Moisture causes downgrades | Warming temperatures will cause moisture to accumulate, agronomists warn
Farmers should be extra vigilant monitoring their stored grain this year, say experts.
A bumper harvest and disappointing winter shipping program is resulting in farmers carrying over far more grain than usual this spring. Some of the crops in temporary storage may need immediate attention.
Digvir Jayas, former Canada Research Chair in stored grain ecosystems and vice-president of research at the University of Manitoba, said growers should attempt to move grain out of bags, Quonsets and piles and into aerated bins before May.
However, the urgency depends on what state the crop was in when put into temporary storage.
His three-year study on canola stored in bags shows the crop can last in plastic without deteriorating for 10 months or until the end of August if it was put away at eight percent moisture content.
As the moisture content rises, so does the storage risk. Canola with 10 percent moisture content, which is still considered dry by industry standards, loses one full grade if kept in bags for 10 months.
Farmers need to take quick action if they are storing canola with 12 percent moisture content in bags. It will be fine if moved to a bin before ground thaw, but product kept in bags for one month after thaw loses one grade.
“If (growers) wait until the summer to unload a bag with 12 percent moisture canola, then basically it became feed grade,” said Jayas.
He expects similar results for wheat. The equivalent wheat moisture content under the three scenarios would be 13 percent, 14.5 percent and 16.5 percent, respectively.
Keystone Agricultural Producers president Doug Chorney thinks farmers would be wise to heed the warnings about grain stored in bags.
“I know of many producers who have told me this winter they were surprised to find crusted bin tops in their good steel bins that have aeration and everything, so I can’t imagine what it would be like inside a bag,” he said.
There are also precautions for grain stored in bins.
Angela Brackenreed, agronomy specialist with the Canola Council of Canada, said the goal is to maintain equilibrium between the temperature of the stored grain and the outside air. Problems occur when grain inside the bin is 10 C cooler than the outside air.
“You get those localized spots in the bin where moisture starts to accumulate. Once that starts to happen, you can get rapid spoilage throughout the bin quite quickly,” she said.
Moisture typically collects in the bottom central core of the bin. Growers should frequently probe that area and others to check for moisture and grain temperature.
“Get into as many spots of the bin as you can to check the temperature because it can be very different from one spot to another,” said Brackenreed.
A 10 C difference between the composite sample and the ambient temperature means it is time to turn on the aeration fans.
“If you don’t have aeration, you really want to consider unloading that bin and turning it manually,” she said.
Jayas said moister grain should be dried first. It can be naturally air-dried when temperatures are higher than 15 C and relative humidity is lower than 65 percent, which can happen on some days in late April.
Cold grain should be turned or aerated to raise the grain temperature to between 5 and 10 C to prevent moisture migration, which leads to spoilage.
Aeration can be delayed if the outside temperature warms slowly, but the fans should be turned on if there is a rapid change.
Jayas advised against mixing last year’s harvest with grain from previous years unless farmers are absolutely certain the older grain has no insect infestation or spoilage. It’s best to avoid mixing if possible.
Oilseeds are particularly susceptible to spoilage. The higher the oil content, the more prone it is to spoilage, although Jayas said there isn’t a statistically significant increase in spoilage until oil content reaches levels of 48 to 50 percent.
Last year’s canola crop had a mean oil content of 44.8 percent for the top grade, which is close to the record of 45.2 percent set in 2011.
Bruce Burnett, CWB weather and crop specialist, said wheat growers need to be extra watchful this year because some of the crop was harvested under high moisture conditions.
“With the drop in prices that we’ve seen here, you can’t afford to lose some of this grain that you produced last year,” he said.
Burnett worries farmers will soon be preoccupied with planting the new crop rather than looking after the old one.
“Check it and check it frequently, even if it slows you down a little bit for some of the other operations that are going to be going on,” he said.