Virginia Tech has a good publication on fertilizer for vegetable gardens. I've put a link to it below. To know exactly what you need to apply, you would need to have a soil test done. Your local cooperative extension office can direct you to a lab in your state. The results will tell you what nutrients are deficient and how much you need to add. Be sure to let the lab know that this is a soil mix, not native in-ground soil, and ask for recommendations for a bushel or cubic yard or some other measure that will work for you. Pounds to apply per 1000 square feet is the usual way the info comes back and that is not what you're looking for.

Good luck. This seems like a good project with potentially great outcome for you.

Sandy

Here is a link that might be useful: Fertilizing the Vegetable Garden

Well, different ones will need different formulas. Leafy crops need high nitrogen, but give that consistently to tomatoes and peppers and you'll get lots of leaves and few fruits.

I have tried this -- the problem will be in finding the components. If you're talking dry granular fertilizer, you'll have an easier time than if you want water soluble. I wanted to make my own version of Miracle Grow this summer like I used to years back -- alas, thanks to Timothy McVeigh blowing up the federal building in Oklahoma, they can't sell Ammonium nitrate anymore at the feed store, because I might be a terrorist, spreading fear, cabbages, and leeks in my wake.

Veggies need from 4-1-2 for leafy greens to 3-1-6 for fruiting things such as tomatoes and peppers. You can reproduce those ratios with mixtures of wood ash, human urine, and "green" compost for small corrections. For example, 1 gallon of urine and 1 lb of wood ash will give you approximately 19 grams of nitrogen, 6 grams of P, and 18 grams of K. Those are, more or less, the needs of 20 sqft of garden for one year. This stuff is best mixed with compost or water, or applied in winter, as it burns plants. Wood ash will provide all micronutrients as well, in sufficient amounts.