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  • Artikel  (11)
  • 15N
  • 1990-1994  (11)
  • 1960-1964
  • 1950-1954
  • 1994  (11)
  • Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft  (11)
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  • Artikel  (11)
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  • 1990-1994  (11)
  • 1960-1964
  • 1950-1954
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  • 1
    Digitale Medien
    Digitale Medien
    Time-course of nitrogen fixation in two bambara groundnut (Vigna subterranea L. Verdc.) cultivars (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 231-236 
    Details
    ISSN: 1432-0789
    Schlagwort(e): A-value ; Bradyrhizobium ; Genotype ; Growth stage ; 15N ; Nitrogen fixation ; Nodulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract TheA-value method, involving the application of a higher15N rate to a reference non-N2-fixing plant, was used to assess the magnitude of N2 fixation in two bambara groundnut cultivars at four growth stages [vegetative, 0–47 days after planting (DAP); early pod-filling, 47–99 DAP; mid-pod-filling, 99–120 DAP; physiological maturity, 120–148 DAP). The cultivars were Ex-Ada, a bunchy type, and CS-88-11, a slightly spreading type. They were grown on a loamy sand. Uninoculated Ex-Ada and CS-88-11 were used as reference plants to measure the N2 fixed in the inoculated bambara groundnuts. In this greenhouse study, soil was the major source of N in bambara groundnuts during vegetative growth, and during this period it accounted for over 80% of the N accumulaed in the plants. However, N2 fixation became the major source of plant N during reproductive growth. There were significant differences between the two cultivars in the ability to fix N2, and at physiological maturity, almost 75% of the N in CS-88-11 was derived from the atmosphere compared to 55% in Ex-Ada. Also, the total N fixed in CS-88-11 at physiological maturity was almost double that in Ex-Ada. Our data indicate that the higher N2 fixation in CS-88-11 was due to two factors, a higher intensity of N2 fixation and a longer active period of N2 fixation. The results also suggest that bambara groundnut genotypes could be selected for higher N2 fixation in farining systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00647672
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  • 2
    Digitale Medien
    Digitale Medien
    Nitrogen utilization by lowland rice as affected by fertilization with urea and green manure (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 215-223 
    Details
    ISSN: 1573-0867
    Schlagwort(e): 15N ; residual N ; Sesbania ; urea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Field studies were conducted during two consecutive wet seasons in flooded rice (Oryza sativa L.) to determine the effect of green manure on urea utilization in a rice-fallow-rice cropping sequence. Replicated plots were fertilized with 60 to 120 kg of urea N ha−1 in three split applications (50, 25 and 25%) with or without incorporation of dhaincha (Sesbania aculeata L.) (100 kg N ha−1). During the first crop only 31 to 44% of the urea added was used by the rice. Incorporatingin situ grown dhaincha (GM) into the soil at transplanting had little effect on urea utilization. Forty-four to 54% of the N added was not recovered in the soil, rice crop, or as nitrate leachate during the first cropping season. Incorporation of GM had no effect on fertilizer N recovery. Only about 2% of the urea N added to the first rice crop was taken up by the second rice crop and, as in the first crop, the GM had little effect on residual N, either in amount or utilization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750468
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  • 3
    Digitale Medien
    Digitale Medien
    Fate of inorganic 15N in the profile of different coniferous forest soils (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 101-107 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Nutrient cycle ; Coniferous forest ; Soil properties ; 15N ; Acidification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The fate of inorganic 15N added to different coniferous forest soils was traced throughout the soil profile (0–25 cm) in a laboratory experiment under controlled conditions of temperature and water content. Six soils with different chemical climates were compared. The sequestration of labelled N was significantly explained by the clay content but the correlation was improved when C and N content were included. The level of acidification, even in soil with a fine texture, reduced the immobilization. For a similar N input, sandy soils with low C content or high acidification showed a reduced N storage capacity, so that N excess would be able to pollute the ground-water.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00337740
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  • 4
    Digitale Medien
    Digitale Medien
    Effect of extracellular-enzyme activities on solubilization rate of soil organic nitrogen (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 32-38 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Organic matter ; Extracellular enzymes ; Solubilization ; Mineral N ; Total soluble N ; 15N
