg kg−1 was found in the earthworms kept in sterilized soil amended with vermicompost and 45.8 μg Anth kg−1 when kept in the unamended unsterilized soil after 14 days. A maximum concentration of 316 μg BaP kg−1 was found in the earthworms kept in sterilized soil amended with vermicompost after 56 days and 311 μg BaP kg−1 when kept in the unsterilized soil amended with vermicompost after 28 days. The amount of BaP in the earthworm was generally largest after 28 days, but after 70 days still 60 μg kg−1 was found in E. fetida when kept in the sterilized soil amended with sewage sludge. It was found that E. fetida survived in PAHs contaminated soil and accumulated only small amounts of the contaminants, but sewage sludge was required as food for its survival and cocoon production. 相似文献
13.
The ultimate goal of soil remediation is to restore soil health. Soil microbial parameters are considered to be effective indicators of soil health. The aim of this study was to determine the effects of phytoextraction on microbial properties through the measurement of soil microbial biomass carbon, soil basal respiration and enzyme activities. For this purpose, a pre-stratified rhizobox experiment was conducted with the Cd hyperaccumulator Sedum alfredii H. for phytoextraction Cd from an artificial contaminated soil (15.81 mg kg−1) under greenhouse conditions. The plant and soil samples were collected after growing the plant for three and six months with three replications. The results indicated that the ecotype of S. alfredii H. originating from an ancient silver mining site was a Cd-hyperaccumulator as it showed high tolerance to Cd stress, the shoot Cd concentration were as high as 922.6 mg kg−1 and 581.9 mg kg−1 at the two samplings, and it also showed high BF (58.4 and 36.8 after 3 and 6 months growth), and TF (5.8 and 5.1 after 3 and 6 months growth). The amounts of Cd accumulated in the shoots of S. alfredii reached to an average of 1206 μg plant−1 after 6 months growth. Basal respiration, invertase and acid phosphatase activities of the rhizosphere soil separated by the shaking method were significantly higher (P < 0.01) than that of the near-rhizosphere soil and the unplanted soil after 3 months growth, so were microbial biomass carbon, urease, invertase and acid phosphatase activities of the rhizosphere soil after 6 months growth. Acid phosphatase activity of the 0–2 mm sub-layer rhizosphere soil collected by the pre-stratified method after 3 months growth was significantly higher (P < 0.05) than that of other sub-layer rhizosphere soils and bulk soil, and so were microbial biomass carbon, basal respiration, urease, invertase and acid phosphatase activities of the 0–2 mm sub-layer rhizosphere soil after 6 months growth. It was concluded that phytoextraction by S. alfredii could improve soil microbial properties, especially in rhizosphere, and this plant poses a great potential for the remediation of Cd contaminated soil. 相似文献
14.
Soil archaeal population dynamics at two experimental sites of the same clay-loam type in Ottawa and Woodslee, Ontario, were investigated to determine fertilizer and manure effects following their different long-term crop rotation and fertilization schemes. Phylogenetic analysis of cloned soil archaeal 16S rRNA gene libraries of both sites identified them with group 1.1b of Thaumarchaeota. The gene population dynamics subtly varied in the order of 107 copies g−1 soil when monitored by quantitative real-time PCR during three growing seasons (2007–2009). In Ottawa, where plots were amended with dairy-farm manure, soil thaumarchaeal gene abundance was double of the unamended plots. At the Woodslee N-P-K-fertilized plots, it remained at least 30% fewer than that of the unfertilized ones. These cultivated plots showed soil carbon limitation while the fertilized ones were low in soil pH (ca. 5.5). Surface soils from an unfertilized sod plot and an adjacent deciduous forest had higher total carbon content (C:N ratio of 9 and 11, respectively). Their thaumarchaeal gene abundance varied up to 4.8 × 107 and 7.0 × 107 copies g−1 soil, respectively. The former value was also attained at the manure-amended plots in Ottawa, where the C:N ratio was just below 10. Where soil pH was above 6.0, there was a weak and positive correlation between soil total C and the estimated gene abundance. Such gene population dynamics consistently demonstrated the stimulating and suppressive effects of dairy-farm manure (Ottawa site) and inorganic fertilizers (Woodslee site), respectively, on soil thaumarchaea. At both sites archaeal amoA and 16S rRNA gene abundance were similarly affected. Archaeal amoA gene abundance also outnumbered bacterial amoA abundance, suggesting that ammonia-oxidizing archaea might be dominant in these soils. Only minor crop effects on gene population dynamics were detected. 相似文献
15.
