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Delayed Soybean Planting Considerations

Soybean Planting Date

DuPont Pioneer research has consistently shown the value of timely planting of soybean; however, spring rain has delayed planting in many areas.
Several management considerations can help maximize soybean yield with late planting.

It is generally not advantageous to switch to an earlier maturing variety unless planting is severely delayed (later than June 15).
In very late planting scenarios, a soybean variety of 0.5 to 1.0 shorter maturity group is recommended.
Because soybeans are photoperiod sensitive, they will flower at the same time despite planting date and relative maturity. Earlier planted soybeans simply have more nodes and greater yield potential.
Delayed planting does delay harvest. Generally, a 3-week delay in planting equates to a 1-week delay in physiological maturity.

Soybean Planting Date Research

Research comparing soybean yield with different relative maturity varieties over a range of planting dates was conducted by Iowa State University at Nashua, IA from 2004-2008 (Pecinovsky and Mueller 2009).
The late maturity varieties had greater yield across all planting dates.
Yield declined with both variety maturities when planting was delayed past early May.
Results showed that there was no yield advantage to switching to an earlier maturity variety with delayed planting within the range of planting dates tested.

Do not switch variety maturity unless planting after June 15.
If planting after the first week of June, increasing seeding rate by 10% may be advantageous.
Increased plant density will hasten canopy closure, make the soybeans taller and increase number of pods per acre.
Earlier canopy closure can also help suppress weeds.
Research has consistently shown a yield advantage with narrow-row spacing (15 inches or narrower) compared to 30-inch rows with late planting.
Late planting will likely not affect soybean yield response to foliar fungicide or insecticide treatments.