Drying soybeans without a dryer is not a tongue twister! Instead, it’s an article to help you succeed in your soybean harvest, especially for seed and IP soybeans. Mastering ambient air conditioning and drying techniques can offer significant benefits, directly influencing the quality and market value of the final product.
In this article, we’ll discuss the issues related to soybean drying, present the ambient air drying technique (low temperature forced ventilation), provide a working method for successful drying, and finally, tools to optimize this drying process.
Issues Related to Soybean Harvest and Drying
1. Risks During Soybean Harvest
Storage of Warm Grain: Generally, soybeans are harvested on sunny days. Sunlight and high temperatures significantly warm the grain. When stored in bins, if the entire mass is not adequately cooled, it can sweat, heat up, and alter its nutritional characteristics.
Storage of Wet Grain: Excess moisture in soybeans can lead to mold growth. This problem is primarily linked to cool nights causing condensation on the interior walls of the bin. Additionally, the presence of still-wet pods or scales in the harvest can also promote mold development.
Storage of Dry Grain: While dry and fresh grain stores easily, overly dry soybeans are more susceptible to mechanical breakage. It’s therefore preferable to harvest them slightly moist or to rehydrate them using ventilation during wet weather.
2. Impacts of Propane Dryer Drying
Loss of Viability: For seed soybeans, overly aggressive or poorly controlled drying can significantly reduce germination rates. This can negatively impact future yields and crop quality, compromising the value and profitability of future harvests.
Thermal Stress: Prolonged exposure to heat, even moderate, can damage the grain’s cellular structure. This affects its quality and physical properties by denaturing proteins and altering lipid composition, impacting its nutritional value.
Weight Loss: Overly dry soybeans have a lower mass, reducing the total weight sold. This can lead to a significant decrease in revenue, as grains are sold based on weight (metric ton) rather than volume. A loss of just 1% moisture in the grain translates to a 1% net revenue loss. That’s huge!
Hull Cracking: Excessive drying can cause cracks in the grain’s hull, making it more vulnerable to damage during handling and transport. For seed soybeans, this can also mean a reduction in germination rates and downgrade a seed lot. These cracks can also allow microorganisms to enter, increasing the risk of contamination and deterioration during storage.
Reduced Nutritional Quality: Intense drying with high-temperature dryers can alter the grain’s chemical composition, affecting its nutritional value. Proteins and other essential nutrients can be degraded, reducing the soybean’s value for human and animal feed. This can negatively impact the product’s market value, especially for specialty markets requiring high nutritional standards.
Breakage from Post-Drying Handling: Overly dry grains become brittle and are more likely to break during handling. This can lead to significant losses throughout the value chain (storage, transport, bagging, processing, etc.).
Storage Issues: Broken grains are more susceptible to insect infestations, mold development, and mycotoxins during storage. This can result in rapid deterioration of grain quality and significant financial losses for producers.
Ambient Air Drying Technique
Ambient air drying is a simple drying method that uses air to dry your grains. It’s essentially the same technique as drying corn using wooden screens, except it’s done with forced ventilation in a bin. This technique is particularly suitable for drying soybeans and seed grains. It can be implemented with minimal investment in equipment: high-flow fan, roof air intake, and a control system to facilitate and speed up the drying process.
1. Advantages of the Method
Ambient air drying has several benefits:
Low Drying Cost: This method doesn’t require expensive equipment, reducing drying costs to $2 to $5 per metric ton.
Simplicity: Ambient air drying is a straightforward method that can be implemented with minimal training and resources. It’s an accessible option for small producers and small grain lots.
Reduced Handling: Drying in a bin avoids handling the grain through various storage and drying equipment. This significantly reduces handling and contamination risks, especially for seed lots.
Quality Preservation: Lower temperatures reduce the risk of grain damage, preserving quality and germination potential. This is crucial for seed soybeans or niche markets, such as human consumption soybeans.
