Subject: [Homestead] Organic farming and biodiversity
Date: Mon, 11 Oct 2004 15:44:27 -0700
*Organic farming boosts biodiversity *
09:45 11 October 04
Organic farming increases biodiversity at every level of the food chain
– all the way from lowly bacteria to mammals. This is the conclusion of
the largest review ever done of studies from around the world comparing
organic and conventional agriculture.
Previous studies have shown that organic farming methods can benefit the
wildlife around farms. But “the fact that the message is similar all the
way up the food chain is new information”, says agricultural scientist
Martin Entz of the University of Manitoba in Winnipeg, Canada.
The study reviewed data from Europe, Canada, New Zealand and the US.
Neither of the two groups of researchers who did the study – one from
English Nature, a government agency which champions wildlife
conservation, and one from the Royal Society for the Protection of Birds
– has a vested interest in organic farming.
“It’s good to have independent people add their voice to the debate,”
says Nic Lampkin, director of the Organic Centre Wales, part of the
University of Wales Aberystwyth.
Typically, each of the 76 studies reviewed measured biodiversity in
groups of organisms ranging from bacteria and plants to earthworms,
beetles, mammals and birds. Of 99 separate comparisons of groups of
organisms, 66 found that organic farming benefited wildlife, eight
concluded it was detrimental and 25 produced mixed results or suggested
no difference between the farming methods.
*Mixed farming*
According to the researchers, organic farming aids biodiversity by using
fewer pesticides and inorganic fertilisers, and by adopting
wildlife-friendly management of habitats where there are no crops,
including strategies such as not weeding close to hedges, and by mixing
arable and livestock farming.
Mixed farming particularly benefits some bird species. Lapwings, for
example, nest on spring-sown crops, but raise their chicks on pasture.
Intensive agriculture has been blamed for the 80% decline in lapwing
numbers in England and Wales since the 1960s. One of the reviewed
studies from the UK also points to benefits for bats. Foraging activity
was up 84% on organic farms and two species, the greater and lesser
horseshoe bats, were found only on organic farms.
The studies might even have underestimated the benefits to wildlife,
says Phillip Grice of English Nature. Some looked at farms shortly after
they turned organic, so wildlife numbers may just have started increasing.
Some argue that farms that adopt a few organic practices, swapping
chemical weeding for mechanical, for example, may help wildlife flourish
just as much as completely organic farms. And it is possible that
farmers who switched to organic farming may have been predisposed
towards environmentally friendly methods. So the biodiversity on their
farms may have been higher than average before conversion. The current
studies are not detailed enough to answer these questions.
Journal reference: /Biological Conservation/ (vol 122, p 113)
James Randerson
[Homestead] Organic farming and biodiversity,
Tvoivozhd, 10/11/2004