A study of 12 expansive soils in four major physiographic provinces in Virginia was initiated to examine and quantify the relationship between shrink-swell potential, shrink-swell indices, and soil properties. The mineralogy classes, soil series, and (physiographic provinces, parent materials) examined include smectitic -- Jackland and Waxpool (Triassic, diabase), Iredell (Piedmont, hornblende); vermiculitic -- Kelly (Triassic, thermal shale); kaolinitic -- Cecil (Piedmont, granite gneiss), Davidson (Triassic, diabase); and mixed -- Carbo and Frederick (Valley and Ridge, limestone), Craven and Peawick (Coastal Plain, fluvial and marine sediments), and Mayodan and Creedmoor (Triassic, sandstones). Three sites in each of the 12 map units were described and major horizons sampled for physical, chemical, and mineralogical laboratory analysis. An expansive soil rating system, termed the Expansive Soil Index (ESI), was developed using the soil properties best correlated with shrink-swell potential. The sum of swelling 2:1 minerals, swell index, liquid limit, and CEC gave expansive soil potential ratings (ESI) for each soil series. The higher the ESI, the greater the shrink-swell potential. Smectite distributions within the soil profiles were investigated. Smectite concentration in the clay fraction increases with depth in soils formed from diabase and thermally altered shale. Smectite weathers to kaolinite and hydroxy-interlayered vermiculite with increasing proximity to the soil surface thus accounting for the observed decrease in smectite toward the soil surface. The highest amount of smectite from the granite gneiss, limestone, sandstones and shales, and Coastal Plain sediments were in the Bt2 horizon where maximum expression of the argillic horizon occurs. Smectite contents decrease away (upwards and downwards) from the maximum in the Bt2 horizon. A satellite study focused on locating and quantifying the variability within five map units in the Culpeper (Triassic) Basin in northern Virginia. Variability of the shrink-swell indices and related properties are high in all map units. Dissimilar inclusions could adversely affect foundations if a home is sited on both moderate and high shrink-swell soils. Although there is extreme variability in the map units, the variability occurs within the delineations of each map unit. Each delineation within an individual map unit contains similar levels of variability. / Ph. D.

Globally, peatlands are vulnerable to degradation via drainage, with consequences for ecosystem structure and function such as increased fire vulnerability, soil oxidation, and altered vegetation composition. Peatland function is largely dependent on hydrologic regimes and their influences on the accumulation and properties of peat soil. Therefore, an understanding of soil-hydrology interactions is needed to inform management in drained peatlands, including expansive systems such as the Great Dismal Swamp (GDS; Virginia and North Carolina, USA) where hydrologic restoration is underway. Two physically distinct soil layers have been observed at GDS, the upper layer thought to be a result of past drainage and the lower layer more representative of an undisturbed state. To understand the occurrence and consequences of these distinct layers, we integrated continuous water level data, peat profile characterization, and analyzed soil physical and hydraulic properties. The transition from upper to lower peat soil layers typically occurred at depths below contemporary water level observations, suggesting that the upper layer may be a result of historical drainage with limited recovery following hydrologic restoration. We also found distinct differences between the properties of the two layers, where upper layers had lower fiber and organic matter contents and higher bulk densities. Further, upper layers had higher proportions of macropores, resulting in an overall lower water retention capacity. These differences in layer properties suggest the upper layer is more susceptible to drying, increasing fire vulnerability, oxidation, and shifts in vegetation composition that do not support current management objectives. / Master of Science / Peatlands provide many valuable ecosystem services, including carbon storage, water quality maintenance, and habitat provision. However, peatlands have been subjected to centuries of drainage (i.e., lowered water levels) to support timber harvesting, land conversion, and other land use actions. Drainage and the resulting drier conditions can lead to soil carbon loss, increased fire vulnerability, and changes in vegetation communities. Additionally, peatland drainage has consequences for peat soil properties and their role in ecosystem services. In an effort to restore peatland ecosystem services, hydrologic restoration, usually in the form of water control structures, is often implemented to reduce drainage and reestablish historical water levels. To guide restoration practices, research is needed to understand how drained peat soils respond to such hydrologic management. In this study, we investigated peat soil profiles, current water level regimes, and soil properties at the Great Dismal Swamp (Virginia and North Carolina, USA), a drained peatland currently undergoing hydrologic restoration. We found a visibly distinct upper soil layer, which we suggest developed as a result of past drainage and with little recovery under restored, wetter conditions. We also found that this upper layer has altered soil properties and thus is more vulnerable to drying, with implications for ecosystem function such as fire vulnerability, carbon sequestration and vegetation composition. Together, our findings will help inform restoration and water level management at GDS and our understanding of drained peatlands more broadly.

