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1.
Influence of soil properties on microbial populations, activity and biomass in humid subtropical mountainous ecosystems of India 总被引:1,自引:0,他引:1
Microbial populations, biomass, soil respiration and enzyme activities were determined in slightly acid organic soils of
major mountainous humid subtropical terrestrial ecosystems, along a soil fertility gradient, in order to evaluate the influence
of soil properties on microbial populations, activity and biomass and to understand the dynamics of the microbial biomass
in degraded ecosystems and mature forest. Although the population of fungi was highest in the undisturbed forest (Sacred Grove),
soil respiration was lowest in the 7-year-old regrowth and in natural grassland (approximately 373 μg g–1 h–1). Dehydrogenase and urease activities were high in "jhum" fallow, and among the forest stands they were highest in the 7-year-old
regrowth. Microbial biomass C (MBC) depended mainly on the organic C status of the soil. The MBC values were generally higher
in mature forest than in natural grassland, 1-year-old jhum fallow and the 4-year-old alder plantation. The MBC values obtained
by the chloroform-fumigation-incubation technique (330–1656 μg g–1) did not vary significantly from those obtained by the chloroform-fumigation-extraction technique (408–1684 μg g–1), however, the values correlated positively (P<0.001). The enzyme activities, soil respiration, bacterial and fungal populations and microbial biomass was greatly influenced
by several soil properties, particularly the levels of nutrients. The soil nutrient status, microbial populations, soil respiration
and dehydrogenase activity were greater in Sacred Grove, while urease activity was greater in grassland.
Received: 14 October 1998 相似文献
2.
Soil-released carbon dioxide from microbial biomass carbon in the cultivated soils of karst areas of southwest China 总被引:1,自引:0,他引:1
Soil microbial biomass and the emission of CO2 from the soil surface were measured in yellow soils (Ultisols) of the karst areas of southwest China. The soils are relatively
weathered, leached and impoverished, and have a low input of plant residues. The measurements were made for a 1-year period
and show a reciprocal relationship between microbial biomass and surface CO2 efflux. The highest (42.6±2.8 mg CO2-C m–2 h–1) and lowest (15.6±0.6 mg CO2-C m–2 h–1) CO2 effluxes are found in the summer and winter, respectively. The cumulative CO2 efflux is 0.24 kg CO2-C m–2 year–1. There is also a marked seasonal variation in the amount of soil microbial biomass carbon, but with the highest (644±71 μg
C g–1 soil) and lowest (270±24 μg C g–1 soil) values occurring in the winter and summer, respectively. The cumulative loss of soil microbial biomass carbon in the
top 10 cm of the soil was 608 μg C g–1 year–1 soil over 17 sampling times. The mean residence time of microbial biomass is estimated at 105 days, suggesting that the carbon
in soil microbial biomass may act as a source of the CO2 released from soils.
Received: 13 July 1999 相似文献
3.
The critical S concentration and S requirement of the soil microbial biomass of a granitic regosol was examined. S was applied
at the rate of 0, 5, 10, 20, 30 and 50 μg S as MgSO4·7H2O, together with either 3000 μg glucose-C or 3333 μg cellulose-C, 400 μg N, and 200 μg P g –1 soil and 200 μg K g–1 soil. Microbial biomass, inorganic SO4
2–-S, and CO2 emission were monitored over 30 days during incubation at 25 °C. Both glucose and cellulose decomposition rates responded
positively to the S made available for microbial cell synthesis. The amounts of microbial biomass C and S increased with the
level of applied S up to 10 μg S g–1 soil and 30 μg S g–1 soil in the glucose- and cellulose-amended soil, respectively, and then declined. Incorporated S was found to be concentrated
within the microbial biomass or partially transformed into soil organic matter. The concentration of S in the microbial biomass
was higher in the cellulose- (4.8–14.2 mg g–1) than in the glucose-amended soil (3.7–10.9 mg g–1). The microbial biomass C:S ratio was higher in the glucose- (46–142 : 1) than in the cellulose-amended soil (36–115 : 1).
The critical S concentration in the microbial biomass (defined as that required to achieve 80% of the maximum synthesis of
microbial biomass C) was estimated to be 5.1 mg g–1 in the glucose- and 10.9 mg g–1 in the cellulose-amended soil. The minimum requirement of SO4
2–-S for microbial biomass formation was estimated to be 11 μg S g–1 soil and 21 μg S g–1 soil for glucose- and cellulose-amended soil, respectively. The highest levels of activity of the microbial biomass were
observed at the SO4
2–-S concentrations of 14 μg S g–1 soil and 17 μg S g–1 soil, for the glucose and cellulose amendments, respectively, and were approximately 31–54% higher during glucose than cellulose
decomposition.
