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  • Electronic Resource  (2)
  • 1995-1999  (2)
  • 1995  (2)
  • nutrient cycling  (1)
  • plant availability  (1)
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  • Electronic Resource  (2)
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  • 1995-1999  (2)
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  • 1995  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 42 (1995), S. 277-296 
    ISSN: 1573-0867
    Keywords: nutrient cycling ; socioeconomic constraints ; sustainable agriculture ; temperate/boreal ecosystems ; tropical ecosystem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper discusses the influence of N resources (fertilizer, legume, soil) on sustainable agriculture in temperate/boreal ecosystems (exemplified by the Canadian prairies), and in the humid, subhumid and semi-arid tropic (exemplified by southeast Asia and central and south America). A sustainable agricultural system is one that is economically viable, provides safe, nutritious food, and. conserves or enhances the environment. Consequently, we discuss the impact of N on crop yields, nitrogen use efficiency (NUE), food quality, environmental quality and on socioeconomic factors. Considerably more long-term research has been conducted in the temperate regions, consequently this was where most information was available. However, the principles governing the behaviour of N are very similar in all ecosystems. It is mainly the rates of nutrient cycling and the socioeconomic constraints that differ. Legumes and N fertilizers, used in a responsible manner, will increase crop production, provide quality food, increase net returns, reduce risk of monetary loss, improve soil quality, and reduce N loss via leaching and gaseous means. The key to sustainable management of N is to synchronize N supply with N use by the crop. Because societies in most temperate ecosystems are more affluent they are better positioned to encourage adoption of management techniques that promote sustainability. In contrast, most producers in the tropics are, subsistence farmers; consequently, their immediate goal is economic survival, not preservation of the environment.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5036
    Keywords: Captan ; ergosterol ; fungi ; plant availability ; organic soil ; radiocaesium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil fungi accumulate radiocaesium from contaminated soil and it has been hypothesised that this may alter the plant availability and movement of the radionuclide in soil. The effect of twice-monthly addition of an aqueous suspension of the fungicide ‘Captan’ on the changes in a peaty podzol soil at 2 sites, contaminated 2 or 3 years earlier by the injection of 134Cs, has been quantified. The sites had different soil acidity and vegetation cover. The less acid soil (pHwater 5.0) had been improved by the addition of lime and fertilizer and was reseeded with grass and clover. The more acid soil (pHwater 3.8) was under hill grasses, herbs and heather. On both sites the addition of fungicide did not alter the amount or concentration of radiocaesium in plant material sampled monthly or the depth distribution of radiocaesium in the soil profile. The concentration of the fungal constituent, ergosterol, in the soil, measured monthly, was unaffected by the fungicide treatment but evidence was obtained from a pot experiment to show that ergosterol decomposes slowly in cold, wet soils. On the more acid soil, two weeks after the last application of fungicide, there was a decline in active fungi as measured by fluorescein diacetate staining. Chloroform fumigation of the more acid soil resulted in a small increase in the amount of 134Cs exchangeable with 1 M ammonium acetate. Radiocaesium in seven different fungi grown in pure culture was found to be almost entirely extractable (〉 95%) with 1 M ammonium acetate. Another, Amanita rubescens, showed some retention and 88% was extractable. These findings do not preclude the fungal biomass as an important soil component controlling plant availability of radiocaesium from acid, organic soils by maintaining radiocaesium in a biological cycle, but make it unlikely that any fixation by fungi in a chemical sense is involved.
    Type of Medium: Electronic Resource
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