Thesis (B. Ag. Sci.(Hons.))--University of Adelaide, 1961. / Includes bibliographical references (leaves 67-70).

Thesis (B. Ag. Sci.(Hons.))--University of Adelaide, 1961. / Includes bibliographical references (leaves 131-135).

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Two soil types, the Ladner silty clay loam and the Nicomekl loam, located in the Lower Fraser Valley, representing the modal profile characteristics were selected to study the permeability and the factors affecting it. Undisturbed core samples and fragmented samples were procured for laboratory characterization of the soils. Measurement of the soil permeability in the laboratory confirmed the field observations that the Nicomekl soil was more permeable than the Ladner soil. There was a good correlation in the soil permeability and the soil macroporosity as determined by tension table at 40 cm. water tension. The texture of the two soils, as determined by pipette method, was not sufficiently different to account for the permeability differences. The variations in the organic matter content, as determined by wet combustion method, seemed to have little effect on the permeability behaviour of these soils. The nature of exchangeable cations, as extracted by the ammonium acetate method and quantitatively determined by flame photometry and versenate titration, in the two soils, were found to be very different; the exchangeable cations, Na⁺, K⁺ and Mg⁺⁺, in the Ladner soil seemed responsible for the lower permeability in comparison with the Nicomekl soil which had very low percent base saturation and appeared to have mostly Al⁺⁺⁺ ions present in the exchange complex. The poorer physical conditions of the Ladner were also, perhaps, due to the differences in the exchangeable cations. The X-ray identification of clay minerals, using oriented "aggregate technique", monochromatic copper radiation and surface reflection method, revealed that the Ladner and Nicomekl soils were qualitatively similar in their clay content. Both soils contained montmorillonite, micaceous mineral, chlorite, feldspar and quartz; the presence of kaolinite and vertniculite could not be established. In an intricate mixture of clays as above, quantitative estimation of clay minerals was not performed; hence the effect of clay minerals on the permeability of the two soil types could not be evaluated. Permeability measurements on soil mixtures containing reference clay minerals, using air pressures in a water permeameter, revealed that Na-Bentonite even in small quantities rendered soil highly impermeable. The permeability of soil mixtures containing clays with exchangeable calcium improved with the application of Krilium while the clays with exchangeable sodium did not respond to similar treatment. The effect of Al⁺⁺⁺ ion and weak acids on the flocculation behaviour of Na-Bentonite suggested that the presence of both Al⁺⁺⁺ ions and weak acids promoted soil permeability. X-ray diffraction diagrams using unflitered cobalt radiation indicated that weak acids formed heat stable complexes with bentonite. The bentonite treated with aluminum chloride as well as phosphoric acid plus aluminum gave diffraction patterns indicating that increased c-spacing was due to the complexes formed with bentonite; the deposition of these complexes at the interlayer positions prevented the complete collapse of lattice at elevated temperatures. / Land and Food Systems, Faculty of / Graduate

The subject of soil absorption is an old one, dating back to before 1850. The nature of soil absorption has been, and still is, a puzzle, in spite of the vast amount of work that has been done in the last few years. Two theories have been held as the cause of the absorption. The first is that the absorption is chemical, the compounds being changed into insoluble ones by double decomposition. The second is that the salts or radicals are physically held, that is, adsorbed by the soil particles. These theories have been held separately and combined.

No description available.

Investigations of soil parameters, infiltration testing, and storm observations are used to determine the infiltration characteristics for three Central Florida stormwater holding basins. Basic soil parameters are investigated and a value for available soil water storage is computed from these data. In-situ permeability and infiltration tests are used to obtain field permeability and infiltration rates. Infiltration test results may be applied to infiltration theory. Data from infiltration tests may be verified using available soil water storage computed from soil parameters. The effect of soil cover conditions is noted and investigated using the drum infiltrometer. Storm observations are used to confirm infiltration models. Infrequency of rainfall activity limited the number and reliability of observations. The effects of precipitation frequency and input intensity to the pond also noted in storm observations. A design procedure incorporating infiltration in stormwater retention basins is presented. This design procedure is based on infiltration theory and observed pond operation.

A significant advantage attributed to surge flow irrigation is that for the same volume of water applied the stream will advance farther along the furrow than with continuous flow. This potentially will reduce runoff and deep percolation which will improve uniformity and application efficiency where this advance phenomenon holds. The mechanism for improvement in advance time has generally been ascribed to surface sealing and surface layer consolidation. However, these phenomena do not satisfactorily explain improved advance times in sandy soils. Widely used infiltration equations which require the determination of empirical coefficients are unsatisfactory as predictors of infiltration conditions of intermittent wetting. The Green-Ampt model and a simple redistribution model are combined into an analytical model to predict infiltration under surge irrigation. The model results are compared to infiltration tests on soil columns of three soils of different soil textures. Also the model and the experimental results from the soil columns are compared to predictions made by two numerical solutions of the Richard's equation. One of the numerical models includes the effect of hysteresis by the use of Mualem's model to predict the variation of moisture content with potential, the other numerical model neglects the effect of hysteresis. A comparison of the analytical and the numerical models shows good agreement in their predictions for the soils and surge cycles tested. A comparison of predictions made by all three models shows good correlation to the experimental results. Although the number of tests done on the analytical model were limited it appears to be nearly as good a predictor of infiltration as the numerical models. The greatest strength of the analytical model is that while the numerical models took many hours to do a single run, the analytical model took only a few minutes. Both model and experimental results indicate that there was no reduction in infiltration rates or volumes infiltrated with intermittent as compared to continuous wetting. Thus the reduction in hydraulic gradient is not a factor in the reduced infiltration observed by others.

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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,1993