EFFECTIVE RAINDROP KINETIC ENERGY INFLUENCE ON SOIL POTASSIUM TRANSPORT INTO RUNOFF ¹

Abstract

The release and migration of soil chemicals from agricultural lands is both an economic loss and a threat to the quality of surface water and groundwater. Kinetic energy from rainfall is one of the most active factors affecting soil solute transport in runoff. To determine the influence of effective raindrop kinetic energy on soil potassium transfer into runoff, a series of laboratory experiments with different raindrop falling heights and rain intensities was performed. The experimental results indicate that effective raindrop kinetic energy affects soil surface properties and infiltration processes, including infiltration volume and wetting front advance. As effective raindrop kinetic energy increased, the infiltration decreased, the wetted depth decreased, time to initiate surface runoff decreased, and the cumulative amount of runoff increased. The concentration and amount of potassium in runoff increased as effective raindrop kinetic energy increased. There appeared to be a minimum value of raindrop energy to cause splash erosion of soil. The effective depth of interaction (EDI) was calculated, and the results indicated that the EDI increased as effective raindrop kinetic energy increased. Hence effective rainfall kinetic energy influences the whole process of infiltration-runoff-potassium transport, and the amount of potassium in runoff may be decreased by controlling the effective raindrop kinetic energy that reaches the soil surface.