Nutrient Basics - Cobalt
Cobalt is needed by all animals in trace amounts.Cobalt is a component of vitamin B12 which is essential to most animals and possibly plants
Studies indicate cobalt is essential to many beneficial bacteria that are involved in nitrogen fixation both in legumes and non-legumes. From what I read, the cobalt is actually being used by the beneficial bacteria and the use in plants is still unknown. I would recommend having cobalt in a fertilizer if you are going to use beneficial bacteria of any type. There is still a lot of unknowns about cobalt.
Cobalt is needed in VERY small amounts. It is toxic to people in large amounts, a few grams will kill a 200 pound person so do NOT search out large quantities. You should not touch cobalt with your bare hands. It was used to settle beer foam in Canada a few years ago and it lead to heart problems.
Dr. E.R. Myers