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Soil moisture distribution resulting from a line source subsurface trickle irrigation system was studied on bare and cropped layered soils. The soil type was an Uchee loamy sand. The Continuous System Modeling Program (CSMP) Model was used to simulate the soil moisture distribution resulting from the linesource. The model was modified and developed in FORTRAN programming language. The modification included the effects of layered soil, source position, number of sources, soil evaporation and plant transpiration. The model was also used to simulate daily and one-in-several-days irrigations. Field and laboratory experiments were conducted to determine the soil moisture retention curve, the hydraulic conductivity, and soil moisture distribution from the line source. This data was used for model verification with the lateral lines buried 13 inches below the soil surface and spaced 36 and 72 inches apart. Simulated and measured soil moisture distributions were in good agreement. Simulated moisture distribution indicated that the wetting front expansion is more a function of irrigation volume than irrigation rate. However, the irrigation rate does affect the soil moisture distribution. A higher rate will result in a larger quantity of horizontal water movement. The simulation also indicated that a one-in-ten days irrigation causes more horizontal movement than a daily irrigation. / Master of Science

Master of Science

Please read the abstract in the section 00front of this document / Dissertation (MSc (Soil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Call number: LD2668 .T4 1956 L33 / Master of Science

One of the major limitations to obtain satisfactory soybean (Glycine max (L.) Merr.) yield in acid soils in many developing countries is the purchasability of liming materials. For many low income farmers, liming to the 'ideal' soil pH of 6.5 using conventional methods is usually too expensive. Pot and field studies were conducted to determine whether satisfactory soybean growth could be obtained by reducing the amount of lime applied and the volume of soil limed. The Quebec soils used in these studies were a Gray-brown Luvisol (pH 5.1) and a Humic Gleysol (pH 5.3) in the pot study and a Gray-brown Luvisol (pH 5.1) and a Dark-gray Gleysol (pH 6.1) in the field study. / Results suggest that localizing the lime in acid Quebec soils would be a more efficient use of the liming material. Further studies in tropical acid soils are required to determine if the localized placement of lime is a viable practice for third-world, low income farmers. (Abstract shortened by UMI.)

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1962. / Bibliography: leaves 135-148. / xii, 148 leaves 3 mount, col. ill., mount. diagrs., tables

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains ix, 128 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2008. / Full text also available online. Scroll down for electronic link.