To learn more about soybean yield variation based on row spacing, Farm Journal Associate Field Agronomist Missy Bauer used a Case IH Early Riser and a Great Plains Yield-Pro planter to plant 15", 30" and twin-row replicated test plots.
In-field studies focus on row spacing, white mold remedies and cyst nematode control
The Farm Journal Test Plots were organized more than 20 years ago to study soybean row spacing. While the program has been expanded through the years to include corn and other agronomic management subjects, Farm Journal Agronomists Ken Ferrie and Missy Bauer still invest time and effort into soybean plots to answer farmer questions.
In 2012, in the eastern Corn Belt, Bauer conducted plots on soybean row spacing as well as methods for treating white mold and controlling soybean cyst nematodes. Ferrie also conducted a soybean cyst nematode test plot in central Illinois. These plots, like all Farm Journal Test Plots, were harvested with a calibrated yield monitor and grain carts with scale packages for accuracy.
Close the Canopy
The discussion of what row spacing is best for soybeans continues to be a hot topic as many farmers transition from more narrow rows to 30" rows to use one planter for both corn and soybeans.
"It’s a trend being driven more by mechanics than agronomics, and there is a high percentage of acres going into 30" soybeans," Bauer says. "As a result, we thought it would be important to compare 15" rows to 30" and twin rows (8" twins on 30" centers). For the past decade, the standard row spacing was 15" in the eastern Corn Belt."
To evaluate yields by management zone, every Farm Journal Test Plot is harvested with a calibrated yield monitor and grain cart with scales.
At one of the test plot locations, Bauer’s crew used a Case IH Early Riser planter for the 15" and 30" soybeans and a Great Plains Yield-Pro planter for the twin-row soybeans. At the second location, the plot compared twin rows planted with the Great Plains planter to 15" rows planted with the Case IH Early Riser planter and 15" rows with a drill. A third location compared twin rows to 15" rows planted with the farmer’s planter.
"We would expect the 15" rows to allow for early canopy closure, which is especially beneficial in a dry year such as 2012, our first year for this study," Bauer explains. "The 30" rows were the slowest to close and in some soil types never did with the dry conditions and short plant heights this past year."
In addition to canopy closure, row spacing affects branching of the plants—and there’s a compromise between early canopy closure and branching. "The 30" rows had more branching followed by the twins then the 15" rows. In the wider rows more sunlight reaches the lower canopy inducing more branching," Bauer says.
But the trade-off of more branching wasn’t enough to make up for the penalty realized because the canopy did not close. For example, at the location that included all three spacings, the 15" and twin-row soybeans yielded similar, but the 30" soybeans yielded 2.5 bu. less.
"In a dry year, the successful establishment of soybean stands really come into play, which is why we also did a study looking at soybeans planted with a planter and a drill," Bauer says. "Farmers probably don’t look at drill performance as closely as they should."
One of the common questions about row spacing is whether the yield advantage solely stems from the row width or is it also linked to the planters’ ability to uniformly seed compared with drills. We compared 15" rows planted with the Case IH Early Riser to a drill at two locations and evaluated uniformity and consistency of stand. The planter provided more uniform spacing and emergence as well as more consistent stand counts when compared with the drill. The stand counts in the drilled plots varied on average by 38% or nearly 50,000 plants per acre, while the variation in the planter plots was only 7% and less than 9,500 plants per acre.
"However, at harvest the yields were comparable," she says. "The lesson comes down to the economics of seed. The stand count that you actually achieve affects how much you’ll overseed your soybeans."
Bauer challenges farmers to narrow the gap between planted seeds per acre and stand counts after emergence.
When White Mold Strikes
It’s common for the eastern Corn Belt (specifically southern Michigan, northern Ohio and northern Indiana) to have outbreaks of white mold. To learn more about the products on the market to control the disease, Bauer oversaw three test plot locations in 2012.
"Two of these plots were irrigated, and the third had a history of white mold," she says. "We applied Contans, Cobra and Domark."
Contans WG, a product from SipcamAdvan, contains fungal spores. Applied to the soil, Contans WG targets and controls Sclerotinia diseases. Domark is a fungicide labeled for suppression of white mold; application is suggested at R1 if the environmental conditions are conducive for the disease. The combination of Cobra at V5 and Domark at R3 is also labeled for suppression of white mold.
