Grain storage management plans typically reflect historical knowledge (“we’ve always done it this way”), convenience, and equipment availability for aeration and monitoring. The process of cooling grain below 40 degrees F for insect control, sealing the bin, and monitoring conditions until spring is much better than turning off the aeration fans, not sealing the bin, and ignoring it for a few months.

There are a few practices to implement in the spring that may provide better grain quality after winter storage and fewer surprises as bins are opened and cleaned in the spring for the next harvest.

Why grain goes bad. Understanding why grain goes out of condition is essential. Why does grain lose quality during the cold winter months? The answer is temperature changes outside the bin, particularly when winter is plagued with wide temperature ranges in short periods of time.

Daytime temperatures in some Midwest locations have exceeded 70 degrees F during the afternoon and dropped to the teens during the night and into the next day. These temperature sweeps mean condensation in areas of the bin that are difficult to monitor. They provide surprises when the bin is opened and emptied in the spring. When air temperatures fluctuate more than 15 degrees F from the grain temperature, condensation along the walls in steel bins, in the headspaces, and at the unloading sumps can occur.

Opening bins in the spring can reveal sprouting on the top surface of grain and mysterious mold clumps around sumps. If the bin has open vent space in the roof, damage from blowing snow may be apparent and can result in sprouting when headspace temperatures warm with spring ambient temperatures.

Moisture and Temperature

So, what is the remedy? The damage that occurred during the winter cannot be reversed, but managers can prevent additional loss of quality and prevent worker accidents due to surprises in grain conditions.

Knowledge of what can happen and why it happens is powerful medicine to prevent further losses and worker injuries.

As temperatures warm in the spring and early summer months, convection currents carry moisture to other parts of the bin. Typically, this is when mold and insects in the center of the bin become a bigger problem. Running aeration fans to keep grain temperatures even throughout the bin is important. Power exhaust fans can help reduce condensation and moisture problems in the headspace.

Use temperature cables to locate hot spots and to observe convection currents in the bin. This helps to predict problems when unloading the bin.

If aeration fan openings have been left uncovered when not in use, clumps of mold at the bottom of the bin and sump areas can be expected. No manager would intentionally leave a bin door open all the time, but that is effectively what happens when fan openings are left open when fans are not in use. The open surface area of a fan can be equal to that of the bin access openings. It is a clear path from the outside air and all of its temperature changes to the surfaces of the grain, especially if the bin has a perforated floor.

Condensation on bin walls or running down bin walls from the headspace is responsible for grain sticking to walls when the bin is unloaded. As managers move grain stored over the winter, historically there is an increase in worker entrapment and engulfment incidents from grain avalanching from bin walls.

Each spring, the number of incident reports increases, because managers and farmers are moving grain out to market and cleaning bins in anticipation of the next harvest.

Any area where temperature differences of more than 15 degrees F have occurred will most likely have moldy clumps of grain. If grain was loaded into the bin with varying moisture contents or not properly cooled, the mold process has been escalated. Managers can expect to have to deal with material that will not go through the reclaim system without some kind of intervention. In extreme instances of moldy grain, contact a contractor to remediate the problems; their specialized equipment can be used instead of risking worker safety.

Handling Grain in Spring

Every year, managers have the discussion about whether it is better to leave the grain cool from the winter or warm the grain to match the ambient temperature. There are pros and cons for each side of the discussion. General consensus is that leaving the grain as cool as possible is the best way to manage mold and insects.

Monitoring for hot spots, insects, moisture, heat in the headspace, and mold development is the best line of defense. Monitoring carbon dioxide levels at aeration fan exhaust points can give an early warning sign of problem development.

If the carbon dioxide levels rise over 600 parts per million (ppm), there is cause for concern about mold and insect activity in the grain. If levels approach or exceed 1,500 ppm, it is time to move the grain, because a serious problem already exists in the bin. In this situation, safety procedures for handling the grain are absolutely essential.

To properly handle mold clumps and out-of-condition grain, first anticipate their presence. You can prepare in the following ways:

Have a marketing or disposal plan for poor-quality grain.

Identify resources and commercial companies that can help remove grain that will not go through the reclaim system. Entering the bin to break up clumps should not be the only remedy.

Obtain safety equipment and inspect existing equipment for grain bin entry. This includes harnesses, lifelines, anchor points, respirators, and bin entry permits.

Train employees on safe bin entry procedures, hazard communication policies, and company policies about entering bins. Refer to OSHA 29 CFR 1910.272, OSHA fact sheets, and information available through professional organizations on safe grain bin entry to develop company policies and procedures.

  • Have an emergency plan and make sure all employees are trained to react appropriately.
  • Run aeration fans before entering the bin to provide essential air quality for bin entrants.
  • Work with local emergency responders to ensure they are prepared to react appropriately. Does the local emergency response team have coffer dams or rescue tubes?
  • Talk with employees about “what-if” scenarios and responses. Impress upon them that they should not make bin entry decisions on their own.

While winter conditions may have provided challenges for good grain quality management, springtime unloading of bins does not have to be wrought with disaster and poor economic decisions.

Knowledge of the potential for poor-quality grain coming out of winter storage, safety procedures to handle poor-quality grain, and training employees for the “what-ifs” can make spring grain handling activities go smoothly and provide the best profits.

Dr. Carol Jones, Ph.D., PE, is a professor emeritus at Oklahoma State University, Stillwater, and president and lead engineer at CL Jones Consulting, LLC