Beetles prefer non-organic

One would imagine that organic farmland-which shuns pesticides and synthetic fertiliser-must be richer in wildlife. However, a review soon to be published in Biological Conservation by Sweden’s Lund University concludes that organic farming is not necessarily advantageous for all creatures-news that will please the NFU, which disagrees with the EU ban on some pesticides. The report analyses 28 studies-four from the UK-comparing conventional and organic cereal growing in northern and central Europe.

It found that ground beetles and many butterflies and moths do better on organic cereal crops largely thanks to the nectar from the arable weeds that result from organically managed crops and that more bird species were associated with organic cereal growing. However, because they prey on other invertebrates, most beetles and spiders are more abundant on conventional cereal crops, partly because high-nitrogen-content fertilisers boost prey such as aphids.

The Soil Association queries the results. ‘The recent large-scale analysis by Oxford [University] looked at nearly 100 studies and found that organic farms have, on average, 34% more species than non-organic farms,’ says Emma Hockridge.

‘The difference was greatest for pollinators, with 50% more species on organic farms.’ Klaus Birkhofer of Lund counters: ‘Our findings don’t diminish the value of organic farming for wildlife, but they do suggest that a mix of conventional and organic cereal-growing might provide the highest diversity.’

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