Fundamentally Speaking

USDA Soybean Pod Weight Questioned

Joel Karlin
By  Joel Karlin , DTN Contributing Analyst

In its September crop production report, USDA lowered the 2019 national soybean yield by 0.6 bushels per acre (bpa) to 47.9 bpa, still higher than the average trade guess but the lowest U.S. yield since 2014.

As part of its September crop production briefing, USDA included a slide that showed the soybean objective yield region, which is the number of soybean pods within an 18 square foot region vs. the implied pod weight expressed in grams per pod.

That graphic showed the number of pods per 18 square feet at 1,561, the lowest since 1,444 pods in the drought year of 2012 and well below the year ago record of 1,924 pods.

Interestingly, USDA has pegged the average pod weight at 0.3491 grams per pod which is easily the highest figure ever, topping the prior peak of 0.3228 in 2016 and the year ago 0.3087 grams.

Difficult to imagine in a year when the soybean crop was planted record late with large sections of the Eastern Corn Belt dealing with dry conditions for much of the year, crop conditions the lowest in seven seasons and still 5%, or four million acres, not even setting pods as of 9/15 could see the largest pod weights ever.

Some say that in years when plants have low numbers of pods the individual pods within the soybeans tend to be larger than normal.

The accompanying graphic shows the weighted number of soybean pods per 18 square foot area on the left hand axis and the implied pod weight (grams/pod) on the right hand axis, and the weighted soybean yield for 11 objective soybean states.

USDA's formula for deriving the implied pod weight is the published yield/pods/0.0889.

The estimated weighted 10 state yield can be derived from this formula, totaling 48.5 bpa, the lowest since 2014.

Keep in mind the years 2004-2018 use final soybean pod counts, yields, production and harvested acreage for each of the 11 objective states.



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