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In a sandy soil containing 15N-labeled active (soluble and easily degradable) and non-labelled passive (recalcitrant) fractions of soil organic matter, the rate of net N mineralization (solubilization) was determined during a 55-day incubation at 25°C, 63% water-holding capacity and different levels of soil extracellular-enzyme activities. The active fraction of soil N was labelled by preincubation (at 5°C and 74% water-holding capacity for 6 months) of soil amended with 15N-labeled plant material. Increases in the activity of extracellular-enzymes in soil were induced by the addition of glucose and KH2PO4 at the beginning of the incubation. The results show that the contents of total soluble N (NO 3 − −N+NH 4 + −N + soluble organic N) were significantly higher in glucose-amended soil compared to the unamended soil. The increases in soluble N in soil amended with 1 and 2 mg glucose g-1 dry soil corresponded to a mean rate of net solubilization of 7.9±1.4 and 18.8±0.7 nmol N g-1 dry soil day-1, respectively. The mean rate of net N solubilization (3.6±1.0 nmol N g-1 dry soil day-1) in unamended soil was significantly lower than those of glucose amended soils. The content of 15N in total soluble N in soil amended with 2 mg glucose, for example, was diluted from 3.11±0.08 atom% before the incubation to 2.77±0.03 atom% after 55 days. This indicates that 89% of soluble-N accumulated in soil by the end of the incubation originated from the active fraction of soil N and the rest, estimated at 11%, originated from the passive fraction. The activities of soluble and total proteases as well as the rate of N solubilization in the soil increased with the application of glucose. The activity of these extracellular enzymes was highly correlated with the rates of net N solubilization. Thus, increases in extracellular-enzyme activities in glucose-amended soils had a priming effect on the solubilization of 15N-labeled active and non-labeled passive fractions of soil organic N. It seems that the activity of extracellular-enzymes expressed in terms of total and soluble protease activities could be a rate-limiting factor in the processes of soil organic N solubilization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00418669
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  • 5
    Digitale Medien
    Digitale Medien
    Bi-directional transfer of nitrogen between alfalfa and bromegrass: Short and long term evidence (1994)
    Springer
    Plant and soil 164 (1994), S. 77-86 
    Details
    ISSN: 1573-5036
    Schlagwort(e): alfalfa ; bi-directional N transfer ; bromegrass ; long-term N transfer ; short-term N transfer ; 15N
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Transfer of N from legumes to associated non-legumes has been demonstrated under a wide range of conditions. Because legumes are able to derive their N requirements from N2 fixation, legumes can serve, through the transfer of N, as a source of N for accompanying non-legumes. Studies, therefore, are often limited to the transfer of N from the legume to the non-legume. However, legumes preferentially rely on available soil N as their source of N. To determine whether N can be transferred from a non-legume to a legume, two greenhouse experiments were conducted. In the short-term N-transfer experiment, a portion of the foliage of meadow bromegrass (Bromus riparius Rhem.) or alfalfa (Medicago sativa L.) was immersed in a highly labelled 15N-solution and following a 64 h incubation, the roots and leaves of the associated alfalfa and bromegrass were analyzed for 15N. In the long-term N transfer experiment, alfalfa and bromegrass were grown in an 15N-labelled nutrient solution and transplanted in pots with unlabelled bromegrass and alfalfa plants. Plants were harvested at 50 and 79 d after transplanting and analyzed for 15N content. Whether alfalfa or bromegrass were the donor plants in the short-term experiment, roots and leaves of all neighbouring alfalfa and bromegrass plants were enriched with 15N. Similarly, when alfalfa or bromegrass was labelled in the long-term experiment, the roots and shoots of neighbouring alfalfa and bromegrass plants became enriched with 15N. These two studies conclusively show that within a short period of time, N is transferred from both the N2-fixing legume to the associated non-legume and also from the non-legume to the N2-fixing legume. The occurrence of a bi-directional N transfer between N2-fixing and non-N2-fixing plants should be taken into consideration when the intensity of N cycling and the directional flow of N in pastures and natural ecosystems are investigated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00010113
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  • 6
    Digitale Medien
    Digitale Medien
    The fate of spring applied fertilizer N during the autumn-winter period: comparison between winter-fallow and green manure cropped soil (1994)
    Springer
    Plant and soil 160 (1994), S. 201-213 
    Details
    ISSN: 1573-5036
    Schlagwort(e): ammonium nitrate ; green manure ; incorporation of plant material ; 15N ; N loss ; N mineralization ; NO emission ; oilseed rape ; organic N pool
