Azomite

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%).

• Apply at 0.25-2 tons/acre, or 0.25-2 lb/10 sq ft.
• Use as an annual top dressing on citrus trees, where soil pH is 6.5 or lower, at 5 lb/tree, or 15 lb on blight-stricken trees.
• Azomite can also used in animal feeds at a rate of 0.5% of feed mixture, as a trace mineral supplement and a natural anti-caking agent.