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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 28 (1998), S. 56-63 
    ISSN: 1432-0789
    Keywords: Key words Animal manure ; Immobilization ; Mineralization ; Nitrogen ; Slurry distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  An improved understanding of the cycling of animal manure N is a prerequisite for making better use of this N source. A sheep was fed 15N-labelled grass in order to study the fate of 15N-labelled ruminant manure N in the plant-soil system. The uniformity of labelling was found to be satisfactory when an appropriate feeding strategy was used. The mineralization of labelled faecal N was compared to the mineralization of labelled feed N and indigestible feed N by measuring residual labelled organic N in unplanted topsoil in the field. After 18 months, 61% of both faecal N and feed N was recovered in organic form in the topsoil, while 94% of the indigestible feed N was still present in the soil. The influence of slurry distribution in soil on the crop uptake of labelled faecal N in slurry was studied in a sandy and a sandy loam soil. The crop uptake of labelled faecal N was compared with the uptake of 15N-labelled mineral fertilizer in a reference treatment. The uptake was 28–32% of that of the reference treatment with simulated slurry injection, 13–25% with incorporated slurry and 18–19% with slurry on the soil surface. The mineralization of faecal N in the autumn after application in spring was low irrespective of the slurry distribution in soil. The results demonstrate that the contact between animal manure and the soil matrix significantly influences the short-term turnover and availability of faecal and ammonium N in slurry, especially in fine-textured soils.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 459-464 
    ISSN: 1432-0789
    Keywords: Crop residues ; Hordeum vulgare L. ; Pisum sativum L. ; Mineralization-immobilization turnover of N ; Symbiotic N2 fixation-labelled N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen acquisition by field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) grown on a sandy loam soil and availability of N in three subsequent sequences of a cropping system were studied in an outdoor pot experiment. The effect of crop residues on the N availability was evaluated using 15N-labelled residues. Field pea fixed 75% of its N requirement and the N2 fixation almost balanced the N removed with the seeds. The barley crop recovered 80% of the 15N-labelled fertilizer N supplied and the N in the barley grain corresponded to 80% of the fertilizer N taken up by the crop. The uptake of soil-derived N by a test crop (N catch crop) of white mustard (Sinapis alba L.) grown in the autumn was higher after pea than after barley. The N uptake in the test crop was reduced by 27% and 34% after pea and barley residue incorporation, respectively, probably due to N immobilization. The dry matter production and total N uptake of a spring barley crop following pea or barley, with a period of unplanted soil in the autumn/winter, were significantly higher after pea than after barley. The barley crop following pea and barley recovered 11% of the pea and 8% of the barley residue N. The pea and barley residue N recovered constituted only 2.5% and 〈1%, respectively, of total N in the N-fertilized barley. The total N uptake in a test crop of mustard grown in the second autumn following pea and barley cultivation was not significantly influenced by pre-precrop and residue treatment. In the short term, the incorporation of crop residues was not important in terms of contributing N to the subsequent crop compared to soil and fertilizer N sources, but residues improved the conservation of soil N in the autumn. In the long-term, crop residues are an important factor in maintaining soil fertility and supplying plant-available N via mineralization.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 24 (1997), S. 39-44 
    ISSN: 1432-0789
    Keywords: Immobilization ; Mineralization ; 15N-labelled crop residues ; Residue quality ; Soil microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The immobilization and mineralization of N following plant residue incorporation were studied in a sandy loam soil using15N-labelled field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) straw. Both crop residues caused a net immobilization of soil-derived inorganic N during the complete incubation period of 84 days. The maximum rate of N immobilization was found to 12 and 18 mg soil-derived N g−1 added C after incorporation of pea and barley residues, respectively. After 7 days of incubation, 21% of the pea and 17% of the barley residue N were assimilated by the soil microbial biomass. A comparison of the15N enrichments of the soil organic N and the newly formed biomass N pools indicated that either residue N may have been assimilated directly by the microbial biomass without entering the soil inorganic N pool or the biomass had a higher preference for mineralized ammonium than for soil-derived nitrate already present in the soil. In the barley residue treatment, the microbial biomass N was apparently stabilized to a higher degree than the biomass N in the pea residue treatment, which declined during the incubation period. This was probably due to N-deficiency delaying the decomposition of the barley residue. The net mineralization of residue-derived N was 2% in the barley and 22% in the pea residue treatment after 84 days of incubation. The results demonstrated that even if crop residues have a relative low C/N ratio (15), transient immobilization of soil N in the microbial biomass may contribute to improved conservation of soil N sources.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 24 (1996), S. 39-44 