Esperanza Romero Jesús Fernández-Bayo Jean Manuel Castillo Díaz Rogelio Nogales 《Applied soil ecology》2010,44(3):198-204
Mineral fertilizers, organic amendments, and pesticides are inputs commonly used in conventional farming practices. The aim of this study was to evaluate the effects of single or combined applications of spent grape marc-vermicompost, urea, and/or diuron on soil-enzyme activities and the persistence of this herbicide in soils with low organic carbon content. The application of vermicompost enhanced dehydrogenase (DHase) enzyme activity over time but altered soil urease activity to a very limited extent. The reduction in diuron concentrations and the increase in DHase activity indicated that the soil microorganisms were capable of degrading the ureic herbicide. Treatment with vermicompost and diuron had a stimulatory effect on soil microbial activity. On the whole, the application of diuron and urea to the vermicompost-amended soil raised DHase and urease activity to maximum levels (>3 μg INTF g?1 h?1 and >47 μg NH4+ g?1 h?1, respectively). The application of urea to the unamended and vermicompost-amended soil decreased diuron persistence from 18.8 and 33 d to 12.5 and 15 d, respectively. Our findings show that although vermicompost additions reduce diuron availability, this boosts diuron degradation when combined with urea. These additions, under different soil management conditions, minimize the bioavailability and persistence of diuron and consequently the risk of leaching and seepage into aquifers. Compared with untreated soils, these types of treated soils could also improve agricultural sustainability and the quality of the environment. 相似文献
16.
Little is know on the impact of biosolids application on soil organic matter (SOM) stability, which contributes to soil C sequestration. Soil samples were collected in 2006 at plow layer from fields that received liquid and dry municipal biosolids application from 1972 to 2004 at the cumulative rate of 1416 Mg ha−1 in mined soil and 1072 Mg ha−1 in nonmined soil and control fields that received chemical fertilizer at Fulton County, western Illinois. The biosolids application increased the soil microbial biomass C (SMBC) by 5-fold in mined soil and 4-fold in nonmined soil. The biosolids-amended soils showed a high amount of basal respiration and N mineralization, but low metabolic quotient, and low rate of organic C and organic N mineralization. There was a remarkable increase in mineral-associated organic C from 6.9 g kg−1 (fertilizer control) to 26.6 g kg−1 (biosolids-amended) in mined soil and from 8.9 g kg−1 (fertilizer control) to 23.1 g kg−1 (biosolids-amended) in nonmined soil. The amorphous Fe and Al, which can improve SOM stability, were increased by 2–7 folds by the long-term biosolids application. It is evident from this study that the biosolids-modified SOM resists to decomposition more than that in the fertilizer treatment, thus long-term biosolids application could increase SOM stability. 相似文献
17.
The incorporation of organic amendments from pruning waste into soil may help to mitigate soil degradation and to improve soil fertility in semiarid ecosystems. However, the effects of pruning wastes on the biomass, structure and activity of the soil microbial community are not fully known. In this study, we evaluate the response of the microbial community of a semiarid soil to fresh and composted vegetal wastes that were added as organic amendments at different doses (150 and 300 t ha−1) five years ago. The effects on the soil microbial community were evaluated through a suite of different chemical, microbiological and biochemical indicators, including enzyme activities, community-level physiological profiles (CLPPs) and phospholipid fatty acid analysis (PLFA). Our results evidenced a long-term legacy of the added materials in terms of soil microbial biomass and enzyme activity. For instance, cellulase activity reached 633 μg and 283 μg glucose g−1 h−1 in the soils amended with fresh and composted waste, respectively. Similarly, bacterial biomass reached 116 nmol g−1 in the soil treated with a high dose of fresh waste, while it reached just 66 nmol g−1 in the soil amended with a high dose of composted waste. Organic amendments produced a long-term increase in microbiological activity and a change in the structure of the microbial community, which was largely dependent on the stabilization level of the pruning waste but not on the applied dose. Ultimately, the addition of fresh pruning waste was more effective than the application of composted waste for improving the microbiological soil quality in semiarid soils. 相似文献
18.
