This module examines the basic properties of soil which have an influence on the success of land treatment of wastes. These relevant properties include soil texture, soil structure, permeability, infiltration, available water capacity, and cation exchange capacity. Biological, chemical and physical mechanisms work to remove and renovate wastes after their application to the soil. Wastes are removed physically through filtration by the soil and altered by dilution, either upon entering the groundwater or by augmentation in the soil with natural rainfall or snowmelt. Absorption and precipitation are the two main processes of chemical retention of wastes in soil. Potentially toxic elements and the macronutrients nitrogen and phosphorus are partially controlled by chemical mechanisms in soil. Biological mechanisms alter waste constituents in stages. Soil organisms decompose organic compounds. The soil's ability to handle wastes is limited by the loading of nitrogen, phosphorus, and water, the addition of potentially toxic materials, and its sodium adsorption ration. This module summarizes these limitations, identifying nitrogen as the major limiting factor in most situations. (Author/BB)