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August 26, 2020

2020 U.S. Soybean Condition Declines 3% to 69% Rated G/E

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

The soybean crop started the month of August with a very high yield potential and I think the USDA was justified estimating the soybean yield at 53.3 bu/ac in the August Crop Report, but things have changed since the first of August. My current soybean yield is estimated at 52.0 bu/ac with a lower bias.

With only a week to go in the month, August is turning out to be very dry in many locations. The seasonal temperatures earlier in the month helped to extend the available moisture supplies, but the temperatures have now warmed back up to above normal, which has accelerated the moisture loss.

The soybean condition declined 3% last week to 69% rated good to excellent. It is no surprise that the condition declined given the lack of rainfall and the higher temperatures. The soybeans are 92% setting pods compared to 76% last year and 87% average. The soybeans are 4% dropping leaves compared to 2% last year and 4% average.

Moisture stress can build very easy during the month of August when the soybean plant is at its peak water demand as it fills pods. Many reports from the field indicated that the soybeans have a large vegetative mass this summer, which means that the plants need even more water to avoid moisture stress.

If soybeans are under moisture stress during the month of August, the result can be less than three seeds per pod and smaller than normal seed size and weight. Moisture stress at the end of August can also accelerate the plant's maturity and as a result, the soybeans start to turn yellow earlier than normal. Once the soybean leaves start to turn yellow, there is no more dry matter accumulation. From that point forward, the seeds simply loose moisture.

A key thing to watch for soybeans is how fast the crop starts to turn yellow. A quick maturing of the crop does not bode well for record yields. A prolonged pod filling period with ample moisture is the surest way to very high yields.