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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The relationship between soil classes, soil properties, plant growth and soil management treatments in the Goondi Mill area of North Queensland, Australia

Monteith, Nigel Hugh January 1967 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves 202-209. / xiv, 209 l illus., maps
12

New approaches to investigate and construct biogeochemical models of inland acid sulfate soils: linkages to environmental degradation processes and mineral exploration.

Baker, Andrew K. M. January 2007 (has links)
Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / "Inland acidic sulfate soils under fresh water conditions where contemporary clearning of native vegetation has caused erosion, rising of local water tables and excess discharge of saline-sulfatic groundwater. A new systematic and interactive web-based approach was used to improve acquisition, collation, integration and communication of diverse soil-regolith data ... Successful application of the interactive web-based data site, as part of this study, resulted in its uptake as a standard tool for coordinating and reporting on a number of current and future national and international soil-regolith studies." -- from Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1289208 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Enviromental Sciences, 2007
13

New approaches to investigate and construct biogeochemical models of inland acid sulfate soils: linkages to environmental degradation processes and mineral exploration.

Baker, Andrew K. M. January 2007 (has links)
Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / "Inland acidic sulfate soils under fresh water conditions where contemporary clearning of native vegetation has caused erosion, rising of local water tables and excess discharge of saline-sulfatic groundwater. A new systematic and interactive web-based approach was used to improve acquisition, collation, integration and communication of diverse soil-regolith data ... Successful application of the interactive web-based data site, as part of this study, resulted in its uptake as a standard tool for coordinating and reporting on a number of current and future national and international soil-regolith studies." -- from Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1289208 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Enviromental Sciences, 2007
14

Investigation of the principles of rapid soil tests for available potash and other plant nutrients of Virginia soils: III. selection, development and calibration of rapid chemical soil tests for available potassium, phosphorus, calcium and magnesium

Wolcott, A. R. 19 May 2010 (has links)
Four rapid soil test extracting procedures for potassium, phosphorus, calcium and magnesium, and one absorption procedure for potassium and phosphorus were compared. The soils studied represented important agricultural soils in the Coastal Plains, Piedmont and the Limestone Valley areas of Virginia. Extracting and testing procedures were evaluated on the basis of laboratory performance by correlation with supplemental yield data from 49 field experiments. Four systems of soil test interpretation were applied in correlating soil tests with crop response to current fertilizer applications. It appeared that only an empirical correlation could be made between crop response and a soil testing procedure which attempts to simulate seasonal crop removal of soil nutrients. A more basic, more tenable correlation appeared possible with soi1 testing procedures which approach total measurement of exchangeable K₂O, CaO and MgO, and adsorbed and acid soluble P₂O₅. With certain modifications, Bray's sodium perchlorate solution was the most promising of the extractants tested for measuring total exchangeable K₂O, CaO and MgO. Neither the acetate or the chloride ion adequately measured adsorbed P₂O₅. No other anions were tested in the phosphorus extractions. It appeared questionable that absorption techniques could be adapted to a correlation with the response of general field crops to fertilizer applications. The chemical testing procedures used for determining K₂O, P₂O₅ and MgO in the soil extracts were found quite satisfactory. Calcium tests on soil extracts were erratic. The variability of calcium readings appeared to result from pH relationships involved both in the extraction and in the developed test solutions. The "high-low-medium" interpretation and the interpretation based upon simple response or non-response permitted only a general correlation to be made. Their potential value appeared to be chiefly that of giving support to fertilizer recommendations arrived at on the basis of more specific information regarding the soil type, soil pH, the crop to be grown, the location, and the cropping and fertilization history of the field. The balance sheet interpretation must, of necessity, be based upon fractional extraction. Such a correlation must be strictly empirical. A balance sheet correlation, using any the extracting procedures that were tested, did not appear to be possible for corn on the heavy soils of the Limestone Valley. The growth curve interpretation as developed by Bray in Illinois appeared moat promising as a means for resolving fertilizer practice based upon rapid soil tests to a simple formula which takes into consideration current soU productivity and the specific behavior of specific crops to soil and fertilizer nutrients in specific soils. The accurate determination of the constants involved will permit a quantitative relationship between soil teats and fertilizer recommendations. / Master of Science
15

The variability and geomorphology of Appling, Cecil, and Davidson soils on sideslopes in the Virginia Piedmont

