Organic food’s green credentials aren’t watertight (Image: Design Pics Inc/Rex Features)

For organic farmers, bad news comes in twos this week. Organic crops seem to be no more nutritious than conventional ones, and are not necessarily great for the planet either.

Organic farming eschews synthetic pesticides and fertilisers, and supposedly produces more nutritious food containing fewer harmful contaminants. Crystal Smith-Spangler of Stanford University in California and colleagues put together 237 studies comparing organic and non-organic food. They found little evidence that organic food was more nutritious. Conventional foods contained more pesticides but were within permitted limits (Annals of Internal Medicine, vol 157, p 348).

Meanwhile, organic farming’s green credentials have been questioned by Hanna Tuomisto of the University of Oxford and colleagues, who reviewed 109 papers. Organic farms were less polluting for a given area of land, but were often more polluting per unit of food produced. They did have better soil, though, and housed more species (Journal of Environmental Management, doi.org/h8v).

“An ‘organic’ label is not a straightforward guarantee of the most environmentally friendly product,” says Tuomisto. She advocates integrated farming, combining a range of existing systems.

“Advanced breeding technologies, combined with the best farming practices from organic and conventional systems, could have the best overall impact in terms of improving crop yield and sustainability,” says Dale Sanders, director of the John Innes Centre in Norwich, UK.