2. Operating Principle
Ambient air drying relies on the following principles:
Use of Ambient Air (Dry Air): Ambient air is used to evaporate moisture from the grains. This method doesn’t require additional heating, reducing energy costs. Ventilation management is done using hygroscopic charts to target the right drying periods.
High Ventilation: Unlike conventional bins, the ventilation of a bin used for ambient air drying is 4 to 10 times higher. For soybean drying, a ventilation rate of 1 CFM/bushel is needed. High ventilation increases the drying effect of the air due to air compression and speed.
3. Required Equipment
To implement this technique, you will need:
Bin of Appropriate Dimensions:
Diameter: 42 feet or less
Height: 18 feet of grain or less
Floor: Perforated floor with large openings, well-sealed silo walls at the base, and a perforated floor support to facilitate air passage.
Grain Auger: Sealed to the silo wall to avoid air loss, well-aligned with the fan to ensure good air distribution.
Ladder: Both external and internal for access to level the grain and test moisture at the roof
Adequate Ventilation Power:
Fan: Good airflow, 0.8 to 1.25 CFM/Bu
Use the University of Minnesota’s digital calculator (University of Minnesota - UofM) to select the right fan for your bin and grain type.
Roof Air Intake: Number of roof intakes equal to the amount of air provided by the fan in CFM.
EXAMPLE CALCULATION
Hygroscopic Charts:
Soybean Chart: Order your free Agrilog drying guide.
Digital Chart: View ventilation ranges via the Agrilog platform. Sign up for free HERE.
Automation System (Optional):
Monitoring Tools (Optional):
Wireless moisture, temperature, and CO2 sensors can be used to monitor drying conditions. These movable wireless probes are tools to track drying progress, optimize the process, and detect malfunctions. If a problem arises, you can take action before grain quality deteriorates.
4. Key Parameters to Monitor
To optimize the ambient air drying process, closely monitor the following points:
Cleanliness of Stored Grain: When filling the bin, fine parts accumulate in the center while grain rolls toward the bin walls. A concentration of dust and debris in the bin center blocks air passage for drying. It’s strongly recommended to remove some grain to clear the debris concentration in the bin center.
Grain Compaction: Grain in the center of the bin becomes more compacted due to hammering during filling. It’s recommended to remove some grain to decompact the bin center.
Grain Settling: Grain spreaders increase grain settling, reducing air passage. It’s also preferable not to use a spreader and remove the grain cone formed during filling to clear debris during bin filling.
Adequate Airflow: Proper airflow is crucial for effective and uniform drying. Recommendations generally range from 0.8 to 1.2 CFM/bushel for cereal and soybean drying and 2.5 to 3.0 CFM/bushel for corn drying.
Air Temperature: Air temperature should be within an optimal range for effective drying. At 5°C, drying efficiency is low; at 10°C, efficiency is good; and above 15°C, drying efficiency is fast. Therefore, aim for dry and warm weather conditions for successful grain drying.
Grain Moisture Content: Ambient air drying is ideal for soybeans with 17% moisture or less. Above 17%, it’s preferable to use a grain dryer to reduce grain moisture. Ambient air drying can then be used to complete drying and standardize moisture levels in stored grain.
Relative Humidity: The relative humidity of the air directly influences the speed and effectiveness of the drying process. Humid air slows drying significantly and can even rehydrate the grains.
Working Method and Tools for Successful Ambient Air Drying
To ensure optimal soybean drying using ambient air, producers should follow a structured working method, adhere to guidelines, and use appropriate tools. Here’s a detailed guide to achieving this:
1. Working Method
Preparation:
Clean and thoroughly inspect your bin.
Ensure proper functioning of the ventilation system and automated system if applicable.
Review your drying guide and consult your advisor if necessary.
Measure the initial moisture content of the soybeans to estimate the required drying time.
