共查询到20条相似文献,搜索用时 625 毫秒
1.
S. Kumaraswamy A. K. Rath S. N. Satpathy B. Ramakrishnan T. K. Adhya N. Sethunathan 《Biology and Fertility of Soils》1998,26(4):362-366
Applications of a commercial formulation of carbofuran, a carbamate insecticide, at rates of 2kg and 12kg active ingredient
ha–1 to flooded fields planted to rice led to significant inhibition of methane emission. Likewise, laboratory incubation studies
showed that carbofuran applied at low rates (5 and 10μgg–1soil) inhibited the net methane production relative to that of the control, but stimulated it when applied at a rate of 100μgg–1soil. Interestingly, carbofuran increased the oxidation of methane when applied at low rates and inhibited it when applied
at a rate of 100μgg–1soil.
Received: 5 May 1997 相似文献
2.
Rates of methane uptake were measured in incubation studies with intact cores from adjacent fenland peats that have been
under arable management and woodland management for at least the past 30 years. On two separate occasions the woodland peat
showed greater rates of uptake than the arable peat. These rates ranged from 23.1 to 223.3 μg CH4 m–2 day–1 for the woodland peat and from 29.6 to 157.6 μg CH4 m–2 day–1 for the arable peat. When the peats were artificially flooded there was a decrease in the rate of methane oxidation, but
neither site showed any net efflux of methane. 15N isotopic dilution was used to characterise nitrogen cycling within the two peats. Both showed similar rates of gross nitrogen
mineralisation (3.58 mg N kg–1 day–1, arable peat; 3.54 N kg–1 day–1, woodland peat) and ammonium consumption (4.19 arable peat and 4.70 mg N kg–1 day–1 woodland peat). There were significant differences in their inorganic ammonium and nitrate pool sizes, and the rate of gross
nitrification was significantly higher in the woodland peat (4.90 mg N kg–1 day–1) compared to the arable peat (1.90 mg N kg–1 day–1). These results are discussed in the light of high atmospheric nitrogen deposition.
Received: 1 December 1997 相似文献
3.
Short-term kinetic response of enhanced methane oxidation in landfill cover soils to environmental factors 总被引:5,自引:0,他引:5
A. De Visscher Michael Schippers Oswald Van Cleemput 《Biology and Fertility of Soils》2001,33(3):231-237
This paper aims at a better understanding of methane oxidation under conditions that are representative of landfill cover
soils. The kinetics of methane oxidation were studied in landfill cover soils that had been exposed to high methane mixing
ratios. This was done in batch experiments, under various environmental conditions. V
max increased exponentially with temperature in the range 5–35 °C, with a Q
10 value of 2.8. K
m increased approximately linearly in this range from 1.2 μM to 7 μM. Consequently, the influence of temperature on methane
consumption was more pronounced at high concentrations than at low concentrations. The inhibition by ammonium of methane consumption
was much stronger after 6–7 months of exposure to high methane mixing ratios than after 5–7 weeks of exposure, indicating
that there was a shift of dominating methanotrophic species in soils after long exposure times. Additions of nitrifying sludge
or compost to soils initially inhibited methane oxidation, followed by a stimulation after a few days.
Received: 19 May 2000 相似文献
4.
Effect of fertilizer application on methane emission/production in the paddy soils of Taiwan 总被引:1,自引:0,他引:1
Methane production in three types of rice paddy soil was investigated under greenhouse conditions. The amount of methane
produced during the first crop season (March to July) was 2–6 times higher than that in the second crop season (August to
December). Application of organic fertilizer hastened the drop in redox potential and increased methane production and emission.
Methane production also increased with the depth of soil with high values in soil samples from 18 to 30cm depth. Methane production
in the first crop season was 18.0, 54.3 and 49.4mgcm–3 for 6tha–1 straw application for Linkou, Tzawchyau and Jiaushi soils, respectively. The value was 33.4mgcm–3 for the second crop season in Jiaushi soil. Methane emission was high during the flowering and maturity stages in the first
crop season and the values were high during the tillering and flowering stages in the second crop season. Methane emission
was high in Tzawchyau and Jiaushi soils in the first crop season. Methane emission rate reached a maximum from 12 noon to
3p.m. due to high temperature and a minimum at 3 to 6a.m. in both planted and unplanted soils.
