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  • Articles  (36)
  • Denitrification  (36)
  • 2000-2004  (6)
  • 1990-1994  (30)
  • Geosciences  (36)
  • Technology
  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of denitrification losses by the acetylene inhibition technique in a permanent ryegrass field (Lolium perenne L.) fertilized with animal slurry or ammonium nitrate (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 327-333 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Acetylene inhibition technique ; Grassland ; Lolium perenne ; Animal slurry ; Dicyandiamide ; Nitrification inhibition ; Ammonium nitrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a field experiment, the effect of animal slurry, (with and without the nitrification inhibitor dicyandiamide on total denitrification losses estimated by the C2H2 inhibition technique was measured over 2 years (1989–1990). During this period, four different plots (each with four replicates) were fertilized six times with 150 kg N ha-1 in the form of cattle-pig slurry or NH4NO3. Soil samples (0–20 cm) were analysed at regular intervals for NH inf4 sup+ and NO inf3 sup− concentrations. The soil water content was determined gravimetrically. During the first year (1989) total denitrification losses from unfertilized, mineral-fertilized, and animal slurry-amended plots (with or without dicyandiamide) were estimated as 0.2, 3.1, 0.7, and 0.6 kg N ha-1, respectively. During the second year (1990) the denitrification losses were 0.4, 1.3, 0.7, and 0.7 kg N ha-1, respectively. There was a clear relationship between the NO inf3 sup− concentration or soil water content and the denitrification rate. The results are siteund experiment-specific and cannot be generalized so far.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570636
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrification and denitrification in the rhizosphere of rice: the detection of processes by a new multi-channel electrode (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 427-435 
    Details
    ISSN: 1432-0789
    Keywords: Key words Rice ; Nitrification ; Denitrification ; Rhizosphere ; Microelectrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003749900190
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  • 3
    Electronic Resource
    Electronic Resource
    Denitrification in the rhizosphere of plants with inherently different aerenchyma formation: Wheat (Triticum aestivum) and rice (Oryza sativa) (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 215-219 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Air-filled porosity ; Rhizosphere ; Aerenchyma ; Rice ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Denitrification in the rhizosphere of wheat and rice was studied in relation to aerenchyma formation. Seedlings were grown in quartz silt amended with mineral nutrients at given bulk densities and water tensions. In adventitious wheat roots the formation of cortical lacunae was strongly dependent on soil aeration. Growing the wheat plants in dry (−20 kPa) and moist substrate (−2 kPa) established aerenchyma contents of 3% and 15%, respectively. Denitrification was measured after the introduction of equal moisture levels in the substrates of both treatments. The higher aerenchyma content of roots pregrown in the wetter substrate did not counteract denitrification in the rhizosphere which had doubled in this treatment. In contrast to the unspecific lysis of cortical cell walls, the well organized formation of aerenchyma in rice roots was independent of soil aeration. Root porosity averaged 14%. As in wheat, it was not related to denitrification. However, the level of denitrification per mg of root dry matter was about four times lower than that of wheat. The addition of decomposable organic matter (cellulose) to the substrate stimulated aerenchyma formation in rice and considerably increased denitrification. The results suggest that denitrification in the rhizosphere is independent of aerenchyma formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336228
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of 3-methylpyrazole-1-carboxamide as a soil nitrification inhibitor (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 252-256 
    Details
    ISSN: 1432-0789
    Keywords: Nitrapyrin (N-Serve) ; Etridiazole (Dwell) ; 2-Ethynylpyridine ; Urea hydrolysis ; Denitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Laboratory studies to evaluate 3-methylpyrazole-1-carboxamide (MPC) as a soil nitrification inhibitor showed that it was comparable to nitrapyrin (N-Serve) for inhibiting nitrification of ammonium in soil, but was not as effective as etridiazole (Dwell) or 2-ethynylpyridine. They also showed that the effectiveness of MPC as a soil nitrification inhibitor is markedly affected by soil type and soil temperature, that MPC is more effective for inhibiting nitrification of ammonium-N than of urea-N, and that MPC has little, if any, effect on hydrolysis of urea or denitrification of nitrate in soil. These observations and other work discussed indicate that MPC is one of the most promising compounds so far proposed for inhibition of nitrification in soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336235
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  • 5
    Electronic Resource
    Electronic Resource
    Denitrification and total fertilizer-N losses from an irrigated cotton field (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 270-278 
    Details
    ISSN: 1432-0789
