Im not really into fertilizers, but i heard seaweed contains nearly all Nutrients that exists. They are not longterm-fertilizers, and thats what i actually would want them to be. There is a fertilizer sold made out seaweed that clamis to be longterm tho. I think it has something added, so Nutrients are relased slowly.
The cooles thing would be if i could find a homemade way to make seaweed longterm… Cause you can find it easily in any lake, and go collecting on a hot summerday, for free.