The levels of phosphorus in media can also be evaluated and discussed as Phosphorus Saturation Index (PSI). PSI is the proportion of extractable phosphorus to extractable aluminum and iron in the soil sample.
+
The levels of phosphorus saturation in a filter or growing media can also be evaluated and discussed as Phosphorus Saturation Index (PSI). PSI is the proportion of extractable phosphorus to extractable aluminum and iron in the soil sample.