    Keywords: Key words Acetylene inhibition ; Denitrification ; Cotton ; Nitrous oxide entrapment ; 15N-balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In a 2-year field study, denitrification loss was measured from an irrigated sandy-clay loam under cotton receiving urea-N at 158–173 kg ha–1. An acetylene inhibition-soil core method was employed for the direct measurement of denitrification, considering also the N2O entrapped in the soil. Taking into account the N2O evolved from soil cores and that entrapped in the soil, a total of 65.7 kg N ha–1 and 64.4 kg N ha–1 was lost due to denitrification during the 1995 and 1996 cotton-growing seasons, respectively. Most (〉70%) of the denitrification loss occurred during June–August, a period characterized by high soil temperatures and heavy monsoon rains. On average, 35% of the denitrification-N2O was found entrapped in the soil and the amount of entrapped N2O was significantly correlated with head space N2O concentration and with water-filled pore space. 15N-balance during the 1996 growing season revealed a loss of 71.8 kg N ha–1. It was concluded that a substantial proportion of the fertilizer-N applied to irrigated cotton is lost under the semiarid subtropical climatic conditions prevailing in the Central Punjab region of Pakistan and that denitrification is the major N loss process under irrigated cotton in this region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050656
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  • 6
    Electronic Resource
    Electronic Resource
    Denitrification enzyme activity is limited by soil aeration in a wastewater-irrigated forest soil (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 385-389 
    Details
    ISSN: 1432-0789
    Keywords: Keywords Aeration ; Chloramphenicol ; Denitrification ; Effluent ; Soil water content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In land-based wastewater treatment systems (LTS), denitrification is an important nitrogen removal process. We investigated the factors limiting the denitrifying population in a forested LTS, by studying the individual and combined effects of soil aeration, water content, nitrate and carbon on denitrification enzyme activity (DEA). The size of the soil denitrifying population in the LTS appeared to be limited by soil aeration, and limiting oxygen availability increased the denitrifying population above that observed in the field. Furthermore, we found that wastewater irrigation altered the short-term response of denitrifiers to anaerobic soil conditions. Under low oxygen conditions, denitrifiers in the wastewater-irrigated soils produced enzymes sooner and at a greater rate than soils without a history of wastewater irrigation. We propose that the size of the denitrifying population cannot be expected to be large in free-draining, coarsely textured soils even when provided with additional nitrogen and water inputs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000267
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  • 7
    Electronic Resource
    Electronic Resource
    Denitrification losses from puddled rice soils in the tropics (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 1-13 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Flooded soil ; 15N ; Nitrogen ; Oryza sativa L. ; Wetland rice ; Urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Although denitrification has long been considered a major loss mechanism for N fertilizer applied to lowland rice (Oryza sativa L.) soils, direct field measurements of denitrification losses from puddled rice soils in the tropics have only been made recently. This paper summarizes the results of direct measurement and indirect estimation of denitrification losses from puddled rice fields and reviews the status of research methodology for measurement of denitrification in rice fields. The direct recovery of (N2+N2O)-15N from 15N-enriched urea has recently been measured at sites in the Philippines, Thailand, and Indonesia. In all 12 studies, recoveries of (N2+N2O)-15N ranged from less than 0.1 to 2.2% of the applied N. Total gaseous N losses, estimated by the 15N-balance technique, were much greater, ranging from 10 to 56% of the applied urea-N. Denitrification was limited by the nitrate supply rather than by available C, as indicated by the values for water-soluble soil organic C, floodwater (nitrate+nitrite)-N, and evolved (N2+N2O)-15N from added nitrate. In the absence of runoff and leaching losses, the amount of (N2+N2O)-15N evolved from 15N-labeled nitrate was consistently less than the unrecovered 15N in 15N balances with labeled nitrate, which presumably represented total denitrification losses. This finding indicates that the measured recoveries of (N2+N2O)-15N had underestimated the denitrification losses from urea. Even with a probable two-or threefold underestimation, direct measurements of (N2+N2O)-15N failed to confirm the appreciable denitrification losses often estimated by the indirect difference method. This method, which determines denitrification losses by the difference between total 15N loss and determined ammonia loss, is prone to high variability. Measurements of nitrate disappearance and 15N-balance studies suggest that nitrification-denitrification occurs under alternate soil drying and wetting conditions both during the rice cropping period and between rice crops. Research is needed to determine the magnitude of denitrification losses when soils are flooded and puddled for production of rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335854
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  • 8
    Electronic Resource
    Electronic Resource
