ABSTRACT
This chapter includes the theory and evolution of the Baker Soil Test (BST), with a summary of the experience gained by the authors on the applicability of the method to land management problems. The method has been used with respect to land application of sewage sludges, reclamation of strip mine spoils, fly ash disposal areas, soils contaminated by smelters, and and especially for the production of synthetic soils from coal refuse at disposal sites. The BST was developed from the theory that ion uptake or availability is related to chemical potentials or relative partial molal free energies of ions in the soil solution. The conclusion from the theory and experimental data presented is that plants respond indirectly to the solid phase of soils. Therefore, nonsoil materials or wastes can be used to produce synthetic soils for the production of vegetative cover. The BST approach involves the concept of “small exchange” of ions to reflect the relative partial molal Gibbs free energy, or pi, for any ion, i, in a soil, spoil, or synthetic soil system. A brief description of the method is included. Most of our experience with the method involves its application to soils treated with municipal sewage sludges. While it is possible to calibrate results for any soil test using one soil, our results show that it is not possible to predict plant uptake of Cd and other elements from amounts extracted from different soils. The theory and applications have been applied to many soil, plant, animal and human health related problems involving different wastes.