    ISSN: 1432-0789
    Keywords: Key words Immobilization ; Mineralization ; 15N-labelled crop residues ; Residue quality ; Soil microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The immobilization and mineralization of N following plant residue incorporation were studied in a sandy loam soil using 15N-labelled field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) straw. Both crop residues caused a net immobilization of soil-derived inorganic N during the complete incubation period of 84 days. The maximum rate of N immobilization was found to 12 and 18 mg soil-derived N g–1 added C after incorporation of pea and barley residues, respectively. After 7 days of incubation, 21% of the pea and 17% of the barley residue N were assimilated by the soil microbial biomass. A comparison of the 15N enrichments of the soil organic N and the newly formed biomass N pools indicated that either residue N may have been assimilated directly by the microbial biomass without entering the soil inorganic N pool or the biomass had a higher preference for mineralized ammonium than for soil-derived nitrate already present in the soil. In the barley residue treatment, the microbial biomass N was apparently stabilized to a higher degree than the biomass N in the pea residue treatment, which declined during the incubation period. This was probably due to N-deficiency delaying the decomposition of the barley residue. The net mineralization of residue-derived N was 2% in the barley and 22% in the pea residue treatment after 84 days of incubation. The results demonstrated that even if crop residues have a relative low C/N ratio (15), transient immobilization of soil N in the microbial biomass may contribute to improved conservation of soil N sources.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 459-464 
    ISSN: 1432-0789
    Keywords: Key words Crop residues ; Hordeum vulgare L. ; Pisum sativum L. ; Mineralization-immobilization ; turnover of N ; Symbiotic N2 fixation-labelled N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen acquisition by field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) grown on a sandy loam soil and availability of N in three subsequent sequences of a cropping system were studied in an outdoor pot experiment. The effect of crop residues on the N availability was evaluated using 15N-labelled residues. Field pea fixed 75% of its N requirement and the N2 fixation almost balanced the N removed with the seeds. The barley crop recovered 80% of the 15N-labelled fertilizer N supplied and the N in the barley grain corresponded to 80% of the fertilizer N taken up by the crop. The uptake of soil-derived N by a test crop (N catch crop) of white mustard (Sinapis alba L.) grown in the autumn was higher after pea than after barley. The N uptake in the test crop was reduced by 27% and 34% after pea and barley residue incorporation, respectively, probably due to N immobilization. The dry matter production and total N uptake of a spring barley crop following pea or barley, with a period of unplanted soil in the autumn/winter, were significantly higher after pea than after barley. The barley crop following pea and barley recovered 11% of the pea and 8% of the barley residue N. The pea and barley residue N recovered constituted only 2.5% and 〈1%, respectively, of total N in the N-fertilized barley. The total N uptake in a test crop of mustard grown in the second autumn following pea and barley cultivation was not significantly influenced by pre-precrop and residue treatment. In the short term, the incorporation of crop residues was not important in terms of contributing N to the subsequent crop compared to soil and fertilizer N sources, but residues improved the conservation of soil N in the autumn. In the long-term, crop residues are an important factor in maintaining soil fertility and supplying plant-available N via mineralization.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 461-464 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: At (approximately-greater-than)1 ML coverage of methyl bromide adsorbed on LiF(100), CH3Br is efficiently "photoejected'' by ultraviolet light at 193 nm, with a mean translational energy of ∼0.3 eV; this is termed PEJ(CH3Br). The system CH3Cl/LiF(100) shows no detectable PEJ(CH3Cl) at this wavelength for which CH3Cl does not efficiently absorb UV. Similarly PEJ(CH3Br) ceased to be observable with 248 nm light, at which wavelength CH3Br does not absorb. Both observations indicate that PEJ is adsorbate mediated. If at 193 nm ∼1 ML of CH3Br is adsorbed beneath ∼1 ML of CH3Cl, efficient PEJ(CH3Cl) is observed. With the sequence of layers reversed (i.e., with the actinic layer on top), PEJ(CH3Cl) is largely suppressed. These observations support the model for PEJ proposed previously [I. Harrison et al., J. Chem. Phys. 89, 1498 (1988)] in which photoexcitation of the underlayer leads, by way of electronic-to-translational (E→T) transfer, to ejection of the top layer. The angular distribution of the photoejected species is peaked along the surface normal, consistent with repulsion operating between the under- and overlayer. The mean conversion of E→T implied by this mechanism is ∼5%, extending to a maximum of 12%. