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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 2, 2009). Thesis advisors: Dr. J. W. Van Sambeek, Dr. Frieda Eivazi. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. Includes facsimile of one published journal article and texts for two articles to be submitted to journals, all by the author and M.L. Jackson. Description based on print version record. Includes bibliographical references (leaves 116-128).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Bibliography: pages 171-181. / Studies of forest ecosystems have indicated that internal sources constitute a significant component of the acid load to forest soils and can result in significant decreases in soil pH, acid neutralising capacity and base status. Despite this, the possibility that these processes can result in a significant transfer of acidity to drainage solutions and consequently to associated surface waters has, to a large extent, been discounted due to the self-limiting nature of " natural" acidification processes which purportedly do not involve significant concentrations of the strong acid anions NO₃⁻, SO₄²⁻ and Cl⁻. In South Africa, extensive plantations of Pinus spp. (pine) are developed in mountainous regions that were previously covered by grassland or fynbos (macchia) vegetation and are mostly not believed to be influenced by significant atmospheric pollution. Thus, a good opportunity exists to study the effects of afforestation without the superimposed influence of acid deposition. This thesis documents the results of a regional investigation of the geochemical impact of pine afforestation in South Africa. The study focuses specifically on factors relating to the transfer of soil acidity to drainage waters. The key questions that are addressed are : 1) to what extent is soil acidification, as previously documented for plantations in the eastern seaboard region of southern Africa, prevalent in other forestry areas within South Africa?; 2) in the absence of acid deposition, can afforestation cause enhanced concentrations of strong acid anions in soil solutions and drainage waters, and can this lead to the transfer of large quantities of acidity from forest soils to surface waters ?; 3) does afforestation-induced acidification lead to increased concentrations of environmentally important metals such as Al and Mn in soil solutions and surface waters ?; and 4) how does afforestation affect the quantity of dissolved organic matter in soils and streams?

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The objectives of this investigation were to (1) segregate the forms of soil acidity in certain Virginia soils and to study each form Independently, (2) to develop techniques to more accurately define the components of soil acidity, and (3) to relate forms of soil acidity to mineralogical and chemical properties and genesis of the soils studied. Three soils, Mayodan, Creedmore and Whitestore, developed from Triassic parent material in Chesterfield County, Virginia, were selected for the study. The high base unsaturation is responsible for the release of Al from the clay and its accumulation in the subsoils. The chemical data show that exchangeable Al is the predominant source of acidity. The mineralogy of these soils is quite similar. The predominant clay minerals present are kaolinite and vermiculite. From the acidity standpoint, the surface soils, compared to the subsoils, have better developed hydroxy-Al interlayers in the vermiculite. In the subsoils of the three soils the hydroxy-Al interlayer development is in this order: Mayodan>Creedmore> Whitestore, the same sequence as the drainage (decreasing). The main reason given for these differences in interlayer development is the frequency of wetting and drying. The ranges of soil acidity include H₃O+ (first range), Al³⁺ (second range) and positively charged hydroxy-Al groups third range). The potentiometric titration of the soils in <i>N</i> KCl do not show significant inflections for the third buffer range. Variations in the rate of titration and in temperature did not seem to influence the inflection for the third buffer range. The potentiometric and conductimetric titrations in H₂O, after the removal of exchange acidity and free-salt, give distinct inflections for the third buffer range. The conductimetric method for the determination of third buffer range in soils, as employed in this investigation, is recommended. The extraction studies with salt solutions and the potentiometric titrations of Al-saturated vermiculite show that only part of exchangeable Al is extracted with salt treatments and the rest is either hydrolyzed or trapped. The hydrolyzed Al is titratable, whereas the trapped Al is chemically inactive. MgCl₂ was more effective than KCl as an extractant. This is probably due to the greater hydrated radius and the higher valence of the Mg-ions. The smaller K ion causes collapse of the vermiculite and trapping of Al in the interlayer space. The results show that the use of KCl in soil titration is not recommended because of its effect on Al-hydrolysis, the competition of added Cl^- ions with OH^- ions and the trapping effect during K-fixation when vermiculite is present. / Ph. D.

The purpose of the study was to determine the effect of four salt concentrations and four acid levels of soil solution on the germination of Quercus emoryi and Robinia neo-mexicana seeds, and to study the effects of the cation concentration changes in solution (Na, Ca, Mg, K) and exchangeable cation concentration. The solution extracts and exchange phases of both soils, salt accumulation in the soil increased by increasing the salinity and acidity of the water applied. Exchangeable sodium was related directly to the SAR of the applied solutions. The soil responded differently to the salty water and acid water. Both soil treatments released Ca, Mg and K to the soil solution from the dissolution of the primary minerals and cation exchange reaction.

Soil acidity is a major land degradation problem that limits crop production globally. The high cost of traditional liming materials (calcitic limestone, dolomite etc.) and the vast areas of land that require liming have led to the exploratory utilisation of alkaline industrial by- products such as fly ash and stainless steel slag. The liming potential and effects of liming with fly ash (from the Duvha power station) and processed stainless steel slag (Calmasil) on two acid soils were investigated in this study. The quality of fly ash and Calmasil as liming materials and their potential impacts on the soil quality and plant growth were investigated. The effects of liming with these materials on soil pH, EC, extractable Al, Mn, base cations and trace elements were investigated in an incubation experiment. A glasshouse trial was conducted to assess the effects of these materials on the growth of an acid intolerant crop, perennial rye grass. The incubation and glasshouse study were of a factorial design with two acid soils (the Avalon and Inanda soils), three materials (fly ash, Calmasil and lime); and five application rates of 0, 50, 100, 200 and 400% of the recommended optimum liming rate (OLR) for the growth of perennial rye grass. Characterization of fly ash showed that the major elements (>5%) present (Si > Al > Fe) are not comparable to lime (Ca > Si > Mg) and that it has a low liming potential (calcium carbonate equivalence (CCE) of 9.6%) in comparison to lime. The chemical composition of Calmasil is comparable to lime with Ca > Si > Mg as the major elements and it has a very high liming potential (CCE = 97%). The incubation experiment showed that adding fly ash and Calmasil increased the pH of both soils. However, at the optimum liming rate (100% OLR), only the treatment with Calmasil in the Avalon soil attained pH levels within the desired pH range. Extractable Al and Mn decreased with addition of fly ash and Calmasil to levels comparable to lime in the incubated soils. Addition of fly ash and Calmasil also increased the extractable base cations of both soils. The yield-response of perennial rye grass to treatments in both soils was in the following order: fly ash > Calmasil > lime. Application of fly ash at > 200% OLR in the Avalon soil caused injury of ryegrass. Application of fly ash and Calmasil at lower rates has great agronomic potential in ameliorating soil acidity. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.