A laboratory testing program was conducted on cement-treated soil mixtures fabricated to represent materials produced by the wet method of deep mixing. The testing program focused on investigating the influences that variations in laboratory testing conditions and in the mix design have on measured property values. A base soil was fabricated from commercially available soil components to produce a very soft lean clay that is relatively easy to mix and can be replicated for future research. The mix designs included a range of water-to-cement ratios of the slurries and a range of cement factors to produce a range of mixture consistencies and a range of unconfined compressive strengths after curing. Unconfined compressive strength (UCS) tests and unconsolidated-undrained (UU) triaxial compression tests were conducted. Secant modulus of elasticity were determined from bottom platen displacements, deformations between bottom platen and cross bar, and from LVDT's placed directly on the cement-treated soil specimens. Five end-face treatment methods were used for the specimens: sawing-and-hand-trimming, machine grinding, sulfur capping, neoprene pads, and gypsum capping. Key findings of this research include the following: (1) The end-face treatment method does not have a significant effect on the unconfined compressive strength and secant modulus; (2) a relationship of UCS with curing time, total-water-to-cement ratio, and dry density of the mixture; (3) the secant modulus determined by bottom platen displacements is significantly affected by slack and deformations in the load frame; (4) the secant modulus determined by local strain measurements was about 630 time the UCS; (5) typical values of Poisson's ratio range from about 0.05 to 0.25 for stress levels equal to half the UCS and about 0.15 to 0.35 at the UCS; (6) Confinement increased the strength at high strains from less than 20% the UCS to about 60% the UCS. In addition to testing the cured mixtures, the consistency of the mixtures were measured right after mixing using a laboratory miniature vane. A combination of the UCS relationship along with the mixture consistency may provide useful information for deep mixing contractors. / MS / Deep mixing is a ground improvement technique that mixes cement with in-situ soil to improve the quality of the soil for supporting embankments, buildings, and other facilities. Deep mixing is also used for earth retention and to form subsurface seepage barriers. When the cement is added in dry powder form, the process is called the dry method of deep mixing, and when the cement is added in the form of cement-water slurry, the process is called the wet method of deep mixing. When using the wet method, both the water-to-cement ratio of the slurry and the amount of slurry added to the soil have important effects on the strength of the cured mixture. Laboratory mixtures are often tested in advance of field mixing to estimate the proportions of cement, water, and soil necessary to produce the desired outcomes. The laboratory test conditions influence the test results, and a wide variety of test conditions are used in practice. This research investigated different testing conditions and different mix designs to demonstrate their impacts on laboratory test results.

