We are know discovering that chemical fertilizers kill millions of beneficial organisms in your garden soil.  Stop killing your garden!  Learn to grow green crops that enrich the soil, fix nitrogen and even kill harmful bacteria.  This is not just for the farmer, but the back gardener as well.  If you are serious about eating organic then this is for you.  

Get started!  Below are a few excellent sources of information to better, healthier, soil nourishing techniques! 

• Fundamentals of Sustainable Agriculture, Overview of Cover Crops and Green Manures.   "Cover crops could be considered the backbone of any annual cropping system that seeks to be sustainable. In this publication we summarize the principal uses and benefits of cover crops and green manures. Brief descriptions and examples are provided for winter cover crops, summer green manures, living mulches, catch crops, and some forage crops. To impart a sense of the importance of these practices in sustainable farming, we summarize the effect of cover crops and green manures on: organic matter and soil structure, nitrogen production, soil microbial activity, nutrient enhancement, rooting action, weed suppression, and soil and water conservation."
• The Organic Way - Selecting Green Manure Crops for Soil Fertility    "In organic growing the philosophy behind soil fertility is to feed the soil and the soil in turn will feed the cash crop. Cover crops, green manures, animal manures and sound crop rotations are used to improve and/or maintain soil fertility. This article focuses on the use of green manures."
• Buckwheat  "It is one of the quickest growing green manure crops, taking only 4–5 weeks from seeding to flowering. It is used to suppress weeds, protect the soil from erosion, attract beneficial insects, and build soil organic matter. Buckwheat can also increase phosphorus and micronutrient availability in the root zone for the following cash crop in a rotation."

• Planting and Growing Green Manures  "Choose the best plants for the time of year and the situation. Growing a mixture of green manures, for example a grass and a legume, is a good idea..."