Bibliography: leaves 207-222 / xvi, 222 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1987

Thermal desorption (TD), a remediation method used to remove hydrocarbons from contaminated soils, may cause changes in soil properties that threaten soil function and plant productivity. The goal of this research is to better understand the effect that TD treatment has on soils intended for agricultural use. A series of soil phosphorus (P) sorption and desorption experiments were conducted on soils before and after TD treatment to determine P availability for plant uptake and risk for run-off. TD-treated soils retained more P, likely due to mineral transformations of Fe- and Al-oxides. In addition, a three-year field study using mixtures of topsoil (A), crude-contaminated soil (SP), and TD-treated soils (TDU) was conducted. Yields were significantly greater in plots that included A in the mixture compared to SP and TDU soils alone. TD-treated soils can be a replacement for topsoil, but the addition of topsoil will reduce the time to successful reclamation.

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In general, the yields of alfalfa were increased by varying amounts of various fertility elements on the Norfolk sandy loam soil type at Williamsburg, Virginia. The yields of corn grown on the Hagerstown silt loam soil type at Blacksburg, Virginia, correspond closely to the fertilizer treatments and their availability. The milligrams of phosphorus absorbed by rye seedlings show no relation to the amounts of phosphorus added to the soil in fertilizers. In fact, in most trials the amount absorbed from treated plats was less than the amount produced from sand checks. It seems that all the phosphorus obtained came from the seed and not from the soil. From the studies reported herein, therefore, it must be concluded that the Neubauer seedling method is not applicable for determining the phosphorus requirements of the soil types used in this investigation. / M.S.

Previous research has shown that crop land application of alum sludge can be a valuable method of residuals disposal and has been demonstrated to cause no adverse effects on soil properties and crop yields. Studies have shown that with good soil management practices essential plant macronutrient levels can be maintained to support good crop growth. This study investigated the application of water treatment residuals in both field studies and greenhouse pot studies in order to determine the effects on soils properties and crop yields. Alum sludge collected from the Blacksburg-Christiansburg-VPI Water Authority and Radford Water Treatment Plant was land applied in the Spring of 1992. Two separate crop rotations, corn followed by wheat, were grown and harvested during the two-year field study. A greenhouse pot study using lettuce and radish plants was initiated in the Spring of 1993. Soil and plant tissue samples were collected and analyzed for the field and greenhouse studies. Harvest yields were also carefully monitored and recorded. The results of the laboratory analysis provided information on nutrient concentrations in soil and uptake by plants, and also soil and plant tissue elemental accumulations. Alum and PACI sludge at loading rates of up to 2.5% had no negative impacts on wheat yield. The growth study using lettuce and radish plants concluded that residual additions at low levels improved crop yield and that residual aging prior to land application was essential for good yield. / Master of Science

M.S.