(Editor’s note: Matthew Hankinson contributed to this article) Spring is right around the corner, and it is time to start thinking about when we are going to get our planters out of the shed and into the field. Timely planting is usually thought of as being less critical for soybeans than in corn, but the date of planting has the greatest effect on yield of any production practice.
Last year, planting was delayed due to wet soil conditions across most of the state. For southern Ohio, planting should begin after April 15th as conditions permit. In northern Ohio, aim to be in the field near the end of April. The I-70 corridor can act as a separation of these two regions that is easy to remember. From the Ohio Agronomy Guide, significant yield reductions occur when planting occurs after May 10th and can be seen in the chart below.
Before heading to the field, consider the conditions you will be planting into. Soybean germination begins when soil temperatures reach 50°F and moisture is present at the planting depth of 1-1.5 inches. In these conditions, emergence can typically be expected 2-3 weeks after planting. Do not plant early if the soil is excessively cold or wet. Slower germination and compaction can negate the benefits of the earlier planting date.
Why plant early? The greatest benefit is that canopy will close sooner in the growing season. In 2013, the rate of canopy closure in 30-inch rows was 1.5% per day. Narrower rows will close quicker than wide rows. Canopy closure has three benefits:
1. Light interception. Maximum light interception occurs when the canopy is closed, which increases vegetative growth and yield potential.
2. Weed control. Weeds that have not grown past the canopy level can be shaded out by the soybeans, reducing competition and yield loss.
3. Soil Moisture. After canopy closure, soil water loss through evaporation is minimized and can be retained for the grain fill period.
However, earlier planting does not come without risk. Factors such as damping off and pressure from the bean leaf beetle are always concerns to keep in mind, as well as the possibility of a late spring frost, all of which were seen in different areas of the state last year. Timely planting is critical for maximizing yield in soybeans, but using good judgment as a grower on field conditions play a role that is equally important to determining yield potential.