Samples of spindle-harvested, conventionally grown cotton (left) and
UNR cotton. Cotton harvested with a stripper
harvester contains more stems and leaves.
For more than a century, farmers
planted cotton in wide rows about 30 to 40 inches apart. Their choices were
limited, as was their equipment, which was usually just a mule-driven plow.
Today, farmers are experimenting with planting cotton much closer together,
in rows ranging from about 7-1/2 to 10 inches wide. Research is under way at
ARS locations to make production of this
ultra-narrow-row (UNR) cotton more economical for farmers.
"With UNR cotton, a farmer can plant more rows and potentially harvest
more cotton per acre," says William T. Molin, a plant physiologist with
ARS' Southern Weed Science Research Unit in Stoneville, Mississippi.
"Also, since rows are planted closer together, cotton crowds the weeds
out, reducing the need for midseason herbicide applications."
Molin and other ARS researchers are participating in a 10-year project
looking at varying aspects of long-term UNR cotton productionfrom
managing weeds to processing.
UNR cotton planted into a cover crop of
black oats. Narrower rows promote canopy closure in just 33 days, helping to
erosion and control weeds.
Conservation practices are
important in growing cottona primary cash crop for early U.S. settlers.
As they scurried to plant more acres in the 1700s, excessive planting allowed
more soil erosion to occur. Now ARS scientists with the Soil Dynamics Research
Laboratory in Auburn, Alabama, and the Coastal Plains Soil, Water, and Plant
Research Center in Florence, South Carolina, are helping farmers put
conservation practices that help prevent soil erosion to work.
For two growing seasons, ARS agronomists D. Wayne Reeves and Philip J. Bauer
conducted a study to look at the effects of residue management and nitrogen
fertilization on UNR cotton in Auburn and Florence.
"We used conservation tillage practices in ultra-narrow-row
cotton," says Reeves, with the Auburn unit. "The cotton was grown on
Coastal Plains soils that are typically sandy, subject to soil compaction, and
unproductive for row crops like cotton."
Bauer adds, "We found the rate of nitrogen fertilizer for UNR cotton
should be between 60 and 80 pounds of nitrogen per acreabout the same as
for conventional-row-width cotton on these soils." He says that when
cotton is planted after a legume cover crop, less nitrogen fertilizer is
Standard wide-row cotton (40-inch rows)
growing among UNR cotton.
Another study using cover crops
revealed a 60 percent higher lint yield when UNR cotton followed a cover crop
of black oats or wheat, compared to conventionally planted cotton in 40-inch
rows. Merging the UNR system with modern conservation technologies and using
cover crops can reduce crop production inputs, conserve soil and moisture, and
improve yields, says Reeves.
Examining Fiber Quality
Many farmers are concerned about the possible lower quality of UNR cotton.
Researchers in the ARS Southern Regional Research Center's Cotton Fiber Quality
Research Unit, at New Orleans, Louisiana, are trying to ease their concerns.
Plant physiologist Judith M. Bradow's specialty is scrutinizing the
properties that make cotton fiber the prized commodity it is today. Bradow and
colleagues did side-by-side comparisons of UNR and conventional cotton fibers.
Though their work is still preliminary, the scientists are finding few if any
differences in lint fiber properties, unless it is harvested with a stripper
When a stripper is used, unwanted trash gets mixed into cotton. "Trash
is primarily sticksthe stems that help support the bollsand leaves
that don't fall off the plant," explains Bradow. "Fiber properties
start going downhill when you use the stripper harvester. Once trash gets stuck
to the fiber, it doesn't come off easily," he says.
Farmers use stripper harvesters primarily for UNR cotton. Fingers or brushes
strip plant parts and cotton bolls from the plant, thus picking up excess
trash. "This is a negative aspect of harvesting UNR cotton, particularly
for ginners," says W. Stanley Anthony, an agricultural engineer with ARS'
Cotton Ginning Research Laboratory in Stoneville, Mississippi.
Most conventionally grown cotton uses a spindle harvester that has many
rotating barbed spindles. The spindles grasp the fiber and selectively pull it
out of the boll, leaving unwanted plant parts or trash behind. Spindle
harvesting yields about 100 pounds of trash per bale compared with 400 pounds
of trash per bale from stripper harvesting. A bale is 500 pounds of fiber.
