By tilling organic matter in, you will not need any fertilizer. Your soil will have everything you need in it. If want to make compost tea, thats the next step, but is not needed with a healthy soil.

Onions love phosphorus, carrots love potassium....neither like much N mid/late-season, but like it early.

Soy meal is a decent N source. Apply it evenly and broken up...clumping soy meal (and other veggie/grain meals) invites insect issues in some areas.

Kelp meal (if you can get it cheap or make your own) is a great trace mineral source. Some people like rock dust, but it needs to be extremely finely ground, from a good source, and it takes a bit longer to work it's "magic" in the soil than kelp sources. Many rock dusts also are a good P source according to their NPK numbers, but it is VERY slowly available and cannot be counted on immediately.

Good post,nc.

I guess the op did want to know about a fertilizer. I was just trying to direct them in getting a healthy soil. Me and nc have a similar approach to gardening I believe.

A "complete fertilizer" is one that contains Nitrogen, Phosphorus, and Potash, maybe not in equal amounts. A "Balanced Fertilizer" is a "complete fertilizer" but with the N, P, K in equal amounts. So a 10 - 10 - 10 fertilizer would be a "complete, balanced fertilizer" while a 5 - 2 - 1 would be a "complete fertilizer".
Compost is considered a soil amendment and not a fertilizer since the nutrients compost contains are not easily measured.
To determine what your soil might need requires a good reliable soil test that tells you the soil pH and the levels of the major nutrients, These simple soil tests might also be of some help.
1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drainsâ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

Onions actually do need a good amount of N at first. But without a soil test how can you fertilize?

How to Make Complete Organic Fertilizer

A Better Way to Fertilize Your Garden: Homemade Organic Fertilizer

Bulb onions are heavy NPK-feeders.

If you are interested in a general purpose, organic fertilizer, because you have not (yet) had a soil analysis done, I suggest you look at what Steve Solomon put together. Steve wrote "The Intelligent Gardener" and other gardening books, and his recipe for a Complete Organic Fertilizer, or COF is what is provided above in the link by Art_1.

After you view that link to COF, if you want a good source for the ingredients, and can't find them locally, I suggest you try:

http://www.soilminerals.com/Minerals_and_Fertilizers.htm

I believe this site also has their own, general-purpose, all-in-one-bag formula, but I've never used it.

Good Gardening,

Glenn

This post was edited by EnoreeG on Mon, Jan 27, 14 at 14:28