A good fertilizer would have a lot of different ingredients, and cover a much wider spectrum of nutrients, not just one, or even the "main 3" indicated by the numbers. Are you asking for ground gardening? I'd be much more interested in making a compost pile of various ingredients, than trying to find one arcane ingredient like chicken feathers. Plants growing in 'good dirt' don't need fertilizers of any kind. If you're gardening in containers, a well-rounded fertilizer would almost surely be superior to one with only 1 ingredient.
Meant to include a link about 'dirt.'
http://permaculturenews.org/20...
