Ask the Doctor: Preparing Grain for Sale After Winter Storage
As temperatures warm, moisture can become a double-edged sword. Too much and grain can spoil through mold or caking, but too little and it isn’t the proper mositure content for selling.
Thus, as Dr. John explains, it’s important to keep a careful eye on the anticipated sell date and focus moisture intake close to that date.
As spring temperatures start to warm up, what is a good target temperature for long term storage?
A good target temperature for long term grain storage depends on the weather. The rule of thumb is to keep the average grain temperature in the bin 10-15°F lower than the average ambient temperature. For example, if the ambient average temperature is 60°F, we should keep the average grain temperature between 45-50°F to avoid condensation. Condensation being one of the major reasons for grain spoilage and caking.
What is the proper way to warm grain based on customers selling dates in the spring vs late summer?
For the Midwest region, if the selling date is between March and May, we do not need to warm the grain. We can keep the grain a little above freezing until the selling date. If the selling date falls after May, then we need to warm the grain beginning in April with 10-15°F lower than ambient average temperatures.
The proper way to warm grain in spring involves the knowledge of dew point temperature. What is the dew point temperature? The temperature at which condensation occurs, and relative humidity (RH) is 100%. The wet-bulb temperature and dry-bulb temperature merge at 100% RH, which is the dew point temperature. If the RH is less than 65%, the possibility for condensation to occur will be relatively low. Therefore, selecting ambient warm air with less than 65% RH is the proper way of warming grain in spring. Also, the warm ambient temperature should not be more than 10-15°F. If the grain temperature is below freezing, the warm ambient temperature should not be more than 5°F. This will avoid ice formation. For example, if the grain temperature is 20°F, use 25°F and < 65% RH ambient air to warm up the grain.
When should customers start hydrating grain? Is there a target temperature?
There is a major risk involved during the hydration process of grain, particularly for soybeans if the hydration is not done properly. Never keep hydrated soybeans in the bin for more than 3-4 weeks. Otherwise, you will end up caking the soybeans.
The average safe storage moisture for current soybean hybrids at 40°F is around 11.0% (65% RH). If you hydrate soybeans to 13%, they are already above safe storage moisture, and their RH is more than 75%. Therefore, they are more susceptible to mold growth and caking.
The best approach would be to start hydrating soybeans just 3-4 weeks before the selling date. If you can't achieve 13% moisture based on weather in that location, that’s better than spoiling the soybeans by prolonging hydration and having caking in your bin. This scenario will be the same for all grain types. There is no target temperature for hydration. However, when the grain temperature is below 40°F, we can prolong how long hydration will take by one or two extra weeks. As the temperature increases above 40°F, hydration will happen easily. However, the risk of spoilage is also increased.