FEATURE STORY
No Surprises - Story Damp Corn
By David Morris
In the words of Clare Brown, of CASCO at Cardinal, last winter’s damp corn storage project was successful and produced no surprises. (See accompanying item by Ken Hough at the end of this article.) The corn, which was put into storage in late November, came out in January smelling fresh and sweet, and it milled without problems.
Don Kenny and Earl Esdale, two of the producers in eastern Ontario who co-operated in this project, also had no unpleasant surprises. Kenny had previously stored damp corn, but this was Esdale’s first experience. Both found it to be a convenient way of handling at least some of their corn. It enabled them to save fuel and it reduced the pressure on the dryer during harvest. Because of the extraordinary conditions last fall, both men were able to put the corn directly into storage from the field. In Kenny’s case, the corn went in at about 21 per cent moisture, while Esdale’s was harvested at about 19 per cent. Project coordinator Dr. Ralph Brown of the University of Guelph says corn should be in the range of 18- to 22-per cent moisture range for this system to work best with minimal risk of spoilage.
Clare Brown says CASCO officials know well what to expect from damp corn, because they have processed a lot of it over the years. During the harvest season, they routinely receive wet corn and mill it directly for about a month and a half. They also have some experience milling damp corn during the winter months. Each year, there are always a few producers who store some damp corn for delivery in February or March. Because the quantities are relatively small, CASCO is simply able to blend the damp corn into the dry corn stream and it goes through almost without being notice.
What set this project apart from the usual winter situation was that enough damp corn was delivered to constitute the entire throughput of the mill for two runs, totaling about a day and a half of production. As described in the project report, oil and starch yields and starch quality were at least as good as with dry corn, and perhaps a bit better. However, whether this success will lead to increased usage of damp corn during the winter remains to be seen.
The key to success in storing damp corn is an aeration system that will cool the corn to a temperature under 5 degrees C within two or three days. Ralph Brown recommends a minimum air flow rate of 0.5 to 1 cfm and emphasizes the importance of having grain that is clean and free from damage. He cautions that some older storage systems have fans that provide as little as 0.1 cfm so it’s important to check out their system before launching into this type of storage.
Another option that has been used successfully by some producers is to delay harvest until the temperature of the corn in the field is below freezing. This approach eliminates the need for any additional cooling in the bin, but it does presume producers can predict when the snow will come.
Both Kenny and Esdale used bins that had full-floor aeration and fans with sufficient capacity, so there was no need to limit the depth of grain in the bin in order to have enough air flow. Kenny also had two other bins of damp corn that were not included as part of this project, one of which was equipped with only a Y-shaped aeration duct. He put a layer of dry corn in the bottom of this bin before filling it with damp corn. This approach worked well in preventing spoilage in the dead air space between the arms of the duct.
Because of the warm temperatures last fall, the corn for this project could not be harvested until late November when the air temperature were consistently near freezing. Otherwise, it would not have been possible to cool the grain quickly enough. Even then, Kenny had to aerate only at night because daytime temperatures were still relatively warm. Before he became aware of this, his grain began to heat a bit, but with proper aeration, it cooled quickly and suffered no permanent damage.
Ralph Brown points out that aerating at night is the best practice for storing damp corn. The objective, he says, is to cool the grain, not to dry it and use exactly the opposite aeration strategy. In most years, there isn’t enough heat in the air to dry the grain. Aerating only during the day the grain may not cool, and if the fans are on all the time, heat brought into the bin during the day, negates any benefit from the cooler night air. There are relatively few problems, except that the noise can make it difficult to sleep. Ralph Brown does recommend, however, the use of in-bin temperature cables and an olfactory check – using your nose – to keep tabs on conditions in the bin, whenever storing damp corn.
Because of its moisture content, damp corn has to be shipped before the temperature warms up significantly in the spring. Throughout the time in the bin, the grain temperature must be kept below 5 degrees C to avoid spoilage. Ralph Brown points out that the same strategy of aerating at night can be used in late winter or early spring to keep the grain uniformly cool by counteracting the effect of either warm days or bright sun on one side of the bin.
Both Kenny and Esdale felt that there were relatively few risks in storing damp corn, provided that all of the above precautions were followed. Both thought that, in wet years, it would be practical to dry wet corn down into the low 20’s before storing it. This would increase throughput through the dryer while saving energy. As Esdale pointed out, “getting those points of moisture out between 20 and 15 per cent is what takes the effort.” However, under current circumstances neither foresaw storing more than a small proportion of their grain this way. Producers who deliver corn over 16.4 per cent moisture are normally assessed the full drying charge at CASCO. (Drying charges were waived as part of this project.) So Kenny and Esdale saw no economic incentive for storing damp corn, because they felt they can dry corn for less than the CASCO drying charge.
Kenny also pointed out that trucking costs are increased with damp corn, because you’re hauling more water. And Esdale noted that storing damp corn also exposes producers to more market risk because they’re locked into delivering the corn in the winter...and because there are very few markets that will accept damp corn.
For his part, Clare Brown felt that CASCO would have to gather more data before the company might consider encouraging storage of damp corn as a common practice. The amount of corn milled during this project didn’t give a long enough run to enable officials to fully compare the practicalities and economics of milling wet corn in the winter relative to dry corn. He also wants to take a closer look at their results from the fall months when they are using wet corn, as compared to other times of the year when the corn has been dried.
The practice of storing damp corn definitely can be made to work without causing significant problems for either the producer or the miller. And there certainly are savings for the producer in terms of reduced fuel usage for drying. What remains to be seen is whether the economic advantages for wet-millers are sufficient for them to create an incentive for more producers to store damp corn.
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