Twin-row planting versus single-row planting

Like most farmers, peanut growers look for ways to improve yield to earn more profit. After all, efficiency is the name of the game these days as overseas competition becomes stronger.

But how do you improve yield without damaging other aspects of your production? Well, one way some growers have found is to plant twin-row peanuts, and the advantages to twin-row planting can outweigh the disadvantages.


The experts say that twin-row planted peanuts yield and grade better than single-row planted peanuts. Yields can increase from 200 to 600 pounds per acre, and grade increases from 1 to 2 points.
PHOTOS COURTESY OF THE UNIVERSITY OF GEORGIA.

Advantages

Specific advantages exist with twin-row peanut planting, especially in yield and grade. “On sandier soils, twin-row peanuts shade the ground quicker,” says Paul Smith Jr., an extension agent in Gates County, N.C., “and it gives you more opportunities for taproot crops.”

Of course, yield improvement is easily recognized. From his experience, Smith says twin-row peanuts yield from 250 to 700 pounds higher because the vines shade the ground quicker to keep weeds from getting out of control. They also produce more taproot peanuts for healthier plants.

Smith says about one-third of the peanut growers in Gates County practice twin-row planting. “Those who don’t probably would if it weren’t for the investment in planters,” he says. “Also, you have to fill up twice as many planters.

“Handling twin, 12-row planters could create a problem,” he continues. “Most of the farmers use the same planter to plant cotton, creating a need for another set of planters if they used twin-row for peanuts.”

In Georgia, peanut growers utilize twin-row peanut planting a great deal, and for them twin-row planting still maintains a yield and grade advantage over single-row planting, “though not as much as in the 1990s and early 2000s when we had peanut varieties that were more susceptible to tomato spotted wilt virus (TSWV),” says Eddie McGriff, the Coffee County, Ga., extension coordinator. He says today’s newer varieties have more TSWV resistance than the popular Georgia Green variety, and one of twin row’s advantages was the reduced incidence of TSWV compared with single-row planting.

The comparison of TSWV in single versus twin rows was evident in a disease study conducted a few years ago by entomologist Steve Brown at the University of Georgia. In the study, TSWV occurred 18 percent in single-row planted peanuts compared with 8 percent in twin-row planted peanuts, both being the Georgia Green midseason variety. In the AP-3 midseason variety, Brown saw only 6 percent TSWV in single rows versus 1 percent in twin rows. Comparing seven varieties, Brown found that TSWV, on average, showed up 13 percent in single rows and 5 percent in twin rows.

To concur with McGriff’s comments and Brown’s findings, Jay Chapin, an extension specialist with Clemson University, says when growers close up rows using twin-row planting, it assists in suppressing TSWV and helps control weeds.

Scott Tubbs, an assistant professor and agronomist with the University of Georgia, says TSWV incidence is lower because “as thrips move across a field and when they are hitting a row, they are hitting half as many plants in any given twin ‘row’ that they hit compared to hitting any given single row.”

He says TSWV does not spread from plant to plant. It is vectored by thrips feeding. As the thrips hit a row, feeding occurs more often on the same plant. So, he says, any given plant may be fed on more heavily in a twin-row pattern versus a single-row pattern, but that results in fewer total plants being injected with TSWV.


Twin-row spacing at 7 inches on each side and 22 inches in between works better than only 9 inches apart on each side and 18 inches in between, says Scott Tubbs with the University of Georgia, because growers can invert the rows at digging time more easily. The closer the rows, the more difficult the plants are to dig.

Tubbs says twin-row planting also helps reduce the incidence of white mold, “because the pathogen spreads rapidly from plant to plant down the row. In twin rows, the plants are spaced out so there is more room from crown to crown of each plant. No seed is closer than 4 inches apart in a twin-row pattern, whereas the seeds are placed 2 inches apart in a single-row pattern, so the disease wipes out more plants more quickly.”

Besides better disease control, Tubbs says growers benefit from a greater plant stand than when they plant single-row peanuts at an equivalent seeding rate. He estimates the advantages of twin-row planting results in a 200 to 600-pound per acre yield increase. “By spreading out the plants, there is less intra-row competition among peanut plants, so they do not compete with each other for space, water, nutrients, etc., as drastically as they do when in single rows,” Tubbs says.

Partly because of better TSWV control with twin-row planting, “we have gotten a yield, usually 200 to 300 pounds per acre, but a 300 to 500-pound per acre potential,” McGriff says, “and grade (1 to 2 points) response to twin over single row on all varieties. But there is limited data on our newer varieties, such as Florida-07, Georgia-07W, Tifguard, etc.”

As he mentioned, grades improved with twin-row, with an average of 71 compared with a 69 grade with single-row. McGriff says the two points extra in grade generated an additional $20 per acre.


With twin-row planted peanuts, the canopy is fuller than with single-row planted peanuts.

Special equipment, such as this Monosem planter, is used to plant twin-row peanuts.

He says the southwest corner of Georgia has definitely adopted twin-row planting by as much as 70 to 80 percent. Growers in the central and southeastern part of Georgia have not adopted the concept of twin-row planting as much. For instance, growers in Coffee County only plant about 20 to 25 percent of their peanuts to twin rows, he says.

In South Carolina, Chapin says twin-row planting offers a consistent yield advantage with Georgia Green, which has a small vine growth. “Yield response is less consistent on newer runners and Virginia types,” he says.


This photo shows the difference in spacing between twin-row and single-row planted peanuts.

Seeding rate

Tubbs says the seeding rate for twin-row peanuts isn’t any different than for single-row peanuts when it comes to total seed planted per acre. “This happens by taking half of the seed that would be planted in the equivalent single-row pattern and moving them over to the most adjacent twin row,” he says.

With twin-row planting, Tubbs says if spacing between two twin rows exceeds 9 inches, then growers can face a problem with inverting the rows at digging time. For that reason, he prefers 7-inch spacing. “Any closer than 7 inches,” Tubbs says, “and there is little advantage over being in a single-row pattern, because there becomes increased plant competition, which reduces plant survivability or plant stand. And it also reduces the benefits from a disease control standpoint for TSWV and southern stem rot (white mold).”

Disadvantages

Planting twin-row peanuts does have disadvantages. Sometimes twin-row peanuts can create a digging problem; however, Smith says a global positioning system (GPS) eliminates this problem. Chapin advises to use a GPS, because it’s “too hard to find rows on rank-growing Virginia types.”

The other disadvantage Smith sees is that twin-row planting requires two sets of planters. Chapin says the additional equipment for twin-row planting means more costs to growers. Of course, twice the number of planters equals more calibration of that equipment and more things to go wrong in general. He adds that twin-row planting doubles the in-furrow inoculants cost.

Tubbs agrees that the higher costs for a planter and slightly elevated input costs for in-furrow insecticide and inoculants applications are real disadvantages to twin-row planting of peanuts. He says those applications are “not doubled over single row, but modified on a per-acre basis to stay within maximum labeled rates without cutting the per twin row amount in half compared to single rows.”

Another disadvantage Tubbs sees is the potential for more difficult inversion if vegetative growth is excessive.

Rocky Womack has written about agriculture and business for more than 25 years and currently serves as a contributing writer and correspondent for agriculture and business magazines, domestically and internationally. In the past, he has worked as a magazine editor and daily newspaper writer.