Received: 17 September 1996 相似文献
5.
Nitrification and denitrification in the rhizosphere of rice: the detection of processes by a new multi-channel electrode 总被引:6,自引:0,他引:6
N turnover in flooded rice soils is characterized by a tight coupling between nitrification and denitrification. Nitrification
is restricted to the millimetre-thin oxic surface layer while denitrification occurs in the adjacent anoxic soil. However,
in planted rice soil O2 released from the rice roots may also support nitrification within the otherwise anoxic bulk soil. To locate root-associated
nitrification and denitrification we constructed a new multi-channel microelectrode that measures NH4
+, NO2
–, and NO3
– at the same point. Unfertilized, unplanted rice microcosms developed an oxic-anoxic interface with nitrification taking place
above and denitrification below ca. 1 mm depth. In unfertilized microcosms with rice plants, NH4
+, NO2
– and NO3
– could not be detected in the rhizosphere. Assimilation by the rice roots reduced the available N to a level where nitrification
and denitrification virtually could not occur. However, a few hours after injecting (NH4)2HPO4 or urea, a high nitrification activity could be detected in the surface layer of planted microcosms and in a depth of 20–30 mm
in the rooted soil. O2 concentrations of up to 150 μM were measured at the same depth, indicating O2 release from the rice roots. Nitrification occurred at a distance of 0–2 mm from the surface around individual roots, and
denitrification occurred at a distance of 1.5–5.0 mm. Addition of urea to the floodwater of planted rice microcosms stimulated
nitrification. Transpiration of the rice plants caused percolation of water resulting in a mass flow of NH4
+ towards the roots, thus supporting nitrification.
Received: 23 July 1999 相似文献
6.
S. R. Mohanty K. Bharati B. T. S. Moorthy B. Ramakrishnan V. R. Rao N. Sethunathan T. K. Adhya 《Biology and Fertility of Soils》2001,33(3):175-180
Application of a commercial formulation of the herbicide butachlor (N-butoxymethyl-2-chloro-2′,6′-diethyl acetanilide) at 1 kg a.i. ha–1 to an alluvial soil planted with direct-seeded flooded rice (cv. Annada), significantly inhibited both crop-mediated emission
and ebullition fluxes of methane (CH4). Over a cropping period of 110 days, the crop-mediated cumulative emission flux of CH4 was lowered by ∼20% in butachlor-treated field plots compared with that of an untreated control. Concurrently, ebollition
flux of CH4 was also retarded in butachlor-treated field plots by about 81% compared with that of control plots. Significant relationships
existed between CH4 emission and redox potential (E
h) and Fe2+ content of the flooded soil. Application of butachlor retarded a drop in soil redox potential as well as accumulation of
Fe2+ in treated field plots. Methanogenic bacterial population, counted at the maturity stage of the crop, was also low in butachlor-treated
plots, indicating both direct and indirect inhibitory effects of butachlor on methanogenic bacterial populations and their
activity. Results indicate that butachlor, even at field-application level, can effectively abate CH4 emission and ebollition from flooded soils planted to rice whilst maintaining grain yield.
Received: 15 March 2000 相似文献
7.
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
8.
Thirty-five Azospirillum strains (13 strains from plant roots and 22 strains from soils) were isolated from Ishigaki island, Japan, which has a subtropical
climate. These strains were different from each other according to polymerase-chain-reaction band patterns obtained by using
a random primer (OPT-08). Two Azospirillum strains (AZ43 and AZ92-2) were also examined for use in further experiments. Inoculation of lowland rice with these strains
enhanced early growth of rice to various degrees. Inoculation of strains VIII.P1-2, AZ92-2, V.S2-2, and V.P5 in sterilized
soil yielded higher shoot dry weights than the application of 90 μg N g–1 soil without inoculation. Only inoculation with strains AZ92-2 and VIII.P1-2 caused higher N uptake than the application
of 90 μg N g–1 soil. Three strains were selected for the next experiment based on the results of their effect on the early growth of rice.
