Many farms already have much of what they need for in-bin drying and conditioning: a grain bin, an aeration fan, and access to power. However, how effectively your existing setup can dry or condition grain depends on factors such as airflow, grain depth, and fan capacity.

This blog covers what to check to assess the capabilities of your existing setup, how to operate the system for drying or conditioning, and how to use grain monitoring to guide the process.

Drying vs. conditioning: What is the difference 

Drying and conditioning both use airflow through the grain, but they have different goals:

• Drying removes moisture from the grain. Natural or heated air is used to bring higher-moisture grain down to a safe level for storage. Drying generally requires higher airflow rates than conditioning.
• Conditioning helps maintain stored grain quality. Fans are usually run without added heat to cool the grain, reduce temperature differences within the bin, and limit moisture migration. Conditioning may cause some drying, but that is not its main purpose.

Preparing an existing bin for drying or conditioning

Before drying or conditioning grain in an existing bin, make sure the fan can provide the airflow you need and that air can move freely through the grain.

Check how much airflow your fan delivers

Airflow is usually measured in cubic feet per minute per bushel (cfm/bu). The amount you need depends on what you are trying to accomplish.

• Conditioning and cooling: Often requires around 0.1 to 0.25 cfm/bu. This is generally enough to move a cooling front through stored grain.
• Natural-air or supplemental-heat drying: Aim for at least 1 cfm/bu. This is needed to push the moisture front through the entire bin.

Fan horsepower alone does not tell you how much airflow you are getting. As grain depth increases, so does resistance to airflow, reducing the amount of air the fan can deliver.

To determine actual airflow, measure static pressure in the plenum and use the fan manufacturer’s performance chart to find the CFM at that pressure. Divide that number by the bushels in the bin to get cfm/bu.

For example, if the fan delivers 10,000 CFM with 8,000 bushels in the bin:

• 10,000 CFM ÷ 8,000 bu = 1.25 cfm/bu

Adjust grain depth if needed

If your existing fan cannot provide the required airflow, consider reducing the grain depth rather than filling the bin completely. NDSU notes that a bin designed to provide about 1 cfm/bu when full may reach roughly 1.5 cfm/bu when filled only three-quarters full, depending on the system.

For natural-air drying, shallower grain depths can improve drying speed and reduce the risk that wet grain spoils before the drying front reaches the top.

Improve airflow through the grain

Even a properly sized fan will struggle if airflow is restricted or uneven. A few steps can help:

• Core the bin after filling: Fines tend to collect in the center and restrict airflow. Removing grain until roughly half of the center peak is gone removes much of this material and makes grain depth more uniform.
• Check the aeration floor and ducts: Plugged perforations, accumulated fines underneath the floor, blocked ducts, or damaged transitions can reduce airflow substantially.
• Provide enough exhaust area: For drying systems, a useful guideline is about 1 square foot of open exhaust area per 1,000 cfm of fan airflow.

Operating your bin for drying or conditioning

How you run the fan depends on whether you’re drying or conditioning your grain.

For supplemental-heat drying

By connecting a construction heater to your aeration fan, you can turn your existing grain bin into an affordable grain drying system. Learn more about Adaptive Agriculture’s grain-bin drying systems here.

Once the system is set up and the bin is loaded, follow these steps to run a drying cycle:

1. Start drying: Turn on the aeration fan and supplemental heater to begin the drying cycle.
2. Monitor conditions: Track grain temperature and moisture as the drying front moves upward through the grain mass.
3. Complete drying: Continue drying until the moisture front has been pushed through the entire bin. This may take a few days.
4. Run the cool-down cycle: Turn off the supplemental heat and continue running the aeration fan for 24–48 hours, or until the grain reaches a safe storage temperature throughout the bin.
5. Allow equalization: Turn off the aeration fan and allow the grain to equalize for up to 24 hours.
6. Check final moisture: Sample the grain and confirm it has reached the target moisture content. Repeat the drying cycle if required.

For natural-air drying

Natural-air drying relies on outdoor air rather than added heat, so suitable weather conditions are especially important.

1. Check drying conditions: Run the fan when the incoming air’s equilibrium moisture content (EMC) is below the grain’s current moisture content.
2. Start the fan as filling begins: Once there is enough grain to cover the aeration floor, start the fan rather than waiting for the bin to fill.
3. Track the drying front: Monitor moisture and temperature at different depths. The bottom of the bin will dry first, while grain above the drying front will remain wetter.
4. Keep the drying front moving: When conditions are suitable, run the fan continuously. Frequent starts and stops can slow drying and leave wetter grain near the top. The process can take days or weeks.
5. Confirm the top is dry. Sample grain near the top before shutting the fan off.

For cooling and conditioning

Once grain is at a suitable storage moisture content, aeration can be used to cool it and maintain safe, uniform conditions throughout the bin.

1. Start aeration early: If grain enters the bin warm, start the fan once the aeration floor or ducts are adequately covered.
2. Use suitable cooling air: Run the fan when outside air is cool enough to lower grain temperature.
3. Cool the entire grain mass: Run each cycle long enough for the cooling front to pass through the entire bin. Stopping early can leave uneven temperatures.
4. Cool in stages: As temperatures fall through autumn and early winter, gradually cool the grain to near the average outside temperature.
5. Monitor stored grain: Check grain temperature regularly for signs of heating or spoilage.
6. Keep grain cool in warmer weather: Avoid unnecessary spring and summer aeration, as warm air can reheat cooled grain.

Monitoring grain for better drying and conditioning

Grain monitoring and conditioning technology can help you see what is happening throughout the bin. It shows whether the grain is drying or cooling as expected and helps you decide when to keep the fan running or shut it off.

Key components of an effective grain monitoring system include:

• Temperature and moisture cables: Help you track grain conditions at different depths in the bin.
• Plenum sensor: Measures the temperature, humidity and static pressure of air entering the bin, helping you assess airflow and drying conditions.
• Grain monitoring device: A system such as Bindapt+ 2.0 Monitor collects sensor readings and sends them to your monitoring platform.
• Automation device: A system such as Bindapt+ 2.0 Automate lets you automate equipment such as aeration fans and supplemental heaters.
• Monitoring dashboard: A platform such as Visual Farm lets you view sensor data, receive alerts and manage compatible bin controls from your phone or computer.

Get more out of the bins you already own

Your grain bins may be capable of more than you think. With enough airflow, the right operating strategy, and reliable monitoring, an existing bin can become an effective tool for drying, cooling, and conditioning grain without requiring an entirely new setup. 

Adaptive Agriculture offers grain monitoring and conditioning systems designed to help you get more from the bins you already have. Explore our solutions or contact our team to find the right setup for your operation. 

Frequently asked questions