Physical properties of nursery potting-mixtures

The bulk density, total porosity, air porosity and water-holding capacity of mixtures of equal parts of either sand or scoria with peat moss, pinebark, poppy straw and sawdust can be predicted from the respective properties of the ingredients. Total porosity of the media was inversely correlated to bulk density, but there is no clear correlation between air porosity and bulk density. Air porosity increased with pot size.