Those skips and doubles can hurt your corn yield more than you think, according to Chad Brewer, a Pioneer agronomy research scientist based in West Memphis, Ark.
Brewer conducted research on skips and doubles on Triple G Farms in Arlington, Ky., the site of a recent Pioneer field day. Plots were planted, then added to or thinned out to make doubles and skips to demonstrate the impact that doubles and skips can have on crop yields.
Ears were pulled from a 2.5-foot section of row and kernels were counted and compared to a uniform stand. The research showed that the double acts as a weed. “In a double, three corn plants are competing for the resources that are available for only two,” Brewer said. “The result is reduced yields from all three, which amounted to about 96 percent of the yield when compared to a uniform 2.5 feet of row.
“A double doesn't add much to your grain yield, but just as importantly, the ears on either side of the double are smaller, too,” Brewer said. “Having that double out there can really impact yield, especially when we think of how many doubles we actually have out there in the field.”
At the other end of the spectrum, a skip, or missing plant, “is not that much of a problem in soybeans because the soybean plant branches out to compensate and all those branches can form pods. Corn can compensate a little bit in that ears on either side of the skip are quite a bit bigger than the ears in the rest of the row. But what we need is for 600 kernels to be made up by the two ears on either side of the skip. Corn can't compensate that well.”
In the research, a single skip in 2.5 feet of row showed a 14 percent yield reduction compared to a uniform 2.5 feet of row.
Brewer stressed that there is no hard and fast rule on how to determine the correct seeding rate for corn. “That information is going to come from walking the fields, taking a look at the crop at the end of the year and determining if the ears were filled out adequately. If they're filled out to the end, you possibly could have raised the plant population.”
However, in abnormal weather years like 2009, which saw all kinds of weather extremes, “the ear can't always give you a good read. On an average year, if the tip is back about an inch and a half, you have the right amount of resources for that corn to reach maximum yield.”