Received: 20 October 1999 相似文献
4.
Ergosterol and microbial biomass C were measured in 26 arable, 16 grassland and 30 forest soils. The ergosterol content ranged from 0.75 to 12.94 g g-1 soil. The geometric mean ergosterol content of grassland and forest soils was around 5.5 g g-1, that of the arable soils 2.14 g g-1. The ergosterol was significantly correlated with biomass C in the entire group of soils, but not in the subgroups of grassland and forest soils. The geometric mean of the ergosterol: microbial biomass C ratio was 6.0 mg g-1, increasing in the order grassland (5.1), arable land (5.4) and woodland (7.2). The ergosterol:microbial biomass C ratio had a strong negative relationship with the decreasing cation exchange capacity and soil pH, indicating that the fungal part of the total microbial biomass in soils increased when the buffer capacity decreased. The average ergosterol concentration calculated from literature data was 5.1 mg g-1 fungal dry weight. Assuming that fungi contain 46% C, the conversion factor from micrograms ergosterol to micrograms fungal biomass C is 90. For soil samples, neither saponification of the extract nor the more effective direct saponification during extraction seems to be really necessary. 相似文献
5.
Giancarlo Renella Amar M. Chaudri Céline M. Falloon Loretta Landi Paolo Nannipieri Philip C. Brookes 《Biology and Fertility of Soils》2007,43(6):751-758
We investigated Cd, Zn, and Cd + Zn toxicity to soil microbial biomass and activity, and indigenous Rhizobium leguminosarum biovar trifolii, in two near neutral pH clay loam soils, under long-term arable and grassland management, in a 6-month laboratory incubation,
with a view to determining the causative metal. Both soils were amended with Cd- or Zn-enriched sewage sludge, to produce
soils with total Cd concentrations at four times (12 mg Cd g−1 soil), and total Zn concentrations (300 mg Zn kg−1 soil) at the EU upper permitted limit. The additive effects of Cd plus Zn at these soil concentrations were also investigated.
There were no significant differences in microbial biomass C (B
C), biomass ninhydrin N (B
N), ATP, or microbial respiration between the different treatments. Microbial metabolic quotient (defined as qCO2 = units of CO2–C evolved unit−1 biomass C unit−1 time) also did not differ significantly between treatments. However, the microbial maintenance energy (in this study defined
as qCO2-to-μ ratio value, where μ is the growth rate) indicated that more energy was required for microbial synthesis in metal-rich sludge-treated soils (especially
Zn) than in control sludge-treated soils. Indigenous R.
leguminosarum bv. trifolii numbers were not significantly different between untreated and sludge-treated grassland soils after 24 weeks regardless of
metal or metal concentrations. However, rhizobial numbers in the arable soils treated with metal-contaminated sludges decreased
significantly (P < 0.05) compared to the untreated control and uncontaminated sludge-treated soils after 24 weeks. The order of decreasing
toxicity to rhizobia in the arable soils was Zn > Cd > Cd + Zn. 相似文献
6.
A field study was conducted to investigate the effect of abandonment of management on net N mineralization (NNM) in subalpine
meadows. NNM, soil microbial biomass N (SMBN), fungal biomass and physicochemical characteristics (total C, total N, dissolved
organic carbon (DOC) and pH) were determined in surface (0–10 cm) soil from May to October 1997 in an intensively managed
and an abandoned meadow at 1770 m a.s.l.. The cumulative NNM was lower in the abandoned area and ranged from 150 to 373 and
from 25 to 85 μg N g–1 soil in the intensively managed and the abandoned areas, respectively. The total organic C increased in the abandoned area,
while total N showed no difference between abandoned and managed meadow. SMBN showed no difference between the investigated
sites, whereas ergosterol, a measure of fungal biomass, increased significantly at the abandoned site. The cumulative NNM
was negatively correlated with total organic C, C : N ratio, DOC and ergosterol content, and positively correlated with the
NH4
+-N content of soil. The decrease in NNM at the abandoned site may be explained by the lower availability of N in substrates
characterized by a high C : N ratio which, together with a decrease in pH in the litter layer, may have increased fungal biomass.
Received: 8 January 1999 相似文献
7.
