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Planting can be Weighty Challenge

Saturday, April 15, 2006
filed under: Planting Systems

Ranging between 24-32 lbs/bushel, both oil and confection sunflower seed are about half the weight of corn and grain sorghum (56 lbs/bu) and soybeans and wheat (60 lbs/bu). The lighter test weight of sunflower amplifies what is often a key factor with the problem of planter skips and doubles – speed.

“I think planting speed that’s too fast is worse with sunflower than it is with corn or soybeans. You have that lighter test weight seed that can float more and bounce around in the planter box,” says John Swanson, product manager with Croplan Genetics, Mentor, Minn.

Compounding the problem is a varying seed shape, from long and narrow to tear-drop round. Throw a planting speed that’s too fast into the mix, and one can see where physics might be a problem, especially with plate and finger-type planters.

The lighter weight of sunflower even prompted one Kansan to experiment with using cracked barley in his air drill when solid seeding ‘flowers for better weight equilibrium to improve plant stand potential. (see article online at - go to ‘Hybrid Selection/Planting’ and then article “Barley Bulk Aids 'Flower Seeding.”

Not that you need to add cracked barley to your own planter box. Paying attention to planter calibration and planter speed can go a long way in achieving a successful, uniform sunflower stand. Your seed rep is the best place to start for recommendations based on the seed you’re planting.

Some seed companies even provide recommendations online. Pioneer, for example, analyzes seed drop for each seed batch in test planters to provide plantability information. Using the Plantability Menu found on Pioneer’s GrowingPoint Website, growers simply enter the batch ID from their sunflower bag tag and select their planter model from a dropdown list. The program then delivers information for optimum planter calibration such as vacuum setting, pressure setting and plate size for the grower's unique combination of seed and machine.

Another excellent resource is the manufacturer/local dealer for your planter. They can provide advice for using correct planter plates, properly sized seed, and proper seed knockers.

Commercial seed companies have plate recommendations for all seed sizes. Grain drills and airseeders are used on some farms where row crop equipment is not available. Uniform depth of planting and seed spacing may be a problem with grain drills and airseeders, but modifications can be made and success obtained in most years. Some equipment dealerships evaluate seed-metering units (or even seed, to match up planter plates) in the shop. While there may be small fee involved, it can be a worthwhile investment.

“Some guys will actually bring us the whole hopper because they don’t want to take the seed metering unit off themselves, and that’s fine. We put it on our metering test stand and run it through that way,” says David Oren of Colby Implement, Colby, Kans. “There’s so many different combinations of things that can affect skips and doubles, from the metering unit either being worn out or brushes wore out or plates warped.”

Sunflower planting tips

Planting date in the Northern Plains – The recommended planting window for the Dakotas is generally mid to late May. Early planting (May 15), usually allows for the best yield, oil, and test weight potential, as well as earlier maturity and hopefully warmer harvest weather. South Dakota State University research has indicated that oil is generally more affected by late planting than yield. Oil content generally begins to decline in sunflower planted after June 15, and yield generally begins to drop in sunflower planted late June.

Planting date in the High Plains – Sunflower can be planted in Kansas from early May to late June, according to the K-State University Extension Service. Generally, irrigated sunflower is planted in May and dryland sunflower during the first three weeks of June, according to KSU. Early plantings often result in larger seed size and higher oil, but they encounter more insect problems, and may require treatment. Conversely, late June and early July plantings are prone to smaller seed and lower oil, but fewer insect problems.

Talc or graphite? Seed flowability can be an issue with treated seed. Thus, take note on whether your operator’s manual specifies to use a lubricant with treated seed, and if so, whether it should be graphite or talc – they are not interchangeable. Generally, talc is used in vacuum and air planters, and graphite in finger pick-up planters. Check your manual to know for sure. Review the manual also for servicing recommendations, settings, depth control, optimum planting speed, and troubleshooting.

Be sure to recalibrate – Do so every time you switch to planting a different variety, and even different seed lots of the same variety. Variances in per-pound seed count and/or seed shape can result in significant seeding error if you don’t recalibrate.

Soil temperature – A soil temperature of 50° or more at seed depth (1.5 to 2.5 inches) is generally needed for germination.

Fertilization – About 5 lbs of nitrogen are required for each 100 lbs of sunflower seed yield. Recommended rates of nitrogen fertilizer application will vary with the yield goal desired and the nitrate nitrogen soil test level. Where the soil has not been tested, a rule of thumb is to apply 3-5 pounds of nitrogen fertilizer per 100 pounds of expected yield. Apply phosphate and/or potassium fertilizer when soil test levels are low to medium for these nutrients. Sidedressing row planted ‘flowers may be considered but don’t wait too long; usually a plant size of 6-18 inches is best.

Seeding depth – Sunflower should generally be planted at a depth of 1.5 to 2.5 inches and into moisture. Percent emergence will decrease as planting depth increases, especially for smaller seed sizes.

Seeding rate – Plant about 10-15% above the desired final population, going with a lower rate if using treated seed. Aim for a final population of about 20,000-22,000 plants/acre for oils, and for the confection in-shell market that stresses seed size, 17,000-20,000 plants/acre. For the de-hull market, target a final population of about 18,000-20,000 plants/acre, and the bird food market, consider a final population of 21,000-23,000 plants/per acre. Planting rates are generally on the lower end in the High Plains, particularly dryland and confection production.

Furrow closing important – Sunflower needs to have excellent seed to soil contact. Because sunflowers have a woody hull, closure of the furrow becomes more important than for corn and most other crops.

Watch for hairpinning – At planting, check to make sure you’re knifing into the soil. Hairpinning – pushing chaff or straw into the seed slot instead of slicing through it – tends to be more a problem with air drills, particularly when seeding into no-till. Sunflower plants where hairpinning is a problem can have weak root systems and thus weak stands. Hairpinning is more of a problem when residue is wet – resolving the issue may be a matter of waiting until standing stubble becomes dry, and slicing through becomes easy. In other cases, you may need to sharpen drill discs/blades, or adjust down pressure.

Replanting – Of course, when planting sunflower late (generally after June 10 in the Northern Plains) or replanting, use an early-maturing hybrid. The fact that sunflower performs well at lower populations suggests that replant is an option that might be best left for extreme early stand losses, especially in the shorter growing season of the Northern Plains. Some agronomists advise replanting only if a stand falls below a threshold of about 12,000 to 15,000 plants, or more than 25% of your yield goal. Otherwise, you’d be losing two weeks of crop maturity, and the successful establishment of the replanted crop isn’t a guarantee either. - Tracy Sayler

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