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You Are Here Sunflower Magazine > Calibrate...Calibrate...CALIBRATE!


Sunflower Magazine

Calibrate...Calibrate...CALIBRATE!
January 1997

There are several commonly touted advantages to using an air drill for planting one’s sunflower in a narrow-row or solid-seed pattern — advantages like speed of planting . . . a more-equidistant spacing of plants in all directions . . . quicker canopy coverage for efficient interception of sunlight and suppression of weeds . . . ability to combine in any direction at harvest . . . and, of course, competitive final yields.

Except for planting speed and harvesting direction, however, none of these benefits can be fully realized without first engaging in a critical up-front procedure: accurate calibration of the air drill’s sunflower seeding rate mechanism.

The majority of manufacturers whose air drills are used for sunflower have recommendations on how to properly set the drills for seeding this crop. Some are more detailed than others when it comes to sunflower; but each in case, growers should review their product manual and contact their dealer or manufacturer for assistance as needed.

Yet veterans of narrow-row/solid-seed sunflower emphasize there’s no good substitute for experimental calibration and test runs — especially if one is a first-time solid seeder or has recently switched drills. After all, it’s pretty tough to undo an error in population counts or distribution after those seeds are in the ground.

On these pages we take a look at the calibration processes followed by three successful North Dakota solid-seed sunflower producers: Ken Lang of Tower City, Ron Aberle of Menoken and Duane Burchill of Page. Here’s what works for them when planting sunflower with their respective air drills. — Don Lilleboe

Tower City, N.D., farmer Ken Lang (seeding in photo at left) has been planting sunflower with his John Deere 777 air seeding system since 1992. He shoots for a seed drop of approximately 24,000 seeds per acre, with the 32-foot drill set up for seven-inch row spacings. Though his 777’s operator’s manual does not include sunflower calibration charts, Lang’s hands-on experimentation quickly resulted in a system which allows him to achieve his desired seed drop with considerable accuracy.

Echoing the advice of other veteran solid seeders, he says it’s very important to recalibrate every time one changes not only varieties, but even different seed lots of the same variety. Variances in per-pound seed count and/or seed shape could result in significant seeding error if recalibration is not conducted, Lang observes.

Knowing the per-pound seed count of the variety he’s planting, the east central North Dakota grower begins his stationary test by dumping two or three bags of sunflower seed into the 160-bushel tank on his six-run 777 drill, which is equipped with “fine” meter rollers commonly used for seeding low per-acre-poundage crops like sunflower. Removing the plate beneath his rollers, Lang installs the drill’s collection container and then proceeds to rotate the crank handle 44 full turns within a 15-second time span.

The cranked sunflower seed inside the container represents the amount he’d be planting in one acre. Rather than weighing the entire contents, however, Lang uses a hand-held density scale with slide weight to help him determine whether any metering rate adjustment needs to be made. Though the scale conversion charts don’t list sunflower specifically, he say there’s a very close correlation between the slide weight location reading and the actual pounds of sunflower to be seeded per acre.

When first unfamiliar with using the 777 for solid-seeded sunflower, Lang conducted a series of “trial and error” meter setting adjustments since there were no sunflower rate charts to go by. Now, unless he decides to revise his desired population, he seldom diverts from his “customized” setting for sunflower. Still, he reiterates the importance of checking one’s calibration if switching from one variety or seed lot to another.

“At first, it’s not easy to adjust for sunflower,” Lang remarks of his JD 777 air seeder. “But I’ve done it enough years to have a real good feel for it. I have a good idea of where to start — and I don’t move much off that point.” Though the 777’s setting increments are very touchy when calibrating for a low-poundage crop like sunflower, Lang is able to achieve an accurate per-acre seed drop. “Once it’s set, it’s exact,” he affirms.

Central North Dakota producer Ron Aberle has been solid seeding sunflower since 1992. He presently uses a Case IH Concord 4812 in concert with a 2400 tow-between tank system. A minimum-till producer, he’ll typically plant into stubble, applying his dry fertilizer and anhydrous while seeding sunflower in 12-inch rows with the 48-foot unit.

Aberle grows both oils and confections. He views 20,000 as an optimum seed drop on the confections, aiming for a final stand of around 18,000. He’s still fine-tuning his oil populations, currently experimenting with seed drops in the mid- to upper-20s, depending on soil moisture conditions at planting. The Burleigh County grower leans toward size four seed, but says he can comfortably plant any size with his air drill — assuming it has been properly calibrated.