Short-term effects of nitrogen on methane oxidation in soils 总被引:6,自引:0,他引:6
P. Tlustos T. W. Willison J. C. Baker D. V. Murphy D. Pavlikova K. W. T. Goulding D. S. Powlson 《Biology and Fertility of Soils》1998,28(1):64-70
The short-term effects of N addition on CH4 oxidation were studied in two soils. Both sites are unfertilized, one has been under long-term arable rotation, the other
is a grassland that has been cut for hay for the past 125 years. The sites showed clear differences in their capacity to oxidise
CH4, the arable soil oxidised CH4 at a rate of 0.013 μg CH4 kg–1 h–1 and the grassland soil approximately an order of magnitude quicker. In both sites the addition of (NH4)2SO4 caused an immediate reduction in the rate of atmospheric CH4 oxidation approximately in inverse proportion to the amount of NH4
+ added. The addition of KNO3 caused no change in the rate of CH4 oxidation in the arable soil, but in the grassland soil after 9 days the rate of CH4 oxidation had decreased from 0.22 μg CH4 kg–1 h–1 to 0.13 μg CH4 kg–1 h–1 in soil treated with the equivalent of 192 kg N ha–1. A 15N isotopic dilution technique was used to investigate the role of nitrifiers in regulating CH4 oxidation. The arable soil showed a low rate of gross N mineralisation (0.67 mg N kg–1 day–1), but a relatively high proportion of the mineralised N was nitrified. The grassland soil had a high rate of gross N mineralisation
(18.28 mg N kg–1 day–1), but negligible nitrification activity. It is hypothesised that since there was virtually no nitrification in the grassland
soil then CH4 oxidation at this site must be methanotroph mediated.
Received: 31 October 1997 相似文献
8.
Influence of N and non-N salts on atmospheric methane oxidation by upland boreal forest and tundra soils 总被引:10,自引:0,他引:10
S. C. Whalen 《Biology and Fertility of Soils》2000,31(3-4):279-287
The short-term (24 h) and medium-term (30 day) influence of N salts (NH4Cl, NaNO3 and NaNO2) and a non-N salt (NaCl) on first-order rate constants, k (h–1) and thresholds (CTh) for atmospheric CH4 oxidation by homogenized composites of upland boreal forest and tundra soils was assessed at salt additions ranging to 20 μmol
g–1 dry weight (dw) soil. Additions of NH4Cl, NaNO3 and NaCl to 0.5 μmol g–1 dw soil did not significantly decrease k relative to watered controls in the short term. Higher concentrations significantly reduced k, with the degree of inhibition increasing with increasing dose. Similar doses of NH4Cl and NaCl gave comparable decreases in k relative to controls and both soils showed low native concentrations of NH4
+-N (≤1 μmol g–1dw soil), suggesting that the reduction in k was due primarily to a salt influence rather than competitive inhibition of CH4 oxidation by exogenous NH4
+-N or NH4
+-N released through cation exchange. The decrease in k was consistently less for NaNO3 than for NH4Cl and NaCl at similar doses, pointing to a strong inhibitory effect of the Cl– counter-anion. Thresholds for CH4 oxidation were less sensitive to salt addition than k for these three salts, as significant increases in CTh relative to controls were only observed at concentrations ≥1.0 μmol g–1 dw soil. Both soils were more sensitive to NaNO2 than to other salts in the short term, showing a significant decrease in k at an addition of 0.25 μmol NaNO2 g–1 dw soil that was clearly attributable to NO2
–. Soils showed no recovery from NaCl, NH4
+-N or NaNO3 addition with respect to atmospheric CH4 oxidation after 30 days. However, soils amended with NaNO2 to 1.0 μmol NaNO2 g–1 dw showed values of k that were not significantly different from controls. Recovery of CH4-oxidizing ability was due to complete oxidation of NO2
–-N to NO3
–-N. Analysis of soil concentrations of N salts necessary to inhibit atmospheric CH4 oxidation and regional rates of N deposition suggest that N deposition will not decrease the future sink strength of upland
high-latitude soils in the atmospheric CH4 budget.
Received: 30 April 1999 相似文献
9.
Influence of nitrogen on atrazine and 2, 4 dichlorophenoxyacetic acid mineralization in blackwater and redwater forested wetland soils 总被引:1,自引:0,他引:1
J. A. Entry 《Biology and Fertility of Soils》1999,29(4):348-353
Microcosms were used to determine the influence of N additions on active bacterial and fungal biomass, atrazine and dichlorophenoxyacetic
acid (2,4-D) mineralization at 5, 10 and 15 weeks in soils from blackwater and redwater wetland forest ecosystems in the northern
Florida Panhandle. Active bacterial and fungal biomass was determined by staining techniques combined with direct microscopy.
