This natural fertilizer (described in Secrets of the Soil as "rock dust") is actually an ancient deposit of aluminum silicate clay and marine minerals. In use for over 50 years as a source of available potash (0.2%) and over 70 trace minerals, including calcium (1.8%), sodium (0.1%), and magnesium (0.5%). OMRI listed. 44 lbs
For local pick up only.