Considerations for Late Planting Of Soybeans

 

Latham Seed Company

 

  1. Don’t change to an earlier-maturing soybean too soon. Stay with mid-maturing adapted varieties until June 15-20.

    2. "The day length sensitivity of soybeans normally allows one to stay with standard maturities until mid-June" (unless you believe the summer will be unusually cool). "Some will argue you can stay with standard maturities even longer than mid-June and indeed it works out that way some years." – Dr. Garren Benson, Former ISU Extension Agronomist, quotes from the Integrated Crop Management newsletter..

     2. Never go to a variety that is too early to be normally planted in your area.

"Not switching maturities carries come risk of poor grain quality due to immature beans. However, if one plants a variety that is a "too early maturity", plants do not develop adequate size and yields are reduced." -- Dr. Garren Benson

3.  Old rule of thumb: Every 4 days delay in planting causes only 1 day delay in maturity. However, not all varieties react exactly the same.

Soybeans are not like corn. Each corn hybrid needs a certain number of heat units for maturity. Soybean maturity is significantly influenced by the length of the night increasing in the late summer.

   4.  Expected yield loss on late planting on soybeans (ISU research at Kanawha, IA):

To June 1: Very little yield loss (variable, 5 to 10% maximum)
June 1 to June 10 ¼ bu./acre for each day delay, or about 2.5 to 3.0 bu./acre total for this    period. June 10 yield down about 3 bu./acre.
June 10 to June 20 ½ bu./acre for each day delay, or about 5bu./acre total for this period. June 20 yield down about 8 bu./acre.
June 20 to July 1 1 bu./acre for each day delay, or about 10 bu./acre total for this period. July 1 yield down an average of 18 bu./acre or more (10 to 30).
July 1 and After 2.5 bu./acre or more for each day delay, extremely variable, poor crop quality is likely. Losing yield fast!
5.  After June 15, we recommend planting all areas that are possible to plant. Come back and plant wet spots later.

6.  Narrow rows or drilling are preferred for very late planting to obtain maximum sunlight interception as early as possible.

Latham Seed Company
131 180th Street
Alexander, Iowa  50420
1-800-798-3258

Fax: (641) 692-3258