An investigation was conducted to determine the ability of two indigenous Azospirillum strains (V.S2-2 and VIII.P1-2) and one stock strain (AZ92-2) to promote growth and nutrient-uptake of lowland rice in unsterilized
soil under several levels of N application (0, 80, 160, and 240 mg N pot–1). Inoculation with these strains without N application increased shoot dry weight by 12–15% compared to the uninoculated
treatment. Inoculation with Azospirillum V.S2-2 together with the application of 160 mg N pot–1 resulted in a shoot dry weight as high as that obtained in the treatment with 240 mg N pot–1 without inoculation. Thus, in this former case, the amount of N applied could be reduced by 80 mg pot–1 due to the effect of the microbial inoculum without a significant change in the high, targeted, yield. 相似文献
9.
Methane emission from paddy fields in Taiwan 总被引:3,自引:0,他引:3
In order to investigate the effect of environmental conditions on CH4 emission from paddy fields in Taiwan, four locations, two cropping seasons and two irrigation systems were studied. CH4 emission was high at the active tillering and the booting stages in the first cropping season, whereas it was low at the
transplanting and the ripening stages with an intermittent irrigation system. CH4 emission was high at the transplanting stage in the second cropping season, and decreased gradually during rice cultivation.
Daily temperature and light intensity increased gradually during rice growth in the first cropping season (February–June),
while it was reversed in the second cropping season (August–December). The seasonal CH4 emission from paddy fields ranged from 1.73 to 11.70 g m–2, and from 10.54 to 39.50 g m–2 in the first and second cropping seasons, respectively. The seasonal CH4 emission in the second cropping season was higher than that in the first cropping season in all test fields. The seasonal
CH4 emission was 32.65 mg m–2 in the first cropping season of the National Taiwan University paddy field with continuous flooding, and it was 28.85 mg
m–2 in the second cropping season. The annual CH4 emission ranged from 12.3 to 49.3 g m–2 with an intermittent irrigation system, and the value was 61.5 g m–2 with a continuous flooding treatment. The annual CH4 emission from paddy fields was estimated to be 0.034 Tg in 1997 from 364,212 ha of paddy fields with an intermittent irrigation
system, which was less than the 0.241 Tg calculated by the IPCC method with a continuous flooding treatment
Received: 23 February 2000 相似文献
10.
Evaluation of alternative substrates for determining methane-oxidizing activities and methanotrophic populations in soils 总被引:1,自引:0,他引:1
The magnitude of methane emission is a net result of methane production and the oxidation rate. The possibility of measuring oxidized products of alternative substrates of methane monooxygenase was examined to determine methane-oxidizing ability of soils, and to count methanotrophic populations in soils. Wetland rice soils were incubated under methane containing air to enirch the methanotrophs. Methane loss and oxygen uptake were inhibited by acetylene, dimethylether, and nitrapyrin (N-Serve). Acetylene was used routinely, because it inhibited methane oxidation even at a low concentration of 0.03 to 0.06 l ml-1 in the incubation headspace. Propylene at 10 kPa was used as an alternative substrate of methane monooxygenase, and the formation of propylene oxide was measured. When soils were incubated under methane, their methane-oxidizing activity increased. Propylene oxide formation increased simultaneously. Acetylene also blocked propylene oxidation. The results of several experiments and propylene oxide formation (r=0.87 after long-transformation). These results indicate that propylene oxide formation can be used as a semiquantitative measure of the methane-oxidizing activity of soils. The colonies of soluble methane monooxygenase-forming methanotrophs were counted on Cu-deficient methanotroph agar medium by the formation of naphthol from haphthalene. The counts increased from 104 (0 days) to 107 (21 days) g-1 soil during oxic incubation under methane. 相似文献
11.
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
12.
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
13.
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
14.
An experiment was conducted to investigate the effects of earthworm (Metaphire guillelmi) activities on rice photosynthates distribution in plant–soil system through 14C pulse-labelling method. Rice was planted in pots, and maize straw was mulched on the surface with or without earthworms.
