Here are some examples of popular groups of organic fertilizers:
- Earth worm casting (organic fertilizer) (for N). You can make your own with a worm farm ($79 at Amazon)
- Dried Kelp (for K and P). It helps plants develop stronger roots. The mixing powder is more cost effective than the prepared liquid form.
- Fish powder or emulsion (for N). This works especially well for lettuce.
I have personal experience with the following products from Amazon:
John from http://www.growingyourgreens.com shares his ideas about organic fertilizers and other soil ammendments to build up your humus and soil so it will provide what your plants need:
Here are some of the products mentioned in the video:
- Azomite rock dust, micronized, 45 lbs for $35, 10 lbs for $17 (microelements)
- Earth worm casting (organic fertilizer)
- Dried Kelp
Some of the products are available from Amazon. I also selected one of the organic fertilizers: Jobe's 09026 Organic Vegetable & Tomato Granular Fertilizer 4-Pound Bag:
How to Grow Larger Vegetables with Rock Dust - Benefits and How to Apply:
Organic Fertilizers - Gardening Articles :: Edibles :: Vegetables :: National Gardening Association - http://goo.gl/v4Blf
Organic Gardening 101 - Gardening Articles :: Edibles :: Vegetables :: National Gardening Association - http://goo.gl/U0CJj