Perspectives Online

Narrowing the Field. New cotton harvester shows potential for higher yields, environmental benefits and cost savings. By Suzanne Stanard.


Photo by Daniel Kim

A new cotton harvester being tested by researchers in the Department of Crop Science may help North Carolina cotton farmers produce high quality, higher yielding cotton - and save money. Dr. Keith Edmisten, professor of crop science and Extension cotton specialist, along with Dr. Alan York, William Neal Reynolds Professor of crop science and Extension weed specialist, are leading a team of graduate students on a three-year project to examine the advantages and disadvantages of using a 15-inch-row cotton picker. So far, the results are promising.

Cotton has traditionally been grown on wide rows, typically 36 to 40 inches, Edmisten said, originally to allow the passage of mules for tillage. Wide-row planting stuck around long after tractors replaced mules, because tillage was still required for adequate weed control in cotton, he said. In the mid-1990s, advances in herbicide technology enabled broadcast over-the-top spraying that eliminated the need for wide rows. Edmisten recognized the potential of narrow-row planting and started to experiment.

He began by using a finger stripper, a type of harvester that literally strips every bit of the plant, except for the stem and fruiting branches. Yields increased, but the quality of the cotton was low because the stripper picked up all sorts of "trash," like bark and leaves, which were difficult for the cotton ginners to separate from the fiber. Edmisten knew he was on to something good, so he approached the John Deere Co. and showed them his yield data. The company's engineers had been developing a picking unit that was able to spindle-pick cotton on 15-inch rows and eliminate the trash that was associated with "stripping" it. They sent Edmisten the equipment for research.

"Agronomically, going to narrow-row spacing makes a lot of sense," said crop science doctoral student Davie Wilson, one of the project's lead researchers. "Narrow-row spaces allow the capture of more sunlight by the plant canopy on a per-acre basis, which is very beneficial for maximizing the yield potential of cotton."

Edmisten added, "The new equipment that John Deere introduced last year offered us a practical way to produce high-quality cotton and maximize light interception by the canopy."


The new harvester can spindle-pick cotton on 15-inch rows and deliver an increased, high-quality yield.
Photo by Daniel Kim
Assembling the equipment was no easy task. The commercial picker produced by John Deere is a huge machine, far too large and bulky for operation in small plot research. So the company sent a scaled-down version of the harvester's heads, requiring that Edmisten's team find a way to put them to use. The group, which includes crop science technician James Lanier, as well as Wilson and fellow graduate students Guy Collins and Gary Hamm, obtained an old two-row cotton picker and worked steadily for about six weeks to mount the new heads.

"Basically, we hand-built everything," Lanier said. "John Deere thought we were crazy [to mount the new heads on the old-model picker], . said it was impossible and couldn't be done. Now, they're calling us with questions. It's a great back-and-forth partnership."

The new picking unit employs the same technology used in a wide-row system but enables harvesting on a narrower row. Like the comb on barbers' shears, the harvester slices through several rows at a time, lopping off every other row and pressing each cut row against its neighboring row of still-standing cotton plants. Small rotating spindles with tiny barbs grab the lint from the stalks, a much more precise technology than the stripper.

The advantages of narrow-row cotton are becoming apparent after the first two years of trials, which showed an average 9.1 percent yield increase, or a difference of 127 pounds of lint per acre, in favor of the narrow-row system. Edmisten, York and their team are exploring a number of factors that will be important to farmers, including weed control tactics, nitrogen fertilization, planting dates and variety selection - and they're building a solid case for the benefits of switching to narrow-row cotton production.

"We found that we can plant later in the growing season and still get just as good a yield," Wilson said. Cotton is typically grown from early May to early November, Edmisten said, and his team's research is showing that it may be possible to shave a few weeks off the growth period and double-crop cotton with small grains like wheat or barley, providing growers a net income from two crops in a growing season instead of one. Their findings also show that narrow rows extend the window for planting cotton, so that farmers who experience bad weather during the typical planting season could wait a few weeks to plant without suffering a blow.

The team's weed management research shows that 15-inch row cotton may require one less herbicide application, resulting in time and fuel savings. And, because the narrow rows produce thick canopies, weeds aren't able to grow as well, which also represents cost savings - and environmental benefits - for farmers.

"The savings on herbicides and fuel are the biggest attractions of narrow-row cotton," Edmisten said. "There is less pesticide load going into the environment, and farmers generally will spend less money on a per-acre basis."

While these benefits are significant, York said, the study's yield data will be the real "clincher" for farmers who are considering investing in narrow-row equipment. A brand new 15-inch picker runs in the neighborhood of $400,000, he says, and increased yields offer the greatest potential to offset the cost of switching equipment.

"A spindle picker that handles 15-inch rows costs about $36,000 more than a picker that handles 30- to 36-inch rows. A 10 percent yield increase will pay for that in a year," York said. "If a grower needed to replace a picker anyway, then going to a 15-inch row system is feasible." But, he added, for farmers who have regular pickers in good mechanical condition, investing in a new 15-inch picker would require proof of substantial benefits.

Encouraged by data from their first two years of trials that show significant increases in yield, as well as myriad other benefits of narrow-row cotton, the research team is forging ahead.

"We still have a lot of questions left to consider," Edmisten said. "Fuel cost is an especially big concern for farmers right now."

"With shrinking profit margins in the cotton business, growers really have to streamline what they're doing just to keep their heads above water," Wilson added.

"This [technology] has opened up a whole new world."