White mold infection can occur at flowering, and wet, humid conditions increase the likelihood of an outbreak. Due to the lack of humidity and high temperatures this past growing season, white mold pressure was low.
"Most years, we would be on the lookout for white mold because it is something we deal with on a regular basis. But we need to remember that disease is a function of the disease triangle, and, in 2012, we didn’t have the environment for white mold infections," Bauer says.
She will keep an eye out for white mold in the eastern Corn Belt this year.
Sights on Cyst Nematode
The yield-robbing soybean cyst nematode is a pest on the rise. Ferrie and Bauer partnered with Syngenta to learn more about how a plant’s genetics and seed treatments could work together to control cyst nematode. Each agronomist selected fields with known histories of pressure and planted two varieties—one with a soybean cyst nematode package and one without.
To better understand soybean cyst nematode control options, Farm Journal partnered with Syngenta, which provided soybean varieties with and without a soybean cyst nematode package and with and without an Avicta treatment.
Ferrie planted S35-T9 with the soybean cyst nematode package and S33-K5 without. Bauer planted S29-V2 with the package and S28-K1 without. All of the varieties were treated with Avicta Complete as well as left untreated. Avicta Complete Beans is a combination of Avicta 500 FS seed treatment nematicide and CruiserMaxx Beans insecticide/fungicide seed treatment.
The Farm Journal Field Agronomists used Normalized Difference Vegetation Index (NDVI) and yield maps to identify hot spots where soybean cyst nematode populations are higher and yields are most affected. Ferrie’s data showed a 1-bu. response to the Avicta treatment overall. The greatest response to the treatment, which was up to 10 bu. per acre, was in the pockets of known higher pressures.
In Bauer’s plot, when the S29-V2 variety was treated with Avicta, yields jumped 2.7 bu. to 3.1 bu. per acre compared with the same variety minus the treatment. When the S28-K1 variety was treated with Avicta, yields increased 0.9 bu. to 1.1 bu. per acre compared with the same variety without the treatment.
"This was our first year to collect data," Bauer notes. "We found that the seed treatment improved yield in both varieties, but the cyst bean with the Avicta treatment yielded best."
The mix of genetics and seed treatment help protect the root system, which leads to more pods per plant and number of beans per pod, Bauer explains. The variety with the soybean cyst package and the Avicta treatment yielded 6 bu. to 10.6 bu. per acre more than the non-cyst variety with the Avicta treatment.
In addition to the genetic differences in the varieties, the maturity difference also might have been a factor in the yield response. Bauer says that in her plots the longer maturity 2.9 soybeans might have been able to take greater advantage of late August rains, helping to improve yields in comparison to the 2.8 maturity soybean.
Both Ferrie and Bauer plan to continue their study in order to provide farmers with more information about which genetics and seed treatment combinations can provide the most reliable soybean cyst nematode protection.
Thank You to Our Test Plot Partners
Our thanks go to: AGCO, Ed Barry, David Webster, Luke Olson, Reid Hamre and Lindsey Pettyjohn; Farm Depot and Mark Laethem; Case IH, Bill Hoeg, Luke Gazaway, and CJ Parker; Contans and Scott Peterson; Great Plains Manufacturing, Tom Evans, Doug Jennings and John Sites; New Holland, Mark Hooper, Gary Wojcik and Paul Canavan; Williams Farm Machinery and Dave Gloor; Syngenta and Palle Pederson; Trimble, Sid Siefkin and Brian Stark; OmniStar and John Pointon; Unverferth Manufacturing and Jerry Ecklund; Wells Equipment; Valent and Neil Badenhop; Jim Caldwell; Mark and Gene Froelich; Bob and Mary Kochendorfer; LDK Farms and Leon Knirk; Adam Richmond and Calvary Farms; Scott Simington; B&M Crop Consulting, Bill Bauer, Vicki Williams, Gary Cooper and Megan Tomlin; and Crop-Tech Consulting and Zach Ferrie.
You can e-mail Margy Fischer at firstname.lastname@example.org.
- Late Spring 2013