Leaching of Container Media

Abstract

Leaching of salt from container media was investigated by means of the miscible displacement theory for 6 peat-perlite-glass bead combinations plus 4 other mixes. Columns were salinized with 15 meq 1−1 each CaCl2 and NaCl, then allowed to equilibrate. Electrical conductivity of the effluent was recorded as columns were leached, using 1 cm constant water head, with solutions of 1, 4, or 7 meq 1−1 each of CaCl2 and NaCl. The replacement efficiency of the soil solution by the leaching solution increased as glass bead content increased. Replacement efficiency of the soil solution had high correlation with mixture physical properties. No relationship to particle size distribution could be ascertained. Leaching solution concentration did not influence replacement efficiency and, generally, after 1 to 1.5 container capacities of effluent, removal of the original soil solution decreased substantially.