Presented as the author's thesis (Ph.D.)--Eberhard-Karls-Universität Tübingen, 2006. / Includes bibliographical references. Also available via Internet.

Thesis (M.S. in environmental engineering)--Washington State University, August 2008. / Includes bibliographical references (p. 16-19).

Thesis (Ph. D.)--Washington State University. / Includes bibliographical references.

Thesis (M.S.)--University of Akron, Dept. of Geology, 2005. / "August, 2005." Title from electronic thesis title page (viewed 11/29/2005) Advisor, Annabelle Foss; Committee members, Teresa Cutright, Ira Sasowsky; Department Chair, John Szabo; Dean of the College, Charles B. Monroe; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 60-68).

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes bibliographical references (leaves 36-39).

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xii, 170 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

In a study to investigate the fate of the applied P in soils, a red-sandy clayey soil (Ferric Luvisols) from Rustenburg (high P fixing) and a red-sandy loam soil (Ferric Acrisols) from Loskop (low P fixing) were used. Sequential P fractionations were used to determine the content of the different P pools to show which pool the applied P was transformed to. The soils treatments consisted of different Prates (0, 25, 50, 100, 150, and 200 mg kg-1), and incubation periods (1, 60, 120, 180, and 240 days) under a laboratory conditions. The sequential P fractionation procedure consisted of extraction with hydrous ferric oxide in a dialysis membrane tube (DMT-HFO), 0.5M NaHC03, O.1M NaOH-P, 1.0M HCI, concentrated HCI, and concentrated H2S04 + H2O2. Approximately 30 to 60 % of the added P were transformed into less labile P pools within one day and 80-90 % after 60 days. This transformation was faster in the Rustenburg than in the Loskop soil showing a higher P fixation capacity. A major part of the P transformation was to the -OH-P1 pool with a recovery of about 30%. In the second experiment an attempt was made to determine P desorption rates by successive DMT-HFO extractions (1, 7, 14, 28, and 56 days) after the transformations of the applied P. This was followed by the sequential extractions to determine the changes and distribution of the added P into different P pools as well as which pools the P was des orbed from. The Rustenburg and Loskop soils were treated to different Prates (0, 25, 50, 100, and 200 mg P kg-1) and incubation periods (1, 120, and 240 days). The cumulative DMT -HFO extraction curves for 56 days showed that desorption could continue for a much longer period. This property is important in the economical management of fertilizer applications rates. Results showed the transformations and distribution of the applied P during incubation periods and proved that all the stable soil P pools contributed to the labile P pool by different proportions after prolonged successive DMT-HFO extractions. Although Rustenburg soil is considered a high P fixing soil, the P release rates under laboratory conditions were high enough to meet the requirements of cotton and tobacco crops. Root systems of these crops do not exploit 100 % soil volume as this laboratory method, which could explain why these crops experience P deficiencies. It is envisage that by using this method the P releasing properties of a soil could be used to develop a P desorption model to determine how much extractable P, with a specific extractant, in a particular soil, should be available at the beginning of a growing season to sustain a high enough P releasing rate to meet the requirements of a certain crop up to the end of the growing season. To do this, a model to describe root development that represents the percentage of the soil exploited P desorption rates that simulate P uptake by plant roots will be necessary. / Thesis (DPhil (Plant Production: Horticulture))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

Swales are designed to infiltrate runoff from intermittent storm events. Present design methodologies have resulted in swales which operate under several conditions; these conditions are soil, vegetation, climatic and geographical location dependent. To attain a swale design which considers and accounts for the important factors under Florida conditions, adequate assessment of rainfall, overland, flow, infiltration and soil moisture must be given priority treatment. Several roadside and residential swales were studied and relationships were drawn for soil moisture, porosity and infiltration rates. A design methodology is included and computer modeling infiltration aids in the design.

No description available.