Abstract available on PDF file. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1978.

Phosphorus uptake cassava (Manihot esculanta Crantz) were tested using on thirty-six plants per plot under dryland conditions at four different sites selected Bioresource group 1 (BRG 1) of northern KwaZulu-Natal of South Africa, which is described as Moist, Coastal Forest, Thorn and Palm veld, exhibiting sub-tropical characteristics. Soils in this region are very low in Phosphorus (P) due to high fixation by iron and aluminium oxides. With its high root yields coupled with efficient nutrients miner, cassava removes large quantities of N, P, K and Mg. With the ever-increasing prices of P fertilizer, which impact on the socio-economic livelihood of smallscale farmers, there is the need to look into improving the P uptake by the crop by alternative means apart from using mineral fertilizers. The objective of this study was to investigate the use of Arbuscular Mycorrhizal Fungi (AMF) to improve P uptake by cassava in agricultural soils. Laboratory studies were conducted at Soil Fertility and Analytical Services in Cedara (Pietermaritzburg). A Latin Square design (LSD) was used. Four treatments used were Untreated (Control), P-fertilizer, AMF, and P + AMF. Correlation and path-coefficient (probabilities) were computed. The P + AMF were significantly (p<0.05) taller than those in P-fertilizer treatment plots but were significantly (p<0.05) similar to those in Control and AMF-treated plots. Percent leaf P was statistically similar at the four sites with grand mean of 0.4%. Adding AMF and P+AMF to the soil substantially increased leaf P concentration to 0.5%. Tubers collected from P+AMF-treated plots were significantly (p<0.05) the longest, while those from Control plots were the shortest. P, and AMF-treated plots increased tuber length relative to the Control. All soil treatments significantly (p<0.05) increased tuber yields over the Control-treatment plots. However, AMF and P+AMF treated plots were significantly higher than P and control plots. This study suggests that using AMF or P+AMF can improve cassava yield as compared P alone or control – untreated cassava plants. Cassava producers in northern KwaZulu- Natal should consider using AMF or P+AMF to optimize tuber yield. A further study into the economic implications of the use of AMF is recommended. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

We examined the physical and chemical soil characteristics in the cleared riparian areas at the Sooke Lake Reservoir, where the growing population has necessitated the expansion of the drinking water reservoir in Victoria, British Columbia. Additionally, hydrologic functioning was studied to establish the pathways riparian nutrients followed to the reservoir. In order to understand the potential release of nitrogen and phosphorous following inundation, both saturated riparian and upland areas were chosen as part of 17 transects encompassing the entire reservoir in four major soil types (Morainal, Colluvial, Fluvial and Organic). Various nutrient concentrations (TDP, TP. PO43- DOC, TC, IC, NO3-, NO2, NH4+, TN, TDN) were measured in relation to geomorphic features. Areal analyses confirm the hypotheses that nutrient concentrations differ with soil type, depth (0-10 cm, 10-30 cm, 30-60 cm) and hill slope. Hydrologic data established that seasonality and therefore transect connectivity is an important aspect for nutrient transport in the riparian areas via leaching and preferential flowpaths.

This thesis investigates the potential advantage of using remote sensing techniques to assess underground transmission tower corrosion. The data used in this study was collected from three electrical transmission towers in the Lower Fraser Valley, British Columbia, Canada. A comprehensive assessment of the corrosive environments have included the following factors: climate, soil pH, soil moisture content, soil resistivity, overlying plant spectral reflectance, and heavy metal content in soil and vegetation. The principal method of protection against steel tower corrosion is zinc galvanization. As zinc serves as a sacrificial coating, once corroded, it leaches into the soil, and is then absorbed by surrounding vegetation. High concentrations of heavy metals may negatively influence plant growth. Plant Root Simulator (PRS™) probes were used to assess heavy metal supply rates by continuously adsorbing charged ionic species while in soil. Heavy metal content analysis was also conducted on sampled tower vegetation using an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Remote sensing techniques, such as field spectroscopy, have great potential for monitoring spectral reflectance variations of various vegetation types and biophysical characteristics. The energy-matter interactions in the UV, VIS, NIR and IR wavelength regions can be used for chemical analysis of compounds and mixtures. The combination of remote sensing analysis techniques, such as NDVI, leaf structural index R110/R810, water content index R900/R970, first order derivative analysis, and continuum removal can provide non-intrusive and continuous monitoring methods for the impact and content of certain heavy metals in plants growing in contaminated soils. However, in this study, the high zinc concentrations recorded from the PRS™-probes and ICP-AES could not be correlated to the reflectance spectra measured by the field spectrometer. Although using zinc as a spectral corrosion identifier was not successful in this thesis, the presence of a chemical process in which by-products were produced and leached into the soil was evident. The integration of remote sensing techniques and underground corrosion explored in this thesis presents unique opportunities for further research in this area of study.