Atrazine and 2,4-D mineralization were measured radiometrically. Treatments were: soil type, (blackwater or redwater forested
wetland soils) and N additions (soils amended with the equivalent of 0, 200 or 400 kg N ha–1 as NH4NO3). Redwater soils contained higher concentrations of C, total N, P, K, Ca, Mn, Fe, B and Zn than blackwater soils. After N
addition and 15 weeks of incubation, active bacterial biomass in redwater soils was lower when N was added. Active bacterial
biomass in blackwater soils was lower when 400 kg N ha–1, but not when 200 kg N ha–1, was added. Active fungal biomass in blackwater soils was higher when 400 kg N ha–1, but not when 200 kg N ha–1, was added. Active fungal biomass in redwater soils was lower when 200 kg N ha–1, but not when 400 kg N ha–1, was added. After 15 weeks of incubation 2,4-D degradation was higher in redwater wetland soils than in blackwater soils.
After 10 and 15 weeks of incubation the addition of 200 or 400 kg N ha–1 decreased both atrazine and 2,4-D degradation in redwater soils. The addition of 400 kg N ha–1 decreased 2,4-D degradation but not atrazine degradation in blackwater soils after 10 and 15 weeks of incubation. High concentrations
of N in surface runoff and groundwater resulting from agricultural operations may have resulted in the accumulation of N in
many wetland soils. Large amounts of N accumulating in wetlands may decrease mineralization of toxic agricultural pesticides.
Received: 26 June 1998 相似文献
10.
Influence of nitrogen on cellulose and lignin mineralization in blackwater and redwater forested wetland soils 总被引:2,自引:0,他引:2
J. A. Entry 《Biology and Fertility of Soils》2000,31(5):436-440
Microcosms were used to determine the influence of N additions on active bacterial and active fungal biomass, cellulose degradation
and lignin degradation at 5, 10 and 15 weeks in soils from blackwater and redwater wetlands in the northern Florida panhandle.
Blackwater streams contain a high dissolved organic C concentration which imparts a dark color to the water and contain low
concentrations of nutrients. Redwater streams contain high concentrations of suspended clays and inorganic nutrients, such
as N and P, compared to blackwater streams. Active bacterial and fungal biomass was determined by direct microscopy; cellulose
and lignin degradation were measured radiometrically. The experimental design was a randomized block. Treatments were: soil
type (blackwater or redwater forested wetlands) and N additions (soils amended with the equivalent of 0, 200 or 400 kg N ha–1 as NH4NO3). Redwater soils contained higher concentrations of C, total N, P, K, Ca, Mn, Fe, B and Zn than blackwater soils. After N
addition and 15 weeks of incubation, the active bacterial biomass in redwater soils was lower than in blackwater soils; the
active bacterial biomass in blackwater soils was lower when 400 kg N ha–1, but not when 200 kg N ha–1, was added. The active fungal biomass in blackwater soils was higher when 400 kg N ha–1, but not when 200 kg N ha–1, was added. The active fungal biomass in redwater wetland soils was lower when 200 kg N ha–1, but not when 400 kg N ha–1, was added. Cellulose and lignin degradation was higher in redwater than in blackwater soils. After 10 and 15 weeks of incubation,
the addition of 200 or 400 kg N as NH4NO3 ha–1 decreased cellulose and lignin degradation in both wetland soils to similar levels. This study indicated that the addition
of N may slow organic matter degradation and nutrient mineralization, thereby creating deficiencies of other plant-essential
nutrients in wetland forest soils.
Received: 7 April 1999 相似文献
11.
