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Optimizing Your Seed Placement

Monday, March 28, 2011
filed under: Planting Systems

How close do you want to live to your neighbors? Even if you have a lot in common and get along well, the answer for most of us — especially if we’re agriculturists — probably is “not too close.”

It’s no different with sunflower plants. They flourish when they’re properly spaced within the row, and they don’t do nearly as well when they’re too close to their neighbors (can you say “doubles and triples”?).

Plant spacing/plant population was named the number-one yield-limiting factor in the 2010 crop survey conducted under the auspices of the National Sunflower Association. That wasn’t totally surprising, given the wet planting season across much of the Northern Plains that resulted in numerous fields being sown under less-than-optimal conditions. Yet it wasn’t a single-year issue, either. Seed spacing and plant stands consistently have been leading yield-limiting factors since the first NSA crop survey was conducted back in 2002.

Even for the best crop managers, a “perfect” plant stand is definitely the exception rather than the rule. But there certainly are steps every sunflower grower can take to help improve consistency of seed placement, uniformity of plant development and, ultimately, final yields. Here’s a recap of several key points, with particular application to row-crop planters:

• Ready for Sunflower? — Numerous equipment dealerships now offer planter test stands where growers can have their seed metering units checked for wear and other potential problems. It’s also a good time to match up planter plates with specific hybrid varieties and sizes, gaining a good idea in advance of the seed placement uniformity you can expect when actually in the field.

• Proper Settings? — If using a vacuum or pickup series planter, do you have the right plates for the specific types and sizes of seed you’ll be planting? Is your vacuum setting correct? How about the singulator? (For useful tips on these and other planter-related troubleshooting steps and adjustments, visit growers/video-clips/. There, University of Nebraska-Scottsbluff machinery systems engineer John Smith discusses topics ranging from seed tube evaluation to meter unit settings.)

• Calibrate, Calibrate — Every grower knows the importance of calibration, though sometimes, in the rush of the planting season, it’s hard to take the time. But variances in per-pound seed counts and/or seed shape can result in significant seeding error if calibration is ignored. Recalibrate every time you change not only the variety being planted, but also different seed lots of the same variety.

• Planting Depth — The standard recommended planting depth for sunflower is 1.5 to 2.5 inches. “Plant to moisture” is the grower’s mantra. However, planting too deep can reduce emergence, as that seed must then expend extra energy to shed its hull, pop out of the ground and grow.

• Right Population — In higher-rainfall areas, a per-acre seed drop of between 18,-22,000 is a good rule of thumb for oil-type sunflower; for lower-rainfall areas, that 16,-18,000 range is recommended. For confections, the planted population typically will be around 17,-19,000 in higher-moisture locales and 14,-16,000 in drier regions.

• Proper Planter Speed — The perils of going too fast have been expounded upon at length. But going too slow may sometimes be a negative as well. “Most new-style planters require a minimum speed so that the seed disk stays at an optimal rpm in order to ensure proper seed singulation,” notes Dana Klaksvik, High Plains key account manager for Seeds 2000. “Depending on the number of holes in the planter disk, increasing planter speed may help you plant more accurately.”

• Seed-Soil Contact — Good seed-to-soil contact obviously is important with any crop, but perhaps none more so than sunflower. Because sunflower seeds have such a woody hull, proper depth and complete closure of the seed furrow becomes especially critical. That’s one key reason for adequate residue clearance within the seed zone — i.e., avoiding hairpinning of straw or chaff from the preceding crop. Clearing away residue from atop the seed zone also exposes that strip of soil to the sun’s warmth, aiding speed of emergence.
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