What Does Zone of Leaching Mean?
The zone of leaching refers to the area above the top soil. When water penetrates the soil surface, it travels downwards through the soil profiles to the water table. The area just below the topsoil contains plant nutrient elements or may contain contaminants. In this soil zone, or zone of leaching, these elements can be dissolved and transported downward through the soil until the zone of saturation is reached.
Safeopedia Explains Zone of Leaching
In the agricultural context, attempts to limit leaching are applied in order to maintain soil nutrient levels, or certain salts may be leached from soils through the application of water. In the industrial context, the zone of leaching can serve as a source for ground-water contamination through leaching of dissolved chemicals. The EPA may conduct soil tests on certain sites in order to determine whether contaminants are present in the soil in order to assess the risk of ground water pollution.