H. Velvis 《Biology and Fertility of Soils》1997,25(4):354-360
A procedure for the measurement of the fungal and bacterial contribution to substrate-induced respiration was tested in three
arable soils. Glucose and different amounts of cycloheximide (eukaryote inhibitor) and streptomycin sulfate (prokaryote inhibitor)
were added to soil suspensions, and respiration (CO2 evolution) was measured. Streptomycin sulfate concentrations from 10 to 120 mg ml–1 soil solution caused a stable inhibition of respiration. Amounts of cycloheximide ranging from 5 to 35 mg ml–1 showed an increasing inhibition. In a test with separate and combined addition of the antibiotics at maximum inhibitory concentrations,
inhibition by streptomycin was completely overlapped by cycloheximide. This indicated non-target inhibition which may lead
to overestimation of fungal respiration. Experiments with sterilized soils inoculated with either fungi or bacteria confirmed
that streptomycin selectively inhibited bacteria. Cycloheximide, however, did not only inhibit fungal respiration already
at 2 mg ml–1, but also increasingly inhibited bacterial respiration at increasing concentrations. Only at less than 5 mg cycloheximide
ml–1 was the condition of selective fungal inhibition fulfilled. When 2 mg cycloheximide and 10 mg streptomycin sulfate ml–1 were applied, the sum of the separate inhibitions almost equalled the combined inhibition by the mix of both inhibitors in
field samples. This method yielded fungal:bacterial respiration ratios of 0.50 to 0.60, and confirmed the dominance of bacteria
in Dutch arable soils. The ratios obtained by the selective inhibitors were not correlated with, and were higher than, ratios
of fungal:bacterial biovolume (0.19 to 0.46) as determined by microscopy and image analysis. Similar measurements in a forest
soil (A-horizon) raised doubts on the reliability of the fungal inhibition by cycloheximide in this soil. It is concluded
that the separate:combined inhibition ratio should always be checked, and comparison with other approaches is recommended.
Received: 17 September 1996 相似文献
12.
L. Landi G. Renella J. L. Moreno L. Falchini P. Nannipieri 《Biology and Fertility of Soils》2000,32(1):8-16
This study was carried out to investigate the effect of very high cadmium concentrations (50 and 500 μg Cd g–1 soil) on some biochemical and microbiological measurements under laboratory conditions involving daily soil samplings. The
data for both DTPA- and water-soluble Cd showed two distinctive patterns during soil incubation; from 0 to 4 days, values
were about 50–500 and 1–100 μg g–1 dry weight soil, whereas they decreased markedly after 7 days. Both daily respiration and the ATP content but not the microbial
biomass C determined by the fumigation–extraction method were lowered by high DTPA- and water-soluble Cd concentrations. Dehydrogenase
and phosphatase activities as well as both enzyme activity : microbial biomass ratios were decreased by the high DTPA- and
water-soluble Cd concentrations. In the first 2 days of incubation, the metabolic quotient (qCO2) was also decreased by the highest values of available Cd. The early (after 6 h) mineralization of l- but not d-glutamic acid to CO2 was inhibited during the 0–4 day incubation period by the highest Cd concentration. Possibly the l-enantiomer was used by a larger fraction of soil microorganisms than the d-enantiomer or, if they were used by the same fraction of soil microorganisms, the d-enantiomer was mineralized at a lower rate. The l- : d-glutamic acid respiration ratio was decreased by the high available Cd content because under polluted conditions soil microorganisms
probably discriminated less between the two stereoisomers of glutamic acid.
Received: 13 July 1999 相似文献
13.
Wood-ash fertilization and fire treatments in a Scots pine forest stand: Effects on the organic layer,microbial biomass,and microbial activity 总被引:6,自引:0,他引:6
H. Fritze A. Smolander T. Levula V. Kitunen E. Mälkönen 《Biology and Fertility of Soils》1994,17(1):57-63
We studied the reactions of humus layer (F/H) microbial respiratory activity, microbial biomass C, and the fungal biomass, measured as the soil ergosterol content, to the application of three levels of wood ash (1000, 2500, and 5000 kg ha-1) and to fire treatment in a Scots pine (Pinus sylvestris L.) stand. Physicochemical measurements (pH, organic matter content, extractable and total C content, NH
4
+
and total N content, cation-exchange capacity, base saturation) showed similarity between the fire-treated plots and those treated with the lowest dose of wood ash (1000 kg ha-1). The ash application did not change the level of microbial biomass C or fungal ergosterol when compared to the control, being around 7500 and 350 g g-1 organic matter for the biomass C and ergosterol, respectively. The fire treatment lowered the values of both biomass measurements to about half that of the control values. The fire treatment caused a sevenfold fall in the respiration rate of fieldmoist soil to 1.8 l h-1 g-1 organic matter compared to the values of the control or ash treatments. However, in the same soils adjusted to a water-holding capacity of 60%, the differences between the fire treatment and the control were diminished, and the ash-fertilized plots were characterized by a higher respiration rate compared to the control plots. The glucose-induced respiration reacted in the same way as the water-adjusted soil respiration. The metabolic quotient, qCO2, gradually increased from the control level with increasing applications of ash, reaching a maximum in the fire treatment. Nitrification was not observed in the treatment plots. 相似文献
14.
