“Avoid harvesting soybeans” too dry is almost a cliché and a seemingly impossible task. Growers try to start combining when beans are 14% or so (no one wants a moisture discount), but before they know it moisture drops from 14 to 12 to 10 and even 8% moisture on a sunny, warm and windy fall day. Even with best intentions soybeans dry down quickly each day once mature.

To avoid moisture discounts from the quoted market price per bushel, soybeans must contain 13.5% moisture or less. Soybeans often come out of the field early at greater than 13 percent moisture and often they are in the 14 to 15 percent range. When soybeans first mature and moisture finally drops down to 14% for the first time, they subsequently dry down slower than soybeans that matured, dried down and then moistened back up and dried down again. It seems that the more times soybean seeds run through this moisture cycle the faster they dry down each day. I have never seen data on this, but my anecdotal experience tells me this is true.

You lose money on soybeans when selling beans below 13 percent moisture because soybeans are sold by weight. Soybeans dry quickly and should be harvested before they become overly dry. Elevators dock for moisture of 13.5 percent, but do not pay you if moisture is less that 13.5 percent. If you deliver beans in the fall, try to get the bulk of your beans delivered in the 13 percent range to minimize shrink and maximize your income. That means starting to combine at 14%.

The rule of thumb I have followed is when plants reach full maturity, (95 percent of the pods have reached their golden brown mature pod color) it takes another 5 to 10 days of drying before the crop is ready to harvest. Growers don’t have to wait until all the leaves have dropped and the whole plant is golden brown. Harvest can begin earlier when some of the leaves are still attached and the some of the stems are still partly green. In a drought year, pods may dry down quicker than the stems and if growers wait to harvest until the whole plant is brown and dry, there could be shattering loss. Combines settings are continually adjusted with soybeans during the course of the day anyhow.

Delaying harvest can overdry the soybeans and increase risk of shattering losses. To reduce the risk of loss, consider these tips.
1. Start harvest when soybeans drop to 14 to 14.5 percent moisture, when shattering losses are lower.
2. If binning the soybeans, harvest earlier at 16 percent moisture and aerate down to 13 percent. Aeration will be needed to dry the beans and control the temperature of stored grain.
3. Consider whether the price dock at the elevator for delivering beans at 14 percent will be less than income loss if delivering beans at 12 percent and shattering losses are higher at 12 percent.
4. Harvest overly dry soybeans in the morning after the dew burns off or after a rain when pods are damp and there is less risk of shattering.
5. Remember, the risk of shattering losses becomes greater after pods have been through several wetting and drying cycles, so harvest these risk-prone fields early in the day.

Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at djdavidson@agwrite.com or leave a comment below.