Tom Tveit had both the “motive” and the “means” when he decided to plant one of his 1997 confection sunflower fields in 15-inch rows.
The motive consisted of a desire for uniformly large head size throughout the field. Tveit believed 15-inch row widths could help achieve this by providing more of an equidistant spacing among plants within rows and between rows. Such a field configuration would, as well, benefit from a more-optimum utilization of soil moisture, nutrients and sunlight.
The means took the form of Tveit’s White 6300 horizontal rear-fold planter which allowed him to easily convert from 30- to 15-inch rows. Precise seed placement — an essential component in the endeavor — would be enhanced by the planter’s individual positive air metering system.
With 30-inch rows and his seed drop rate of 17,000, the spacing between in-row plants is about 11 inches — the result often being heads smaller than what Tveit preferred. By going to the 15-inch rows, the in-row spacing between seeds was actually closer to 18 or 19 inches.
The result of this central South Dakota experiment was a field which generally fulfilled Tveit’s objectives. Head size among the confection plants was uniformly quite large, and the eventual plant stand of approximately 16,000 per acre fit in well on the 15-inch rows, he says.
(The field did incur some rust infection and stem weevil/Phoma damage, which affected final test weight and seed size. But it’s not believed those problems were connected to the narrow-row spacings.)
Though the ’97 confection field, located about 12 miles north of Pierre, was under a center pivot, the area’s adequate precipitation last season negated any need for irrigation. The field had been seeded to spring wheat in 1996, but was hailed out prior to harvest. Tveit chisel plowed the ground late that fall and then worked it twice the following spring — the second time with a soil finisher while incorporating Treflan. (Con’t. on Page 18)
The convertible planter — which seeds 16 rows when set up on 30-inch spacing — covers 17 rows at 15 inches. It’s set up for no-till conditions with Dawn Trash- wheels and John Deere fertilizer openers. The openers are set for 2x2 placement on the 30-inch rows. When running on 15-inch rows, however, “I take out of play the eight rows that we normally run with the ends; so four on each side don’t deliver any fertilizer,” Tveit explains. Of the unit’s two squeeze pumps, one is shut off when he’s running the narrow-row configuration, and the other one pumps to the middle eight units.
“I use quite a bit of phosphorus,” Tveit indicates. “We put down 8.5 gallons of 10-34-0 with the confections, which is probably a little above average for sunflower in this area.” He also applied 125 pounds of liquid nitrogen, using it as a carrier for the Treflan.
Seed drop was slightly over 17,000 per acre, with a mid-season estimated plant stand right around that 16,000 level. The Hughes County grower says he’s comfortable with that population under 15-inch rows and may even increase it slightly in 1998.
Weed control was aided by rapid canopy closure of the 15-inch rows. Despite a cooler-than-normal spring, the confection field was almost fully canopied within 40 days of planting (see photo on page 16). Between the Treflan and the narrow-row canopy, weeds were effectively controlled throughout the field, Tveit reports. Some nightshade did poke through the ’flower canopy in isolated spots toward the end of the growing season, but it was too late to have an impact on crop yield.
Tveit definitely plans to go with 15-inch row spacings on his sunflower crop again in 1998, though he has yet to decide whether to plant 15s across his entire acreage. Depending on the field, his tillage program runs the gamut from conventional to no-till. While the ’97 field was conventional, he may try 15-inch rows on some no-till ground this coming spring, applying Roundup preplant and then counting on the crop canopy to suppress later-emerging weeds.
Though he likes what he’s seen thus far with the narrow-row approach, Tveit does admit to at least one downside in the program: tramping through the field while scouting for mid-season insects. “It was difficult,” he laughingly acknowledges. “About the time we were looking for seed weevil, I was out there once and became totally disoriented” by the tight rows and tall, thick canopy.
Given the system’s various advantages, however, he concedes it’s a fairly minor dilemma. — Don Lilleboe
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