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Strip-Till Success

Tuesday, January 1, 2008
filed under: Minimum Till/No-Till

Sometimes, getting halfway to your original objective is good enough; maybe even better.

Such is the case for Ravenkamp Farms of Hugo, Colo. The Ravenkamps — Stan, Lyle (Stan’s brother) and Scott (Stan’s son) — began raising sunflower in the mid-1990s under conventional tillage. Already producing no-till wheat, corn and proso millet, their goal was to transition sunflower into a no-till crop as well.

But sunflower stands under no-till in their southeastern Colorado vicinity were not very satisfactory at the time — mainly because of seed-to-soil contact issues. That, coupled with the scarcity of herbicide options for no-till ’flowers, prompted the Ravenkamps to pursue an intermediary step: strip-till sunflower.

The Ravenkamps did have a couple sunflower fields under no-till this past season, following a low-residue 2006 wheat crop. But most of their 1,500 acres of ’07 sunflower went in strip-tilled on old corn ground. “Corn stalks are a tremendous nurse crop,” Stan says in reference to the protection provided young sunflower plants.

Weed control is another benefit accrued by following corn. The Ravenkamps stress the critical importance of good weed management in their preceding wheat and Roundup Ready® corn crops. “We don’t want any weeds,” Stan affirms. “We don’t have enough moisture for the crop alone, much less to share with the weeds.”

Their corn ground is typically quite clean through harvest. The Ravenkamps come back the following spring with a Spartan treatment, counting on an early spring rain for incorporation. That’s followed by a preplant Roundup burndown. Prowl is an option for grass control in the sunflower, if needed.

“We have a lot of broadleaves, but [between the Spartan and Roundup] we don’t have much trouble controlling them,” Scott indicates. “We don’t have many grasses; but a couple (jointed goatgrass and stinkgrass) are really hard to control.” The only situation under which the Ravenkamps cultivate their strip-tilled sunflower acreage is if significant late-season flushes of puncturevine show up. Stan estimates they’ve cultivated about 10% of their strip-till acreage over the past five years.

The Ravenkamps’ strip-till unit is a converted 12-row Hiniker cultivator. Their strip-till zone is narrow (less than 5”) and shallow (just 4 to 6”) in order to conserve as much moisture as possible. Rather than run a rolling basket behind the strip-till unit, they’ve fitted it with rubber press wheels to break up clods and pack the seed row.

“We don’t ‘rip’ with our strip-till machine, and we don’t have much of a mound (berm),” Stan notes. “The narrower the point, the better.

“Sunflower is, in my opinion, the best ‘ripper’ you can have,” he continues. “If you have a hardpan and can get ’flowers to grow into it, you’ll eliminate that hardpan.” The Ravenkamps believe deep ripping in their arid climate is an unnecessary and to-be-avoided mistake due to the additional moisture loss it generates. “All we’re trying to do is make the seedbed and put down some fertilizer,” Scott emphasizes. “The sunflower is going to ‘rip’ for us.”

The Ravenkamps run their strip-till unit and sunflower planter at about a 10° angle to the old corn rows. They don’t want to plant into the corn stalks, of course; nor do they want to run their strip-till unit or planter in between the corn rows (too hard on tractor tires running on the corn stalks). The slight 10° angle allows them to avoid those situations while minimizing “wasted” acreage in field corners.

They’ll typically do the strip-till pass by mid-May and then plant the ’flowers in early June. “If we can strip till and then get a rain, the conditions are ideal,” Scott says. They raise strictly high-oleic varieties, which thrive under their cool-nighttime high-altitude (5,300 feet) conditions. Seed drop runs around 20,000, with a targeted plant stand between 17,500 to 18,000.

Being in an extremely rural locale, the Ravenkamps’ early season plant stands are threatened not only by insects (wireworms and cutworms), but also by rabbits, ground squirrels, deer and antelope. And how many other sunflower growers find field portions pockmarked with coyote and badger dens? Cruiser®-treated seed controls the wireworm effect. As for the coyote and badger dens, they’ll run sweeps 4 to 6” deep prior to planting proso millet the year after sunflower. “That’s simply to to get rid of badger and coyote holes,” Scott remarks, “so we can swath and pick up [the proso millet] without fighting those big holes.”

Given their sparse precipitation (15” is the long-term annual average), the Raven-kamps’ dryland sunflower yield goal is typically 1,000 pounds per acre. They’ve exceeded that quite often, though, and have averaged 1,800 pounds across several fields in recent years. — Don Lilleboe

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