Death comes to us all. Life's but a walking shadow | It turns out that since 1990 the USDA has been sampling and publishing soybean pod counts in Sept. The Profarmer tour's pod counts in late Aug. roughly run in the range of 1000 to 1500, up to 1800 for a 9 square foot area. The USDA's run in the range of 1200 to 2200 for an 18 square foot area, roughly half as many. This suggests that my question about pod abortion is correct, half the pods present in Aug. don't make it to Sept. so the 2-3 beans per pod is explained. Second if you plot pod counts vs yield you can see right away pod counts aren't much use in predicting yld. You can have the same 40 bpa yield with 1400 pods or 2200 pods and everything in between. Likewise, if you have a reasonable number of pods, say between 1700 & 1800 you can have yields that range between 30 and 60 bpa.
So for all those who think they know what the soybean yield will be, maybe, but maybe not.
 (iowa yld vs pod ct-page-001.jpg)
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 iowa yld vs pod ct-page-001.jpg (41KB - 63 downloads)
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Pod counts...
