Twin-Row Expectations

February 17, 2011 03:07 AM

Mike Kavanaugh loves to talk about his twins. For the past two growing seasons the AgriGold Agronomy Manager and his agronomy team have conducted intensive on-farm row spacing studies. Both years, twin rows outperformed 30-inch rows.

TwinRowCornIn a twin-row configuration, corn is planted in paired rows, usually 7 to 8 inches apart, on 30-inch centers. The idea behind this system is to gain a more uniform spacing of plants, similar to narrow-row corn. The theory is reducing the amount of inter-row competition above and below ground allows the corn plant to maximize yield. The project also allows AgriGold to evaluate 30-inch rows to determine if planting population can be managed to limit the amount of competition the corn plant is under to enhance yield potential.
“Elevating genetic yield potential on every acre is our top priority and the reason we continue to do these studies,” says Kavanaugh. “Different plant populations and row spacing systems are two critical areas of interest that we feel must be understood to achieve maximum yields while still holding the plant together agronomically.”
In 2010, AgriGold conducted 118 tests in commercial fields using each grower’s individual cultural practices.
Kavanaugh is fully aware that not everyone believes in twins or 20-inch rows or the whole theory behind them. However, he says AgriGold results have consistently shown the trend line for twin rows continues to increase up to 43,000 plants per acre,” Kavanaugh says. “The yield trend line for 30-inch row systems begins to plateau around 36-38,000 plants per acre, although 34-36,000 ppa is best for maintaining overall plant integrity and standability.”
 AgriGold’s 2010 study found an average 5.3 bushel increase yield response of all hybrids and all regions over 30-inch rows at populations of 38,000 plants per acre (ppa). There were regional differences—the central Corn Belt showed the largest regional increase as yields increased by 6.4 bushel per acre at the 38,000 plant population level. At 43,000 ppa, trials in the central Corn Belt exhibited a 9.2 bushel benefit. However, Kavanaugh says producers must take into account seed cost, genetic differences in hybrids, soil capabilities and management before pushing populations into these upper ranges.
Still it was data gathered from yield environments that average less than 150 bushel that tells a tale. Yields jumped by 7 bushel at 38,000 ppa and 8.4 bushel at 43,000 ppa compared to 30-inch plantings at similar populations. The 30-inch rows held nearly steady, regardless of population density.
Kavanuagh says this trend line suggests that spreading the plants out over more area allowed corn plants to be more efficient with water and nutrients in stressful conditions. “Although we really hoped to see this trend begin at the 28,000 ppa too,” he says.
“Typically, population and row spacing are not the most limiting factors on yield in lower yielding scenarios,” Kavanaugh notes. “Factors that typically limit yield include poor drainage, drought, low fertility, low pH, heat and compaction.
“Data generated from 30-inch rows showed basically no response to increasing populations over 28,000 ppa in low yield environments,” he says. “Narrow row systems, however, reduced inter-row competition and allowed additional rooting area to negate some of the yield limiting factors associated with lower yield environments in 2010.” He stresses that growers need to address other limiting factors in these environments—population and row spacing can’t do it all.
He says multiple years of testing twins confirm that there are real differences in genetic families and how they respond to twin and 30-inch rows. “Understanding the style of your genetics is so important in knowing how to position hybrids,” Kavanaugh adds.
For example, Kavanaugh says AgriGold’s Family B genetics definitely showed that providing more room for each plant allowed the flex ear hybrid a chance to spread out and maximize yield. However, there is a point of diminishing returns and the company recommends bumping populations by 2,000 to 4,000 ppa when planting most Family B hybrids in narrow row situations.
Family F genetics tend to be ear count dependant and respond favorably to higher plant populations regardless of row spacing. Maximum yield potential is usually achieved at 36,000 ppa or slightly more due to limited ear flex capabilities.
“We realize that narrow row corn on a big scale is probably still a few years ahead of its time, but with new genetic introductions and technology, it is certainly around the corner,” Kavanaugh says. “Our ultimate goal from this two year study has been to confirm our theories about genetic interaction at different populations and row spacings and to continue to find ways to make the corn plant more efficient and agronomically sound on every acre.”
The company also gathers important comparisons on plant height, ear height and stalk diameter in twin row configurations.
For more information on this twin row study go to or call 1-800-262-7333 to ask for a comprehensive report.


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