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Testing a Hydraulic Down-Pressure System

With about 500 acres of corn and soybeans divided between the Missouri River bottom near Percival, Iowa, and the rolling hills north of Sidney, Randy Grudle and his son, Erik, deal with a wide range of soil types and planting conditions. While the Loess Hills near their home farm consist of light soils that were deposited by the wind over several million years, the river-bottom fields some 10 miles away are table-top flat and consist of heavy, black soil. Adding to the challenge are the dozens of terraces the Grudles have installed on hillside fields to conserve topsoil.

Fortunately, the Grudles essentially leveled the playing field in early 2013, when they field tested a new hydraulic downforce system from Ag Leader on their 16-row John Deere planter. This past spring, they swapped out that system for the newest edition that has since gone on the market.

As Randy explains, he and Erik had already opted for a factory-installed pneumatic down-pressure system when they purchased the planter four years ago.

“I’m not sure the air bags really worked any better than down-pressure springs,” he admits. “The biggest problem is with corn-on-corn, which accounts for about 200 acres. Soybeans are pretty forgiving. Even if the depth isn’t consistent when planting into corn stubble, as long as the seeds make contact with moisture, the crop will come up.”

But corn isn’t like that. “You’ve got to get it in the ground; and that’s why we switched to the hydraulic system. It’s not as much of a challenge when planting corn into soybean stubble, but corn-on-corn can be a challenge due to the residue and root balls on the surface,” he notes. 

Even though the air bags could be adjusted from the cab, Grudle says it was hard to know where to set them. Since there was no individual or paired-row adjustment, there also was no variation across the width of the planter.

“With this system, I don’t know as I’ve ever found corn laying on the surface,” Erik adds. “In fact, it’s a rare occasion to find corn seed that’s not right there at 2 inches. The emergence is tremendous. Virtually all of it comes up at the same time.”

Randy admits that even though he has heard good things about some of the aftermarket pneumatic downforce systems, one of the things that appealed most about the hydraulic system was the fact that it used the same Ag Leader monitor he already had in the cab for satellite-assisted guidance.

Biggest surprise
As the one who most often does the planting, Erik says the thing that surprised him the most was the amount of variation across the width of the planter bar.

“Sometimes I saw the center section reading 300 pounds when the outside ends were at 80,” he recalls. “Other times, it would be under 100 all the way across. I think 385 was as high as I ever saw it go, and 80 was about as low as it ever went. But it was almost always the center section, where the tires ran, that required the most down pressure.”

They saw added benefit in the way the hydraulic down-pressure system increased the value of their 3-bushel seed boxes. Purchased as an optional replacement for the standard 1.5-bushel boxes, the larger boxes were supposed to allow them to run longer between stops.

“They tell you at crop seminars that you shouldn’t fill them all the way because there will be too much weight difference, and you’re not going to be planting at the right depth when they are close to empty,” Erik relates. “That seemed to be true, whether we had springs or the air bags.”

With the hydraulic down-pressure control, they don’t have to worry about that because the system accounts for the weight of the seed in the box. They can fill them up and get the full benefit.

“Having seen how the hydraulic system is constantly changing as I am going across the field, I can’t imagine how bad of a job I was doing with the springs and air bags,” Erik says, noting that the hydraulic system also responds much quicker. “I had to be greasing the sidewall in a lot of places.”  

Ironically, they even saw a huge benefit that first season from the hydraulic downforce system in soybeans.

“It was so dry last year that a lot of farmers had to replant soybeans. Others were lucky to get a 60% stand,” he says. “Thanks to the hydraulic down-pressure system, we got our beans consistently planted in moist soil and didn’t have to replant anything. We probably had a 90% to 95% stand on all the soybeans.”

According to Randy, the hydraulic downforce system also works well with their current fertility and tillage programs. “We used to no-till everything,” he says. “But when the corn residue got thicker and tougher over the years, due to higher plant populations and newer hybrids, we decided we needed to do something.”

Consequently, the Grudles’ tillage program now includes a vertical-tillage machine to size stalks and mix residue with a small amount of soil. They generally use a ripper on their bottom ground in the fall to break up the hardpan.

“Occasionally, we’ll vertical-till the soybean stubble prior to planting corn,” Erik relates. “But most of the time soybean fields are planted no-till.”

Beginning in the fall of 2013, they also began applying anhydrous ammonia, phosphate, sulfur, and zinc in fields destined for corn using a 15-coulter, high-speed dual-placement machine that consists of a fertilizer bar equipped with a MonTag dry fertilizer system.

“We used to sidedress all our nitrogen,” Randy says. “We bought this system last fall so we could put the majority of it down ahead of time. On our fields in the hills, we’re putting down both dry fertilizer and anhydrous in a variable-rate application based on grid samples.

However, on our bottom fields, we’re currently putting on a straight rate of 100 pounds of N in the fall or winter and coming back with about 60 pounds in a sidedress application. Dry fertilizer, though, is still variable-rate applied by 3-acre grids.”

The beauty of the new machine is it allows them to rip, fertilize, and plant on the same strip using satellite guidance on an RTK signal.

“Even though we’re still leaving the majority of residue on the surface, the seed is going into a fairly mellow strip that already has the fertilizer right there where roots can reach out to it,” Erik says.

They’re already pushing average corn yields to 185 to 200 bushels per acre, with soybeans averaging around 50 bushels. 

Next step
Prior to the 2014 planting season, they installed hydraulic drive units on the planter, which allows variable-rate seeding. As a trial, they planted three fields to match a preprogrammed prescription: a 240-acre field in the bottoms and two fields in the hills of 170 and 190 acres.

“The planter is split in half with the prescription based on soil type, pH, fertility, rainfall history, the hybrid being planted, etc.,” Randy explains. “The nice thing about the Ag Leader Optimizer program we use is it allows Erik to customize the grids. In effect, he can enter the information on seed brand, fertilizer applied, and planting population for a given yield goal, and it will tell him the limiting factors for the yields we have chosen, including predicted moisture for that field.”

Most of the time, the planter was running the same rate across the full width, ranging from 28,000 to 36,000 seeds per acre. “However, we did see times when one half was running at 30,000, while the other was at 34,000,” he adds. “We’ll have to see how it all turns out, since we’re trying two new programs in the same year.”

One thing is certain. Hydraulic down pressure has definitely been worth the investment. “We’re totally sold on it,” Randy concludes. “It works extremely well, and we haven’t had a bit of trouble. Even more important, we’ve never had such even emergence.”

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