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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Study Says Pesticides Block Crops' Natural Nitrogen Production
  • Date: Thu, 07 Jun 2007 08:55:32 -0600


Study Says Pesticides Block Crops' Natural Nitrogen Production
http://www.organicconsumers.org/articles/article_5513.cfm
* ENS - Environment News Service, June 6, 2007
Straight to the Source

EUGENE, Oregon, June 6, 2007 (ENS) - Farmers applying pesticides intended
to boost crop yields may instead be contributing to plant growth problems,
University of Oregon scientists report in a new study.

The research revealed that artificial chemicals in pesticides disrupt
natural nitrogen-fixing communications between crops and soil bacteria.

The disruption results in lower yields or in delayed growth whether the
pesticides are applied deliberately or reach the crops through runoff.

In a paper appearing online this week ahead of the regular publication by
the Proceedings of the National Academy of Sciences, the five-member team
reports that pesticides bind to and block connections to specific receptors
inside rhizobia bacteria living in root nodules in the soil.

Rotation legume crops such as alfalfa and soybeans require such interaction
to naturally replace nitrogen levels that, in turn, benefit primary market
crops like corn grown after legume rotations.

Alfalfa roots secrete chemical signals into soil to attract and recruit
bacteria. These bacteria live in a plant's roots and provide a natural
fertilizer source.

Legume plants secrete chemical signals that recruit the friendly bacteria,
which work with the plants to convert atmospheric nitrogen into ammonia
that, then, is used as fertilizer by the plants.

"Agrichemicals are blocking the host plant's phytochemical recruitment
signal," said the study's lead author, Jennifer Fox, a postdoctoral
researcher in the Center for Ecology and Evolutionary Biology at the
University of Oregon.

"In essence, the agrichemicals are cutting the lines of communication
between the host plant and symbiotic bacteria," she said.

"Our research provides another explanation for declining crop yields," Fox
said. "We showed that by applying pesticides that interfere with symbiotic
signaling, the overall amount of symbiotic nitrogen fixation is reduced."

"We feel that this is a previously unforeseen factor contributing to
declining crop yields," she said. The researchers say that field-wide
experiments now are needed, in addition to tests to determine the exact
elements of pesticides that inhibit natural plant-bacteria interaction.






  • [Livingontheland] Study Says Pesticides Block Crops' Natural Nitrogen Production, TradingPostPaul, 06/07/2007

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