Genthner, Michael Hoffman 11 June 2009 (has links)
Delineations of Applinq, Cecil, and Davidson soils were sampled on a grid pattern (4 to 9 m spacings), using a bucket auger, to determine their modal character and variability with regard to various chemical and morphological parameters. Delineations were located on south-southwest facing, 5 to 12% slopes, in gently rolling landscapes that typify the Virginia Piedmont. Appling soils had the thickest A horizons and sola and were highest in A horizon P but were lowest in A horizon pH, K, Ca, Mg, and organic matter and B horizon pH, P, K, Ca, and Mg. Cecil soils were highest in A and B horizon pH and in B horizon P, K, and Mg, but had the thinnest sola. Davidson soils were highest in A and B horizon Ca and in A horizon organic matter but were lowest in A horizon P. Soil variability was considerable at all sites, with A horizon thickness and pH and B horizon P and K varying the most over short distances. Subsequent to the grid sampling study, we dug soil pits in areas in which approximately modal soil characteristics had been observed. pit studies revealed negative effects of agriculture upon these soils; A horizons were high in clay, had high bulk densities, and had low organic matter contents. Predictably, tilth was poor. pit studies also showed that locally supplied colluvial materials cover a significant portion of the upland Piedmont soilscape. Of 18 pedons studied, 12 appeared to be formed in colluvial materials. However, colluvium-derived soils were usually distinguished from their residual counterparts only by the presence of a stone line that roughly paralleled the present soil surface at depths of 0 to 2 m. Therefore, these colluvial inclusions should rarely affect soil interpretations for Appling, Cecil, and Davidson map units. / Master of Science
16

Some factors affecting anion retention in acid soils

Chang, Monica Liu January 1962 (has links)
The purpose of this investigation were to use chromatographic methods to study the effects of pH, time of equilibration, and the effect of anions themselves in the anion retention in an acid red soil. It was found that chloride was held much less tightly than sulfate by soils. It was also noted that more sulfate was retained at higher concentration. A time factor was also noted in this investigation. It took a longer period to reach true equilibrium when sulfate was used. Results showed a positive correlation between sulfate retention and time to reach true equilibrium. The disappearance of aluminum from the solution added to soil suggested that the continuing hydrolysis of aluminum being the main cause of the time effect. Such hydrolysis produces hydrogen ions which can neutralize the hydroxyl ions exchanged by anions and kept the pH of the system from going up and continuing the reaction. The non-symmetrical elution patterns indicated the retention of anions• The longer the tail of the elution patterns, the more tightly the anions are retained. Distribution coefficients (Kd) for Cl⁻, NO₃⁻, and SO₄ showed approximately linear relationships between pH 3 and 6. Chloride and NO₃⁻ exhibited similar Kd values at similar pH values. It also indicated that SO₄⁻ was held much more tightly at low pH values. / Master of Science
17

SPATIAL VARIABILITY OF ELECTRICAL CONDUCTIVITY AND SODIUM ADSORPTION RATIO IN AN ALFALFA FIELD (COOLIDGE).

Ajibogun, Solomon Afolabi. January 1984 (has links)
No description available.
18

Mathematical analysis of soil temperatures in an arid region.

Foster, Kennith E.(Kennith Earl) January 1972 (has links)
A mathematical model study was made to compare simulated soil temperature variations with a field situation. The study involved the use of two plots, one of which was cleared of all vegetation and the other left in its natural vegetative state. Each plot was watered at the beginning of three different trial periods and as drying occurred, the following atmospheric parameters were measured on an hourly basis: incoming solar radiation, air temperature, relative humidity, cloud cover, and wind speed. The above parameters provided input for solution of the energy budget equation to determine soil surface temperature variation. Using the soil surface temperature variation as an upper boundary condition, and assuming heat movement by conduction, the temperature at 5 cm increments down to 70 cm in the soil was calculated. The two plots provided model testing for a bare soil surface and also for a soil surface beneath a 30 percent and a 40 percent plant cover. Actual and calculated temperature difference was in most cases less than 2°F. The mathematical model is applicable to any area where the above parameters may be monitored.
19

