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  • Inorganic Chemistry  (2)
  • Leucaena leucocephala  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    Alley cropping on an Ultisol in subhumid Benin Part 3: nutrient budget of maize, cassava and trees (1997)
    Springer
    Agroforestry systems 37 (1997), S. 213-226 
    Details
    ISSN: 1572-9680
    Schlagwort(e): cajanus cajan ; fertiliser recovery ; intercropping ; Leucaena leucocephala ; nutrient budget ; sustainability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract An alley cropping experiment was conducted from 1986 to 1992 near Cotonou, Benin Republic on a field previously used as four-year bush-fallow. A no-tree control was compared with Leucaena leucocephala (Lam.) de Wit and Cajanus cajan (L.) Millsp. grown in 4 m distant hedgerows. In the same experiment, application of 90-39-75 kg ha-1 NPK fertiliser vs. no fertiliser and maize-cassava intercropping vs. rotation of sole crops was also tested. Topsoil samples (0–30 cm) were taken initially and again after four and six years. Alley cropping enhanced nitrogen recycling relative to the no-alley control by 253 kg haha-1 yr-1 for Leucaena and 131 kg ha-1 yr-1 for Cajanus in the overall average but a maximum of 22 kg N ha-1 yr-1 was recovered in total crop exports. Apparent fertiliser-N recovery increased from a low average of 14% in the first year to 66% in the second year up to a maximum of 109% in the no-tree control in the last year. Soil nutrient depletion during the six years was significant for all nutrients except P, K falling from 0.5 to 0.1 cmolc kg-1 soil and N from 0.08 to 0.05%. Hedgerow accumulation of N in the topsoil- plant system calculated as difference to a no-tree control was only 18 to 37 kg ha-1 yr-1 during the first four years after clearing, increasing to 208 kg in Leucaena and 111 kg ha-1 yr-1 in Cajanus without NPK during the last two years. During the first four years, average N, K, Ca and Mg losses from the topsoil-plant system of 223 kg, 160 kg, 176 kg and 80 kg ha-1 yr-1 were high but probably stored in the subsoil because corresponding leaching losses were only 10, 1, 15 and 6 kg ha-1 yr-1 at 150 cm depth during the second to fourth cropping year. Beyond the fourth year, markedly reduced nutrient losses from the topsoil and stable food crop yields in no-tree plots suggest that continuous maize-cassava cropping using balanced rates of mineral fertiliser is producing sustainable yields with almost closed nutrient cycles of the soil-plant system on our site.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1005863818511
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  • 2
    Digitale Medien
    Digitale Medien
    Alley cropping on an Ultisol in subhumid Benin. Part 1: Long-term effect on maize, cassava and tree productivity (1996)
    Springer
    Agroforestry systems 34 (1996), S. 1-12 
    Details
    ISSN: 1572-9680
    Schlagwort(e): Cajanus cajan ; intercropping ; Leucaena leucocephala ; mineral fertiliser ; sustainability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In southern Benin, West Africa, two alley cropping systems were studied from 1986 to 1992. Yield development was followed in a maize and cassava crop rotation vs. intercropping system, with alleys of Leucaena leucocephala (Lam.) de Wit and Cajanus cajan (L.) Millsp. vs. a no-tree control, with and without NPK fertiliser. Without alleys, NPK fertilisation maintained high yield levels of 2–3 t maize dry grain plus 4–6 t ha−1 cassava root DM in intercropping, 3–4 t ha−1 maize and 6–10 t ha−1 cassava in solercropping. Without NPK, final yields seemed to stabilise at about 1 t maize plus 2 t cassava in intercropping and twice as much in each solecrop. Alley cropping induced significant yield increases by about 50% with both tree species in unfertilised, intercropped maize, and with Cajanus in fertilised, solecropped cassava. In monetary terms, the NPK-fertiliser response of stabilised yields was significant for all treatments except the solecropped Leucaena alleys. It is concluded that on Ultisols with low nutrient status in the upper rooting zone, alley cropping with low-competitive tree species may improve food crop yields but the greatest monetary output is achieved by intercropping with mineral fertiliser independent of the presence or absence of an agroforestry component.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00129628
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  • 3
    Digitale Medien
    Digitale Medien
    Ein N/P-Analogon des Cyclotetraphosphazens: Reaktionen und Struktur des Octaphenyl-1,5,2λ5,3,4λ5,6λ5,7,8λ5-diazahexaphosphocins und seines PdCl2-KomplexesProfessor Kurt Issleib zum 70. Geburtstage am 19. November 1989 gewidmet (1989)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 579 (1989), S. 158-172 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: An N/P-Analogue of Cyclotetraphosphazene: Reactions and Structure of Octaphenyl-1,5,2λ5,3, 4λ5,6λ5,7,8λ5-diazahexaphosphocin and its PdCl2-ComplexThe eight-membered heterocycle 6 indicated in the title is analogous to the octaphenyl cyclotetraphosphazene in which two antipodal nitrogen ring members have been replaced by two-coordinate phosphorus. It can be obtained from (Ph2P)2NLi and P4. Very strong nucleophiles attack the PP-bonds and eventually degrade the ring in a way reverting the synthesis. 6 is selectively methylated at the two-coordinate phosphorus and forms cis-chelates with PdCl2 and PtCl2 by coordinating both of these phosphorus members.The structur of 6 and its PdC12-complex 8 were investigated by X-ray analysis and allowes multiple comparisons. All in all 6 certainly resembles a cyclophosphazene, its two-coordinate phosphorus displays phosphide character however. This is also confirmed by an MNDO calculation.
    Notizen: Die im Titel genannte Achtringverbindung 6 stellt ein Analogon zum Octaphenyl-cyclotetraphosphazen dar, in dem zwei gegenüberliegende Stickstoff-Ringglieder durch zweifach-koordinierten Phosphor ersetzt sind. Sie ist aus (Ph2P)2NLi und P4 zugänglich und wird von sehr starken Nucleophilen an den PP-Bindungen angegriffen und im Sinne einer Syntheseumkehr abgebaut. Sie wird selektiv am zweifach-koordinierten Phosphor methyliert und bildet mit PdCl2 und PtCl2 durch Koordination dieser Phosphorglieder cis-Chelate.Die Strukturen von 6 und des PdC12-Komplexes 8 wurden röntgenographisch bestimmt und ermöglichen eingehende Strukturvergleiche. Insgesamt ergibt sich bei aller Cyclophosphazen-Ähnlichkeit ein phosphidischer Charakter des zweifach-koordinierten Phosphors in 6. Eine MNDO-Berechnung bestätigt das ebenfalls.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19895790120
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  • 4
    Digitale Medien
    Digitale Medien
    The Interlocking of Salicylic Aldehydes and Ketones with a 2h-1,2,4,3-Triazaphosphole (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1493-1495 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Phosphorus heterocycles ; ortho-Hydroxybenzaldehydes ; Phosphonic amide ; Michaelis-Arbuzov rearrangement ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Salicylic aldehyde (2a) adds to 2-methyl-5-phenyl-2H-1,2,4,3-triazaphosphole (1) to yield the bicyclic phosphonic amide 3a. The OH group adds to the P=N bond, the carbon atom the carbonyl group is inserted into the other P - N bond, and the phosphorus atom is oxidized. In the crystal the compound forms dimers by a double hydrogen bond between two HN-PO units. Substituted salicylic aldehydes as well as ortho-hydroxyacetophenone and benzophenone react in the same way.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19961291215
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