Thesis (Ph.D.)Soil Science)--University of Pretoria, 2000. / Includes bibliographical references.

Soil properties are examined from two perspectives: (1), in relation to classes and categories of classification systems, and (2), in terms of mathematically tractable, chemical and physical continuums. Through four independent studies, major limitations of each approach are defined and evaluated. The first study examines samples from six different types of horizons commonly found in podzolic soils. The results suggest that in a chemical context the horizons do not represent distinct entities; rather they appear to dominate overlapping regions along a multidimensional chemical spectrum. The second study analyzes the extent to which V.J. Krajina's phytosociological classification of biogeocoenoses explains the variability of a number of site properties. It is determined that many of the physiographic properties are significantly related to the association category of the system, but that many of the pedologic properties are not. The two studies lead to a dichotomy concerning classification and the statistical relationships both among soil properties and between soil properties and other elements of an ecosystem. Where sampling is restricted to comparatively limited ranges along environmental gradients, relationships may be so weak that a classification based on only a few properties or elements may not be that useful for associated properties and elements. On the other hand, because of the implied high degree of variability, attempts to develop a holistic, integrated classification are not likely to be highly successful either. In the third study chemical and physical changes across a prograded beach chronosequence are examined. It is found that soil development over both time and depth may be modelled by a non-linear regression equation. The last of the four studies concerns an evaluation of the extent to which the inherent variability of soil properties masks expected trends across a morainal chronosequence. For those properties most affected by vegetation succession, the same type of regression equation as used in the previous study was applied with excellent results. For the other, less dynamic properties, assumed trends were too obscure to model. The two studies suggest that, where soil properties are directly influenced by strong environmental gradients, ordination techniques may be quite illuminating. In less biologically stressful environments and in those which have reached steady state, both the predictive and explanatory capabilities of such techniques may be relatively low. These findings closely parallel those discussed earlier concerning classification. The thesis concludes that for many applications attempts to model and map the landscape as an integrated whole should be abandoned. Furthermore, instead of viewing the landscape from either a classification or ordination perspective, digital terrain models should be considered. Data for the models could be generated from regionalized, statistical, stochastic, and deterministic equations, calibrated with ground truth observations. Traditional polygon and contour maps can also be transformed into digital terrain models. Landscape interpretations could then be tied directly to measured and estimated data. This approach involves a minimum loss of information and is conceptually simple. / Land and Food Systems, Faculty of / Graduate

Whether a particular soil should be used for cropping, pasture, woodland or some other purpose, involves consequences which are far too important to be left to chance. Soil is a natural body having a specific morphology and in order to understand its behaviour as fully as possible, it is necessary to determine and to correlate its characteristics or properties under various sets of circumstances. [...]

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Thesis (Ph. D.)--University of Hawaii at Manoa, 1982. / Includes bibliographical references. / Microfiche. / xviii, 344 leaves, bound ill. 29 cm

Thesis (PhD (Soil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

An airborne multispectral video system was used to collect soil spectral data over a four-square mile region in northeastern Arizona. Six multispectral video images were digitized. Using the red and blue bands of each image, an unsupervised classification was performed. Each was referenced to a digitized U.S. Soil Conservation Service map resulting in classification precisions ranging from 0-92.4 percent. Ground radiometric measurements were made to ascertain spectral separability of the soil samples. Soil color was determined to try to relate Munsell value to classification precision. Misclassification of soil map units was unrelated to soil brightness or areal extent of each soil. Rather, features such as slope, boundary complexity, and surface condition was responsible for misclassifications seen in this study. Best classification results occurred when soil mapping units were relatively homogeneous, possessed slight changes in slope, and had a regular surface with smooth and distinct boundaries.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Dada a importÃncia das condiÃÃes climÃticas para o desenvolvimento dos solos, aliado a ocorrÃncia de variaÃÃes de umidade e temperatura em Ãreas muito prÃximas, este trabalho teve como objetivo identificar e caracterizar os solos altimontanos nas vertentes Ãmida (VU) e seca (VS) do MaciÃo de BaturitÃ, considerado, em parte, um enclave Ãmido inserido na regiÃo semi-Ãrida do Estado do CearÃ. Analisaram-se 08 (oito) perfis, sendo 04 (quatro) em cada vertente, a partir da descriÃÃo morfolÃgica, atributos fÃsicos, quÃmicos e micromorfolÃgicos necessÃrias para o entendimento dos principais processos pedogenÃticos atuantes. Foram identificadas as seguintes classes de solos: Cambissolo HÃplico (P1 e P4) e Argissolo Amarelo (P3 e P4) na vertente Ãmida e Argissolo Vermelho (P1), Luvissolo CrÃmico (P2) e Cambissolo HÃplico (P3 e P4) na vertente seca. O lado Ãmido apresentou caracterÃsticas de um maior potencial de percolaÃÃo da Ãgua que ocasionou maiores perdas de bases por lixiviaÃÃo e altos conteÃdos de Al trocÃvel, cujos valores mÃdios foram de S = 2,2 cmolc.kg e Al = 4,1 cmolc.kg e, consequentemente, reaÃÃo fortemente Ãcida (pH mÃdio = 5,1). A vertente seca apresentou caracterÃstica de ambiente mais propÃcio a oxidaÃÃo, causada pela maior aeraÃÃo do pedoambiente, denunciado pela cor mais avermelhada. Confrontando os dados da VU com os da VS, a menor espessura do solum dos pedons desta Ãltima, assim como, menor concentraÃÃo de argila nos horizontes B (306 à 343 g.kgÂ) e elevados teores de cÃtions trocÃveis (S = 12,8 cmolc.kgÂ), alÃm de outros atributos fÃsicos, quÃmicos e morfolÃgicos, indicam o menor grau de evoluÃÃo dos solos na VS, confirmando o contraste entre os solos localizados em lados opostos do MaciÃo. / Given the importance of the climate conditions for the development of soils, together with the occurrence of moisture and temperature variations in very near areas, The purpose of this work was to identify and characterize the soils into a sequence in the moist and dry slopes of MaciÃo de BaturitÃ, which is considered a moist enclave inserted in the semi-arid region of Cearà State. It was analyzed eight profiles, 04 out of them in each slope, from the morphological description, physical, chemical and micromorphological attributes on necessaries for the understanding of the main pedogenetic processes acting. It was identified the following soil classes: Haplic Cambisoil (P1 and P4) and Yellow Argisoil (P3 and P4) in the moist slope and Red Argisoil (P1), Chronis Luvisoil (P2) and Haplic Cambisoil (P3 and P4) in the dry slope. The moist side showed characteristics of a large potential of water percolation that caused greater loses of bases by lixiviation and high contents of exchangeable A1, whose values were S = 2,2 cmolc.kg and Al = 4,1 cmolc.kg and, consequently, strongly acid reaction (middle pH = 5,1). The dry slope showed a characteristic of an environment favorable for oxidation caused by greater aeration of the pedoenvironment, denounced by the reddish color. Comparing the moist slopeâs data with the dry slopeâs, the smallest thickness of the solum of the dry slopeâs pedons, as well as, lower concentration of clay in the horizons B (306 to 343 g.kgÂ) and high contents of exchangeable cations (S = 12,8 cmolc.kgÂ), besides other physical, chemical and morphological attributes, indicate the lower degree of evolution of soils in the dry slope, confirming the contrast among the soils located in opposite sides of MaciÃo.

