Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 82-87).

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 58-60).

Inaug.-Diss.--Halle. / Vita.

Thesis (doctoral)--Wageningen University, 1999. / Includes bibliographical references (p. 255-265).

No description available.

The solubility of calcium carbonate in calcareous soils was studied with a view of testing the validity of the application of equations based on calcite solubility in calcareous soils. For this purpose the solubility of calcium carbonate in calcareous soils was examined under a variety of experimental conditions. Calcareous soils equilibrated in water at constant partial pressure of carbon dioxide showed a state of supersaturation with respect to calcite. The values for pH-½pCa for each soil were constant, but varied from one soil to another. Varying the soil-water ratio over a range of 1:2 to 1:10 did not affect the constancy of pH-½pCa values in the soils studied. The addition of CaCl₂ varying in concentration from 0.0025 to 0.01 mole/l. did not affect the constancy of values for pH-½pCa. When dissolution of part of the calcareous materials present was effected by the addition of increments of a H-Resin or dilute HCl acid, the values for pH-½pCa did not remain constant. The reactions between orthophosphate solutions and calcareous soils varying in calcium content was examined. It was found that in all cases the initial rate of phosphorus fixation was rapid with about 98% of the phosphate added being fixed within 2 days. The calcium carbonate exerted its normal effect on the solution equilibrium regardless of the mechanism of the reaction between solid calcium carbonate and dilute solutions of KH₂PO₄. The application of solubility criteria revealed a state of supersaturation with respect to dicalcium phosphate. A study was made to determine whether the proton transfer mechanism associated with hydrated aluminum ions was responsible for the constancy of the values for pH-½pCa in soils. The constancy of ion ratios was studied in cation exchange resin suspensions. It was found that the values for pH-½pCa were constant in resins saturated with calcium and hydrogen over a range of calcium saturation from 21% to 85%. At 95% calcium saturation, constancy of pH-½pCa was not observed. In a calcium-aluminum resin saturated 47% with aluminum, the values for pH-½pCa were found to be relatively constant with a maximum difference of 0.08. / Land and Food Systems, Faculty of / Graduate

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

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