Adjusting planter speed can improve yield and uniformity

High yields and uniform potatoes start with homogenous seed pieces planted at even intervals, Mir-M Seyedbagheri told growers at the University of Idaho Potato Conference in Pocatello Jan. 16-18. Seyedbagheri is an Extension educator with more than 20 years experience helping potato growers increase their planting efficiency.

Planter efficiency has other benefits as well.

When you have high efficiency, disease suppression is better and nutrient distribution is more even,” he said.

When Seyedbagheri started, grower efficiency was at about 32 percent. Now, all the growers he works with have efficiencies higher than 60 percent. He even has one grower that regularly plants at 98 percent efficiency, which is as good as planting by hand. Much of the improvement he’s seen has been the result of simply adjusting the speed of the planter.

To find the planter’s efficiency, Seyedbagheri recommends digging 25 feet of a row and measuring between the centers of the seed pieces for that stretch. Plot on a graph the number of doubles, acceptable plantings and skips. Divide the number of acceptable plantings by the total to find the efficiency.

For example, in western Idaho, where Seyedbagheri works with growers, the optimum spacing is 10 inches between seed pieces, so spacing between 8 and 12 inches is considered acceptable. Less than 8 inches is a double and more than 12 inches is a skip. So in a 25-foot row, he may find 10 doubles, 10 acceptable plantings and five skips, making the efficiency of that planter 40 percent.

“If you have more than 65 percent efficiency, it’s generally very good,” Seyedbagheri said.

A three-year study at the University of Idaho’s Aberdeen Research and Education Center found that yield was not significantly reduced until skips hit 30 percent. Yield was reduced in the study for a 16-inch, in-row spacing at 70 percent stand.

“This is actually good news, because no planter can be 100 percent accurate all the time,” said Bill Bohl, an Extension educator at the University of Idaho.

Planter Speed

The second way to control efficiency is to accurately measure the actual speed of the planter and adjust the speed to avoid doubles or skips.

“Speed plays a very important role in planter performance,” Seyedbagheri said. “Sometimes, 0.1 mile per hour will make a big difference in planter efficiency.”

The speed the planter is working at is likely different than what the planter says, Seyedbagheri said. To find the actual pace, measure the amount of time it takes to go a set distance. Next, divide the number of feet traveled by the seconds it took to go the distance and multiply that number by the integer 0.692 (found by dividing the number of seconds in an hour by the number of feet in a mile).

For example, if it took the planter 23 seconds to go 100 feet, then the formula would be (100/23) X .692 = 3 miles per hour.
“You will see that it’s different than what your planter shows,” Seyedbagheri said.

While an inch or two doesn’t seem like much, over the course of planting a field that extra space can affect yield. For example, research conducted in Idaho found that the desired spacing for cup planters was about 10.6 inches, but the actual spacing was almost 12 inches. The desired spacing for pick planters was 9.6 inches, but the actual spacing distance was 11.7 inches. The average 1.2-inch difference between desired planting space and actual space would amount to more than 1,000 fewer seed pieces than desired, or 9 percent fewer plantings per acre — if there are no skips.

There has been little difference in the make and model of planters. He found that new planters will go faster with a higher efficiency, but that can still be improved by optimizing speed. A new planter won’t solve the problem of planting speed it’s still important to dig the rows and measure spacing. Knowing how the planter operates and planting carefully will make up for any differences among planters.

“If you know your planter and know what you’re doing, you can get good efficiency,” he said.

Ultimately, that’s what Seyedbagheri wants growers to learn. It’s possible to have a high efficiency without inputting data into a formula or graph.

“My point is, it’s an art and a science.”

Other Issues

Most seed efficiency problems can be fixed by adjusting planter speed, Seyedbagheri said. But he does recommend growers take a few steps to ensure greater efficiency.

Monitor the seed cutter performance. Seed pieces should be homogenous for optimum planting, between 1.5 and 2.5 ounces. Standard sizing starts with uniform seed potatoes, which should weigh between 3 ounces and 10 ounces. Sample about 100 seed pieces for their consistency. Seventy percent or more should fall in the acceptable range.

“Seed pieces that are cut to the correct size and profile will generally plant more uniformly, but correct seed piece size can only be attained by using correctly sized seed tubers,” Bohl said.

Large tubers don’t necessarily have more eyes than small tubers, because the number of eyes only slightly increases as size increases. Cutting tubers larger than 10 ounces will usually result in blind seed pieces.

Take the variety into account when planting. Each variety has its own depth characteristics, and going too deep or too shallow affects yield and germination as well as planter efficiency, Seyedbagheri said. Growers sometimes try to avoid tuber greening by planting deeper than 6 inches, but there is little or no benefit to planting deeper, according to University of Idaho research. Russet Burbanks had reduced yield and fewer No. 1 potatoes, while trials with Shepody saw no significant differences.

Moisture can affect the planter’s performance because static energy is built up if the ground is too wet resulting in more doubles so Seyedbagheri recommends planting when the ground is dry and closely monitoring the fields prior to planting.
General maintenance and being aware of the specifics of the planter are good techniques for avoiding skips or doubles. Failing to check the hopper to make sure nothing is jammed can mean whole sections are missed, which may not be evident until row closure. Overfilling the hopper can cause seed pieces to get stuck, resulting in skips.

“When you look in your seed gates, make sure they are opened up,” Seyedbagheri said. “Make sure everything is flowing smoothly down there.”

Lastly, Seyedbagheri recommends growers be a “shadow” during planting. Making sure farmhands are digging to check a full 25 feet of row, checking hoppers, overseeing planter maintenance and monitoring the planter speed can increase the efficiency of a grower’s planting operation.

75 Applewood Dr. Ste. A
P.O. Box 128
Sparta, MI 49345


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