OOPs... I forgot a thing or two.
Banana peels are a rich source of potassium. I save them and coffee grounds, bury them in the garden. Worms love them. Most produce, if I remember correctly, is rich in potassium ... so composting can really help.
If you want perfect soil, add lots of organic material. And try "Perfect Balance" fertilizer from GardensAlive.com . They analyze soil samples that you send them, then they formulate fertilizer that is balanced with all the macro and micronutrients. I haven't tried it, but the idea seems like a powerful one, they explain it well, and they charge enough that the service is credible. Probably one could do the same for less with a really good ag extension service and a spreadsheet.
