Welasco, Texas
May 19, 2003
From
Texas A&M Agriculture News
For years, Lower Rio Grande
Valley farmers have been laying row after row of plastic sheets
in their vegetable fields. Plastic mulch atop planting beds
helps grow healthier, more abundant crops in a shorter period of
time. Plants grow right through holes punched in the plastic and
drip lines under the plastic use much less water than flood
irrigation.
Plastic mulch has been used
successfully in South Texas for years on a variety of high-value
vegetable crops. But new studies are showing that colors other
than the standard black used here almost exclusively may perform
better.
Dr. Bob Wiedenfeld, a soils
scientist at the Texas A&M System Agricultural Research and
Extension Center at Weslaco, has been working this year with
Ampacet Corp., a company that produces many types of plastic
mulch that differ in color, composition, texture, finish and
transparency.
"The goal of plastic mulch," said
Wiedenfeld, "is to raise the soil temperature, and we'd like the
plastic to be durable, to stand up to our high winds. So we're
comparing Amapcet's different plastic films to see which ones
perform best here."
In January, Wiedenfeld installed
a rainbow of different plastic mulches on a research field plot
at the center. Drip lines down the middle of beds are currently
providing water and fertilizer to a watermelon crop, while drip
lines on either side of the bed will tend to fall peppers when
they are planted. Each plastic mulch is evaluated by measuring
vine lengths of the watermelon plants and soil temperature.
The colors include red, blue, clear, silver, black, white and
olive. Some films are shiny, others matte, some opaque, some
translucent and one clear.
"The clear mulch has done the
best job of warming up the soil and it appears to be the most
durable. Unfortunately, clear plastic provides little or no weed
control. The clear plastic serves as sort of a
mini-greenhouse for weeds that push up the mulch," Wiedenfeld
said. Among the better performers so far for Wiedenfeld is a
silver colored plastic that he said has produced extraordinary
results in vine lengths of watermelon, as well as higher soil
temperatures. Weed control also was good. Another film with a
white surface and black undersurface is also performing well.
"The white on black film would do
well for those fall crops that are planted in the heat of
summer. The white on the surface reflects heat and cools the
soil to protect the young plants, while the black underside
keeps weeds from growing," said Wiedenfeld.
Mark Jordan, manager of Pliant
Corporation, which actually manufactures the film using Ampacet
additives, said plants react differently to different colors.
"Phytochromes (plant pigmentation
that absorbs light waves) make the difference," he said. "The
silver, for example, is used extensively in California and
Mexico. It also showed great results in squash, tomatoes and
peppers in studies at Penn State. The best film to use will
probably depend on when and where you are going to use it and
what results you want it to achieve."
Braionna Barber, an Ampacet
development engineer, said her company is currently testing
colored mulches in Mexico, Michigan, California, Indiana,
Florida, Georgia and now Texas. "We're testing in different
regions to see what effects the different films have in each
growing condition," she said. "In Michigan, where it's cooler,
for example, the object is to trap heat and extend the growing
season. Here, where it's much hotter, you want to reflect the
heat onto the plant."
She said her company was also
working on a photo-degradable film that is tilled into the soil
after harvest, since removing the plastic at season's end is one
of the biggest expenses of using plastic mulch. Wiedenfeld said
once the summer watermelons are harvested, a crop of fall
peppers will be planted on the same mulches to determine
durability of the films. Results, he said, should be available
by year's end.
For more information, or to visit
the colored mulch research field plot, contact
Dr. Bob Wiedendfeld
at (956) 968-5585.
Writer: Rod Santa Ana III,
(956) 968-5581,
r-santaana@tamu.edu
Contacts: Dr. Bob Wiedenfeld, (956) 968-5585,
r-wiedenfeld@tamu.edu
Mark Jordan, (267) 879-1544,
mark.jordan@pliantcorp.com
Braionna M. Barber, (812) 466-9828,
bbarber@ampacet.com
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