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report here a direct measurement of the spatially resolved atomic hydrogen concentration profiles during hot-filament-assisted chemical-vapor deposition (HFCVD) of diamond films. The ground-state hydrogen (1s 2S1/2) atoms generated in this process are monitored by an optical four-wave-mixing technique, third-harmonic generation (THG). For THG, a 364.6 nm dye laser beam is focused into the HFCVD reactor and the third-harmonic radiation near resonant with the Lyman-α (2p 2P0j↔1s 2S1/2) transition in atomic hydrogen at 121.6 nm is observed. The resultant THG intensity and THG peak shift with respect to the Lyman-α transition are both dependent on hydrogen atom concentration. Titration experiments based on the reaction NOCl+H→HCl+NO were conducted to obtain absolute hydrogen atom concentrations from the relative concentrations determined in the THG experiment. Spatially resolved molecular hydrogen temperature and concentration profiles obtained by coherent anti-Stokes Raman scattering in a similar HFCVD reactor are reported. The observed H atom concentrations exceed computed equilibrium concentrations based on the measured gas temperatures. Transport of the atomic hydrogen from the hot filament surfaces is discussed and diffusion is shown to be the principal mechanism controlling the H atom distribution.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We studied the influence of nitrous oxide on the maintenence dose of propofol and recovery characteristics in 42 patients, aged 18–62 years, ASA 1 or 2, scheduled for day case inguinal herniotomy. Using a double-blind, randomised design, patients received anaesthesia with propofol-alfentanil-vecuronium-oxygen and either nitrous oxide or room air (Fio2= 0.30). The rate of propofol infusion was adjusted depending on anaesthetic depth as judged using standard clinical criteria; alfentanil was administered on a weight basis. Patients’ lungs were manually ventilated after tracheal intubation and muscle relaxation was reversed at the end of surgery with neostigmine and atropine. A series of psychomotor tests was performed pre-operatively and 30 and 120min postoperatively. The mean maintenance doses of propofol were 0.084 mg .kg-1 .min-1 in the N2O group and 0.088 mg.kg-1.min-1 in the air group (p = 0.97). In the nitrous oxide group the mean (SD) interval to spontaneous eye opening was 13.1 (7.3) min compared to 8.1 (4.9)min in the air group (p = 0.01). Similarly, the interval until obtaining a standardised response was 13.5 (5.3) min and 9.8min (5.4) in the nitrous oxide and air groups, respectively (p = 0.04). The addition of nitrous oxide to propofol-alfentanil-vecuronium anaesthesia does not reduce propofol requirements and prolongs early recovery compared to air.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 93 (1995), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the temperate-zone woody species Salix pentandra elongation growth is regulated by the photoperiod. Long days sustain active growth, whereas short days induce cessation of apical growth, which is a prerequisite for winter hardening. It is shown that this is correlated to quantitative changes in levels of endogenous GA19 GA20, and GA1. Within two short days the amount of the active GA1 and its immediate precursor GA20, decreased markedly in young leaves us well as in stem tissue. Also, the amount of GA19, declined, but the decrease was delayed relative to that of GA1 and GA20. The ability of S. pentandra seedlings to respond to exogenous GA19, decreased with increasing numbers of short days. Observations that support the hypothesis that the level of GA1 in S. pentandra is regulated by the photoperiod in a quantitative mode with conversion of GA19, to GA20, being one target for control.Different distribution of GAs in various plant parts was observed. The level of GA was higher in young leaves than in other plant parts, and the amount of GA19 was 5–10 times higher in stem tissue than in leaves and roots. The ratios of GA8 to GA1 and GA20, were higher in roots as compared with other parts, as rods contained very low levels of GA1 and GA20, but amounts of GA20 comparable with other parts.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Wild-type and ACC-oxidase antisense tomato plants (Lycopersicon esculentum Mill. cv. Ailsa Craig and pTOM13) were grown in environment-controlled rooms for 21 days under photoperiods of 8, 16 or 23.5 h at an irradiance of 300 µmol m−2 s−1. Photosynthetic pigments, photosynthesis, soluble carbohydrates, starch and ethylene were measured on the last fully expanded leaf. Increasing the photoperiod from 8 to 16 h stimulated all measured growth parameters in both cultivars. However, when the photoperiod was increased to 23.5 h, foliar yellowing and deformation were observed in the wild-type Ailsa Craig whereas no change was observed in pTOM13. It was not possible to relate these foliar changes in Ailsa Craig to destruction of the photosynthetic apparatus by excess carbohydrate levels in the leaves. Because pTOM13 was antisense to ACC-oxidase. it is proposed that yellowing and deformation in leaves of wild-type tomato plants grown under long photoperiods may be caused by stress ethylene induced by a long photoperiod.
    Type of Medium: Electronic Resource
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