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The "Too-Dry" Dilema

Friday, August 1, 1997
filed under: Harvest/Storage

Every sunflower producer knows that if he delivers seed to his local elevator at moistures above 10 percent, he’ll be discounted. He also knows that delivering seed below 10 percent will not earn him a premium. In fact, those lower moisture levels carry a distinct monetary penalty: fewer pounds delivered and paid upon. One hundred pounds of sunflower at 10 percent moisture, for instance, will end up as slightly less than 95 pounds when at five percent.

Using the example of (1) 250 acres, (2) an average yield of 1,500 pounds and (3) a market price of 10 cents, delivering five-percent moisture sunflower will cost the grower nearly $1,900. And that’s not taking into account the harvest losses left in the field due to what almost certainly will be a higher level of shatter with exceptionally dry seeds. So the moral of this story is to harvest one’s sunflower seed crop as close as possible to 10-percent moisture.

Now, if only it was that simple!

Northern producers often contend with the opposite problem: bringing their crop down to 10 percent from field moistures in the mid- or upper ’teens. Some Minnesota and Dakota producers deliberately opt for an early high-moisture harvest, believing that the cost of drying is more than offset by the reduction in shatter loss and exposure to pests and late-fall weather, along with generally lower foreign matter.

Across the High Plains and parts of South Dakota, however, harvested seed moistures well below 10 percent are common. “When we have a south wind, 20-percent or less humidity and tempera-tures in the 80s or 90s, they’ll lose three points a day. I think many people get caught because they come down so rapidly,” says Ken Berndt, field represen-tative for Northern Sun at Goodland, Kan.

Berndt cites the case of a grower who had done a test cut the day before he arrived for a field visit. “They were wet, so he figured he’d come back in about two weeks,” the processor representative recalls. Berndt told the grower the ’flowers would probably be ready to harvest within two days, not two weeks. “He couldn’t believe it; but sure enough, they were ready to go.”

Veteran central South Dakota sun-flower sales agronomist Sam Heikes says low-moisture seeds often take dollars out of the pockets of growers in his area as well. “There definitely are problems every year,” he remarks, “especially with the typical end-of-September South Dakota weather following a 26- or 27-degree frost. There’ll be a couple of 60- or 70-degree days, windy, with low humidity.” Moistures can plummet from 14 or 16 percent down to seven or eight. “And all of a sudden the grower thinks, ‘Now my ’flowers are ready,’ when in fact they were ready five days before that,” Heikes says.

Complicating the achievement of a timely sunflower harvest, of course, is the producers’ workload with their other crops. “High Plains producers start out seeding winter wheat; they go to harvesting dry beans; and then, right after they’re done with the beans, the ’flowers are usually ready,” points out Ron Meyer, Burlington, Colo.-based area agronomist for Colorado State University. “If they can’t get to the sunflower fields right away, it’s corn harvest time.” By the time the area’s irrigated corn acreage is combined and the producer jumps back to his sunflower crop, “we’re often harvesting five-percent moisture sunflower,” Meyer indicates.

Meyer, Heikes and Berndt all emphasize the additional shatter loss that typically occurs with low-moisture sunflower — not only at the combine header, but while the plants are still standing in the field with their heads jostling against each other. “There’s more foreign matter, too,” Berndt stresses, “because the plant heads are so brittle and break out easier.” Adds Meyer: “If there’s any wind in the area — which we always have at that time of year — we get stalk breakage. And if they have any stem weevil activity, it can become a disaster.” Heikes would like to see his area’s sunflower harvesting begin when the seeds are around 12 to 13 percent moisture — mainly because the level could be down to 10 percent within a day or so. The ideal would be to start “two points wetter than you like and end a point or two drier [than 10 percent],” he suggests. Even if the crop averages 12 percent or so, the aeration systems installed in many area farm bins can easily bring that down to 10.

With confection sunflower, Heikes strongly encourages harvesting on the damp side. Given the confections’ low populations (12,- to 14,000) and larger heads, they tend to dry quickly around the outer edge of the heads. “So with a couple warm, dry, windy days, all of a sudden there’s a lot of shatter on the ground because the edges of the head relax their hold on the seed,” Heikes notes. “I tell people, ‘If you’re going to grow con-fections here, you have to plant them thin and uniform, keep the bugs out of them, and be able to harvest at 13 to 14 percent to avoid shatter, keep the FM down and then air-dry them to maintain quality.”

“When you see the plants starting to dry down, get ready,” advises Northern Sun’s Ken Berndt. “When you see very little green, unless you’ve had a rain, they’re going to be dry.” —Don Lilleboe
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