Del Voight – Penn State Extension – Crop Management
I have recieved a few calls on estimating soybean yield to determine which areas to select for the Soybean Yield Contest. I can relate that this is very difficult to estimate accurately. To come up with some idea of yield here is a simple procedure to follow to determine yield.
- Determine plant population
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Reference row needed to equal 1/1000th acre. I use this primarily since it is difficult to walk beans at later stages of growth.(inches) Length of Row Needed to Equal 1/1000th AcreRow Width6 87 feet 1 inch7 74 feet 8 inches7.5 69 feet 8 inches15 34 feet 10 inches
30 17 feet 5 inches
Determine the Pods Per Plant- This will vary with weather. Be sure to count the pods on the branches as well. Do this for at least 10 plants to get more accuracy.
- Determine Seeds Per Pod
- Typically you will find 2.5 seeds per pod. In ideal weather 3 and 4 beans might be noted. In dry conditions this can drop to 1-2. Get a handle by counting a few and averaging what you think is the average seeds per pod.
- Determine Seeds Per Pound. This is difficult. Beans vary in wieght dramatically from 2000-3600 beans per pound. The average is about 2500 and this is what I typically would use. If a drought year exists during pod fill then higher seeds per pound will exist.
- Enter Information into a calculation to determine estimated yield
the following yield estimate is determined:(plants per acre) x (pods per plant) x (seeds per pod) ÷ (seeds perpound) ÷ (pound per bushel) = (bushels per acre)121,968 x 22 x 2.5 ÷ 2,500 ÷ 60 = 44.72 or 45 bushels per acre
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Keep in mind that accuracy is difficult. Harvest loss and other deviations can make the estimate way out of line.
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Here is a sheet that may assist you in recording field information.
