NY00006 - Development and Evaluation of New Test for Water Retention Efficiency of Potting Media

Three simple laboratory tests for measuring the water retention efficiency (WRE) of potting mixes were developed in a two-year trial completed in May 2002. The drip, ‘hand’ and capillary absorption tests provided information about the rewetting properties of potting mix under sprinkler, drip and sub-irrigation. The trial included a survey of commercial potting mixes, which showed highly variable results for WRE and air-filled porosity, water-holding capacity, bulk density and wettability under Australian Potting Mix Standard AS 3743. No one test or combination of tests was sufficiently correlated with WRE to be useful for predicting potting mix performance under irrigation.