The problems of land resources degradation as a result of misuse of arable land for non agricultural development and lack of appropriate methods and guidelines for land resources assessment are currently evident in Eritrea. These problems, have called for an urgent need for an appropriate land resources assessment in Eritrea. In response to this, a land capability classification in the areas around Asmara city that covers about 11742.7 ha was conducted. The intended aim was to properly assess the potential of the land resources in the study area and classify the capability of the land so as to designate the land according to its capability and foster appropriate land use. All the available natural resources in the study area were carefully assessed. A detailed soil survey was conducted and soil units were examined, described, classified and mapped out. Several criteria for the limitations were selected from the reviewed literature mainly USDA and RSA Land Capability Classification systems and in consultation with the soil survey and natural resources experts of the Ministry of Agriculture in Eritrea. In formation on land and soil characteristics, and the specified limitations and criteria were captured in a spatial digital format and then analysed within a GIS. Based on the specified parameters, different land capability units, subclasses, classes and orders were identified and mapped out. Finally, the sub classes were grouped to create,land capability classes ranging from Class I to Class VII and consequently the capability classes were grouped and mapped out at the level of land capability orders. The results revealed seven land capability classes (Class I to VII). Class III land in the study area covers 4149.43 ha (36.9 percent of the total area). The largest portion of this class is found in the central, southern and south eastern parts of the study area. However, classes I and II are very limited and cover 1562.95 ha (13.9 percent) of the study area. These classes are found mainly in the southern and central parts of the study area. Most of the gentle and steep sloping lands in the north and north eastern parts of the study area are classified as classes IV and VI. These classes have an area of 2652.08 ha (23.6 percent) and 2594.87 ha (23.1 percent) of the study area, respectively. Classes V and VII are very limited. These classes cover 221.53 ha (2 percent) and 57.55 ha (0.5 percent), respectively. The largest portion of class V land is found in the central part of the study area. Class VII land is mainly confined to the north eastern, western and southern corners of the study area. Four land capability orders were arrived at ranging from (high to moderate potential to non-arable land). The high to moderate potential arable lands are largely found in the southern and central parts of the study area. These lands cover 5715.39 ha (50.8 percent) of the study area. However, low potential arable (marginal productive) and non-arable lands have a considerable area of 2652.08 ha (23.6 percent) and 2652.42 ha (23.1 percent) of the study area, respectively. The largest portion of these lands is found in the north, north eastern and eastern parts of the study area. A small portion of the lands in the study area is classified as seasonally wetland. This land has an are~\ of 221.53 h~{2 percent) of the study area and is mainly found in the central part of the study area. It was concluded that nearly 50 percent of the land in the study area is classified as of moderately to high agricultural potential whereas the rest of the land is classified as marginal to non-arable land. However, the steady growth of demand for land for nonagricultural development due to the increasing population that depend on farm production in the study area, renders the prime arable lands as too limited to support the current population in the study area. Hence, protecting the prime arable lands and properly using such lands based on their sustained capacity can only secure the livelihood of the community. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1984. / Bibliography: leaves 319-329. / Microfiche. / lMaster negative: Microfiche MS33170. / xxiii, 329 leaves, bound ill., maps 29 cm