Copper Ion

   

Copper has been used as one of the oldest fungicides and bactericides used in the garden, it has a history of over 1,500 years, in European gardens over 5,000 years in China.  Using Copper tools leave trace amounts of copper in the soil to provide benefits to plants as well as reduce fungi and bacteria.
Repell  Slugs  and  Snails

Snails, slugs and spiders have Copper in their blue colored blood (called haemolymph). Trace amounts of Copper deposited in the soil from using Copper tools, causes the slugs and snails to get a mild electric shock (chemical reaction) to the copper particles in the soil, they don't like the feeling and find another place to feed.