Ontario Grain Farmer February 2024

14 Research Determining soybean yield INFLUENCE, FACTORS, AND VARIABLES Ontario Grain Farmer NOTHING IN AGRICULTURAL RESEARCH ever unfolds quickly, nor are desired results guaranteed. Delving into data and distinguishing between viable recommendations and the anomalies that may arise is enough to discourage the most resilient individuals. Every treatment, weather vagary, soil characteristic and parameter is under scrutiny to achieve consistent and reliable results to help growers. When it comes to increasing soybean yield, there have been advances in plant performance through selective breeding and transgenics, the effects of tillage, and the use of fertilizers and chemical products. The ultimate question before researchers and extension personnel is whether reducing the variability in soybeans is possible. A more enticing view of this research is the project, “100-Bushel Soybean: What’s Really Holding Us Back?” A joint three-year effort between the University of Guelph, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), and funded by Grain Farmers of Ontario, it is trying to unravel the mystery of the primary influences in production. It is also the focus of Matt Rundle’s master’s project, with the goal of examining the critical variables of soybean production during growth stages R2 to R5. Rundle has been working since 2021 with Drs. Hugh Earl, Dave Hooker, and Istvan Rajcan from the University of Guelph, and Horst Bohner from OMAFRA. THE PROJECT PARAMETERS The research plots were laid out in three locations each year, providing nine site years: at Bornholm, Elora, and Woodstock in 2021 and Elora, Woodstock, and Maryhill in 2022 and 2023. Three varieties (A, B, and C) were tested in 2021 and 2022; a fourth, longer-maturing variety (D) was added in 2023. Twelve different treatments were used (see Table 1), with four untreated checks, one intermediate (half-rates of fertilizer, nitrogen and foliar fungicide) and “everything” treatments on all four varieties. IMPORTANT DETAILS The R2 to R5 stages encompass flowering and pod set, and the research hopes to explain how that range determines yield, including pod numbers, seeds per pod, and seed size. Since 2021, Rundle has been tracking above-ground biomass, interception of incoming solar radiation into the canopy and greenness, among other characteristics. Not achieving 100 bushels/acre yields or higher in soybeans will not make the project a failure, notes Rundle. The goal is to learn more that could be used in managing the crop, not to uncover some type of “silver bullet.” The 2023 data were still being analyzed at the time of writing, but there are some visible results that could be shared from those plots. Although they were not what Rundle hoped to see in some treatments, there were some intriguing indications. “There was a significant yield response to the ‘everything’ package with 61.8 bushels/ TABLE 1: 2023 COMBINED YIELD—ALL LOCATIONS Rank Treatment (number, variety and type) Yield (bushels/acre) at 13 per cent moisture 1 #6 “Everything, Variety C” (fertilizer, N and foliar fungicide) 69.5 2 #5 “Everything, Variety B” (fertilizer, N and foliar fungicide) 69.0 3 #7 “Everything, Variety A” (minus foliar fungicide package) 66.6 4 #4 “Everything, Variety A” (fertilizer, N and foliar fungicide) 65.4 5 #9 “Everything, Variety A” (minus fertilizer package) 65.3 6 #10 “Intermediate, Variety A” (half rates*) 63.0 7 #12 “Everything, Variety D” (fertilizer, N and foliar fungicide) 61.8 8 #8 “Everything, Variety A” (minus N package) 58.3 9 #2 “Control, Variety B” (uncreated check) 58.0 10 #11 “Control, Variety D” (untreated check) 56.8 11 #1 “Control, Variety A” (untreated check) 56.5 12 #3 “Control, Variety C” (untreated check) 53.0 Source: Matt Rundle, University of Guelph

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