This chapter provides an understanding of the implications of sorption and binding of pesticides to soil minerals and organic matter with respect to bioavailability. It reviews the effects of sorption and binding of organic compounds. The chapter also reviews the development, application, and ecological significance of bioremediation to treat organic chemical contaminants. It focuses primarily on the challenges and potential problems of using bioremediation techniques on pesticide residues in soil. The bioavailability of adsorbed pesticides in soil is dependent upon the extent of the adsorption reaction and rate of desorption. In the adsorption-desorption and degradation processes, diffusion into soil aggregates plays a major role in controlling microbial utilization of organic chemicals. To determine the effects of sorption on spherical aggregates and diffusion into the aggregates on biodegradation processes, a deterministic model called the diffusion-sorption-biodegradation model was developed by Scow & Hutson.