Source: University of Nebraska Extension
When planting soybeans in late April, remember:
1. Plant close to May 1. If soil temperatures are warm enough, plant soybean fields as close to May 1 as possible to provide optimal yields. University of Nebraska research has shown that for every day soybeans are planted after May 1, ½ bushels per acre of yield potential is lost. Delaying soybean planting until May 15 could result in a 7½ bushel-per-acre yield decrease (15 days x ½ bushels per acre = 7½ bushel-per-acre loss).
2. Treat seed with fungicide. Soybean seed should be treated with a fungicide because water-soaked soggy soil, when coupled with very low soil temperatures, will result in post-imbibition, germinating seedlings being exposed to pathogens that will attack them.
3. Prevent bean leaf beetle feeding. If a grower has experienced overwintering bean leaf beetles infesting early planted soybean fields, seed should be treated with fungicide and insecticide to prevent bean leaf beetle feeding and potential infection with bean pod mottle virus (BPMV). These beetles feed on early planted soybean seedling cotyledons and unifoliate leaves to get enough food to lay their eggs in the soil beneath emerged soybean seedlings. Those eggs will hatch and the beetle larva will feed on your soybean seedling root system.
The article Predicted Mortality of Bean Leaf Beetle is Highly Variable provides bean leaf beetle overwintering information from Iowa State University for the 2014-15 winter season. More in-depth information on the life cycle and biology of bean leaf beetles can also be found in this information from Iowa State University: Bean Leaf Beetles.
Additionally, new research this month shows higher soybean plant populations are obtained with the use of fungicide/insecticide seed treatments.
4. Consider seeding rate reduction. With increased cost of production, consider reducing seeding rates in clay loam/silty clay loam soils in 30-inch rows. Nebraska On-Farm Research has shown seeding rates can be reduced to 120,000 seeds per acre in these conditions without significantly affecting yield. (See Nebraska On-Farm Research Network Soybean Seeding Rate Findings and browse all data by year and location at Soybean Population Studies.)
5. Don't plant dry. Soybean seed requires 50% more water than corn seed to initiate germination. Do not put soybean seed into a dry furrow — imbibition does not start until germination begins. Consider planting deeper to moisture in some cases.
6. Plant at 1¾ inches. Soybean planting depth research from University of Nebraska from 2011-13 at four locations showed across all site-years, regardless of early or late planting dates or tillage type, a planting depth of 1¾ inches maximized soybean yields.
7. Consider replanting payments. In most counties in Nebraska, replanting payments will not be made on acreage planted prior to April 25 with crop insurance. However, numerous seed companies provide 100% replant coverage on soybean seed treated with a fungicide/insecticide product or through brand loyalty policies.