Grain quality matters when storing grain on the farm
By KRISS NELSON
During an on-farm crop storage management webinar, Dr. Dirk Maier, professor and post-harvest engineer with Iowa State University Extension, said quality grain is the No. 1 job when keeping grain stored on the farm.
“It really doesn’t matter what the end use is. Whether you are holding your grain a few months for market and it goes to a grain elevator that eventually sells it to an overseas destination or whether the grain will end up as animal feed on your own farm or whether it eventually ends up in a feed mill which are all primary uses here in Iowa – it’s important for these end uses to preserve quality and avoid being rejected at the point of sale,” said Maier.
As producers begin this year’s corn harvest, Maier said there is still quite a bit of carryover with corn and some of it has been impacted with mold damage. These mycotoxin issues, he added, were due to the poor quality conditions from the 2016 harvest.
“We are not expecting those issues this year, but if you did experience drought conditions, and if you observed a lot of insect damage in the field then mycotoxins could be present,” he said. “They can be in the ear in the corn without necessarily seeing a lot of evidence of mold growth on the ear, so be aware of that.”
With the potential of carryover from the 2016 cropping season, Maier advised it is never a good idea to mix crop years in the same bin.
Maier said the way producers handle their grain is a key issue to keeping a higher quality of grain.
“Physical kernel damage in both the exterior and internal area of the kernel, soybeans that are split,” he said. ” Breakage susceptibility ranges from hybrids we select to the way we operate our combines, to the way we operate or drying systems, and cumulatively, that can make a difference between a good quality kernel versus one that is very susceptible because of high level of brittleness,”
Many times, Maier said if there is some damage to grain, those damaged kernels will cause a core of fines that concentrate at the top.
“This core of fines prevents air flow through them effectively, which can cause heating in this area, and this is typically where you will see most of the problems in storage,” he said.
Maier said it takes a lot more time and energy of operating fans to cool that area out, so what should a producer do to manage the core?
“One way to deal with that is to take a portion of the grain out through the unloading system,” he said. “Take some of the core out and aerate it and see, after seven days, if you have a nice, even temperature throughout the bin.”
According to Maier, this practice of “coring” is relatively simple.
“You eliminate the grain peak, remove the core of broken corn and foreign material, you improve air flow through the center and you’re better able to monitor the grain surfaces,” Maier said.
One way to accomplish this, he said, is after you fill the bin, unload a portion of the grain for long enough of a period to where you have a third, to a half of a diameter of width inverted of grain mass.
“This doesn’t have to be done right after you fill the bin, especially during the busy time of harvest, but what you do is, if you have multiple bins to manage, is you unload the core out of all of the bins as you have the opportunity to ship or feed,” he said. “So you get rid of that core so that by the middle of winter, spring or early summer, you are managing a grain mass that is stable and preserved in quality.”
A larger diameter bin, may need to be cored multiple times.
“If it takes you a few weeks to fill the bin, maybe you should core it after every quarter that you’ve added so you’ve managed to get that core versus filling it all of the way to the top and try to core it all in one setup,” Mair said.
Maier said when we’re drying, we’re primarily concerned of chemical damage and processing value.
“Meaning that if you have too high of a temperature the kernels are exposed to, we are taking away from the potential for starch conversion at the ethanol plant, we’re taking away potentially nutrient efficiency in animal feeds and what we are trying to manage in the drying system is the kernel temperature, not just the drying air temperature and the drying rate so that we can minimize stress cracks,” he said.
A challenge while drying is, there is no drying system in the world that can change a difference between drying kernels and wetter kernels in one pass through the dryer.
“What happens is, you shift the average of 18, 19, 20 percent down to 14.5 to 15.5 percent,” he said. “But those dryer kernels, initially, are going to be well below 15 percent, maybe 10 to 12 percent and the kernels that were above 20 percent might shift down to 17 percent and that is what you end up with in the bin.”
The primary way to deal with that issue, Maier said, is to interrupt the drying process and allow the kernels to steep.
Steeping does two things: relieves the stress in a single kernel as a result of drying, reducing stress cracking, and it equivalates the moisture content not only in the kernel, but among the kernels.
“So, if you hit that grain a second time in a drying situation, now you move that and that average is much more uniform, down to that final moisture content,” he said. “That is really the only way to reduce the standard deviation and the variability that you have on corn kernels. And that can be done with different types of drying systems, if you pay attention and go after that.”
Insect activity, Maier said, is not typically a problem in Iowa, but mold problems, such as mycotoxins are definitely an issue in corn.
“Spoilage as a result to molding or mycotoxins is definitely an issue we need to pay attention to,” he said. “It affects storability, it affects what may have to happen in order to take care of a hot spot. You need to catch a bin before it goes out of condition and avoid having to enter a bin.”
Optimal mold development happens with the relative humidity of the air surrounding the grain kernels in the bin is above 65 to 70 percent and mold can grow at different temperatures as well.
“At 40 degrees, you have a lot more flexibility of the moisture content the grain can be stored at and at higher temperatures at like 90 degrees, we have less flexibility of lower moisture content that we have to store it,” he said. “It becomes a critical thing in your decision. If you’re going to store grain into late spring and summer, you need to be close to 14 percent moisture content in order to avoid mold development or even a little below that if you’re going to keep grain in to the summer to avoid mold development on the surface of the grain as a result of the air surrounding the kernels.”
What exactly is a safe grain moisture content?
“During the winter time, we can afford to store grain at higher moisture contents. We are safe if we are between 15 to 16 percent and keep temperatures below 50 which we can definitely do in Iowa,” he said.
Maier said a quality grain best practices management approach is “SLAM: sanitation, loading, aeration and monitoring.”
For sanitation, Maier said you want to have the bins clean before harvest.
“If you’re still a little bit behind on it, now is a good time before harvest to go out and check the bins, make sure there isn’t grain residue in there, that things are in good shape and the equipment is running because once we get to harvest, we don’t have enough time,” he said.
Loading, Maier is all about safe handling of the grain to help avoid breakage and other issues.
For aeration, Maier said the standard recommendation by September and October is aerate the grain in the bin after harvest, then again a few weeks or a month later, aerate the grain a second time and then later on, aerate the grain for a third time.
“What we are trying to do is take advantage of the average temperature in our region to bring grain down versus turning on fans at the beginning of filling the bin and running them until December,” he said. “That takes way too much electricity, so instead, we want to do it in two to three steps.”
Maier said his recommendation has been to bring the grain down to a cool temperature range, hold it and keep it there into the spring and summer.
“Cold grain that is cored has been stable and will stay cool and stable into the following spring and summer,” he said.
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