The study compared a conventional farm that used recommended fertilizer and pesticide applications with an organic animal-based farm (where manure was applied) and an organic legume-based farm (that used a three-year rotation of hairy vetch/corn and rye/soybeans and wheat). The two organic systems received no chemical fertilizers or pesticides. [...]
The research compared soil fungi activity, crop yields, energy efficiency, costs, organic matter changes over time, nitrogen accumulation and nitrate leaching across organic and conventional agricultural systems.
"First and foremost, we found that corn and soybean yields were the same across the three systems," said Pimentel, who noted that although organic corn yields were about one-third lower during the first four years of the study, over time the organic systems produced higher yields, especially under drought conditions. The reason was that wind and water erosion degraded the soil on the conventional farm while the soil on the organic farms steadily improved in organic matter, moisture, microbial activity and other soil quality indicators.
[We can only assume that the organic fields they monitored were not organic before the experiment. If they had been, the higher yields would probably have been there from the start. -MGR]
The fact that organic agriculture systems also absorb and retain significant amounts of carbon in the soil has implications for global warming, Pimentel said, pointing out that soil carbon in the organic systems increased by 15 to 28 percent, the equivalent of taking about 3,500 pounds of carbon dioxide per hectare out of the air.
This is helpful, but a footnote compared to the importance of stopping soil erosion. The "Green Revolution" way of doing things has been destroying most of our most fertile land for decades now.