Organic farms are more efficient than their conventional cousins and leave soils far healthier, researchers report today in the journal Science. In a long-term study comparing productivity, environmental health, biodiversity and energy consumption of organic cultivation to conventional methods, Paul Mder of the Research Institute of Organic Agriculture in Switzerland and his colleagues discovered that the organic approach used significantly less energy to produce the same quantity of crop. Although organic farms typically produce lower overall yields than common plots do, their ecological benefits are greater—a larger number of pest-eating creatures and other advantageous organisms live in soil farmed organically, and decomposition occurs more efficiently on these lands, releasing much needed nutrients into the soil.

In 1978 the researchers began studying four plots of land planted with winter wheat, potatoes, beets, grass clover and barley (see image). Farmers cultivated two of these fields conventionally. For the remainder, they utilized organic methods, substituting compost and manure for synthetic fertilizers and using mechanical weeding and plant extracts instead of chemical pesticides. The scientists found that organic soils harbored about 50 percent fewer nutrients (because plants received no artificial fertilizer) but yielded on average only 20 percent less crop. Thus, plants farmed organically used available nutrients more efficiently. How does this happen? It seems that biodiversity on organic land is far higher than in traditionally cultivated soils. Moreover, root-colonizing fungi that help plants absorb nutrients, as well as pest-eating spiders and nutrient-cycling soil microbes, exist in significantly greater numbers on organically tilled plots.

Detractors of organic farming point out that even though such methods may work well in Switzerland, they might not be profitable in countries where the government does not subsidize farmers. In addition, such so-called natural methods may be difficult to apply on a larger scale, as in commercial farms in the U.S. But this 21-year study suggests that organic cultivation may be both more sustainable than traditional pesticide and fertilizer-driven practices and as prosperous. "I think our research could stimulate governments to encourage [organic methods] by showing long-term benefits," Mder remarks. "These results are encouraging for farmers, because they can see that yields are stable over time and that soil fertility has increased."