《Soil biology & biochemistry》2001,33(12-13):1797-1804
Sulphur transformations were monitored in a unique set of arable, grassland and woodland soils from the Broadbalk Classical Experiment, which started in 1843. In an open incubation experiment with periodic leaching, 14–35 mg SO42−-S kg−1 was mineralised in 28 weeks at 25°C, equivalent to 4.4–8.3% soil organic S. Cumulative amounts of S mineralised increased linearly during the 28 weeks, indicating constant rates of mineralisation. The rate of mineralisation was the greatest in the woodland soil (170 μg SO4-S kg−1 day−1), followed by the grassland (120 μg SO4-S kg−1 day−1) and the arable soil from the farmyard manure (FYM) plot (110 μg SO4-S kg−1 day−1). Three soils from arable plots receiving different inorganic fertiliser treatments but no FYM had similar rates of S mineralisation (~70 μg SO4-S kg−1 day−1). In an incubation experiment with 35SO42−, addition of glucose greatly enhanced S immobilisation. In 132 days, the woodland and grassland soils immobilised more S than the arable soils, with or without glucose amendment. Immobilisation and mineralisation of S occurred concurrently, and both were stimulated by glucose addition. The results show that S mineralisation and immobilisation were influenced strongly by the type of land-use and long-term organic manuring, whereas annual application of sulphate-containing fertilisers for over 150 years had few effects on short-term S transformations. 相似文献
19.
《Pedobiologia》2014,57(4-6):277-284
Assimilating atmospheric carbon (C) into terrestrial ecosystems is recognized as a primary measure to mitigate global warming. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is the dominant enzyme by which terrestrial autotrophic bacteria and plants fix CO2. To investigate the possibility of using RubisCO activity as an indicator of microbial CO2 fixation potential, a valid and efficient method for extracting soil proteins is needed. We examined three methods commonly used for total soil protein extraction. A simple sonication method for extracting soil protein was more efficient than bead beating or freeze–thaw methods. Total soil protein, RubisCO activity, and microbial fixation of CO2 in different agricultural soils were quantified in an incubation experiment using 14C-CO2 as a tracer. The soil samples showed significant differences in protein content and RubisCO activity, defined as nmol CO2 fixed g−1 soil min−1. RubisCO activities ranged from 10.68 to 68.07 nmol CO2 kg−1 soil min−1, which were closely related to the abundance of cbbL genes (r = 0.900, P = 0.0140) and the rates of microbial CO2 assimilation (r = 0.949, P = 0.0038). This suggests that RubisCO activity can be used as an indicator of soil microbial assimilation of atmospheric CO2. 相似文献
20.
《Agricultural and Forest Meteorology》2007,142(1):50-65
Underestimation of nocturnal CO2 respiration using the eddy covariance method under calm conditions remains an unsolved problem at many flux observation sites in forests. To evaluate nocturnal CO2 exchange in a Japanese cypress forest, we observed CO2 flux above the canopy (Fc), changes in CO2 storage in the canopy (St) and soil, and trunk and foliar respiration for 2 years (2003–2004). We scaled these chamber data to the soil, trunk, and foliar respiration per unit of ground area (Fs, Ft, Ff, respectively) and used the relationships of Fs, Ft, and Ff with air or soil temperature for comparison with canopy-scale CO2 exchange measurements (=Fc + St). The annual average Fs, Ft, and Ff were 714 g C m−2 year−1, 170 g C m−2 year−1, and 575 g C m−2 year−1, respectively. At small friction velocity (u*), nocturnal Fc + St was smaller than Fs + Ft + Ff estimated using the chamber method, whereas the two values were almost the same at large u*. We replaced Fc + St measured during calm nocturnal periods with a value simulated using a temperature response function derived during well-mixed nocturnal periods. With this correction, the estimated net ecosystem exchange (NEE) from Fc + St data ranged from −713 g C m−2 year−1 to −412 g C m−2 year−1 in 2003 and from −883 g C m−2 year−1 to −603 g C m−2 year−1 in 2004, depending on the u* threshold. When we replaced all nocturnal Fc + St data with Fs + Ft + Ff estimated using the chamber method, NEE was −506 g C m−2 year−1 and −682 g C m−2 year−1 for 2003 and 2004, respectively. 相似文献