Two natural soils from Bahrain were used in this study to investigate the feasibility of using Arabian oil residue as a means to stabilize collapsible saline soils. Since the presence of oil residue in soils can pose an environmental threat, the high oil retention capability of the stabilized soils is critical to its application. / The behavior of the stabilized soils has been experimentally investigated in the laboratory. This study has concentrated on the evaluation of the mechanical properties of the stabilized soils, the oil retention characteristics and its bonding mechanisms, and the leaching and migration behaviors of oil residue from the stabilized soils. / The geotechnical investigation results indicated that the addition of 4% oil residue, by weight, was sufficient to significantly enhance the strength performance of the tested soils. The geochemical tests showed that the bonds formed between the oil and the soil surfaces were predominantly Van der Waal's attraction, weak hydrogen bonding, and cation and water bridging. These bonds were found to be relatively weak but stable and insensitive to leaching forces. The geo-environmental results revealed good oil retention in these samples, with less than 3% of the oil residue by weight leached from the stabilized soils after 40 days of leaching in distilled water. / The migration of oil from the stabilized soils has also been theoretically evaluated. The theoretical study utilizes the model developed by Yong et al. (1992) with a few modifications made to accommodate this particular situation. The model was solved using an explicit finite difference method, Powell's optimization technique, and experimental results. The predicted oil migration profiles were found to be slightly over-estimated as compared to the experimental profiles.

Current estimates of terrestrial carbon (C) fluxes overlook explicit hydrological controls. In this research project, a spatially explicit hydro-ecological model, BEPS-TerrainLab V2.0 was further developed to improve our understanding of the non-linearities associated with various hydro-ecological processes. A modeling study was conducted in a humid boreal ecosystem in north central Quebec, Canada. The sizes and nature of various ecosystem-C-pools were comprehensively reconstructed under a climate change and disturbance scenario prior to simulation in order to ensure realistic biogeochemical modeling. Further, several ecosystem processes were simulated and validated using field measurements for two years. A sensitivity analysis was also performed. After gaining confidence in the model’s ability to simulate various hydrologically controlled ecophysiological and biogeochemical processes and having understood that topographically driven sub-surface baseflow is the main process determining the soil moisture regime in humid boreal ecosystem, its influence on ecophysiological and biogeochemical processes were investigated. Three modeling scenarios were designed that represent strategies that are currently used in ecological models to represent hydrological controls. These scenarios were: 1) Explicit, where realistic lateral water routing was considered 2) Implicit, where calculations were based on a bucket-modeling approach 3) NoFlow, where the lateral sub-surface flow was turned off in the model. In general, the Implicit scenario overestimated GPP, ET and NEP, as opposed to the Explicit scenario. The NoFlow scenario underestimated GPP and ET but overestimated NEP. The key processes controlling the differences were due to the combined effects of variations in plant physiology, photosynthesis, heterotrophic respiration, autotrophic respiration and nitrogen mineralization; all of which occurred simultaneously in different directions, at different rates, affecting the spatio-temporal distribution of terrestrial C-sources or sinks (NEP). From these results it was clear that lateral water flow does play a significant role in the net terrestrial C distribution and it was discovered that non-explicit forms of hydrological representations underestimate the sizes of terrestrial C-sources rather than C-sinks. The scientific implication of this work demonstrates that regional or global scale terrestrial C estimates could have significant errors if proper hydrological constraints are not considered for modeling ecological processes due to large topographic variations of the Earth’s surface.

