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Title: Some studies on the effects of long-term stockpiling of soils
Author: Abdul Kareem, Amer W.
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1984
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During many quarrying, civil engineering and landscaping schemes topsoil is stripped from the site and stored in large heaps. They remain in situ for many years before the soil is re-used and it is generally believed that there is a great reduction in the 'quality' of the soil during that period. A study of stockpiles of different sizes, age, soil type and method of construction has revealed that biological, chemical and physical changes do occur, mainly as a result of anaerobic conditions within the stockpiles, but also as a result of mechanized handling under unfavourable conditions. Visible changes occur within 0.3 ni of the surface of the clayey textured stockpiles, but only below 2 m depth for sandy textures. No visible changes were noticed within the sampling depth of the heaps which were created by techniques other than the earthscraper method whereby soil is not compacted by machinery. These visible changes are accompanied by chemical changes, particularly in the form of nitrogen, iron and manganese present, but also in the content of available nutrients (P, K and Mg), pH and organic matter levels. Biological changes include reductions in potential for mycorrhizal infection, earthworm biomass and population and to a lesser extent in soil microbial biomass. Physical changes include reduction in aggregate stability measured on 1-2 mm aggregates accompanied by considerable variation with depth, increase in bulk density mainly on stockpiles constructed by earthscrapers. Laboratory work has indicated that stockpiled soils attained higher bulk densities at equivalent pressures and moisture content than corresponding unworked soils. The breakdown of the domain structure in stockpiles was sharply revealed by scanning electron microscopy. The soil atmosphere in the stockpiles contains high levels of carbon dioxide, methane, ethane and ethylene but these did not reach critical limits. Limited evidence suggests that many of the adverse effects quickly disappear when the soil is respread.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available