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Removing moisture from grain

How to handle many aspects of farming depends on the individual nature of each unique farm, as well as the farming systems used. Grain drying certainly falls under this category, but while there are many different ways to accomplish it, universal rules still apply.  

“In general, the capability of a producer to dry, condition and store their own grain can provide flexibility and open up some marketing options,” notes James Dyck, Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) engineer for crop systems and environment. “If you do it yourself, you avoid elevator drying charges, and you can dry and condition the grain to your own requirements. It also allows growers to market their harvests at their preferred time.”

Grain dryers and storage systems come with the same questions that apply to any new on-farm equipment. There are capital installation costs to consider, as well as ongoing maintenance and repairs, operational differences, benefits and risks.

In grain drying, both natural and heated moving air can be used. Dyck says that choice depends on the crop to be dried, incoming moisture level, desired final moisture content and ambient air conditions. “Numerous systems are available, including bin aeration, batch-in-bin, elevated-batch-in-bin (drying section on top of bin, with stored dry grain below the drying section), auto-feed, continuous flow and portable dryers,” he says. “There are also multiple fan technologies, including backward-curved centrifugal and axial flow. Each technology has different requirements, options and efficiencies, and the merits and drawbacks of each must be considered when determining the best fit.”

A good moisture tester is an important tool for producers planning to store their own grain. Dyck says many commercially-available testers allow for easy recalibration, and can be readily checked against an elevator tester. “Some newer testers also have the ability to link to a computer via USB and an online connection, and can be quickly and easily calibrated or updated in this way,” he says. “Remember that periodic calibration is prudent to ensure consistent results.” Dyck adds that proper care and storage of the tester is also key. Leaving a tester exposed in freezing temperatures or in high-moisture conditions such as dew or rain may be detrimental to the device’s operation and lifespan.

Hybrid selection may have some bearing on drying and storage in Dyck’s view, and a primary consideration in choosing varieties is ensuring they will have time to mature before harvest.  The local climate and the planting date will have significant impact on this, he notes, and each hybrid will pollinate, mature and dry differently. Given that weather is always unknown at the start of a growing season, planting a range of hybrids can allow a producer to spread this risk.

Whether or not to use a pre-cleaner to remove fines is another consideration. “It can be beneficial, but similarly to dryers, pre-cleaners present another source of costs, maintenance and repair,” Dyck explains. “I think that for control of fines in stored grain, coring bins are very important. Fines tend to collect in the centre of a bin as it is filled. Coring removes grain with the highest concentration of fines and also establishes the flow funnel through the bin. This all results in better airflow patterns.” Coring should be done within a few days of filling the bin, to prevent fines from setting up, he notes. Cored material can be sold or cleaned and put back into the top of the bin. 

Once grain is dried, maintaining grain condition is all about aeration. Aeration accomplishes many important things, such as removing heat, equalizing bin temperature, helping to eliminate hot spots and preventing convective air movement within the grain. For long-term storage, Dyck says grain mass temperature should be maintained within a few degrees of ambient air (and in winter, this means the grain is frozen), and aeration is key to accomplishing that. “It will maintain uniform grain temperature profiles and prevent spoilage as ambient air temperatures change,” he says.

Spot monitoring of stored grain can be used to check for temperature differences, but Dyck points out that inserting sensors more than a few inches into dense grain in a bin can be difficult. “And even with sensors, it’s important that growers remember that hot spots can be missed,” he states.  

Grain producers deal with many uncontrollable variables, chief among them the weather, but also including market conditions, fuel prices, disease and pest pressure, and maintenance issues. But once the harvest is complete, it’s all about looking after it. “In drying your grain, there is no ‘magic bullet’ best system or strategy or equipment to consistently achieve the best results,” Dyck says. “I advise growers to study the issue thoroughly. There are many resources available to producers to assist with these decisions, including industry publications, manufacturers’ information and also OMAFRA resources, to name a few.”

October 5, 2015  By Treena Hein


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