permaculture

["Lawrence F. London, Jr." <lflj@bellsouth.net>]

-------- Original Message --------
Subject:        New Tool for Cleaning Up Soils and Waterways: Prickly Pear
Date:   Wed, 18 Jan 2012 06:59:17 -0500
From:   ARS News Service <NewsService@ars.usda.gov>
Reply-To:       ARS News Service <NewsService@ars.usda.gov>
To:     ARS News subscriber <lflj@bellsouth.net>

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ARS News Service
Agricultural Research Service, USDA
--View this report online, plus photos and related stories, at
www.ars.usda.gov/is/pr
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*Read the magazine story
<http://www.ars.usda.gov/is/AR/archive/jan12/cactus0112.htm> to find out
more.*

Photo: Prickly pear cactus (Opuntia ficus-indica) being grown a field.
Link to photo information
<http://www.ars.usda.gov/is/graphics/photos/jan12/d2407-1.htm>
Some prickly pear cactus varieties can be grown as a gentle
bioremediation tool for high levels of salinity and selenium in arid
soils./Click the image for more information about it./


For further reading

  * Using plants to clean up soil
    <http://www.ars.usda.gov/is/pr/2007/070123.htm>


    New Tool for Cleaning Up Soils and Waterways: Prickly Pear

By Dennis O'Brien </is/contacts.htm#Dennis>
January 18, 2012

A U.S. Department of Agriculture
<http://www.usda.gov/wps/portal/usda/usdahome> (USDA) scientist has
discovered what may be an effective tool for cleaning up soils and
waterways in parts of California's San Joaquin Valley: a
drought-tolerant cactus.

Ancient seas once covered the west side of the valley, and those seas
left behind marine sediments, shale formations and deposits of selenium
and other minerals in the soil. Crops grown there need to be irrigated,
but the resulting runoff, when it contains high levels of selenium, can
be toxic to fish, migratory birds, and other wildlife that drink from
waterways and drainage ditches. Selenium runoff is subject to monitoring
by regional water quality officials.

Soil scientist Gary Bañuelos
<http://www.ars.usda.gov/PandP/docs.htm?docid=15512> with USDA's
Agricultural Research Service <http://www.ars.usda.gov/main/main.htm>
(ARS) thinks he has found a promising way to rid the soil of selenium:
planting prickly pear cactus (/Opuntia ficus-indica/). The plant takes
up selenium from the soil and volatilizes it, reducing deposits that
would otherwise enter drainage ditches and waterways.

ARS is USDA's principal intramural scientific research agency, and this
research supports the USDA commitment to agricultural sustainability.

Bañuelos, who works at the San Joaquin Valley Agricultural Sciences
Center <http://www.ars.usda.gov/main/site_main.htm?modecode=53-02-00-00>
in Parlier, Calif., initially conducted greenhouse studies to evaluate
the ability of different varieties of /O. ficus-indica/ to tolerate poor
quality soils. Based on those observations, he then spent three years
evaluating five prickly pear varieties from Mexico, Brazil, and Chile
for salt and boron tolerance in selenium-laden soils by collecting soils
and sediments from the area and growing the varieties in field test
plots. He followed normal agronomic practices and used a drip irrigation
system that produced very little run off.

Prickly pear was thought to be sensitive to high salinity, and many of
the plants grown in test plots were smaller and produced less fruit than
those in control soil plots. But the results, published in /Soil Use and
Management
<http://onlinelibrary.wiley.com/doi/10.1111/j.1475-2743.2010.00258.x/abstract>/, 

showed that prickly pear grew reasonably well in the poor quality soils
with very little water.

The studies also showed that the plants took up selenium, volatizing
some of it and keeping some in their fruit and leaf-like stems
(cladodes), and that tolerance to salinity and boron depends on the
genotype. The cactus variety from Chile showed the highest tolerance, as
well as being the best at producing fruit and accumulating and
volatizing selenium. The work is continuing with a focus on selecting
specific varieties that can be used as bioremediation tools.

Read more <http://www.ars.usda.gov/is/AR/archive/jan12/cactus0112.htm>
about this research in the January 2012 issue of /Agricultural Research/
magazine.

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