Thinking Outside the Traditional Row
February 28, 2022 
Photo: Dennis Burns/LSU AgCenter
Researchers across the Southeastern Cotton Belt are intrigued with the possibilities of using wider, non-traditional row spacing for cotton. It’s been the topic of recent studies conducted by several Southern universities. And while there are potential benefits to be gained, it’s not going to be for everybody.
Dr. Steve Brown, Alabama Extension Cotton Specialist, shared some of the logic behind his studies during the 2022 Beltwide Cotton Conferences.
“Cotton row patterns in Alabama are probably not different from elsewhere across the Belt,” he says. “In south and central Alabama, it’s mostly 36- and 38-inch row spacings. We may have some 40-inch row spacings in north Alabama. We also have some commitment to skip-row cotton in north Alabama.
“My logic in approaching this is we have to make the same amount of money or better, or at least our net returns have to be just as good,” he continues. “Possibly, we can reduce seeding rates. It may also provide some endurance to allow growers to handle a mid-season drought period a little better. But a big part of this study is to see if we can better manage some of the problems with late season moisture, humidity, and rainfall to help reduce or minimize hard lock and boll rot.”
Some potential harvest savings may also be possible by picking with only four or five heads rather than the standard six heads, notes Brown.
In wide row cotton research, it’s convenient to work in row increments based on the current spacing used. In 36-inch rows, it’s simple to extrapolate to 72-inch rows. Likewise, 30-inch rows can easily translate to 60-inch rows.
“If you draw it out, 60-inch spacings make great sense because you can use four heads of a standard six-row picker and cover the exact same area,” says Brown.
But convenience doesn’t always translate to positive results. Studies looking at a standard 36-inch row compared to 60- and 72-inch spacings led Brown to conclude that 60 and 72 were too wide, especially on Coastal Plains soils. There just wasn’t enough growth.
Additional studies compared 36-inch to 48-inch spacing in locations in southwest and southeast Alabama. All plots were subsoiled under the rows to minimize surface compaction that could restrict root growth, and three PGR rates were evaluated.
“We got a lot of information but not a whole lot of difference,” says Brown. “We did have greater plant height on the 48-inch spacing, but there weren’t a lot of differences in overall plant growth or yield between the patterns.”
Brown remains optimistic about the potential benefits of wider rows.
“We think we can make comparable yields on 48-inch row patterns,” he states. “I do think we can reduce seeding rates and save some costs there. We haven’t really tested our system in a true high-yielding environment, and we need more information in terms of measuring the system during a summer drought.
“I like 48-inch spacing,” says Brown. “It’s going to vary by growing environment. In the lower Coastal Plains under drought stress, I don’t think we get the canopy coverage we need in 60-inch rows. Plus, you have to think about the entire farm and the adjustments needed to tractors, sprayers, planters, and other equipment.
“But, if my seeding rate calculations are right, we should be able to see an immediate savings of at least 25% in seed costs, he adds. “In the lower Southeast, our cost for seed with all the bells and whistles on a per bag basis can exceed $750 per bag. If we can knock that down, that’s a very positive part of this.”
Other Options
Dennis Burns, LSU AgCenter Agent and Research Coordinator at the Northeast Research Station near St. Joseph, LA, has been conducting trials with cotton planted on 40- and 60-inch rows, both with and without cover crops.
“The reason for the cover crop was we were concerned somewhat about weed control with those wide middles,” he says. “Turned out, weed control was not as big of an issue as we thought. The residual herbicides helped us with that.”
All of the cotton received the same nitrogen fertilizer and PGR treatments.
The cotton grown on 40-inch rows was a few inches taller than the 60-inch-row cotton, which expanded outward and lapped into the middles, reports Burns. These differences in height and growth habit can affect yields.
Burns sees two key results from this initial study, which is ongoing – be sure to pick the right variety, and wider rows may need higher nitrogen rates and multiple, smaller PGR applications.
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