What he refers to as “shallow ridge-till” is providing Dennis Demmel with a very viable means of effective weed control in his dryland sunflower — without the use of herbicides.
The southwestern Nebraska producer raises about four-fifths of his confection ’flower crop under dryland conditions and the remainder under center-pivot irrigation. Sunflower typically follows corn in his dryland scheme, with wheat going in the fall of the following year on the sunflower ground. It’s a sequence he says has resulted in improved yields for both wheat and sunflower — and generally better weed control throughout the rotation.
The first order of business on Demmel’s dryland sunflower fields is a shallow preplant tillage pass with his Buffalo cultivator. That occurs anywhere from a few days to a few weeks prior to his typical early June planting date. “We have special sweeps so we can undercut across the full width, including beneath the row,” he indicates. The shorter of the over-lapping sweep blades (see photo below) is 24 inches in length; the longer blade, 36.
“We’re establishing a traffic pattern,” Demmel notes regarding this preplant pass. “The idea is to move residue over the row to conserve moisture within that row.” The overlapped sweep blades also cut off the stumps in the previous year’s corn rows.
At planting, the slightly angled sweeps on Demmel’s Buffalo ridge planter run about two inches below the soil surface, cleaning out any volunteer corn and other weeds from the row and creating a shallow furrow where the sunflower is planted. He’s seeding in 30-inch rows, shooting for an eventual confection stand of around 14,000 plants per acre. (That population jumps up to 18,000 on the irrigated acreage, where Demmel uses a more-conventional ridge-till approach.)
When cultivating while the sunflower is in the 12- to 18-inch stage, Demmel moves soil back into the sunflower furrow, covering small weeds within the row while simultaneously taking out emerged and shallow-germinating weeds in the row middles. Because he is working so shallow, he says he has no problems with pruning of sunflower roots.
In 1997, Demmel also seeded a sweetclover cover between the sunflower rows with a Gandy applicator mounted on the cultivator. The Buffalo cultivator additionally has served as an application tool for sidedressing liquid nitrogen on the dryland ’flowers.
To maintain as much surface residue as possible, Demmel hasn’t run a disk across his dryland ground for several years. Employing only shallow tillage also tends to keep weed seed populations at or near the soil surface, he notes, where his planter sweeps can clean them out of the row.
Demmel, who is an active member of the Nebraska Sustainable Agriculture Society, says his objective “is to reduce herbicide use to zero, if possible.” He hopes to eventually produce certified organic crops on his Perkins County fields. — Don Lilleboe
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