If you've got any doubts that organic agriculture can be just as productive as farming with synthetic chemicals, hopefully this will stop those doubts: Rodale Institute has been running side-by-side comparisons of conventional and organic farm plots growing corn and soybeans for nearly three decades and the latest data is in. The result is that the plots continue to have similar yields, with the organic plots performed much better in terms of building soil carbon and retaining nitrogen in the soil.

Over at Grist, Tom Philpott has an excellent analysis of the newest data--including this choice bit about how the organic plots performed in drought conditions, which are predicted to increase in many places due to climate change and for which its often claimed genetically modified crops are needed to combat:
So the old canard about how organic ag produces dramatically less food than chemical ag has been debunked, yet again. But it gets more interesting. As the globe warms up, increased droughts are likely to reduce global crop yields. The ag-biotech industry is scrambling to come out with "drought-resistant" GMO crops. But organic ag might already have that covered: "In 4 out of 5 years of moderate drought, the organic systems had significantly higher corn yields (31 percent higher) than the conventional system."
Source http://www.treehugger.com/files/2011...paign=daily_nl