Knowledge about forests undergoing restoration across the world is becoming increasingly essential due to the benefits of restoring forest for ecosystem functions related to water, such as water infiltration. Although there is a growing literature regarding the biodiversity and some ecosystem functions in forest undergoing restoration, soil responses in these forests remain virtually unknown. Moreover, few works have analyzed the effects on soil of different restoration approaches (e.g., planting of native species and natural regeneration). In this context, the main objective of this work was to evaluate and gain a better understanding of the effects of different forest restoration methodologies on the recovery of soil physical and hydraulic properties, more specifically on water infiltration. In the first part of this study (Chapter 2) was conducted a systematic review of scientific literature, reporting and discussing the infiltration measures in tropical forests undergoing restoration by tree planting. The results of this review indicated that infiltration was likely to increase after tree planting; that infiltration recovery was faster when agriculture was the prior land use; that clayey soils (>30% clay) tended to exhibit greater increases in infiltration after tree planting; and that restored forests after 10 years evidenced more similar infiltration values with the pre-disturbance soil conditions (e.g., natural reference forest). The following two parts of the thesis (Chapter 3 and 4) were based on a restoration program using a high-diversity mix of native plantings in the county of Campinas, São Paulo, Brazil. In the Chapter 3 was investigated the effect of forest restoration on saturated soil hydraulic conductivity (Ks), verifying the Ks recovery to the pre-disturbance soil conditions. We sampled field Ks under three land-cover types: (i) a pasture; (ii) a restored forest of 9 years of age; and (iii) a remnant forest patch. Our results showed that Ks recovery differ markedly among the forests undergoing restoration; and that soil attributes and Ks recovery are influenced by the duration and intensity of land use prior to forest restoration. In the Chapter 4 we assessed the effects of land use history on the recovery of Ks, soil and vegetation attributes, comparing active vs. passive restoration (e.g., assisted restoration). In these chapters we conclude that forest restoration actions may improve soil physical and hydraulic properties, but in some cases a complete recovery to reference levels can be difficult, especially when land use was more intense prior to forest restoration actions. It is very important to understand soil recovery in forests undergoing restoration on different climate, forest and soil types. Thereby, in future research long-term studies are essential, which should focus in the water movement through the soil profile and aiming to understand how the forest restoration can recover the infiltration process, also including landscape scale (e.g., watershed). / O conhecimento sobre as florestas em processo de restauração florestal ao redor do mundo está cada vez mais em evidência, devido principalmente à sua importância nas funções ecossistêmicas relacionadas à água, tais como a promoção da infiltração. Contudo, apesar de existirem muitos estudos sobre áreas em restauração, abordando sua biodiversidade e algumas funções ecossistêmicas, o papel do solo nessas florestas em restauração permanece ainda pouco conhecido, por exemplo, poucos trabalhos têm analisado o efeito sobre o solo das diferentes estratégias de restauração (e.g., plantio de espécies nativas e regeneração natural). Nesse contexto, o objetivo desse trabalho foi avaliar e obter uma melhor compreensão dos efeitos de diferentes metodologias de restauração florestal na recuperação das propriedades físicas e hídricas do solo, mais especificamente na recuperação da infiltração de água no solo. Na primeira parte desse estudo (Capítulo 2) foi realizada uma revisão sistemática da literatura científica, reportando e discutindo os resultados de trabalhos sobre infiltração de água no solo em florestas em processo de restauração nos Trópicos, por meio do plantio de árvores. Os resultados desses trabalhos mostraram que houve um aumento da infiltração após o plantio de árvores; também observamos que a recuperação da infiltração foi mais rápida quando a agricultura era o uso anterior do solo; que solos mais argilosos (>30% argila) tenderam a exibir maiores aumentos na infiltração após plantio de árvores; e que as florestas em restauração com 10 ou mais anos evidenciaram valores de infiltração mais similares com as condições pré-distúrbio do solo (e.g., floresta natural de referência). Os dois capítulos restantes do trabalho (Capítulos 3 e 4) foram realizadas em uma área em processo de restauração florestal, com plantio de espécies nativas e elevada diversidade, no município de Campinas, São Paulo, Brasil. No Capítulo 3 foi investigado o efeito da restauração florestal na condutividade hidráulica do solo (Ks), verificando a recuperação da Ks até as condições pré-distúrbio. A Ks foi amostrada no campo em três tipos de uso do solo: (i) pastagem; (ii) área em restauração com 9 anos de idade; e (iii) florestal natural remanescente. Os resultados desse capítulo mostraram que a recuperação da Ks diferiu entre as áreas em processo de restauração; e que os atributos do solo e a recuperação da Ks foram influenciados pela intensidade e tempo de uso do solo anterior à restauração florestal. No Capítulo 4 foi avaliado o efeito do histórico de uso do solo na recuperação da Ks, dos atributos do solo e da vegetação, comparando as estratégias de restauração ativa vs. passiva (e.g., restauração assistida). Nesses capítulos concluímos que as ações de restauração florestal podem melhorar as propriedades físicas e hídricas do solo, porém, a recuperação de valores próximos aos valores de referência tem grande dificuldade, especialmente quando a área em restauração teve um histórico de uso intenso do solo. É fundamental entender como ocorre a recuperação do solo nas áreas em processo de restauração ecológica em diferentes tipos de climas, florestas e solos. Assim, fica claro a necessidade de pesquisas de longo prazo que foquem no movimento da água no perfil do solo, visando entender como a restauração florestal recupera o processo de infiltração da água no solo, inclusive na escala de paisagem (e.g., bacia hidrográfica).

