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Sunflower Row Direction

Monday, March 28, 2011
filed under: Planting Systems

North/South or East/West. Does the direction in which your sunflower fields are planted make any difference in your bottom line at year’s end?

For many growers, it’s a mute point. They may be locked into one or the other due to the field’s shape, terrain or access points — or by their particular cropping system. For others, though, it’s a topic that could merit some consideration.

The question is hardly new. Back in the mid-1970s, University of Minnesota agronomist (and pioneer sunflower researcher) Robert Robinson conducted experiments on the effect of sunflower row direction. He concluded there was no significant difference in yield, oil percentage, seed weight or test weight of sunflower planted in east/west versus north/south rows. (He did, however, find significantly more lodging in the east/west rows.)

In 1988-90, Kansas State University agricultural engineer Gerald Thierstein conducted a study to learn whether sunflower row orientation had a measurable impact on harvest shatter loss and final yield. He planted three different hybrids, used three different combine header attachments and also factored in three different cutting heights. The three years produced differing results, and Thierstein ended up concluding that when it came to harvest losses, there was no appreciable difference.

Bruce Due, Breckenridge, Minn.-based agronomist with Mycogen Seeds, says he suggests growers who do have a choice should opt for the north/south route. Why? He lists several reasons:

• “North and south rows have potentially better weed control, as most of the row is shaded from sunlight when sunflower reaches the three-foot height stage,” Due observes. In east/west fields, more sunlight strikes the ground surface during more of the day, he points out, whereas the sunflower plants catch more sun, overall, in north/south rows.

• “Sunflower heads end up facing east during seed fill and into harvest,” Due continues. “In north/south rows, that means the head is facing out into the inter-row area. So there’s less chance of heads rubbing against their neighbors, causing seed loss.”

• Also, since sunflower heads remain facing east following the bloom period, plants in north/south rows “tend to be more difficult for birds to feed on, because the head is facing away from nearby plants in the row — thus creating less-available perch sites from which to feed on neighboring heads.”

• Finally, Due says, “rows planted north/south tend to fare better than east/west planted rows during summer and early fall wind storms. Most of our summer storms come out of the west. When plants partially lodge, it’s more difficult to pick them up and gather into the combine header when they’re leaning down the row rather than across the row.”

Scott Foth is in agreement with Due. The Onida, S.D., grower says most of his sunflower is planted in north/south rows for the above-described reasons, although occasionally he’ll have a field whose shape does not allow it.

As in North Dakota and western Minnesota, winds in central South Dakota predominantly come from the northwest, Foth notes. If sunflower plants lodge from strong winds, he has pipe extensions on his header that slide on the ground to facilitate picking up the stalks and heads and feeding them into the combine. “With the heads already facing east and with wind gusts tipping the flowers over to the east, the head helps hold the stalk up off the ground, allowing the pipe extensions to get under the stalk that helps pick the heads up off the ground and bring them into the combine header,” Foth says. “The success rate would not be as high, were the downed plants lying parallel with the row.”

Corn often precedes sunflower in Foth’s rotation, and that’s another consideration. The corn is planted north/south, “and we plant our sunflower between the old corn rows,” he notes. He doesn’t like planting perpendicular to the corn rows in his minimum-till fields “because you don’t get as good a stand, it is harder to move the trash, and it’s hard on the planter going across those rows.”

Ron Meyer also leans in favor of north/south rows. The Burlington-based Colorado State University area agronomist cites the reduced amount of head contact with neighboring plants during High Plains wind events, lessening shattering potential, as a key reason why. That’s naturally more of a factor in higher-population fields where plants stand closer together. “At a lower population of 17,000 plants per acre in 30” row spacings, there’s a one-foot interval between plants, easing the sunflower head rubbing concern,” Meyer points out. “With thicker stands, plants are closer together.” — Don Lilleboe
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