INFILTRATION AND PERCOLATION INFLUENCED BY ANTECEDENT SOIL WATER CONTENT AND AIR ENTRAPMENT

Infiltration and percolation rates are influenced by soil water content, but the effects of soil water on thesetwo parameters have not been separated. Our objective was to clarify some of the effects of initial soil water content,time, and an interruption of soil water flow on infiltration and percolation. Infiltration and percolation measurementswere made by ponding soil cores and by using a double ring infiltrometer and a sprinkling infiltrometer in the field.Aggregate stability measurements were made on field-collected surface soil. The infiltration rate after one hour of waterapplication on soils above 15% antecedent soil water content was greater than on the same soil at less than 5%antecedent soil water content. Wet aggregate stability measurements followed the same trend. It is suggested that the slowbreakdown of aggregate bonds under wet conditions causes this phenomenon. In contrast, percolation rates were higherwith higher soil water contents. An interruption in water application for percolation measurements reduced the wet ratesmore than the initially dry rates. It is suggested that air bubble entrapment is the main retardant to percolation for boththe initially dry situations and for interrupted flow.