Many proponents of organic gardening have long maintained that not only are organic methods better for the soil, the environment and the safety of gardeners, but they produce nutritionally superior crops as well. But there hasn't been a lot of hard evidence to back up their claims.
Now research done in Spain suggests that, at least in the case of eggplants, organic methods may result in a crop with higher nutritional value. In a study published in the Journal of Agricultural and Food Chemistry (58(11), June 9, 2010, 6833-6840), there were significant differences in the concentrations of certain nutrients in eggplants that were grown using organic methods as opposed to conventional ones. For example, levels of potassium, calcium and magnesium were higher in the organically produced eggplants. According to the researchers, there was an increased benefit when plants were grown in soil that had been managed organically long term and that simply adding more fertilizer to conventionally grown eggplants did not increase their nutrient value relative to organic produce.
While this is only one trial with one crop, it reinforces the importance to all gardeners of building up the soil to produce healthy and nutritious crops.
For an abstract of this research, go to: Effects of Organic and Conventional Cultivation Methods on Composition of Eggplant Fruits .