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The long-held rules about ideal planting speeds are under challenge today. Large farms and high-priced seed have pushed growers to plant more ground faster and hit that all-important planting window. Equipment manufacturers have helped by offering wider planters, more precise seed meters, GPS guidance and better lighting.
"This past year, Iowa farmers planted 1.5 million acres in one day," said Roger Elmore, former Iowa State University agronomist. "That's extremely fast. The previous record was 1.4 million."
But it's still not fast enough. The focus now is on increasing planting speeds, which has opened an old debate of how fast you can plant.
"Planting speed has always been an interesting thing," said Elmore, now with the University of Nebraska. "Master corn grower Francis Childs claimed 2 mph planting speeds worked best for him. He'd put a pop can on a planter box and drive so it didn't drop off. But most guys couldn't go 2 mph."
Nor do they need to go that slow. Speed recommendations for most planters average 5 to 6 mph. Newer planter models are capable of even higher speeds, 7 to 8 mph and more.
EMERGENCE, NOT STAND
"I have a tendency to believe farmers are probably going slower than they need to, which is counter to what you usually hear," says Bill Hoeg, Case IH planter marketing manager. "Why? I think there is too much focus on picket-fence stands. Instead, the focus really needs to be on photocopy plants and the seed environment, which affects yields 9% to 22%."
Hoeg refers to university research that shows irregular seed spacing has less yield impact than irregular plant emergence. Some of the research was conducted by Purdue University in the 1990s. Purdue agronomist Bob Nielsen was involved with it.
"Yield consequences due to uneven spacing from planting speed for most growers is no more than 1% to 2% yield loss," Nielsen said. "It is minor, but it is usually an easy fix.
"The bigger issue is if a faster speed results in uneven seeding depth or uneven seed-to-soil contact where some seeds are sitting in nice moist soil and others have air pockets around them," he said. Uneven emergence is more problematic and can cause "yield losses of 10% to 15%."
Poor emergence is caused by a number of things, including planter bounce. Elmore has seen this happen "I was in a field a few years ago where one out of five plants was coming up slowly across the whole field," he said. "They were one to two leaves behind the bigger ones. Yield potential is reduced when you get that kind of variation across a field."
Most planters have adjustable downpressure settings to help ensure even seed depth. Growers need to test their equipment and make the right adjustments.
Iowa State University ag engineer Mark Hanna explained: "Uneven emergence is not so much speed or seed singulation but depth control of the planter.
"We had an experience several years ago where we planted at up to 10 or 12 mph and checked corn spacing and yield," Hanna said. "Surprisingly, we did not see yields deteriorate much even at quite high speeds. But these were seed meters that were looked over quite closely before going into the field. We did see some seed spacing variation, but not to a great degree."
Individual grower differences in the ability to speed showed up in the Purdue trials. Nielsen reported some growers experienced no consequences from planting at 7 mph versus other farmers planting at 4 mph.