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Bibliography: leaves 105-129.

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The effects of feeding soy protein (SP) or SP plus isoflavones (IF) (150 and 400 mg IF/kg diet) on bone metabolism were assessed in female weanling and retired breeder (RB) rats fed low calcium (Ca) for five weeks. Young rats fed SP-based diets had significantly smaller reductions in bone mineral density (BMD) and bone mineral content (BMC) as a result of the low Ca diet compared to those fed casein-based diets. Added IFs had no further benefits. Soy protein also affected bone metabolism in both the young and RB rats as indicated by markers of bone resorption. Neither the SP nor the added IFs had any effects on BMD or BMC in the RB rats. Feeding SP to young rats resulted in beneficial changes in BMD, BMC, and biochemical markers of bone metabolism. This study indicates that SP positively affects bone metabolism and minimizes the negative effects associated with low Ca intakes in young rats.

Graduation date: 1933

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Surface (0-20 cm) dolomitic limestone treatments of 0, 4.48, 8.96, and 13.44 Mg ha⁻¹ on the Coastal Plain and up to 17.92 Mg ha⁻¹ on the Piedmont and Ridge and Valley soils were made to seven acid Virginia soils. These amendments were made to document movement of Ca and Mg as well as neutralization of soil acidity within these soil profiles. During the fourth growing season following application, samples in 5 or 10 cm increments were taken to a depth of 60 cm. Soil chemical properties (soil water pH, soil mol L⁻¹ KCl pH, exchangeable Ca, Mg, and Al) were determined. Calcium and Mg movement and depth of neutralization decreased as soil clay content increased. These cations moved through the sampling depth in the coarse-textured Emporia loamy sand, but neutralization was only evident to the 50 cm depth. The Pacolet sandy clay loam, with the high percentage of clay in the surface horizon, showed no movement of Ca from the surface layer and Mg movement was limited to 25 cm. Liming increased pH dependent CEC which increased cation retention in the horizons receiving direct lime application. Depth of neutralization was lime rate dependent with higher rates resulting in greater acidity neutralized. The Pacolet soil illustrated increasing water pH values to the 25 cm depth, in comparison to the subsoil at the 8.96 and 17.92 Mg ha⁻¹ rates of lime application. Magnesium movement was detected at greater depths than Ca in all soils. Neutralization of acidity did not accompany Mg movement, demonstrating that the cation moved as a neutral salt. Results indicate that subsurface chemical properties will be affected in soils cropped in continuous corn or corn-soybean rotations as opposed to crops of continuous alfalfa. Despite cation movement in the profile, neutralization of acidity may not occur beyond the plow layer, i.e. the Frederick silt loam or may occur to a depth of 50 cm, i.e. the Emporia loamy sand, with the other soils being intermediate. / Master of Science