Market Matters Blog

Stored Corn Going From Good to Bad

Mary Kennedy
By  Mary Kennedy , DTN Basis Analyst
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Corn piled in northwest Minnesota in mid-November 2016. Piles like this can last through the winter, especially if corn was dry and is piled on a concrete slab, then equipped with fans underneath the tarp to keep air moving. (DTN photo by Mary Kennedy)

Reports are surfacing of wet corn stored in piles turning sour, and in some cases, sprouting. While some of the piles were uncovered and hit with heavy snow and rain, some covered piles have been affected as well if corn was too wet when stored. It's a shame, given the 2016 corn quality was deemed "excellent."

In their sixth-annual corn quality survey, the U.S. Grains Council (USGC) reported the 2016 corn crop "had an excellent crop condition during reproductive growth, as well as high yields, particularly from the Western Corn Belt. Overall, 2016 was characterized by a warm, dry vegetative period, followed by a warm and wet grain-filling period and harvest. Such favorable weather conditions in the United States have led to a projected record amount of corn in 2016 available for export."

According to the report, the average U.S. aggregate moisture content recorded at the elevator in the 2016 samples was 16.1%, higher than 2015 (15.7%), lower than 2014 (16.6%), and the same as the five-year average (16.1%). USGC noted that general moisture storage guidelines suggest that 14% is the maximum moisture content for storage up to six to 12 months for good-quality, clean corn under aerated storage in typical U.S. Corn Belt conditions; and 13% or lower moisture content is recommended for storage of more than one year.

"Because of higher moistures in 2016 than in 2015, and higher total damage levels in 2016 than in previous years, care should be taken to monitor and maintain moisture levels sufficiently low to prevent possible future mold growth," USGC stated in its report.

Here is a link to the entire quality report: https://grains.org/…

SNOW, RAIN CREATE PROBLEMS FOR STORED CORN IN PILES

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Various reports from the Midwest say some corn was still too wet when stored, or corn in open piles was hit with rain and snow. A grain elevator manager in North Dakota told me that he talked with a farmer who was having trouble when his corn pile was rained on at Christmas, and the farmer is now feeding most of it because the quality downgraded. The elevator manager told me as far as elevators that have outdoor piles, the weather and BNSF railroad slowing down isn't helping any, and he thinks the corn should "come in ASAP and be put through the dryer and screener to make shuttle grade."

Over Thanksgiving weekend, there was talk of a corn shuttle that was billed with 99 sour cars and the buyer made the loader take the shuttle back and then reload it. I have no knowledge of what that may have cost the shipper, but the demurrage penalties alone are $600 per hour past the 24-hour free time for loading a shuttle and then $1,000 per hour beyond 48 hours. Another shuttle was reported having trouble making grade early in December. Part of the reason corn went out of condition was likely due to some elevators being unable to secure freight and being unable to clean out their full elevators and bring the piles in and get it in condition to load ahead of the arrival of the shuttle.

Another North Dakota elevator told me that they are seeing some damaged and sour corn -- some from uncovered piles and some from bins where corn went in wet. "There are a few elevators fighting the snow and sour in their own piles; the snow is plugging up conveyors and sprouting. I hear it picked up about 3% moisture from the rain over Christmas," he added.

Besides the corn piles, there is plenty of bagged corn in the country due to lack of storage space at harvest. Sources tell me those appear to be OK. They are frozen solid, and the bagged corn will likely need to be run through a dryer or cleaner when it's ready to move to market. The danger with bags is if deer or other animals chew on them and the bag breaks open, the grain could spoil unless it gets picked up off the ground right away.

Tim Luken, manager Oahe Grain Corp. in Onida, South Dakota, told me that he saw an open corn pile that was steaming due to heating up, which likely occurred after the 1 inch of rain that fell Christmas weekend. "I spoke to an elevator north of here that has 4 million bushels on the ground and said it was looking pretty good yet. There was likely some damage caused by the 2 inches of rain, especially underneath the piles where the ground is not frozen. He did say he is hoping by the end of January all his piles would be cleaned up."

VOMITOXIN IN STORED CORN

Angie Setzer, vice president of Grain Citizens LLC in Charlotte, Michigan, told DTN, "We are starting to have a few guys surprised by vomitoxin levels coming out of the bin. Some may not have had loads tested during harvest because end users at that point weren't testing every load, while others are finding levels are creeping up from where they were during the fall. If corners were cut in drying and the corn is 16%-plus, the toxin can continue to grow and problems will quickly multiply. I have heard, though, that some are finding levels increasing even with corn dried below that magic 16% level."

I spoke via email with Charles P. Woloshuk, a botany and plant pathology professor at Purdue University, whose responsibility is mycotoxins associated with grain production. The objective of his Extension effort is to inform and educate the grain producers, handlers and processors about mycotoxins. Surveying fields for disease and mycotoxins is a major component of his program, because diseases prior to harvest are the primary source of mycotoxins.

Professor Woloshuk said, "The growth of this fungus requires a minimum water activity of about 90% and minimum temperature of low 20s degrees Celsius (70 Fahrenheit) for growth and to produce vomitoxin (DON). In corn, this would translate to a moisture content of above 18%. So, I would not be too concerned about the 16% grain increasing in DON. My concerns with holding corn at 16% moisture and higher into the spring would be the potential accumulation of aflatoxins. The fungus that produces aflatoxin can grow at a moisture content at about 16%, and if the temperature is right, aflatoxins will accumulate. There is also a higher potential for storage fungi that will grow at 16% moisture. These fungi will destroy the grain as it warms."

Woloshuk added that the grain should be properly dried to 14% to 15.5%; 13.5% if it is to be carried into the summer. "If there are farmers that have 16% grain in their bins, it should be sold before the weather begins to warm in the spring," he added.

Setzer added that we won't know the full extent of how badly the stored corn may or may not be infected until the corn really starts to move off the farm, "but at this point, in my particular trade area, it seems to be a rapidly growing problem."

Mary Kennedy can be reached at mary.kennedy@dtn.com

Follow Mary Kennedy on Twitter @MaryCKenn

(AG/BAS)

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