    The interdependence of ammonia volatilization and denitrification as nitrogen loss processes in flooded rice fields in the Philippines (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 31-36 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Ammonia volatilization ; Wetland rice soils ; Urea ; 15N-balance method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relative importance of ammonia volatilization and denitrification as loss processes following the application of urea to flooded rice by the traditional method was assessed at four sites with different characteristics in the Philippines. The effect of reducing ammonia loss on denitrification and total N loss was also studied. The total N loss was determined by a 15N-balance method and ammonia volatilization was assessed by a bulk aerodynamic method following the application of urea to small plots (4.8×5.2 m). As run-off was prevented and leaching losses were negligible, the denitrification loss was assessed as the difference between total N loss and ammonia loss. When urea was broadcast into the floodwater at transplanting, the ammonia loss varied from 10% to 56% of the applied N. Loss was smallest at Aguilar where wind speeds were low and the greatest at Mabitac where floodwater pH values and temperatures were high and the winds were strong. The ammonia loss was reduced at all sites by incorporating the urea into the soil by harrowing. However, the reduction achieved varied markedly between sites, with the largest reduction (from 56% to 7% loss of the applied N) being observed at Mabitac. The total N lost from the basal application into the floodwater ranged from 59% to 71% of the applied N. Incorporating the urea by harrowing reduced the total N loss at two sites, increased the total N loss at the third site, and had no effect at the fourth site. The denitrification losses ranged widely (from 3% to 50% of the applied N) when urea was broadcast into the floodwater at the four sites. The denitrification loss was low when the ammonia loss was high (Mabitac) and high when the ammonia loss was low (Aguilar). Reducing ammonia losses by incorporating the urea into the flooded soil resulted in increased denitrification losses at three of the sites and appeared to have no effect on denitrification at the fourth site. The results show that reducing the ammonia loss by incorporating urea into the soil does not necessarily result in reduced total N loss, and suggest that the efficiency of fertilizer N will be improved only when both N-loss processes are controlled simultaneously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335858
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  • 9
    Electronic Resource
    Electronic Resource
    Modelling spatial and temporal variability of denitrification (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 71-77 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Diffusion/reduction model ; Microsites ; Pseudo-equilibrium ; Spatial and temporal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Denitrification shows both spatial and temporal variability. Any attempt to model the process must take this into account. A model has been developed in which the soil is treated as a large assembly of potentially denitrifying microsites (a modification of the “hot-spot” concept). Chemical and biological heterogeneity is represented by a log-normal distribution of microsite respiration potential. Structural heterogeneity (where present) is accommodated by associating individual microsites with soil aggregates, the radius of which varies log-normally. Spatial variation arises naturally from the existence of microsites. Model microsites are assumed to be in a state of pseudo-equilibrium (a “steady state”). This means that they respond rapidly to any perturbation; it does not imply that they are static. A pseudo-equilibrium model can readily encompass temporal variation provided that the response time of the system is relatively short. Examination of the response times of typical model microsites, by numerical solution of the partial differential equations governing the transient processes occurring within them, suggests that in soils with few large (greater than 10-2m in radius) denitrifying microsites the steady-state approximation is probably adequate. Where denitrification occurs predominantly in large microsites, however, a pseudo-equilibrium model is inappropriate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335865
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  • 10
    Electronic Resource
    Electronic Resource
    Evolution of dinitrogen and nitrous oxide from the soil to the atmosphere through rice plants (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 61-67 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Flooded soil ; 15N ; Urea ; 15N balance ; Wetland rice ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary It is commonly assumed that a large fraction of fertilizer N applied to a rice (Oryza sativa L.) field is lost from the soil-water-plant system as a result of denitrification. Direct evidence to support this view, however, is limited. The few direct field, denitrification gas measurements that have been made indicate less N loss than that determined by 15N balance after the growing season. One explanation for this discrepancy is that the N2 produced during denitrification in a flooded soil remains trapped in the soil system and does not evolve to the atmosphere until the soil dries or is otherwise disturbed. It seems likely, however, that N2 produced in the soil uses the rice plants as a conduit to the atmosphere, as does methane. Methane evolution from a rice field has been demonstrated to occur almost exclusively through the rice plants themselves. A field study in Cuttack, India, and a greenhouse study in Fort Collins, Colorado, were conducted to determine the influence of rice plants on the transport of N2 and N2O from the soil to the atmosphere. In these studies, plots were fertilized with 75 or 99 atom % 15N-urea and 15N techniques were used to monitor the daily evolution of N2 and N2O. At weekly intervals the amount of N2+N2O trapped in the flooded soil and the total-N and fertilized-N content of the soil and plants were measured in the greenhouse plots. Direct measurement of N2+N2O emission from field and greenhouse plots indicated that the young rice plant facilitates the efflux of N2 and N2O from the soil to the atmosphere. Little N gas was trapped in the rice-planted soils while large quantities were trapped in the unplanted soils. N losses due to denitrification accounted for only up to 10% of the loss of added N in planted soils in the field or greenhouse. The major losses of fertilizer N from both the field and greenhouse soils appear to have been the result of NH3 volatilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335863
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