Double Cropping Soybeans

Winter wheat is maturing rapidly and harvest is expected to begin by the end of the week. This early start to harvest may provide the opportunity to double crop soybeans after winter wheat harvest for some producers. Double cropping is not generally practiced in Ontario, because our growing season is too short and there is often not enough moisture in mid-summer to establish the crop. With the likelihood of an early wheat harvest there is renewed interest in double cropping this year. Attempting to double crop soybeans is risky though because beans may not have time to mature and Agricorp will not insure beans planted after June 30th. The lower yield potential of such a late planted crop also means that input costs must be kept at a minimum to make it profitable. The keys to a successful soybean double crop are adequate moisture and a long, open fall. Below are a few points to consider:

• Harvest wheat as early as possible. In Southwestern Ontario it's still possible to achieve a 20- 30 bu/ac crop if planting on July 1st. However, a 30 bu/acre yield potential on July 1st drops approximately 1 bu/ac/day. Do not attempt to double crop after July 10th.
  
  
• Moisture is essential. Plant seeds into moisture. If there is no moisture to a depth of 2.5 inches, plant at 1.5 inches and wait for rain. Success will be rain dependent. If conditions are extremely dry, do not attempt to double crop. Most double crop failures can be attributed to beans being planted into dry conditions.
  
  
• In fields where soybean diseases are a major problem, double-cropping will make those problems worse. Consider the rotational implications.
  
  
• Fields should not be worked to conserve all available moisture.
  
  
• Control weeds in wheat, either before planting or before emergence of soybeans. Also, plan the herbicide program around volunteer wheat.
  
  
• Plant in narrow rows with high seeding rates. Aim for 250,000 seeds/acre in 7.5 inch rows. The quicker a full canopy is achieved the better.
  
  
• Choose tall, small seeded varieties;
  

1. In greater than 2800 CHU areas choose a full season variety.
   
   
2. In areas with less than 2800 CHU's choose a variety with slightly lower CHU's than full season. Choosing very short day maturities (<2500) is not a good option. Short season soybeans planted very late will not yield well because the plants will not grow tall enough. Full season beans will provide greater height and better pod set. Due to the photo period affect a full season bean will not mature significantly later than a short day bean.
   

• Most seed companies will offer a discount on soybean seed planted after wheat so check with your dealer.
  
  
• Aim for an 8- 12" stubble height - this helps to ensure stem elongation for higher bottom pod height without impeding early growth.
  

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