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  • General Chemistry  (4)
  • Seasonal dry tropical forest  (2)
  • 1980-1984  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 55 (1980), S. 415-427 
    ISSN: 1573-5036
    Keywords: Maize ; Nutrient levels ; Seasonal dry tropical forest ; Shifting agriculture ; Weeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Grain production in two 1/4 hectare plots gave 2971 and 1380 kg/ha for an average yield of 2175 kg/ha. Average yield for local farmers was 1700 kg/ha. Weed biomass accounted for 50% of total bioomass in the hydric Site 4, but held 64–83% of the total nutrients. In the mesic Site 1, values were 5% and 3–29% respectively.Canna edulis was the most abundant weed species. Soil nutrient levels neither increased or decreased significantly between clearing and harvesting. Any decline in future crop production would be due to increased weed competition and not a decline in soil fertility. Weevil (Sitophilus zeamais) infestation is a serious problem in hybrid corn not encountered with local varieties.
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  • 2
    ISSN: 1573-5036
    Keywords: C/N ratio ; Litter ; Nutrient levels ; Seasonal dry tropical forest ; Total biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Total above ground plant biomass in a 45 year old seasonally dry tropical hardwood forest was estimated to be approximately 56,000 kg/ha oven dry weight. Nutrients immobilized in the standing vegetation were: N, 203 kg/ha; P, 24 kg/ha; K, 234 kg/ha; Ca, 195 kg/ha; Mg, 47 kg/ha; Na, 9 kg/ha; Mn, 1 kg/ha; Cu, 0.5 kg/ha; Zn, 3 kg/ha; Fe, 4 kg/ha. Total nutrients returned each year through the litter were: N, 156 kg/ha; P, 9 kg/ha; K, 59 kg/ha; Ca, 373 kg/ha; Mg, 32 kg/ha; Na, 5 kg/ha; Mn, 1 kg/ha; Al, 21 kg/ha; Zn, 0.3 kg/ha; Fe, 9 kg/ha. Half of the nutrients immobilized in the standing vegetation were found in the leaves and are returned annually to the soil. Although litter fall is interrupted during the year, the mean nutrient content of the litter was high −5.2%. A decomposition rate of 0.48 percent per day was considered high for a seasonally dry tropical hardwood forest. Fluctuations in soil nutrient levels showed a sharp increase at the start of the rainy season. Later during the dry season nutrient levels decreased to concentrations similar to what they were just prior to the rainy season. Soil organic matter levels were very high −20% in the top 12 cm.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 93 (1981), S. 553-566 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die Bestimmung der Spin-Gitter-Relaxationszeit (T1) bietet eine Alternative zu den üblichen NMR-Linienformanalysen, um die Kinetik intramolekularer Reaktionen zu untersuchen; obendrein kann der durch NMR-Spektroskopie erfaßbare Bereich sowohl nach hohen als auch nach niedrigen Energiebarrieren hin ausgedehnt werden. Die Dipol-Dipol-und die Quadrupol-Relaxationszeiten sprechen auf sehr schnelle Vorgänge wie die Rotation von Methylgruppen an. Die Analyse der Relaxation im rotierenden Koordinatensystem (T1ρ) gibt Information über die Kinetik vieler Prozesse, insbesondere über diejenigen, für die der dynamische Bereich zu schnell für Linienform-Methoden ist. Sättigungsübertragung und die Koaleszenz von Relaxationszeiten bei hohen Temperaturen können zur Bestimmung hoher Energiebarrieren genutzt werden. Die Möglichkeiten und Grenzen dieser Methoden werden beschrieben.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 94 (1982), S. 875-875 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 21 (1982), S. 862-863 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 20 (1981), S. 487-500 
    ISSN: 0570-0833
    Keywords: Kinetics ; Relaxation ; Analytical methods ; Relaxation ; NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of spin-lattice relaxation (T1) provides alternatives to the standard line shape procedures for the investigation of intramolecular reactions; furthermore it expands the NMR range at both the high and the low energy barrier limits. Dipole-dipole- and quadrupole-relaxation times are sensitive to very rapid processes such as methyl rotation. Analysis of relaxation in the rotating frame(T1ρ) provides kinetics for many sorts of processes, particularly those in the dynamic range that is too rapid for line shape methods. Saturation transfer and the coalescence of relaxation times at high temperatures can be used to measure high energy barriers. The scope and limitations of these methods are described.
    Additional Material: 1 Ill.
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