Fundamentally Speaking

Soybean Leaf Drop

Similar to corn, early soybean yields are exceeding expectations even in some of the more stressed areas.

It is too early since the soybean harvest is just getting started and none of the crop in the late planted areas is even close to ready.

Still, as opposed to sentiment a month ago that the USDA reduction in the national soybean yield from the August to the September crop production report would be the first in a series of downward revisions ideas are now for a higher yield.

Reasons include indications that a late developing soybean crop with many plants still green are actually benefiting from better Midwest precipitation seen in the second half of September.

It may turn out that the lateness of the crop is a blessing in disguise for rather than getting hurt by a normal freeze, the string of unseasonably warm temperatures this late in the growing season is allowing the beans within the pods to plump out a little more from the recent rains.

We were curious if there was a relation between the percent of the national soybean crop dropping leaves and the percent that the U.S. soybean yield changes from the September to the final report in January.

We looked at the years between 1981 and 2012 with regard to the percent of the U.S. crop dropping leaves by September 30 and the percent yield changes.

There really is not much correlation as certain years where the crop seemed well advanced given a high percent of the plants dropping leaves such as 2002, 2005 and 2012 saw large September to January yield increases though other quick developing seasons such as 2000 and 2003 saw yield declines.

Conversely, slow developing years such as 1981, 1984 and 1983 saw yield declines while other years of relatively low September 30 leaf drop such as 1983, 1985, 1990, and 1996 saw yield increases.

We think much depends on late season rains and the timing of the first frost.

(KA)

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