ORGANIC FARMING has a key role to play in restoring biodiversity to agricultural landscapes, according to a new report from the British Trust for Ornithology (BTO).

The survey of 89 pairs of organic and non-organic farms over a four-year period found particular differences in the variety of plants.

“Organic fields were estimated to hold 68-105% more plant species and a 74-153% greater abundance of weeds than non-organic fields,” says the report.

There were also significant differences in the number of birds (+32%) spiders (+17%) and bats (+33%). Bird species were 5% more prolific on organic farms than non-organic.

“Organic farms clearly have positive effects for wild flowers,” said report author Rob Fuller, director of habitat research at the BTO.

“If they are to provide similar benefits for species that need more space, like birds, we need them to be larger or for neighbouring farms to be organic too.”

With less than 3% of English farmland being organic, there is plenty of scope for expansion.

The report lists many reasons why organic farmers create more biodiversity, including the fact that they tend to sow crops later and always include a ley as part of the arable rotation.

They were also more likely to include livestock and cut their hedges less often.

Soil Association policy director Peter Melchett described the increase in wildlife numbers and species as “hugely significant” and urged more farmers to convert, to increase the organic area and meet rising consumer demand.

But the NFU has questioned whether the survey was comparing like with like. “We’re not against organic farming at all, but we are concerned at the methodology used,” said Andrew Clark, head of policy services.

The fact that the organic farms included livestock and grass leys meant they were not strictly comparable with conventional cereal farms. “It would be better to compare a mixed conventional farm with an organic cereal farm.”