Dynamics and stratification of bacteria and fungi in the organic layers of a scots pine forest soil 总被引:1,自引:0,他引:1
The abundance and micro-stratification of bacteria and fungi inhabiting the organic layers of a Scots pine forest (Pinus sylvestris L.) were investigated. An experiment using stratified litterbags, containing organic material of four degradation stages
(fresh litter, litter, fragmented litter and humus) was performed over a period of 2.5 years. Dynamics and stratification
of fluorescent stained bacteria and fungi, ratios between bacterial and fungal biomass, and relationships with moisture and
temperature are described. Average bacterial counts in litter and fragmented litter were similar, i.e., approximately 5×109 bacteriag–1 (dry weight) organic matter, and significantly exceeded those in humus. The mean bacterial biomass ranged from 0.338 to 0.252mg
carbon (C) g–1 (dry weight) organic matter. Lengths of mycelia were significantly below the usually recorded amounts for comparable temperate
coniferous forests. The highest average hyphal length, 53mg–1 (dry weight) organic matter, was recorded in litter and decreased significantly with depth. The corresponding mean fungal
biomass ranged from 0.050 to 0.009mg Cg–1 (dry weight). The abundance of bacteria and fungi was influenced by water content, that of fungi also by temperature. A litterbag
series with freshly fallen litter of standard quality, renewed bimonthly, revealed a clear seasonal pattern with microbial
biomass peaks in winter. The mean hyphal length was 104mg–1 (dry weight) and mean number of bacteria, 2.40×109 bacteria g–1 (dry weight). Comparable bacterial and fungal biomass C were found in the freshly fallen litter [0.154 and 0.132mgCg–1 (dry weight) organic material, respectively]. The ratio of bacterial-to-fungal biomass C increased from 1.2 in fresh litter
to 28.0 in humus. The results indicate the existence of an environmental stress factor affecting the abundance of fungi in
the second phase of decomposition. High atmospheric nitrogen deposition is discussed as a prime factor to explain low fungal
biomass and the relatively short lengths of fungal hyphae in some of the forest soil layers under study.
Received: 26 June 1997 相似文献
15.
Carbon and nitrogen dynamics in ageing earthworm casts in grasslands of the eastern plains of Colombia 总被引:5,自引:0,他引:5
The effects of a large species of anecic earthworm, Martiodrilus carimaguensis Jiménez and Moreno, on soil C and N dynamics were investigated in a native savanna and a man-made pasture of the eastern
plains of Colombia. We compared, across time (11 months), the total C, total N, NH+
4 and NO–
3 contents in the earthworm casts, the underlying soil and the adjacent soil. Additional sampling of root biomass and macrofauna
was performed. In the two management systems, the total C and N contents were higher in casts (4.33–7.50%) than in the bulk
soil (2.81–4.08%), showing that the earthworms selected food substrates with high organic contents. In general, C contents
significantly increased during cast ageing (+100%), possibly because of CO2 fixation processes, dead root accumulation and/or macrofaunal activities in casts. In fresh casts, NH+
4 levels were very high (294.20–233.98 μg g–1 dry cast) when compared to the soil (26.96–73.95 μg g–1 dry soil), due to the intense mineralisation processes that occurred during the transit of soil and organic matter through
the earthworm gut. During the first week of cast ageing, NH+
4 levels sharply decreased, while NH–
3 levels showed successive peaks in the casts, the underlying soil and the adjacent soil. These results suggested the rapid
production of NO–
3 by nitrification processes in the fresh casts, followed by diffusion to the nearby soil, first vertically, then horizontally.
After 2 weeks of cast ageing, NH+
4 and NO–
3 levels only showed slight variations, likely because of organic matter protection in stable dry casts. The root biomass was
higher (1.6–4.7 times) below the old earthworm casts. The ecological significance of these results is discussed.
Received: 22 October 1998 相似文献
16.
