Organic farming may produce lower yields, but in the long run it is more efficient and is much easier on the environment, Swiss researchers have reported.
Organic farms have more fertile soil and a higher biodiversity, both of which have been shown to increase efficiency, the researchers report in Friday's issue of the journal Science.
Paul Mader of the Research Institute of Organic Agriculture in Frick, Switzerland, and colleagues at the Swiss Federal Research Station for Agroecology and Agriculture in Zurich spent 21 years comparing conventional farming to organic farming, which uses no synthetic pesticides or fertilisers.
"Mean yields are 20 per cent lower, that's true, depending on the crop," Mader said in a telephone interview. For instance, organic wheat yields are 10 per cent lower, while there is a 40 per cent reduction for potatoes.
"But mean energy input per hectare (2.4 acres) was about 50 per cent higher (in conventional plots). As a consequence, energy input per crop unit is lower in organic."
Energy input includes fuel used to produce fertiliser and pesticides, and the actual ingredients of such chemicals. Mader's team found 34 to 51 per cent less nitrogen, phosphorus and other nutrients were added to the soil in the organic systems than in the conventional ones.
But, because the crop yields from the organic systems were 80 per cent as large conventional yields, the organic systems use resources more efficiently, they concluded.
In Europe, Mader said, consumers are willing to pay 10 per cent to 30 per cent more for organic produce. They also often get government support.
At the start of the study, only 1 per cent of Switzerland's farms were organic, but that has grown to 9 percent, Mader said. "There are farmers converting to organic."
Overall, he said, 3 per cent of all farms in the European Union are organic, and the numbers are increasing by about 25 per cent each year. In Italy, 10 per cent of farms are organic.
Mader said he believed the study to be free of bias, although he works for an organic institute. Government scientists also worked on the project, he said."Of course, I try to have an objective view," Mader said. "But I have become a big fan of organic because I have seen the positive effects of organic."
Some of the processes that make organic more efficient are going on at the microbe level, he said. "The micro-organisms in organic plots work more efficiently than in conventional plots," he said. These tiny organisms make carbon into a form that can be used by plants, for instance.
"If there is less stress caused by fertilisers, caused by pesticides, the microbe community works more efficiently," he said.
Mycorrhizae, root-colonising fungi that help plants absorb nutrients, fared better in organic systems as well. Such fungi were also at least partly responsible for the more stable physical structure of the organic soils, the researchers said.
Insects such as pest-eating spiders and beetles flourished in the organic systems. Earthworms and weeds, which can often be beneficial, also were more common in organic farms.
Organic soils also decomposed more efficiently, which makes the soil more nutritious for plants.