Update:
Final Report: Updating Agronomic Recommendations for SoybeanPI: Laura LindseyGraduate Student: Michelle Shepherd (To graduate May 2018; received employment with DuPont Pioneer in Napoleon, Ohio)Project Summary: The objectives of this project wereto: 1.) Evaluate the effect of planting date and relative maturity on soybean yield, 2.) Evaluate the effect of row width and seeding rate on soybean yield, 3.) Develop agronomic strategies that reduce temperature stress on soybean plants to maximize yield, 4.) Update Ohio Agronomy Guide recommendations and distribute results to Ohio soybean farmers at field days/winter meetings and newsletter articles. Completion of these objectives will help farmers determine best management practices that will improveyield for Ohio soybean farmers by providing revisions to Ohio planting date x relative maturity recommendations which were originally developed over 20 years ago.Objective 1: Evaluate the effect of planting date and relative maturity on soybean yield.Results: The soybean relative maturity that resultedin the highest yieldvariedyear-to-year based on the environment and growing conditions. Table 1 summarizesthe range of relative maturities where yield was the greatest.In general, soybeans yield well over a range of relative maturities, and should not be the first factor considered when purchasing seed.Table 1. Soybean relative maturity that resulted in the highest yield across two years.Wood CountyWayne CountyClark County Mid-May3.3-3.62.8-3.63.3-3.8 Early June3.1-3.32.2-3.32.8-3.6Objective 2: Evaluate the effect of row width and seeding rate on soybean yield.Results: There was no difference in yield between 7.5-and 15-inch row widths. On average, there was a 9 bu/acre yield reduction when soybeans were planted in 30-inch rows compared to narrow rows (7.5-or 15-inch row widths).When planting soybean in May (in general), a harvest stand of 100,000-120,000 plants/acre is required to maximize yield. How much seed to plant to achieve 100,000-120,000 plants/acre at harvest depends on soil, weather after planting (crusting), planter/operator, etc. In most situations, planting 140,000 seeds/acre is adequate to achieve a final stand of 100,000-120,000 plants/acre. In areas where emergence may be poor or for later planting dates, higher seeding rates may be required.
Objective 3.Develop agronomic strategies that reduce temperature stress on soybean plants to maximize yield.Results: Across the Midwest, high temperatures in July reduce soybean grain yield (Mourtzinis et al.,2015). Promoting soybean canopy cover is one strategy to reduce the effect of high temperature in July.Soybeans planted in mid-May achieved canopy closure during the third to fourth week of July while soybean planted in early June achieved canopy closure up to ten days later.At the Northwest Agricultural Research Station in 2016, the soil surface temperaturein July was influenced by planting date.When soybeans were planted in May, soil temperature ranged from 79 to 85°F while soil temperature was 87 to 93°F when soybeans were planted in June. Additionally, when planted in May, soybeans with later relative maturity (3.3-3.8) also had cooler soil temperatures. Cooler soil temperature was associated with higher soybean yield (Figure 1).
Objective 4.Update Ohio Agronomy Guide recommendations and distribute results to Ohio soybean farmers at field days/winter meetings and newsletter articles.Results: The Ohio Agronomy Guide(15thedition)was updated and is available for purchase (hardcopy) or download as a free pdf here: https://stepupsoy.osu.edu/soybean-production/ohio-agronomy-guide-15th-edition