Weather permitting; planters will start rolling across the Eastern Corn Belt in a few weeks. Soybeans, just like corn, will benefit from careful planning and attention to detail. Today’s soybean varieties have the potential to achieve yields of more than 70 bushels/acre when managed intensively. As growers head to the fields this spring, they should start planning management programs to harvest top-end yields this fall.
Planting Date and Field Conditions
Planting date is an important factor determining soybean yields. Purdue research demonstrates that optimum planting dates for soybeans are from late April to mid-May. Ohio State University planting date studies show a .6 bushel per day loss in yield potential when soybeans are planted after mid-May. Just like corn, delayed soybean planting can result in significant yield losses. Earlier planting will benefit soybean fields in several ways. In a recent C.O.R.N newsletter (link: https://agcrops.osu.edu/newsletter/corn-newsletter/2015-09/soybean-planting-date-seeding-rate-and-row-width ), Ohio State University’s Laura Lindsey wrote: “The greatest benefit of planting May 1 to mid-May is canopy closure which increases light interception, improves weed control by shading out weeds, and helps retain soil moisture.” Soybeans should be planted at a depth of 1-1.5 inches when soils are at least 50 degrees F and and dry enough to perform field work. Planting when soil is too wet, or “mudding-in” seed will cause more yield loss than delaying planting a few days to let soils dry out.
Row Spacing and Seeding Rate
Higher soybean yields result from narrower row spacing (20in or less). According to an article published in Corn and Soybean Digest: “Just switching from 30-inch rows to spacing of 20 inches or less boosted soybean yields an average of 2.9 bushels per acre. That is greater than the 2.3-bushel yield bump that resulted from implementing a full program of fertilizer (both dry and foliar), inoculants, seed treatments and foliar fungicides on beans planted in 30-inch rows.” Appropriate seeding rates will vary based on planting date and row spacing. Planting populations will vary based on planting date, row width, and soil type. Using university recommendations for planting rates is a great place to start. While recent data suggests it is possible to lower planting rates and still achieve high yield potential, field conditions, timing, and row spacing should be considered when making adjustments to rates. Premium seed treatments are needed to insure a uniform stand.
Starting with, and maintaining a weed-free field is essential to achieving high yields. With increases in herbicide-resistant weed populations, competition with soybean plants for nutrients is becoming a larger concern. A marestail fact sheet published by Purdue and Ohio State documents an 8 bushel/acre yield loss when spring burndown is effective but no residual herbicides are applied and as much as a 14 bushel/acre yield loss when spring burndown is not effective. This fact sheet recommends the following actions to control weeds: 1) fall and spring burndown treatments (or two spring treatments – early spring and at plant) to ensure that the field is free of marestail at the time of soybean planting, and 2) spring-applied residual (PRE) herbicides to control marestail for another 6 to 8 weeks after planting.”
Because planting sets the stage for the entire growing season, it is a critical factor that determines yield potential. Taking the time to get soybean plants off to the best possible start will pay off in the end. Paying attention to details while intensively managing soybeans will allow growers to maximize productivity and reap the rewards of higher yields in the fall of 2018.