Soil N dynamics were compared in Alpine pastures on two mountains. N-pool sizes and N fluxes were measured relative to N
losses via leaching and denitrification in summer. On each mountain, four types of pasture were studied: (1) forest pastures,
(2) recently developed pastures formed by forest clearance ("new pastures"), (3) older established pastures, and (4) pastures
planted with clover. At both study sites (Scheuchegg and Teufelstein) we obtained similar results. Compared with forest pasture
soils, open pasture soils were found to have greater microbial biomass and faster mineralisation potentials, but net field
mineralisation rates were slower. In the forest pastures, highest N losses via denitrification were found. Higher potential
leaching of NO3
–, estimated by accumulation of NO3
– on ion-exchange resins, in the forest pasture soils suggests lower N uptake by microbes and herbaceous plants compared with
open pastures. N2O-production rates of the forest pasture soils at the Scheuchegg site (11.54 μg N2O-N m–2 h–1) were of similar magnitude to those reported for spruce forests without pastures, but at Teufelstein (53.75 μg N2O-N m–2 h–1) they were higher. However, if forest pastures are not overgrazed, no elevated N loss through N2O production and leaching of NO3
– is expected. Denitrification rates in the open pastures (0.83–7.50 μg N2O-N m–2 h–1) were low compared with reports on lowland pastures. In soils of the new pastures, rates of microbial N processes were similar
to those in the established pastures, indicating a high capacity of soils to restore their internal N cycle after forest clearance.
Received: 19 August 1999 相似文献
17.
Björn Probst Christian Schüler Rainer Georg Joergensen 《Biology and Fertility of Soils》2008,44(3):443-450
Eight vineyards in Pfaffenheim (P) and Turckheim (T) close to Colmar, France, forming four pairs of organic and conventional
vineyards, were analyzed for microbial biomass and activity indices in relation to important soil chemical properties (carbon,
nutrient elements, heavy metals) and also to differences between the bottom and top positions on the vineyard slope. The question
was whether the vineyard management affects especially the soil microbiological indices. Three locations were on limestone
(P-I, P-II, T-II), one on granite (T-I). The gravel content (>2 mm) ranged from 9 to 47%. The management systems had no significant
main effect on the contents of organic C, total N, P, and S. The mean total contents of man-derived heavy metals decreased
in the order Cu (164 μg g−1 soil) > Zn (100 μg g−1 soil) > Pb (32 μg g−1 soil). The contents of microbial biomass C varied between 320 and 1,000 μg g−1 soil. The significantly highest content was found at location P-II, the significantly lowest at the moderately acidic location
T-I. The contents of microbial biomass N and adenosine triphosphate showed a similar trend. At location T-I, the fungal ergosterol-to-microbial
biomass C ratio and the metabolic quotient qCO2 were significantly highest, whereas the percentage of soil organic C present as microbial biomass C was lowest. Highest percentages
of soil organic C present as microbial biomass C and lowest qCO2 values were found in the organic in comparison with the conventional vineyards. None of the soil microbiological indices
was significantly affected by the position on the slope, but all were significantly affected by the management system. This
was mainly due to the highest index levels in the organic vineyard location P-II with the longest history in organic management. 相似文献
18.
Dwipendra Thakuria Narayan C. Talukdar Chandan Goswami Samarendra Hazarika Mohan C. Kalita Gary D. Bending 《Biology and Fertility of Soils》2009,45(3):237-251
To achieve higher yields and better soil quality under rice–legume–rice (RLR) rotation in a rainfed production system, we
formulated integrated nutrient management (INM) comprised of Azospirillum (Azo), Rhizobium (Rh), and phosphate-solubilizing bacteria (PSB) with phosphate rock (PR), compost, and muriate of potash (MOP). Performance
of bacterial bioinoculants was evaluated by determining grain yield, nitrogenase activity, uptake and balance of N, P, and
Zn, changes in water stability and distribution of soil aggregates, soil organic C and pH, fungal/bacterial biomass C ratio,
casting activities of earthworms, and bacterial community composition using denaturing gradient gel electrophoresis (DGGE)
fingerprinting. The performance comparison was made against the prevailing farmers’ nutrient management practices [N/P2O5/K2O at 40:20:20 kg ha−1 for rice and 20:30:20 kg ha−1 for legume as urea/single super-phosphate/MOP (urea/SSP/MOP)]. Cumulative grain yields of crops increased by 7–16% per RLR
rotation and removal of N and P by six crops of 2 years rotation increased significantly (P < 0.05) in bacterial bioinoculants-based INM plots over that in compost alone or urea/SSP/MOP plots. Apparent loss of soil
total N and P at 0–15 cm soil depth was minimum and apparent N gain at 15–30 cm depth was maximum in Azo/Rh plus PSB dual
INM plots. Zinc uptake by rice crop and diethylenetriaminepentaacetate-extractable Zn content in soil increased significantly
(P < 0.05) in bacterial bioinoculants-based INM plots compared to other nutrient management plots. Total organic C content in
soil declined at 0–15 cm depth and increased at 15–30 cm depth in all nutrient management plots after a 2-year crop cycle;
however, bacterial bioinoculants-based INM plots showed minimum loss and maximum gain of total organic C content in the corresponding
soil depths. Water-stable aggregation and distribution of soil aggregates in 53–250- and 250–2,000 μm classes increased significantly
(P < 0.05) in bacterial bioinoculants-based INM plots compared to other nutrient management plots. Fungal/bacterial biomass
C ratio seems to be a more reliable indicator of C and N dynamics in acidic soils than total microbial biomass C. Compost
alone or Azo/Rh plus PSB dual INM plots showed significantly (P < 0.05) higher numbers of earthworms’ casts compared to urea/SSP/MOP alone and bacterial bioinoculants with urea or SSP-applied
plots. Hierarchical cluster analysis based on similarity matrix of DGGE profiles revealed changes in bacterial community composition
in soils due to differences in nutrient management, and these changes were seen to occur according to the states of C and
N dynamics in acidic soil under RLR rotation. 相似文献
19.