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Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-08-17T17:49:24Z No. of bitstreams: 1 2017 - Jo?o Henrique Gaia Gomes.pdf: 3515689 bytes, checksum: 6a7151f0e574d679527cd2a45c6c5668 (MD5) / Made available in DSpace on 2017-08-17T17:49:24Z (GMT). No. of bitstreams: 1 2017 - Jo?o Henrique Gaia Gomes.pdf: 3515689 bytes, checksum: 6a7151f0e574d679527cd2a45c6c5668 (MD5) Previous issue date: 2017-02-23 / CAPES / As a result of activities such as agriculture, pastures for cattle raising, mining areas, logging and improper occupation in urban areas, about 28% of the Brazilian territory is classified as degraded. In some regions of Brazil, due to their geomorphological aspects associated to the intense precipitations that occur in summer, degradation problems such as erosive processes and slope slides can be verified. The Pinheiral-RJ region currently has only 18% of its territory under native forest cover at different levels of alteration and regeneration, with 88% of its area classified as high or very high vulnerable to erosion. Therefore, the objective of this work was to evaluate the effect of soil attributes and morphology of the sub-basin of the CachimbalRiver as conditions to the erosive process in different topographic features (pedoforms), concave and convex, in the Middle Vale do Para?ba do Sul -RJ, in order to generate information that contributes to the recovery programs of degraded areas. The digital elevation model (DEM) was generated using topographic maps of the municipalities of Volta Redonda (Page SF-23-Z-A-V-2) and Pira? (Page SF-23-Z-VI-1) using ArcGis 10.2 software. The quantification of gull numbers was performed through Google Earth. Morphometric characterization, trench opening for soil classification, collection of soil samples, physical and routine fertility analysis and analysis of soil attributes variability were performed based on literature criteria. It was verified that there is no susceptibility to flood in the studied area due to its elongated shape. The sub-basin has a dendritic drainage pattern, flow order of 5th degree, and very large drainage density(Dd). In particular, the average hydrographic density (Hd) value indicates a high potential for generating new channels. Although roughness coefficient (Cr)indicates agricultural capacity for agriculture, roughness index (Ir) demonstrates the need to adopt more nuanced agricultural practices that take into account the particular characteristics of the area and recognize variations in the terrain and soil characteristics. 30 gullies were quantified throughout the sub-basin, 24 being in the convex pedoform and 6 in the concave. The physical and chemical attributes differ in the environments. / Em decorr?ncia de atividades como agricultura, pastagens destinadas a pecu?ria, ?reas de minera??o, explora??o madeireira e ocupa??o impr?pria nas regi?es urbanas, cerca de 28% do territ?rio brasileiro ? classificado como degradado. Em algumas regi?es do Brasil, em fun??o dos seus aspectos geomorfol?gicos associados ?s intensas precipita??es ocorridas no ver?o, s?o verificados problemas de degrada??o como processos erosivos e deslizamentos de encostas. A regi?o de Pinheiral-RJ apresenta atualmente, apenas 18 % de seu territ?rio sob cobertura florestal nativa em diferentes n?veis de altera??o e regenera??o, possui88% de sua ?rea classificada como alta ou muito alta vulnerabilidade ? eros?o. Sendo assim, o objetivo desse trabalho foi avaliar o efeito dos atributos do solo e da morfologia da sub-bacia do ribeir?o Cachimbal como condicionantes no processo erosivo em diferentes fei??es topogr?ficas (pedoformas), c?ncava e convexa, na Regi?o do M?dio Vale do Para?ba do Sul-RJ, com finalidade de gerar informa??es que contribuam para os programas de recupera??o de ?reas degradadas. Foi gerado o modelo digital de eleva??o (MDE)atrav?s das cartas topogr?ficas dos munic?pios de Volta Redonda (Folha SF-23-Z-A-V-2) e Pira? (Folha SF- 23-Z-VI-1), utilizando o software ArcGis 10.2. A quantifica??o do n?mero de vo?orocas foi