Is organic farming better for the environment than conventional farming? Despite a decade of study a clear picture is still lacking, because most organic farming goes on where scientific studies have yet to reach.

 

In 2004 – and again in 2005, several literature surveys concluded that organic farms did indeed host more wild species than conventional farms.

 

Since then, however, many more studies have been published, so plant ecologist Lindsay Turnbull at the University of Oxford and her colleagues felt it was time for an updated survey. The researchers dug up a total of 95 studies with good data on species richness – more than three times the previous number.

 

Sure enough, organic farms contained an average of 30 per cent more species of birds, insects, and plants than conventional ones, confirming the results of earlier surveys, than in areas with more woodlots and other wild places.

 

When Turnbull's team looked at where the 95 studies were located, though, they found a huge bias: three-quarters were in Europe, even though most organic production takes place elsewhere. Tropical areas, in particular, have received almost no research attention – even though bananas and cacao are important organic crops.

 

Organic farming in the tropics may carry the same benefits as it does in Europe, Turnbull notes. But it might not. Many of the species that benefit from organic farming in Europe have evolved for many centuries alongside intensive farming – which was effectively organic until after the second world war. Tropical wildlife lacks this history with intensive farming, so it may benefit less.

 

In fact, organic farming may even be worse for wild species in the tropics. Organic farming yields are lower than they are for intensive farming, points out Turnbull. So to produce a given amount of produce organically, more natural habitat must be cleared and more wildlife disturbed.