Thesis (MScAgric)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6119. Adviser: Robert G. Hoeft. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

We examined the physical and chemical soil characteristics in the cleared riparian areas at the Sooke Lake Reservoir, where the growing population has necessitated the expansion of the drinking water reservoir in Victoria, British Columbia. Additionally, hydrologic functioning was studied to establish the pathways riparian nutrients followed to the reservoir. In order to understand the potential release of nitrogen and phosphorous following inundation, both saturated riparian and upland areas were chosen as part of 17 transects encompassing the entire reservoir in four major soil types (Morainal, Colluvial, Fluvial and Organic). Various nutrient concentrations (TDP, TP. PO43- DOC, TC, IC, NO3-, NO2, NH4+, TN, TDN) were measured in relation to geomorphic features. Areal analyses confirm the hypotheses that nutrient concentrations differ with soil type, depth (0-10 cm, 10-30 cm, 30-60 cm) and hill slope. Hydrologic data established that seasonality and therefore transect connectivity is an important aspect for nutrient transport in the riparian areas via leaching and preferential flowpaths.

Orientador: José Marques Júnior / Coorientador: Diego Silva Siqueira / Banca: Ricardo marques Coelho / Banca: Alan Rodrigo Panosso / Resumo: São escassas as informações a respeito do recurso solo em escala adequada. Tais informações subsidiariam o estabelecimento de politicas públicas de uso e manejo e também o aprimoramento dos próprios mapas de solos. O presente trabalho tem por objetivo estabelecer um protocolo para o mapeamento de solos a partir de informações auxiliares e médias dos atributos do solo (diagnósticos e não diagnósticos). Foram coletadas 553 amostras de solo na profundidade de 0-0,20 m ao longo das rodovias do Estado de São Paulo, dentro do domínio geológico do Planalto Ocidental Paulista. Utilizaram-se informações de geologia, dissecação, pedologia e mapa de formas da paisagem, com diferentes escalas. Foram avaliados o conteúdo de argila, a suscetibilidade magnética, o ferro ditionito e o ferro oxalato, a hematita e a goethita, a caulinita e a gibbsita para cada informação auxiliar e para a união dessas informações. A variabilidade dos atributos foi estudada a partir de suas amplitudes (valores mínimo e máximo), e as médias foram utilizadas para o estabelecimento do protocolo. As amostras que representaram a mesma geologia, dissecação, pedologia e forma da paisagem foram concatenadas, dando como resultado 96 grupos. As médias destes grupos foram submetidas à análise de agrupamentos, visando a observar a estrutura dos dados e a diminuir a quantidade final de grupos. Os grupos obtidos a partir da análise de agrupamentos foram submetidos à análise geoestatística para a obtenção do mapa dos padrões ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Information about the soil resource is scarce in an adequate scale. This information would support the establishment of public policies of its use and management and as well the improvement of the soil maps. This work aim to establish a protocol for the design of soil bodies from soil data legacy and average information of diagnostic and non-diagnostic soil attributes. It was collected 553 soil samples from 0-0.20 depth along the highways of São Paulo State, within the geological province of the Western Plateau of São Paulo. Data from geology, geomorphology, pedology and landform maps were used. Clay content, magnetic susceptibility, oxalate and dithionite iron, hematite and goethite, kaolinite and gibbsite were assessed for each auxiliary information and for the union of these data. The variability of the attributes was analyzed through their amplitude (maximum and minimum values) and the means were used for the establishment of the protocol. Samples that presented the same geology, dissection, pedology and landform were concatenated, leading to 96 groups. The means of these groups were submitted to cluster analysis to evaluate the data structure and reduce the final number of groups. The groups obtained from cluster analysis were submitted to geostatistical analysis for the creation of isoline maps. The results indicated remarkable difference between the attributes mainly for the geological and pedological data. Cluster analysis revealed the influence of each information on... (Complete abstract click electronic access below) / Mestre