Don't know. Never thought about it but kelp is extremely important in OK because of the heat.
I think I'll do a little checking on this myself and follow this thread. This year hasn't been too bad so far, not too hot. We just had a rain shower for about 15 mins of heavy rain.
Are you talking about soil as in outside in the ground? Or in pots? I'm thinking about using it in Ms DWW's flowers and veggie gardens along with my pot garden.