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.
“So clearly, yield loss ties back to how the planter works at high speeds,” he said. “But it also depends on how the planter was maintained, field conditions and no-till. If the planter is well maintained and adjusted properly, and field conditions permit it, guys can plant fast and experience no problem with seed spacing and even plant emergence.”
Growers with questions about how fast to plant should answer them through field tests, Case IH’s Hoeg explained. “There are so many factors, and the right answer is on your own farm,” he said. Growers need to find the planting speed that best impacts yield.
Field speed checks were how Jim Irwin learned his optimum planting speed was 8 mph.
“I bought a new Case IH planter in 2004 and asked how fast it would plant; but nobody would answer,” the Arthur, Iowa, farmer said. “I’ve always had a test plot, so I started checking speeds of 6, 7 and 8 mph. The 8 mph speed always won.”
He then tested 10 mph and different populations. But 8 mph proved to be the “sweet spot” of planting. Yields at 8 mph were 3 to 4 bushels per acre higher on average than at 6 and 10 mph.
High-speed planting is not for all farmers, he added. Driving fast can be unsettling in the field. “I’d say going 6 mph is like driving 60 mph on the highway, and 8 mph is like 80 mph,” Irwin explained. “So driving 10 mph is like 100 mph. I’m not going to plant that fast.”
Irwin isn’t sure why planting at 8 mph works well in his strip-till operation. He speculates this speed gets the air out of the soil best so he obtains excellent seed-to-soil contact. He doesn’t experience problems with uneven emergence
The Case IH planter design handles high speeds, Irwin added. For example, the seed disk has 48 holes, compared to other brands with fewer holes. His latest Case IH Early Riser planter also features pulled gauge wheels that are offset from the seed trench.
Hoeg said that as a result of being offset, the planter’s gauge wheels don’t exert excessive pressure on the seed trench and affect plant emergence.
Generally, as planter speeds increase, down pressure must also increase to stabilize row units and maintain good depth control. The problem is that most conventional row units hold the seed trench open with soil pressure or compaction, which gets transmitted to the bottom of the trench. Excessive soil pressure will adversely affect plant emergence.
Before a grower can successfully plant at high speed, the planter must be well maintained. ISU’s Hanna recommends growers thoroughly check their planters for equipment issues.
The seed-metering systems need close examination, especially the mechanism needed to eliminate seed doubles. If worn, these may need replacement.
Air-type systems use rubber gaskets for maintaining a seal. The gaskets will age and wear out. Check these and replace, if necessary.
Hanna also said growers should know the manufacturer’s recommended planter speed for different row spacings, plant populations and seed types. Then you can decide what speed to plant.
Purdue’s Nielsen offered a final word of caution: “Growers still need to pay attention to the uniformity of seed spacing, seed depth and seed-to-soil contact before bumping planter speed full out over every single acre planted,” he said. “Once the seed is in the ground, you are stuck with the results unless you decide later to replant.”