Green as Green Can Be... BUT????

Published on: 13:01PM Aug 19, 2008
Last week I observed some of the corn, soybean, and deciduous vegetation across a limited portion of Iowa (Des Moines to about 150 miles to the east).  In my 30 plus years in the Midwest, I don’t think I have ever seen it quite that “Green”…that includes my time spent in the Le Sueur Valley of Minnesota in 1965 (when some folks may remember another “500 Year Flood” occurred).  Most of the corn looked great with the exception of varied heights within some fields.  (Although, there was one field near the Des Moines river that had four Herons high stepping in pooled water still left behind by the earlier season flooding.)  But it was not the corn that caught my attention.  It was the soybeans.  

Lush, deep green shades everywhere we passed by…however, the soybeans also looked “short” for most areas…high spots, low spots, terraced…it didn't matter, they just looked exceptionally short, especially for the 12th of August.  I guess we can blame that on the late planting and the fact that the crop is 10 to 15 days behind in vegetative growth.  Which brings me to the true topic of this week’s blog… how does the soybean crop catch up? Three things that work against soybeans increasing pod set for this time of year are: 

 1.Cool night time temperatures dropping below 60 degrees (basically shutting down at night);
 2. Daytime cloudiness reducing sunshine’s impact on the plant;
 3. Shortening daylight hours.  

Ideally, warm nights, sunny days, and some timely rains are beneficial for filling out the pods.

Minimum Temperature (F) - 7 Day Mean Ending August 13, 2008
In the accompanying graphics, the top panel shows that the mean low temperature for the past week has been below 60 degrees for large portions of the Soybean Belt.  In the bottom picture are the average departure from the normal low
temperature for the past week.   

In short,  temperatures have NOT been ideal for the soybean crop to catch up across Iowa, Illinois, Indiana, and Ohio this past week (Michigan is further along, but cool nights slow filling beans here as well).  

While an early to normal frost might make this a moot issue, a continued dominance of cool temperatures and cloudiness has to be considered when assessing the final yield numbers. There is still time for lots of growing...with some cooperative weather.