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  • Blackwell Publishing Ltd  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 20 (2004), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. On the volcanic soils of the uplands of the French West Indies, banana monocropping has been practised since about 1980, mostly with large inputs of chemicals and replanting every three to five years after ploughing. However, in Guadeloupe less intensive cropping systems with only few added chemicals are still being used. The effects of the intensive practices on the physical, chemical and biological attributes of soils were evaluated on 34 farmed fields, which were selected to include the diverse soils and management practices found in the uplands of South Basse-Terre. Management was classified into four groups to differentiate effects of fertilizers, nematicides and tillage over at least 10 years. The population of the parasitic nematode Radopholus similis was, on average, greater 3 months after the application of nematicides. Thus, the use of nematicides increases the dependency of yield on nematicides. Ploughing decreased soil organic matter in the 0–10 cm layer as well as microbial respiration and earthworm biomass, but increased banana root infestation by R. similis. Ploughing was also associated with a change in soil structure, as revealed by the decrease in soil water content at −1 kPa potential and the increased infiltration rate of water into the 0–10 cm layer. The use of fertilizers has advantages for the maintenance or increase of soil reserves of K. However, due to the decreasing of negative electrical charges in the lower layers of andosols, where pH remains low, the majority of the cations supplied by fertilizers, mainly potassium, are prone to leaching.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 46 (1995), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: In many clay soils, drying and wetting cause non-uniform changes in water content and in the volume of soil and peds. Theoretical relations between total volume of soil, soil thickness and water content are sought for non-uniformly swelling and shrinking soil. Such soil is assumed to be composed of small elemental volumes, each of which does swell or shrink uniformly. It is also assumed that the non-uniformity of swelling or shrinking in such soils arises solely from spatial variation brought about by variations in evapotranspiration and infiltration. A constant ratio between movement of the soil in the vertical and horizontal dimensions is assumed for all elements of soil. By averaging over the soil volume the equations describing the volume change of individual elemental volumes, the averaged equations for non-uniform volume changes may be obtained. They show that the average and the spatial distribution of the changes in soil thickness determine the average changes in water content of the soil. It is concluded that the equations for uniform and non-uniform volume changing soils, though formally different, should in practice produce nearly identical results for clay soils.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 46 (1995), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A theoretical model of volume change in swelling clay soil is applied in a field study to determine the swelling-shrinking behaviour of a Vertisol in Guadeloupe (French West Indies). The field experiment estimated the spatial averages of vertical soil movements and soil water content changes by measurements at the intersections of a sampling grid. The geometry of volume change was found to be anisotropic with vertical soil movements slightly larger than horizontal ones. The observed anisotropy seems to arise because the peds slide along oblique slickensides whereas individual peds shrink and expand isotropically. The discrepancy with earlier field results which indicated strictly isotropic volume changes is thought to arise in part from a difference in the nature of the clay soils investigated. An uncertainty analysis of the experiment shows that the main source of error is due to the estimation of the spatial averages of soil elevation.
    Type of Medium: Electronic Resource
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