HYDROPHILIC POLYMERS AND WETTING AGENTS AFFECT ABSORPTION AND EVAPORATIVE WATER-LOSS

A plantless system using subirrigation was developed to measure water absorption and loss in soilless media amended with hydrophilic polymer s, a wetting agent, or combinations of these amendments. Peat-perlite- vermiculite and bark-peat-perlite controls achieved 67% and 52% of con tainer capacity, respectively, after 20 daily irrigation cycles. Maxim um water content of amended media was 78% of container capacity. Addin g only a hydrophilic polymer did not increase total water content sign ificantly. Adding a wetting agent increased water absorption in both m edia. However, when hydrophilic polymer and wetting agent were present , the medium absorbed more water than with wetting agent alone. More e xtractable water was removed from media containing wetting agent. Wate r loss rate by evaporation was not affected significantly by medium, h ydrophilic polymer, wetting agent, or any combination of these variabl es.