realizada atrav?s do Google Earth. A caracteriza??o morfom?trica, a abertura de trincheiras para classifica??o do solo, a coleta das amostras de terra, as an?lises f?sicas e de rotina da fertilidade e a an?lise da variabilidade dos atributos do solo foram realizadas baseando-se em crit?rios da literatura. Verificou-se que n?o h? susceptibilidade de enchente na ?rea estudada, devido a sua forma alongada. A sub-bacia tem um padr?o de drenagem dendr?tico, ordem de fluxo de 5? grau, e Densidade de drenagem (Dd) muito boa. Em particular, o valor da densidade de hidrogr?fica (Dh) indica um elevado potencial para gerar novos canais.Embora o Coeficiente de rugosidade (Cr) indique capacidade agr?cola para a agricultura, o ?ndice de rugosidade (Ir) demonstra a necessidade de adotar pr?ticas agr?colas mais nuan?adas que levem em conta as caracter?sticas particulares da ?rea e que reconhe?am varia??es no terreno e caracter?sticas do solo. Foram quantificadas 30 vo?orocas em toda a sub-bacia, sendo 24 na pedoforma convexa e 6 na c?ncava. Os atributos f?sicos e qu?micos diferiram quanto aos ambientes.

Land loss in South Louisiana is increasing at a fairly rapid rate. In an effort to reduce land loss and save the marshes of Louisiana, marsh creation projects have been proposed in carefully selected regions around the coast as part of the CPRA Coastal Master Plan 2017. Properties and characteristics of the soil obtained from soil borings were analyzed and used to determine the various design parameters that allow the marsh creation process to occur. Other properties that were taken into consideration for Louisiana coastal sediment are the geothermal properties. This research analyses those different properties obtained from geotechnical reports from CPRA and other data bases, in order to find correlations between the different soil characteristics, specifically between the soil’s compressive strength, consolidation properties, Atterberg Limits and moisture content. Furthermore, this research also studies the geothermal properties of selected Louisiana soils and the correlation between moisture content and thermal conductivity.

Thesis (M.Sc. (Soil Science)) --University of Limpopo (Turfloop campus), 2007 / The influence of parent material on physical and chemical properties of soil was studied on granite and schist derived soils on the Syferkuil Experimental Farm, situated in the Mankweng area of the Limpopo Province of South Africa. A total of 49 samples of virgin soils were collected, where granite soils constituted 26 samples and schist soils 23. The study design that was used is cross-sectional. The samples were analysed for physical and chemical properties. The physical properties of granite and schist soils were determined as percentages coarse sand, percentages medium sand, percentages fine sand, percentages very fine sand, percentages silt and percentages clay, whilst the chemical properties were determined as concentrations (cmol (+) kg-1) of Na, Mg, Ca, K ,ESP, CEC and P (mg kg-1), as well as pH. Statistical analysis of the results was performed by application of the Unpaired Student’s T Test, with the level of significance at p<0.05. The results showed that soils derived from granite had significantly higher coarse and medium sand fractions than schist soils; whereas schist soils were significantly higher in fine sand, very fine sand, silt and clay. The concentrations of Na, Ca, ESP and P, as well as CEC and pH in schist derived soils were higher than in granite derived soils although the differences were insignificant. However, significant differences occurred in K and Mg concentrations where schist derived soils had higher concentrations than granite derived soils. However, the concentrations of nutrient elements were found to be insufficient for proper production in agriculture. The sodium concentration was found to be low enough to not lead to sodic soil conditions. It was concluded that both granite and schist soils can be used for agriculture but require careful management because both soils indicated poor nutritional status.