Rice plants at tillering stage or heading stage were labelled with 14CO2. Plant and soil were sampled 15 days after labelling at the tillering or heading stage and at harvest. Rice growth was inhibited
by earthworms (M. guillelmi) at early stage, but the inhibition disappeared at later stage. Earthworms significantly (P < 0.01) increased the 14C percentage in root at day 15 after tillering stage labelling, but the effect disappeared at harvest. Earthworms (M. guillelmi) significantly (P < 0.01) increased the 14C percentage in root at day 15 after heading stage labelling and increased 14C percentage in soil at harvest. Earthworms decreased the percentages of total organic 14C (TO14C) present as microbial biomass 14C (MB14C) and increased the percentages of total organic 14C present as dissolved organic 14C (DO14C) at all sampling times. It is suggested that earthworms might alter the transfer of plant photosynthates from the aboveground
to the belowground, and thus, soil active C pool. However, these data should be also confirmed in the field. 相似文献
15.
C. Van Nieuwenhove L. Van Holm S. A. Kulasooriya K. Vlassak C. Van Nieuwenhove L. Van Holm 《Biology and Fertility of Soils》2000,31(2):143-149
Azorhizobium caulinodans strongly colonized the rhizosphere of rice plants after incorporation of Sesbania rostrata in a field trial throughout the growing season and during the fallow period until 19 weeks after incorporation of S. rostrata. A. caulinodans became well established in the rhizosphere (7.17 log cfu g–1 dry rice root) and colonized subsequent S. rostrata test plants. Three traditional and three improved high-yielding rice varieties were inoculated with A. caulinodans under gnotobiotic conditions. In none of the combinations did acetylene reduction activity significantly increase. Ethylene
production on colonized rice roots only started after the growth medium had been supplemented with an extra C source (0.1
to 0.25% Na-lactate). This indicates that the bacterial nitrogenase activity is limited by energy supply. Four possible inoculant-carriers
(peat, coir dust, bagasse, rice straw) were compared for long-term survival of the bacterial strain. Independent of the storage
temperature (26 °C or 4 °C), the survival of A. caulinodans in peat and coir dust was very high during a 12-month period (>8 log cfu g–1 dry carrier), whereas the bagasse and rice straw carriers showed a serious decline from 3 months onwards.
Received: 6 April 1999 相似文献
16.
In a greenhouse study, methane emissions were measured from two diverse Indian rice-growing soils planted to five rice cultivars
under similar water regimes, fertilizer applications and environmental conditions. Significant variations were observed in
methane emitted from soils growing different cultivars. Total methane emission varied between 8.04 and 20.92gm–2 from IARI soil (Inceptisol) and between 1.47 and 10.91gm–2 from Raipur soil (Vertisol) planted to rice. In all the cultivars, emissions from IARI soil were higher than from Raipur
soil. The first methane flux peak was noticed during the reproductive phase and the second peak coincided with the grain-ripening
stage of the rice cultivars.
Received: July 7, 1996 相似文献
17.
Methane uptake in Swedish forest soil in relation to liming and extra N-deposition 总被引:11,自引:0,他引:11
Methane uptake to soil was examined in individual chambers at three small forest catchments with different treatments, Control,
Limed and Nitrex sites, where N-deposition was experimentally increased. The catchments consisted of both well-drained forest
and wet sphagnum areas, and showed uptake of CH4 from the ambient air. The lowest CH4 uptakes were observed in the wet areas, where the different treatments did not influence the uptake rate. In the well-drained
areas the CH4 uptakes were 1.6, 1.4 and 0.6 kg ha–1 year–1 for the Limed, Control and Nitrex sites, respectively. The uptake of methane at the well-drained Nitrex site was statistically
smaller than at the other well-drained catchments. Both acidification and increase in nitrogen in the soil, caused by the
air-borne deposition, are the probable cause for the reduction in the methane uptake potential. Uptake of methane was correlated
to soil water content or temperature for individual chambers at the well-drained sites. The uptake rate of methane in soil
cores was largest in the 0- to 10-cm upper soil layer. The concentration of CH4 in the soil was lower than the atmospheric concentration up to 30 cm depth, where methane production occurred. Besides acting
as a sink for atmospheric methane, the oxidizing process in soil prevents the release of produced methane from deeper soil
layers reaching the atmosphere.