Ethylene production and decomposition in soils 总被引:6,自引:0,他引:6
Six soils differing in texture and use were investigated for their ability to produce and decompose ethylene. In addition,
changes in methane and CO2 concentrations were monitored. The effects of organic amendments and different water tensions were studied, and a method
using low concentrations of acetylene as an inhibitor of ethylene degradation was tested. Possible reduction of acetylene
to ethylene was identified by the use of CO or NH4
+-N, of which the latter turned out to be the more reliable method. This reduction only occurred in a grassland soil. Under
aerobic soil conditions, gross ethylene production rates of up to 4.7pmol g–1 h–1 could be measured. Highest ethylene production and lowest ethylene decomposition was detected in a spruce forest soil. Fine
textured soils produced more ethylene than coarse textured soils. Amended soils produced more ethylene at –100kPa and –5kPa
than at 0kPa water tension. Ethylene decomposition was most effective in soils from deciduous woodlands and reached rates
of up to 137pmol g–1 h–1. Parallels between ethylene and methane decomposition were observed. The addition of 5mgg–1 glucose and 1mgg–1 methionine not only promoted ethylene production but also inhibited ethylene decomposition.
Received: 4 April 1997 相似文献
20.
The composition of soil microbiota in four heated (350 °C, 1 h) soils (one Ortic Podsol over sandstone and three Humic Cambisol
over granite, schist or limestone) inoculated (1.5 μg chlorophyll a g–1 soil or 3.0 μg chlorophyll a g–1 soil) with cyanobacteria (Oscillatoria PCC9014, Nostoc PCC9025, Nostoc PCC9104, Scytonema CCC9801, and a mixture of the four) was studied by cultural methods. The aims of the work were to investigate the potential
value of cyanobacteria as biofertilizers for accelerating soil recolonization after fire as well as promoting microbiotic
crust formation and to determine the microbial composition of such a crust. The inoculated cyanobacteria proliferated by 5
logarithmic units in the heated soils which were colonized very quickly and, after 2 months of incubation, the cyanobacterial
filaments and associated fungal hyphae made up a matrix in which surface soil particles were gathered into crusts of up to
1.0 cm in thickness. These crusts were composed, on average, of 2.5×1010 cyanobacteria, 2.8×106 algae, 6.1×1010 heterotrophic bacteria (of which 1.2×108 were acidophilic, 1.3×106 were Bacillus spp. and 1.5×108 were actinomycetes) and 77.8 m fungal mycelium (1.4×106 were fungal propagules) g–1 crust. Counts of most microbial groups were positively correlated to cyanobacterial numbers. The efficacy of treatment depended
on both the class of inoculum and the type of soil. The best inoculum was the mixture of the four strains and, whatever the
inoculum used, the soil over lime showed the most developed crust followed by the soils over schist, granite and sandstone;
however, the latter was comparatively the most favoured by the amendment. In the medium term there were no significant differences
between the two inocula rates used. Biofertilization increased counts of cyanobacteria by 8 logarithmic units while heterotrophic
bacteria, actinomycetes, algae and fungal propagules rose by >4 logarithmic units, acidophilic bacteria and Bacillus spp. by around 3 logarithmic units and fungal mycelia showed an 80-fold increase. The results showed that inoculation of
burned soils with particle-binding diazotrophic cyanobacteria may be a means of both improving crust formation and restoring
microbial populations.
Received: 8 March 2000 相似文献