This thesis is a comparative study of the life history strategies, and in particular seed germination requirements, in Australian species of the halophyte plant genus Frankenia L. (Frankeniaceae). Frankenia is a cosmopolitan genus that occurs in Mediterranean, semi-arid, and arid regions on distinctive soil types – commonly on saline, sodic or gypseous soils – in habitats such as coastal cliffs, and on the margins of salt lakes, salt-pans and saltmarshes (Summerhayes 1930; Barnsley 1982). The plants are small shrubs or cushion-bushes with pink, white or pale purple flowers, and salt-encrusted recurved leaves. This project investigates germination requirements for Frankenia in relation to seed age, light requirements, temperature preferences, salinity tolerance, and soil characteristics. It also explores two divergent reproductive strategies – notably seed packaging strategies – in relation to environmental variables. Within the 46 currently recognized endemic Australia species, some species have a few ovules per flower and produce only a few larger seeds per fruit, while other species have many ovules per flower and produce many small seeds per fruit. Large-seededness is thought to increase the probability of successful seedling establishment in drought and salt-stressed environments. As both larger- and smaller-seeded species of Frankenia co-occur in close geographical proximity, hypotheses regarding the advantages of large-seededness in stress environments can be tested. By restricting the analysis of seed mass variation to similar habitats and within a single plant genus, it is possible to test ecological correlates that would otherwise be masked by the strong effects of habitat differences and phylogenetic constraints. Overall, larger-seeded Frankenia species were demonstrated to be advantageous for rapid germination after transitory water availability, and for providing resources to seedlings if resources became limiting before their successful establishment. Smaller-seeded species delayed germination until both soil-water availability and cooler temperatures persisted over a longer time period, improving chances of successful establishment for the more slowly growing seedlings that are more reliant on their surroundings for resources. This study produces information on the seed and seedling biology of many Australian species of Frankenia including several that are of conservation significance, e.g. F. crispa with its isolated populations, and the rare and endangered F. plicata. This information is important for the development of conservation management plans for these and other arid zone, halophyte species. In addition, the results of this study are of practical significance in determining the suitability of Frankenia for inclusion in salinity remediation and mine-site rehabilitation projects, and for promoting Frankenia as a drought and salt tolerant garden plant.

The objective of this study was to determine if the presence of two ALS inhibiting herbicide residues in three Saskatchewan soils would result in an additive, synergistic, or antagonistic interaction. This was determined through field trials where herbicides were applied sequentially over the course of two years and through dose-response modelling. The herbicides examined in these experiments were imazamethabenz, flucarbazone-sodium, sulfosulfuron, and florasulam, each in combination with imazamox/imazethapyr. The phytotoxicity and persistence of the herbicides in soil was assessed using an Oriental mustard root inhibition bioassay. The determination of herbicide interaction was made through the comparison of the experimentally observed values to theoretically expected values derived from a mathematical equation.<p>The dose response curves created by placing incremental concentrations of these herbicides in soil were compared using the I50 parameter, which is the concentration resulting in a 50% reduction in root length. It appeared that soil organic matter followed by soil pH had the greatest effect in reducing herbicide residue phytotoxicity in the tested soils. Based on the bioassay analysis of sequentially applied ALS inhibiting herbicides, it is proposed that the phytotoxic effect of herbicide residues in soil result in additive injury effects rather than synergistic or antagonistic interactions.