Figure 1
There is still time left to get a good yield with late planted or double-cropped soybeans. First, it rained too much, and now for much of the Four State area, the rains have completely stopped. This is hard on soybeans as they don’t do well growing though crusted soil but also they don’t germinate well in drier soils. 
 
It could be important this season to preserve the soil moisture that is still available and perhaps wait until the weather conditions are more conducive to soybean germination. At the current soil temperatures, soybean emergence will take a week or less after planting. 
 
The importance of good germination can be a bigger yield driver than quick planting to a certain extent. Past research at the Southeast Research and Extension Center has shown that soybeans planted late, even in late June to early July, can still have high yields with favorable weather. 
 
Figure 1 shows little yield changes from planting at the beginning of June to planting towards the end of June, given proper soil moisture and planting longer day length beans that have time to develop before flowering. Rain after a few days after planting in both the early June and late June plantings helped for quick germination. The study showed that ultimately weather patterns played a bigger role in soybean yields than specific planting dates. 
 
As of mid-June, wheat is not far away from harvesting but soil moisture is currently low. Hopefully, the rains will return towards the end of the month and provide a point when planted soybeans will have the moisture they need to germinate and before the soil crusts. There is still time left for good soybean yields in southeast Kansas with concern taken for the following tips for double-cropping beans.
 
• Wheat herbicide cropping restrictions is an important factor to good soybean germination. When necessary, the soybean herbicide genetics must line up with that specific herbicide and not just that class of herbicides.
 
• Reduce tillage to conserve soil moisture. No-till drilling soybeans or reduced shallow tillage to preserve the currently available soil moisture. 
 
• Proper soil nutrients. Balanced pH and optimum levels phosphorus and potassium but also a limited amount of nitrogen could be useful when there is low soil N available in early season. 
 
• Narrow row spacing to cover the canopy quicker to capture more light quicker and also suppress weeds.
 
• Generally, increase seeding rates depending on current seeding rates of full season beans to compensate for less branching. Unlike corn, poorer yielding areas need a slightly higher seeding rate than higher yielding areas. Plant based on seeds per acre.
 
• Use quality seed stored properly. Often planting in June is a stressful time period for germination and seeds need a high vigor.
 
• Seeding depth around 1.5 inches. Soybeans can still emerge from being planted deeper than 2 inches but germination will be slower and makes it harder for the hypocotyl to break through a crust. 
 
• Maintain or slightly increase season length of variety. Maximize the vegetative period before flowering starts but still complete full maturity by frost.  
Double-cropped beans can have a high yield in southeast Kansas given proper care at planting, weed control, and favorable weather. While yields will decrease at a certain point of late planting, having everything in order with a forecast of favorable weather could be more important in the long run to maximize the yield. 
 
If you have any questions about planting decisions or would like to see the ongoing results for the soybean yield by planting date and maturity group study, please contact me at  620-331-2690.
 
(James Coover is the crop production agent for the Wildcat Extension District.)

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