In a 1998 gin study, Anthony found that UNR cotton quality measured up to
that of conventionally grown cotton based on traditional grading. He evaluated
cotton grown at 10 locations in the South and Southeast.
Anthony says that when additional cleaning machinery was used for the UNR
cotton at the gin, the grades of UNR cotton were equivalent to those of
conventional cotton. But since more gin machines are used and more material
must be processed, it costs more to gin UNR cotton, and the fiber suffers more
damagemainly in the form of increased neps and shorter fibers.
Cleaning Is the Key
Once the UNR cotton was ginned at Stoneville, Anthony sent it to ARS' Cotton
Quality Research Unit at Clemson, South Carolina, where it was processed at the
pilot spinning plant. Initial evaluation by textile researcher David McAlister
showed minimal disadvantages during textile operations.
"Our 1998 study showed only minor differences in fiber properties
between UNR and conventionally grown cotton," says McAlister.
"However, the differences in fiber properties did not affect the quality
of the yarn." He's hoping their research will help cotton mills understand
how to process and handle UNR cotton.
Supporting this evidence, a previous study conducted at Clemson gave
now-retired ARS scientist Charles K. Bragg a clue as to how UNR cotton might
act in textile processing. He says that limited preliminary experiments suggest
UNR cotton does not act differently than standard conventional cotton.
UNR in Other Regions
V.T. Walhood, in Shafter, California, who has since retired, conducted
pioneering experiments in the 1960s through 1980s on the growth and yield of
ultra-narrow-row cotton. His experiments showed that planting three rows of
early-maturing cotton in the space normally allocated for one row of a mid- to
late-season cotton produced the same yield and gave a bonus: They harvested the
early cottons before populations of pink bollworms had a chance to build up to
Another Shafter scientist, Angus Hyer, included narrow-row cottons in his
research nursery of more than 150 experimental lines. When he offered his
experimental cottons, with features such as improved resistance to insects or
diseases, to commercial breeders in the late 1980s, most U.S. cotton seed
companies tried some.
Several years after Hyer's death, F. Douglas Wilson, a collaborator at ARS'
Western Cotton Research Laboratory, Phoenix, Arizona, scrutinized Hyer's
collection to make sure the best-performing lines made their way safely into
ARS genebanks as permanent resources for breeders worldwide.
At Lubbock, Texas, ARS scientists in the Cotton Production and Processing
Research Unit are also conducting experiments comparing yield and fiber quality
of UNR versus conventional cotton using two varieties. ARS agricultural
engineer Alan D. Brashears harvested 40-inch-row cotton and narrow-row cotton.
"Our preliminary results showed there wasn't much difference in quality or
yield between UNR and conventional cotton," he says.
Soil scientist R. Louis Baumhardt, at ARS' Conservation and Production
Research Laboratory in Bushland, Texas, is testing whether UNR cotton can be
grown in the northern Texas Panhandle. Farmers in this area usually don't grow
cotton because yields are low from cooler temperatures and a shorter growing
season. Instead, they grow grain sorghum and wheat with rest periods in
between. However, by using new early-season cotton varieties and by growing
more plants per acre, farmers could boost cotton yields enough to make the crop
more profitable than wheat.
The Bottom Line Is Profits
With low commodity prices and tough international competition, farmers are
looking hard at the economics of growing cotton. Current information about the
economics of UNR cotton production is lacking. Martin Locke, head of the
Southern Weed Science Research Unit, and Ray Williford, head of ARS'
Application and Production Technology Research Unit in Stoneville, began
cooperative studies this year to evaluate UNR cotton in various tillage and
Results from these and other studies could mean a promising future for UNR
Becker, Don Comis,
Jan Suszkiw, and
Marcia Wood, Agricultural
Research Service Information Staff.
This research is part of Soil Resource Management (#202), Integrated
Farming Systems (#207), Crop Protection and Quarantine (#304), Crop Production
(#305), and New Uses, Quality, and Marketability of Plant and Animal Products
(#306), ARS National Programs described on the World Wide Web at
Scientists mentioned in this story can be contacted through
Tara Weaver-Missick, USDA-ARS
Information Staff, 5601 Sunnyside
Ave., Beltsville, MD 20705-5129; phone (301) 504-1619, fax (301) 504-1641.