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A field experiment was carried out at a pilot plot that was cropped with oilseed rape, and then left partly fallow and partly cropped with a green manure (mustard) during the autumn after harvest of the oilseed rape. The rape residues were incorporated in the soil. Methods used to quantify the N fluxes from harvest until sowing of the next crop were (1) 15N balance method, (2) total mineral N analysis and (3) NO emission measurements. Losses of spring applied fertilizer N were negligible in cropped plots and minimal in fallow plots during the following autumn-winter period. Most of the plant-N residues was retained by the organic N pool of the upper 30-cm soil layer. The green manure contributed slightly to soil available N at sowing of the next crop. However, the incorporation of plant material resulted in a nitrate flux that was at risk of leaching on the fallow plots, and on the green manure plots after incorporation of the green manure. This nitrate was largely derived from soil organic N, not from unused fertilizer applied in spring or from immobilized fertilizer. The NO emissions from the green manure plots were significantly higher than emissions from the fallow plots. The plants had a stimulating effect on the NO emission. A relationship between the NO emission and the soil nitrate concentration could not be established. No emissions were measured after green manure incorporation due to the low temperatures at the pilot plot. However, a greenhouse experiment showed an increased emission after incorporation. The NO emissions seemed to be related with the soil ammonium concentration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00010146
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  • 7
    Digitale Medien
    Digitale Medien
    Transfer of nitrogen from damaged roots of white clover (Trifolium repens L.) to closely associated roots of intact perennial ryegrass (Lolium perenne L) (1994)
    Springer
    Plant and soil 166 (1994), S. 181-185 
    Details
    ISSN: 1573-5036
    Schlagwort(e): mobile N ; N transfer ; 15N ; root damage ; stored N ; white clover
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract An experiment is described in which the magnitude of N transferred from damaged white clover roots to perennial ryegrass was determined, using 15N labelling of the grass plant. There was no effect on the growth and N-fixation of the clover plants after removing part of the root system. The 15N data suggested that N had been acquired by all grass plants, even in plants grown alone with no further N supplied after labelling. However, after quantifying the mobile and stored N pools of the grass plants it was evident that significant transfer of N from clover to grass only took place from damaged clover roots. Dilution of the atom% 15N in the roots of the grass plants grown alone, and in association with undamaged clover roots, was explained by remobilisation of N within the plant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00008331
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  • 8
    Digitale Medien
    Digitale Medien
    Fertilization rates and clay fixed ammonium in two Quebec soils (1994)
    Springer
    Plant and soil 163 (1994), S. 103-109 
    Details
    ISSN: 1573-5036
    Schlagwort(e): soil mineralogy ; 15N ; clay fixed ammonium ; fertilizer rate ; fertilizer nitrogen recovery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Clay fixed NH4 + can provide a significant sink for fertilizer N, as well as a source of N for plant uptake. Knowledge or soil NH4 + fixing capacity and release for crops is necessary to develop long-term fertilizer programs. Field experiments with corn (Zea mays L.) were carried out to investigate soil NH4 + fixing capacity and subsequent release as influenced by fertilizer rates using 15N in a Ste. Rosalie clay (fine, mixed, frigid, Typic Humaquept) and a Chicot sandy clay loam (fine-loamy, mixed, frigid, Typic Hapludalf). With high N rates increased NH4 + fixation occurred only in the Ste. Rosalie soil. At the end of the first growing season, fertilizer N recovery as clay fixed NH4 + for high and normal rates of fertilizer in the Ste. Rosalie soil was 17.8% and 28.7%, respectively and the recovery for the high and normal rates in the Chicot soil was 4.6 and 10.5%, respectively. Significant amounts of clay fixed NH4 +-N were released in the soil profile in the second year after 15N application on the Chicot soil. Recently clay fixed fertilizer NH4 +N was released more rapidly than that of the native fixed NH4 +, from the surface layer of the Ste. Rosalie soil. The fertilizer fixed NH4 + seems to be in a more labile N pool than the native fixed NH4 +-N in the Chicot soil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00033946
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  • 9
    Digitale Medien
    Digitale Medien
    Solubilization of soil organic N by alkaline-hydrolysing N fertilizers (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 131-139 
    Details
    ISSN: 1573-0867
    Schlagwort(e): aqua ammonia ; di-ammonium phosphate ; gamma-irradiated soil ; 15N ; organic matter solubility ; urea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Interactions between15N-labelled fertilizers applied at concentrations representative of the fertilizer microsite and the solubility of the nitrogenous component of soil organic matter were investigated in laboratory experiments. Soil organic N was solubilized in aγ-irradiated soil due to addition of NH3(aq), and the fertilizer-induced loss of unlabelled total N in the extracted soil (ΔTUs) increased with increasing N fertilizer concentration and soil pH. ΔTUs was linearly correlated with ammoniacal-N concentration and the pH of the fertilized soil within the range of 7.5-10 (r = 0.94). Total organic N in the soil extract (OTe) increased rapidly up to day 14 following addition of 2000 mg urea-N kg−1 soil, but was then stable up to day 28. OTe of a range of soils increased from between 5 and 148 to between 15 and 368 mg N kg−1 soil after application of 1045 mg NH3-N kg−1 soil. While up to 25% of the organic N was solubilized by the fertilizer in nine soils, the change in total organic N in the extracts (ΔOTe) of three soils was not significant. The highest ΔOTe of 399 mg N kg−1 soil (35.4% of soil organic N) was measured after application of 2000 mg NH3-N kg−1 soil. pH and ΔOTe decreased in the order of NH3(aq) 〉 urea 〉 di-ammonium phosphate 〉 ammonium sulphate at equivalent rates of N addition. A negative ΔOTe was measured following application of ammonium sulphate. ΔOTe was correlated with the pH of the fertilized soil but not ammoniacal-N concentration for different N fertilizer sources.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00748773
