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  • Azospirillum brasilense  (2)
  • Denitrification  (2)
  • Ammonia volatilization  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 229-235 
    ISSN: 1432-0789
    Keywords: Denitrification ; N2-fixation ; Fermentation ; N2O/N2 ratio ; C-availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrate and glucose additions were investigated for their role in the C and N dynamics during anaerobic incubation of soil. A gas-flow soil core method was used, in which the net production of N2, N2O, NO, CO2, and CH4 under a He atmosphere could be monitored both accurately and frequently. In all experiments clayey silt loam soil samples were incubated for 9 days at 25 °C. Addition of nitrate (50 mg KNO3-N kg-1 soil) had no effect on total denitrification and CO2 production rates, while the N2O/N2 ratio was affected considerably. The cumulative N2O production exceeded the cumulative N2 production for 6 days in the treatment with nitrate addition, compared to 1.2 days in the unamended treatment. Glucose addition stimulated the microbial activity considerably. The denitrification rates were limited by the growth rate of the denitrifying population. During denitrification no significant differences were observed between the treatments with 700 mg glucose-C kg-1 and 4200 mg glucose-C kg-1, both in combination with 50 mg KNO3-N kg-1. The N2 production rates were remarkably low, until NO inf3 sup- exhaustion caused rapid reduction of N2O to N2 at day 2. During the denitrification period 15–18 mg N kg-1 was immobilised in the growing biomass. After NO inf3 sup- shortage, a second microbial population, capable of N2-fixation, became increasingly important. This change was clearly reflected in the CO2 production rates. Net volatile fatty acid (VFA) production was monitored during the net N2-fixation period with acetate as the dominant product. N2-fixation faded out, probably due to N2 shortage, followed by increased VFA production. In the high C treatment butyrate became the most important VFA, while in the low C treatment acetate and butyrate were produced at equal rates. During denitrification no VFA accumulation occurred; this does not prove, however, that denitrification and fermentation appeared sequentially. The experiments illustrate clearly the interactions of C-availability, microbial population and nitrate availability as influencing factors on denitrification and fermentation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0789
    Keywords: Key words Carbon dioxide production ; Nitrous oxide ; production ; Ammonia volatilization ; Pig slurry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dynamics of nitrogen (N) and carbon (C) were investigated in a loamy soil amended or injected with pig slurry. Treatments were with or without acetylene C2H2 (which is assumed to inhibit reduction of nitrous oxide (N2O) to dinitrogen (N2), and soil cores were conditioned for 15 days at 25°C while pH, production of CO2 and N2O, ammonia (NH3) emission and (nitrate) (NO3 –) and (ammonium) (NH4 +) concentrations were monitored. There was no significant difference in CO2 production between the injected and surface applied pig slurry treatments, and within 15 days ca. 5% of the C applied had been mineralized, if no priming effect was assumed. Neither the production of N2O nor the total gaseous production of the denitrification process (N2O plus N2) were affected by the way the pig slurry was added to the soil. NH3 volatilization, however, decreased by 90% when pig slurry was injected. The addition of C2H2 significantly increased the CO2 production and the concentration of NH4 +, but significantly decreased the concentration of NO3 –. It was concluded that the injection of pig slurry to a dry soil was an acceptable alternative to its application to the soil surface, as not only was NH3 volatilization reduced, but the production of N2O and N2 through denitrification was not stimulated. It is also suggested that the composition of the organic C fraction in the pig slurry, most likely the concentration of fatty acids, had an important effect on the dynamics of N and C in the soil.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Triticum aestivum ; Inoculation ; N and dry matter yield ; N percentages in plant parts ; Associative N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat plants (Triticum aestivum) grown in pots and in the field under the Mediterranean climate of the south of France were inoculated with a strain of Azospirillum brasilense. Comparisons with non-inoculated plants grown under the same conditions showed significant responses to inoculation with an increase in the number of fertile tillers, shoot and root dry weight, and root to shoot biomass ratio. The roots of inoculated plants attracted relatively more assimilates than those of the control plants until a late stage of growth (heading stage) but the rhizosphere respiration expressed per unit of root growth was not increased by inoculation. Nitrogen yield, both total and in grains, was also enhanced; however, N percentages of all aerial parts of the plants grown in pots were always statistically lower after inoculation than in the control. At maturity, the N % in seeds was 1.81 and 2.45, respectively. The possible mechanisms of this effect of inoculation under the experimental conditions of this study are discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 26 (1998), S. 224-228 
    ISSN: 1432-0789
    Keywords: Key words CO2 production ; N2O production ; Nitrification ; Denitrification ; NH3 volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Carbon (C) and Nitrogen dynamics and sources of nitrous oxide (N2O) production were investigated in a loamy soil amended with pig slurry. Pig slurry (40000kgha–1) or distilled H2O was applied to intact soil cores of the upper 5cm of a loamy soil which were incubated under aerobic conditions for 28 days at 25°C. Treatments were with or without acetylene (C2H2), which is assumed to inhibit the reduction of N2O to dinitrogen (N2), and with or without dicyandiamide (DCD), which is thought to inhibit nitrification. Volatilization of ammonia (NH3), pH, carbon dioxide (CO2) and N2O production, and ammonium (NH4 +) and nitrate NO3 –) concentrations were monitored. The pH of the pig slurry amended soil increased from an initial value of 7.1 to pH 8.3 within 3 days; it then decreased slowly but was still at a value of 7.4 after 28 days. Twenty percent of the NH4 + applied volatilized within 28 days. Sixty percent of the C applied in the pig slurry evolved as CO2, if no priming effect was assumed, but only 38% evolved when the soil was amended with DCD. Pig slurry significantly increased denitrification and the ratio between its gaseous products, N2O and N2, was 0.21. No significant increases in NO3 – concentration occurred, and N2O produced through nitrification was 0.07mg N2O-N kg–1 day–1 or 33% of the total N2O produced. C2H2 was used as a C substrate by microorganisms and increased the production of N2O.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 66 (1982), S. 217-223 
    ISSN: 1573-5036
    Keywords: Azospirillum brasilense ; Biofertilizer ; Spring-wheat ; Triticum aestivum ; Winter-wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three field experiments were conducted on ten cultivars of winterwheat and four cultivars of springwheat to estimate the growth promoting effect ofAzospirillum brasilense under varying nitrogen doses. Independent of cultivar selection or nitrogen dose a highly significant yield increase could be observed in winterwheat: strains S631 and SpBr14 increased the average grain yield with 9.14% and 14.82% respectively. When the yield components were studied a coinciding increase in ear density could be demonstrated of resp. 10.57% and 13.55%. Less significant results were obtained with springwheat although in one experiment strain SpBr14 significantly increased grain yield. As with winterwheat tillering of the plant was markedly affected by inoculation with both strains. In a companion greenhouse experiment it was found that inoculation with Azospirillum can cause a decrease in the root mass of wheatplants except when strain SpBr14 is used. Therefore it is suggested that the presence of a higher tillering together with an undisturbed nutrient uptake capacity can result in yield increases after inoculation withAzospirillum brasilense.
    Type of Medium: Electronic Resource
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