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....I have no idea what this means for organic farming of other crops, but since corn and soybeans are among the farm products most in demand worldwide, this is encouraging news. I wonder if growing these crops organically in less monocultural environments would also have an impact...
"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.
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.
Among the study’s other findings:
* In the drought years, 1988 to 1998, corn yields in the legume-based system were 22 percent higher than yields in the conventional system.
* The soil nitrogen levels in the organic farming systems increased 8 to 15 percent. Nitrate leaching was about equivalent in the organic and conventional farming systems.
* Organic farming reduced local and regional groundwater pollution by not applying agricultural chemicals.
Pimentel noted that although cash crops cannot be grown as frequently over time on organic farms because of the dependence on cultural practices to supply nutrients and control pests and because labor costs average about 15 percent higher in organic farming systems, the higher prices that organic foods command in the marketplace still make the net economic return per acre either equal to or higher than that of conventionally produced crops.
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