Restoration of nitrogen and carbon cycling in an Appalachian mine spoil

Schoenholtz, Stephen H. 28 July 2008 (has links)
Nitrogen deficiencies have long been acknowledged as a factor limiting the restoration of ecosystems destroyed by surface mining in the Appalachian Region of the U.S. The fundamental ecological structure and function common to intact terrestrial ecosystems are largely lacking in mine soils. Reliable guidelines for effective long-term restoration require a detailed understanding of the ecological processes occurring within the mine-soil system. The objective of this study was to determine the extent to which inorganic N fertilization, native topsoil replacement, or whole-tree wood-chip amendment affected the restoration and reforestation of an Appalachian mine-soil system through changes in C and ~ dynamics. Eighteen concrete tank lysimeters filled with mine spoils served as experimental microcosms to test hypotheses set forth in this study. Treatment effects on soil N and C pools, herbaceous biomass production, N uptake, N fluxes between pools, net leachate N losses, and early growth of pitch x loblolly hybrid pines were evaluated at regular intervals between July 1987 and October 1989. Inorganic N fertilization increased aboveground herbaceous biomass yield and N uptake by 87 and 71%, respectively, during the first growing season, but did not significantly affect yield or N uptake thereafter. During the first growing season, biomass production was 38% higher in the topsoil-amended mine soil than the unamended control. This resulted in an additional 17.4 kg N ha-1 sequestered in comparison to the control. Biomass yield was 270 and 19% lower in the wood-chip-amended mine soil than the unamended control after the first and third growing seasons, respectively. This resulted in 63 and 25% less N uptake, respectively, than the control. Survival of pitch x loblolly pine after two growing seasons was 90% in the N-fertilized mine soil and 71% with the fertilizer control treatment. This difference in survival was the result of lower water potential in the unamended mine soil during the growing season in which the trees were planted. Nitrogen fertilization did not significantly affect tree growth or nutrition. Pine survival after two growing seasons was 83, 98, and 60% for the unamended control, wood-chip, and topsoil treatments, respectively. By the end of the second growing season, the wood-chip treatment also resulted in greater tree height, ground-line diameter, and stem-volume index by 30, 49, and 203% respectively, when compared to the control. Increased survival and growth in the wood-chip-amended mine soil were directly related to higher soil water potential than the control or topsoil treatments. Total inorganic N leaching loss from N-fertilized mine soil was 47.64 kg ha-1 yr-1 higher than the control during the first growing season. However, N fertilization losses were not significantly higher during the remainder of the study period. Drainage was significantly higher during all three growing seasons in the wood-chip-amended mine soil. This resulted in lower N sequestering during the third growing season when precipitation was most abundant. Topsoil amendment did not significantly affect N leaching losses. Inorganic N fertilization did not significantly affect total organic C, total N, or N availability indices in the mine soil. Following topsoil addition, mine-soil total N was 294% higher than the unamended control. Wood-chip effects on the soil organic-matter pool were more gradual; however, by the end of the study, total N and total organic C were 18 and 95% higher, respectively in the wood-chip-amended mine soil than in the unamended control. Aerobic incubation of soil samples collected near the end of the second growing season showed that the topsoil and wood-chip amendments increased the N mineralization potential by 101 and 55%, respectively, in comparison to the unamended control. Furthermore, the mineralization rate constant of the wood-chip-amended mine soil was 44% lower than the control. This shows a slower rate of N turnover and more stable mine-soil N pool with the wood-chip treatment. This study shows that inorganic N fertilizer effects on N and C dynamics were rapid but transient. In contrast, the surface-applied amendments of native topsoil and whole-tree wood chips improved the potential for successful restoration of forests by increasing the N cycling capacity of the developing mine-soil system. / Ph. D.
20

Effective properties for flow in heterogeneous porous media

Zhu, Junlin 20 September 2005 (has links)
Modeling of groundwater flow and chemical transport calls for a good characterization of heterogeneity of soil properties. The effects of variabilities of soil properties at local scale on the mean behavior of heterogeneous flows were investigated via Monte Carlo method. Assuming log-normal distribution of conductivity and capillary pressure head being a stochastic process, the mean behavior model defined by effective properties was derived to predict the mean behavior of heterogeneous flows. Effective parameters were evaluated numerically and were parameterized in terms of statistics of randomly distributed soil properties and flow characteristics. Monte Carlo simulations were performed to reveal the mean behaviors of steady unsaturated gravity flows, transient areal source infiltration and transient point source infiltration in heterogeneous porous media. The most important findings include (a) the effective conductivity is between the geometric mean and the arithmetic mean, (b) the effective conductivity is time dependent. The derivation of a mean behavior model and the capability of parametrizing the effective properties make it possible to use current deterministic models to predict the mean behavior with minimum changes in the constitutive relations, specifically adding the dependence on the flow characteristic to the K-S-P relations. The mean model derived in this study was applied to a field site, good agreement was found between the model prediction and field data. / Ph. D.

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