|MadSci Network: Agricultural Sciences|
The nutritional value of non-organic and organically grown produce is the same, the reason people support the organic movement is a concern for the environment, not for nutritional value of the food. Scientific agriculture is carefully researched to provide the best food supply with the least damage to the environment. The FDA does not label foods as organically grown since there is no chemical test which allows them to distinguish between "organically" and non-organically grown vegetables.
The U.S. Department of Agriculture has proposed national guidelines for what a grower should do to call a product "organically grown". You can read more about this rule on the WWW at http://www.ams.usda.gov/NOP/.
Try the links in the MadSci Library for more information on Agricultural Sciences.