Twin Row Corn
By Greg Stewart, OMAFRA Corn Specialist

Interest in narrow row corn and more recently, twin row corn has been intense over the past decade. But research results indicate sharp pencils are still required when considering changes.

By the mid 1990s, research conducted in various locations across the northern Corn Belt and southern Ontario was indicating significant yield advantages could be expected from narrowing corn rows from traditional 30 - 38 inches down to row widths that ranged from 15 - 24 inches. Results showed that narrow row advantages would be greater in more northerly latitudes, compared to results coming out of the mid to southern portions of the Corn Belt. Ontario producers who converted to narrow row production systems at this time did so, for the most part, by converting to 20-inch rows and anticipated paying for planter and corn header conversions with an expected yield boost of three to eight per cent.

Starting in 1995, twin row configurations (two rows generally seven or 7.5 inches apart but still centered on 30 inches) were introduced into research projects. Gordon Sheifele's work out of Ridgetown College showed that the twin row concept could deliver yield increases over 30-inch single rows (Table 1) and in some cases were equivalent to those obtained with single narrow rows 15 or 20 inches apart. Work done by Durham East Soil and Crop Improvement Association in conjunction with the University of Guelph began in 1996; results from that year showed significant yield gains for twin 30-inch rows over other row configurations (providing plant populations were increased as well). This particular study has continued for the past several years and results have indicated less yield advantage for twin rows than in that first year (see Table 2).

Further studies have also been ongoing at Woodstock (University of Guelph) and Ottawa (Agriculture and Agri-Food Canada) to evaluate corn response to narrow rows. These studies have included various nitrogen rates and physiological measurements to try and sort out the basis for narrow row response. The yield results from the Woodstock site have indicated absolutely no yield difference between the twin and single rows (Table 3). Similar patterns
have been observed at the Ottawa site (data not shown).

Recently, numerous on-farm trials have been conducted to examine twin row corn on a field scale basis. Trials from Bill Litwin and Hartholme Farms are reported in Table 4. These tests have examined numerous hybrids and have shown yield advantages for twin rows with some hybrids more than others. Reasons for differential response among hybrids is still unclear. Pioneer research has generally indicated all of the hybrids the company has tested in Ontario have responded similarly to narrow row configurations.

In general, the yield advantages to twin row corn have been inconsistent across the various years and locations where trials were conducted. One of the main advantages to twin row corn has been the cost savings from not having to make any modifications to the corn header or tractor tire spacing. Some of these savings are perhaps offset by additional wear on the corn header, as it is continually required to pull corn stalks and operate at lower harvest speeds.

When considering twin row corn, it appears corn yield increases over traditional 30-inch corn may not always be adequate to justify equipment and management changes. Those operators most likely to enhance net profitability will be those who can combine the changes in corn planter configuration to mesh with soy or edible bean planting systems and make one piece of equipment do for all crops.

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