Groundwater pollution is one of the main factors justifying the study of soil solute movement and the processes of soil solute interaction. A deeper penetration than the expected of the chemicals applied to the soil surface, together with laboratory observations of the decrease of the amount of solutes in the solution passing through the soil, led researchers to consider the soil water (or solution) as having two phases: a mobile phase, θm, and an immobile phase, θim. In this paper, the mobile concentrations of water were determined for an unsaturated soil in the field, by using two concentrations of KCl solution (0.1 and 0.05 mol L-1). Three plots were set up for the experiment in the experimental area of the Department of Sciences of Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ-USP), in Piracicaba (SP), Brazil. The soil was classified as a Rhodic Kanhapludalf, a clayey soil, bulk density of 1,410 kg m-3, for a 0.30 m superficial layer. A disk permeameter (125 mm radio) was used and fitted to supply a matric potential of - 1 KPa of water column. Results showed that the mobile content for the 0.05 mol L-1 KCl concentration was about 50 % lower than that for 0.1 mol L-1 KCl concentration, in which only 30 % of the solution was mobile.
mobile content solution; KCl; infiltration