Received: 27 September 1996 相似文献
18.
Pot experiments were carried out to evaluate the response of rice to Sesbania rostrata green manure N as compared to urea fertilizer N under flooded conditions. After growing S. rostrata for 21 days with a 15N-labelled N source, the labelled Sesbania was applied to wetland rice as a green manure and the uptake of 15N from this substrate was compared to that from labelled urea. Rice was cultivated twice in the same pots. The rice was grown
for a period of 49 days in each case, separated by a period of 21 days when the soil was allowed to dry. The 15N content of the soil and shoots and roots of rice was determined and 15N balances established. The total N content of the shoots and roots of rice was determined by a non-tracer method. The percentage
recovery of 15N from shoot material which was derived from urea N was more than twice that from S. rostrata. The recovery of 15N from the pots receiving both green manure and urea was low, and not significantly different from that recovered from the
green manure treatment. As much as 64.5–73.5% and 40.1–41% of the 15N remained in the soil which had received green manure or urea, respectively. The overall recoveries of 15N varied between 86.5% and 94.4%. At the second harvest, the oven-dry weight of shoots was significantly (P<0.05) higher in green-manure treated pots, but the total N content did not differ significantly. Labelled N remaining in
the soil after amendment with the green manure was much more available to the rice crop than that remaining after the addition
of urea-N. The total recovery of labelled N (shoots plus roots) amounted to 65.5% and 74%, respectively of the residual labelled
N in the two S. rostrata treatments (i.e. 19.55 mg 15N pot–1 and 39.10 mg 15N pot–1) and 23.2% and 23.2% of the residual labelled N in the two urea treatments (i.e. 19.55 mg 15N pot and 39.10 mg 15N pot–1), respectively.
Received: 8 December 1997 相似文献
19.
Incubation of soil under low partial pressures of acetylene (10 Pa) is a widely used method to specifically inhibit nitrification
due to the suicide inhibition of ammonium monooxygenase (AMO), the first enzyme in NH4
+ oxidation by nitrifying bacteria. Although the inhibition of AMO is irreversible, recovery of activity is possible if new
enzyme is synthesized. In experiments with three different soils, NH4
+ concentrations decreased and NO3
– concentrations increased soon after acetylene was removed from the atmosphere. Recovery of NO production started immediately
after the removal of acetylene. The release rates of NO and N2O were higher in soil samples which were only preincubated with 10 Pa acetylene than in those which were kept in the presence
of 10 Pa acetylene. In the permanent presence of 10 Pa acetylene, NH4
+ and NO3
– concentrations stayed constant, and the release rates of NO and N2O were low. These low release rates were apparently due to processes other than nitrification. Our experiments showed that
the blockage of nitrification by low (10 Pa) acetylene partial pressures is only reliable when the soil is kept in permanent
contact with acetylene.
Received: 17 July 1996 相似文献
20.
Nitrous oxide emission from wetland rice soil as affected by the application of controlled-availability fertilizers and mid-season aeration 总被引:5,自引:0,他引:5
N2O emission from a wetland rice soil as affected by the application of three controlled-availability fertilizers (CAFs) and
urea was investigated through a pot experiment. N2O fluxes from the N fertilized paddy soil averaged 44.8–69.3 μg N m–2 h–1 during the rice growing season, accounting for 0.28–0.51% of the applied N. The emission primarily occurred during the mid-season
aeration (MSA) and the subsequent re-flooding period. Fluxes were highly correlated with the NO3
– and N2O concentrations in the soil water. As there were relatively large amounts of NH4
+-N present in the soil of the CAF treatments at the beginning of MSA, leading to large amounts of NO3
–-N during the MSA and the subsequent re-flooding period, the tested CAFs were not effective in reducing N2O emission from this paddy soil. The potential of applied CAFs to reduce N2O emissions from paddy soil is discussed.
Received: 25 May 1999 相似文献