Twin Row Corn

Some ideas are just so appealing that it is hard to leave them alone, even when they have proven in the past to not work out as well as expected. The narrowing of corn rows seems to fit into this category.

Row Width Research

An extensive amount of research over the last two decades has investigated the yield improvements that could be gained by narrowing corn rows to something less than 30 inches. By the mid-1990's, research conducted across the northern Corn Belt and southern Ontario indicated significant yield advantages by narrowing corn rows from the traditional 30 - 38 inches (75-95 cm) down to 15 - 24 inches (38-60 cm). The research indicated that narrow row advantages would be greater in more northerly latitudes compared to the mid to southern portions of the Corn Belt. Ontario producers who converted to narrow row production systems at this time did so mostly by converting to 20 inch (50 cm) rows. They anticipated paying for planter and corn header conversions with an expected yield boost of 3 to 8 per cent.

Twin Row Research

Starting in 1995, twin row configurations were introduced into research projects. Twin rows are two rows usually 7 or 7.5 inches (17.5-19 cm) apart but still centered on 30 inches (75 cm). A summary of the results from University of Guelph plots, Soil and Crop Improvement Projects, independent producers and OMAFRA research over last two decades is presented in Table 1.

Net Profitability?

In general, the yield advantages to twin row corn have been inconsistent across the various years and locations were trials have been conducted. On average, twin rows represent about a 3% increase in yield. 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 by lower harvest speeds. Header losses have not been documented, but some producers have experienced corn cobs that get flung into the header and then bounce out.

When considering twin row corn, it appears that corn yield increases over traditional 30 inch rows 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 soybean or edible bean planting systems and make one piece of equipment due for all crops.

There is also discussion about maximizing light interception with twin row corn. A few studies have looked at this carefully. In a good stand of corn at 30,000 plants per acre. 95-99 percent of all the light is intercepted from tassel emergence forward and there is no impact of row spacing. The twin row spacing might improve light interception in the few weeks leading up to full canopy cover, when the twin rows can show some advantage over the single rows. This usually calculates out to be a fairly minor impact and not far off what the average yield advantages have tended to be for twin rows.

If planting at high densities (35,000 to 40,000 plants/ac) is the key to yield improvements, then some have suggested that twin rows will contribute significantly to this yield boost when tested at these high densities. Once again, it is an appealing concept, but so far not well proven. I am certainly interested in the developments around plant populations, hybrids and planter equipment that easily accommodates twin row planting. However, as one who jumped on the Twin Row Band Wagon once, you will forgive me if I don't sprain an ankle trying to get back on.