Filling and Starting Ventilation:
Limit grain height to 16-18 feet maximum to ensure good air circulation. Ideally, use a static pressure gauge to determine the maximum amount of grain that can be stored.
Start ventilation as soon as you begin filling your bin.
Once filled, remove the core of the bin, clean it, return the clean grain to the bin, and level the grain.
Drying:
Regularly monitor the drying process, checking moisture levels, airflow, and grain temperature.
Maintain consistent ventilation and adjust as needed based on external weather conditions.
Final Steps:
Once the desired moisture level is achieved, turn off the ventilation system and prepare for storage.
Perform a final inspection of the bin and clean if necessary.
2. Tools
Grain Hygroscopic Charts: Use grain charts to determine the optimal time to activate your fans. You can obtain your guide with the charts by filling out the following form: Practical Guide for Drying and Storage.
Ventilation Forecast: View the ideal ventilation ranges for drying your soybeans via the Agrilog platform. To sign up for free, click HERE.
Moisture Tester: Essential for measuring the moisture content of your grain before binning, during drying, and also when loading your truck for shipment to your buyer. Available at www.precisionce.com.
Grain Sampling Probe: Use a sampling probe to obtain a moisture profile of the top layer of your bin. This probe will also allow you to sample a grain load upon receipt or before shipment. We recommend using a 6-foot probe to ensure a good representation of the top of the bin. Available at www.precisionce.com.
Ventilation Performance Analysis Software: Use the University of Minnesota’s digital calculator (University of Minnesota - UofM) to estimate the ventilation capacity of your bins.
Static Pressure Probe: Use a static pressure probe to determine the maximum amount of grain to place in your bin. It is also useful for assessing the drying efficiency of your ventilation.
Ventilation Automation System: Use a ventilation automation system (Hygrolog or Silog) to maximize daily ventilation windows. An automated system will prevent ventilation in humid weather, avoiding grain rehydration during drying. This will allow you to dry your grain faster, reduce management time, and lower energy consumption.
Wireless Sensors: Use Agrilog’s wireless sensors for monitoring your bins. Ideal for tracking humidity, temperature, and CO2 levels at the outlet of your bins. These sensors will help you determine if your grain is cooled, if the drying process is complete, and if your grain is safe.
Challenges and Considerations
Despite its advantages, this method also presents some challenges:
Slow Process: Ambient air drying is a slow process that can take several days, typically 4 to 6 days, depending on weather conditions, the initial moisture content of the grains, and ventilation power. Although ambient air drying is slower, it is important to complete the drying within 12 days. Beyond this period, the drying process becomes risky.
Dependence on Weather Conditions: The efficiency of drying varies with the humidity and temperature of the ambient air. You must carefully monitor weather conditions and adjust your drying practices accordingly.
Risk of Mold Development: If the process is too slow, there is an increased risk of mold development, particularly in the upper layers of the grain mass. Close monitoring and active management of the process are necessary to mitigate this risk.
Additional Heat Input: If needed, to accelerate the drying process, an additional 3 to 5 degrees Celsius of heat can be applied, mainly at night and in humid weather. This allows for extending ventilation periods in the fall, when temperatures are cooler, to reduce drying time.
Conclusion
Drying soybeans with ambient air is a process that requires careful attention to detail and an understanding of the challenges involved. By using low-temperature drying methods with forced ventilation, you can preserve the quality of your soybeans while minimizing drying costs.
Integrating advanced technological solutions like Hygrolog, Silog, and Drylog can significantly improve the efficiency and quality of the drying process. These technologies offer precise control over ventilation activation and provide remote monitoring, allowing you to maximize the quality of your soybeans while reducing the risk of grain damage.
By adopting these technologies and following best drying practices, you can not only preserve the quality of your harvest but also enhance your operational efficiency and profitability. The future of soybean drying lies in balancing proven traditional methods with technological innovation, offering solutions tailored to the specific challenges of each farming operation.
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