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  • 10
    Digitale Medien
    Digitale Medien
    The effect of root temperature on the induction of nitrate reductase activities and nitrogen uptake rates in arctic plant species (1994)
    Springer
    Plant and soil 159 (1994), S. 187-197 
    Details
    ISSN: 1573-5036
    Schlagwort(e): ammonium ; arctic plants ; nitrate reductase ; nitrogen uptake ; 15N ; root temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract We investigated whether six arctic plant species have the potential to induce nitrate reductase (NR) activity when exposed to NO3 --nitrogen under controlled environment conditions, using an in vivo assay that uses the rate of NO2 --accumulation to estimate potential NR activity. We also assessed the effect of low root temperatures on NR activity, growth and nitrogen uptake (using 15N applications) in two of the selected species. Five of the six species (Cerastium alpinum, Dryas intergrifolia, Oxyria digyna, Saxifraga cernua and Salix arctica) were capable of inducing NR activity when exposed to solutions containing 0.5 mM NO3 - at 20°C for 10 days. Although in vivo NR activity was not induced in Saxifraga oppositifolia under controlled conditions, we conclude that it was capable of growing successfully on NO3 -, due to the presence of moderate rates of NR activity observed in both NH4 +-grown and NO3 --treated plants. Exposure of O. digyna and D. integrifolia to 3°C root temperatures for two weeks, with the shoots kept at 20°C, resulted in root and leaf NR activity rates of NO3 --treated plants being reduced to rates exhibited by NH4 +-grown plants. Although these decreases in NR in both species appeared to be due to limitations in NO3 --uptake and growth rate (rather than direct low-temperature inhibition of NR synthesis per se), direct low-temperature inhibition of root NR synthesis could not be ruled out. In contrast to the temperature insensitivity of NH4 + uptake in D. integrifolia, NO3 --uptake in D. integrifolia was inhibited by low root temperatures. We conclude that the selected arctic species have the genetic potential to utilize NO3 --nitrogen, and that low root temperatures, in conjunction with other environmental limitations, may be responsible for the lack of induction of NR in D. integrifolia and Salix arctica under field conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00009280
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  • 11
    Digitale Medien
    Digitale Medien
    Hyphal N transport by a vesicular-arbuscular mycorrhizal fungus associated with cucumber grown at three nitrogen levels (1994)
    Springer
    Plant and soil 160 (1994), S. 1-9 
    Details
    ISSN: 1573-5036
    Schlagwort(e): 15N ; Cucumis sativus ; Glomus intraradices ; hyphal N transport ; plant N status ; VA mycorrhiza
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Cucumis sativus L. cv. Aminex (F1 hybrid) was grown alone or in symbiosis with Glomus intraradices Schenck and Smith in containers with two hyphal compartments (HCA and HCB) on either side of a root compartment (RC) separated by fine nylon mesh. Plants received a total of either 100, 200 or 400 mg N which were applied gradually to the RC during the experiment. 15N was supplied to HCA 42 d after plating, at 50 mg 15NH4 +-N kg−1 soil. Lateral movement of the applied 15N towards the roots was minimized by using a nitrification inhibitor and a hyphal buffer compartment. Non-mycorrhizal controls contained only traces of 15N after a 27 d labelling period irrespective of the amount of N supplied to the RC. In contrast, 49, 48 and 27% of the applied 15N was recovered in mycorrhizal plants supplied with 100, 200 and 400 mg N, respectively. The plant dry weight was increased by mycorrhizal colonization at all three levels of N supply, but this effect was strongest in plants of low N status. The results indicated that this increase was due partly to the improved inflow of N via the external hyphae. Root colonization by G. intraradices was unaffected by the amount of N supplied to the RC, while hyphal length increased in HCA compared to HCB. Although a considerable 15N content was detected in mycorrhizal roots adjacent to HCB, only insignificant amounts of 15N were found in the external hyphae in HCB. The external hyphae depleted the soil of inorganic N in both HCA and HCB, while the concentration of soil mineral N was still high in non-mycorrhizal containers at harvest. An exception was plants supplied with 400 mg N, where some inorganic N was present at 5 cm distance from the RC in HCA. The possibility of a regulation mechanism for hyphal transport of N is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00150340
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