Technical Abstract: Soils were exposed to three consecutive simulated rains under dry, wet, and water table conditions with gypsum as a tracer placed at 5-mm depth to evaluate the extent and nature of chemical transfer from soil solution to runoff and to determine the effective depth of the mixing zone. No electrolyte release was detected in runoff during the dry run for all three soils. Initial electrical conductivity (EC) was 60-120 µS/cm, which decreased exponentially to <6 µS/cm after 5 min. of rain during the wet run (2 d after dry run). Initial EC was 250-400 µS/cm for the water table run, and reduced rapidly to 50 µS/cm. Results indicated that the complete mixing concept is valid, and the effective mixing depth appears to be <3-4 mm. Fast- and slow-rate processes can be identified. The fast-rate processes, driven by rain drop impact and confined to the mixing zone, cause an exponential depletion of chemicals in the mixing zone. The slow-rate processes, dominated by molecular diffusion and mechanical dispersion, describe chemical transfer to the mixing zone from below.