Adopting an idea which apparently originated with another central North Dakota producer, Aberle employed a new low-tech calibration tool in 1996: an open-ended rectangular wooden box. The box, made from half-inch plywood bolted onto 2x2s, is 16 inches by 20 inches by seven feet in length.

Aberle lowers the box on end inside the empty tank of his air drill, securing it directly above the seed flute. Knowing the box’s exact length (i.e., 84 inches), he empties a couple bags of seed into the box. After driving around the yard to let the seeds settle, he’ll measure the distance from the top of the box to the top of its interior seed pile. If, for example, that distance is 70 inches, it means the seeds would have taken up 14 inches at the bottom of the box).

Next, Aberle heads to the field and plants a few acres. He then re-measures the distance down to the top of the seed to see how far the level has dropped. Since he already knows the number of seeds which were in the bags emptied into the box, he can now calculate how many were sown during the experimental field run.

The monitor on his air drill tells Aberle exactly how many acres he seeded during the test run, so from there it’s a matter of simple division to come up with the per-acre seed drop, after which he’ll make any necessary adjustments in his seed-metering mechanism and fill the box with seed.

For example, if two inches equate to 50,000 seeds, he’s planted four acres, and the box’s seed level has dropped by four inches, that translates into 100,000 divided by four, for a seed drop of 25,000 per acre. If that’s his desired population, he fills up the box and is off and running. If not, he makes his adjustments and re-tests.

The process is easy and accurate, Aberle professes. It’s critical, though, to recalibrate if switching seed lots or varieties. Duane Burchill and sons Duane, Jr., Douglas and Dustin are on their second air seeding system, having purchased their Great Plains tri-tower drill for the 1993 crop. They seed in 14-inch rows with the 45-foot unit.

Duane used to shoot for a final plant stand of 26,-27,000 plants per acre, but now believes a stand of approximately 23,000 is optimum in most years. To arrive at that harvesttime objective, he’ll seed at 27,000 (having factored in an estimated two-percent machine loss, six-percent germination loss and 10-percent stand depletion across the growing season). When buying a certain variety, Burchill insists that all bags include the same size seed and be from the same lot.

Burchill says one reason for going with the dual-tank Great Plains system is the relative ease with which seeds can be dumped to make counts during calibration. Also, “you change nothing except speed — and once set, speed is consistent. When we change a gear and get a certain setting, that should be constant.”

The Great Plains sunflower chart lists gear settings for various per-acre seed counts. However, the respective windows between setting increments are about one-half pound — e.g., 2.8, 3.4, 3.7, 4.2. Since a half pound can translate into 3,500-4,000 or more seeds per acre, depending upon variety and size, the Burchills felt they needed to fine-tune the gear system for their drill. So they built a series of customized gears which allow them to refine the seed drop so that it’s closer to their desired population.

For example, to seed 3.7 pounds of sunflower per acre with the Great Plains drill, the driver would be a 20-tooth sprocket while the driven sprocket would be a 30-tooth. To go up to 4.2 pounds per acre, however, the setting would be reversed: the driver sprocket would be 30-tooth and the driven sprocket a 20.

The Burchills calculated they would be reducing the planted seed population by 3.33 percent by changing the 30-tooth driver down to a 29; by another 3.33 percent if dropping the 29-tooth driver down to a 28; and so forth. Likewise, the population would increase in similar increments if going up to a 31- or 32-tooth driver. Such a small window would, they believed, provide them with a very accurate seed drop.

So last year they constructed driver sprockets with 25, 26, 27, 28, 29 and 32 teeth, respectively. (They’re expanding the range this winter.) To test their system, they weighed a sample of seed, came up with a count of 442 seeds per ounce and extrapolated that into 13,039 per half acre.

Using seed from the same lot, they then installed the 26-tooth sprocket, cranked out the correct number of turns for half an acre, and physically counted the number of seeds that fell into the tub set beneath their drill. The result was 13,098 — a deviation of less than one-half of one percent from their projection of 13,039.

“So I’m confident we can put the [desired] number of seeds out. Then it just becomes a matter of the ‘old man’ guessing correctly on what that number should be!” Duane quips.

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