Big harvest, big challenges
W ith low prices and a big harvest this fall, farmers want to store corn and soybeans until prices improve. That may take a while. If you plan on storing long term into summer 2016, you should dry and cool the grain as quickly as possible when it comes out of the field to maintain grain quality and a long shelf life.
That advice, along with other tips for handling this year’s harvest, comes from grain management specialists Charlie Hurburgh and Dirk Maier, professors of ag and biosystems engineering at Iowa State University.
Hurburgh, a grain quality expert and longtime member of the ISU faculty, heads the Iowa Grain Quality Initiative. Maier recently joined ISU in August, from Kansas State, to teach and conduct research. He is associate director of the Global Food Security Consortium at ISU.
The 2015 growing season was wet and cool. Most of Iowa averaged slightly below-normal temperatures, and all but the Northeast crop reporting district received 2 to 10 inches above normal rainfall. These conditions produced very high yield potential, but there are many fields where disease and premature death in both corn and beans after Labor Day affected test weight and quality of the crop.
As signified by yellowing of corn plants late in the growing season, some corn ran out of nitrogen. “While yield is determined over the full season, crop quality is often established by conditions at the very end of the growing season,” says Hurburgh.
Effect of corn dying early
Premature and irregular death in corn retards kernel fill, which in turn reduces test weight from what it would have been with completely filled kernels, Hurburgh explains. Some yield is lost, but more importantly, field drydown and storage properties will not be as good as they might have been. A test weight of 54 to 55 pounds per bushel may be high this year, whereas in early August, the expectation was around 58 to 59 pounds, with the normal being 56 pounds.
When wet and humid weather persist, regardless of temperature, you can expect wetter-than-normal corn at harvest. Hurburgh and Maier also point out that stalk strength is not good in many fields this fall, requiring early harvest to prevent yield loss from downed corn. Overall, looking at Iowa’s 2015 corn crop, the net result is a high-yielding crop that will require artificial drying and may not have good long-term storage properties.
The effect of the 2015 growing season on soybean quality is showing up as widely varying grain moistures and maturities in the same field. Soybeans typically dry down to 12% to 13% eventually, the ISU specialists note. The scenario that creates a large amount of wet (greater than 15% moisture) soybeans is when you have a long period of cool and wet weather after the beans have dried down once, and then they become rewet, matching the higher humidity conditions.
This fall, if weather stays warm until beans reach maturity, protein content will likely be good (above 35%). However, the oil content, which is formed earlier in the season, may be lower than normal, says Hurburgh.
Hurburgh observed a lot of mixed-moisture soybeans in fields in late September. “There are places where the beans are dry and places where they’re still green in the same field. And they are the same variety.”
In addition to weather creating this variability, another factor involved in some fields is sudden death syndrome and some other diseases, especially on low ground. Disease issues were not showing up very much this year until September.
Mixed-moisture grain coming out of the field is always hard to deal with. Some farmers say “soybeans don’t need air.” They don’t believe you need to turn the fan on and aerate beans in the bin. But that’s just asking for trouble, according to Hurburgh and Maier. They recommend aerating beans. “Even if soybeans come out of the field dry, you should run some air through them,” says Hurburgh.
Usually, the average October natural air conditions will take soybeans down to 12.3% to 12.5% moisture content in the field. Beans will often get drier than that because soybean moisture falls fast a week or two at the start of harvest. A dry wind will drop a field of beans to perhaps 8% to 10% moisture content. Typically, if you don’t harvest then, the pods will split and you lose yield. So you try to harvest them before that happens.
However, if you don’t get them harvested, the beans will rise back up in moisture, and they won’t come down as fast the second time as they did the first.
The natural moisture content in October is about 12.5%, and in November it’s about 13.5% to 14% for beans, notes Hurburgh.
“What this also tells you is you can aerate soybeans in the fall and probably not overdry them. If you aerate beans in the spring, you’re going to overdry them, but likely will not if you aerate in the fall,” he says.
Manage moisture at harvest
While you want to dry grain to moisture levels for safe storage, you also want to avoid over-drying corn and beans. It costs money to run a drying system, and you lose bushels by removing more moisture than necessary. If beans in a bin are below 13% moisture, that’s considered overdried. For corn, it’s 15%.
Where do those figures come from? The market generally allows 13% moisture content before buyers begin docking the price for moisture on soybeans, “which means you’re losing weight with beans below 13% moisture content,” says Hurburgh.
“Also, consider that 13% moisture beans will store like 15% moisture corn. It’s not a perfect correlation, but it’s similar.” The moisture level for safe corn and soybean storage depends on how long you plan to store.
The table above provides guidance. With wet corn coming out of the field this fall, take special note of the last column.
“I included that column for 24% moisture corn to show how fast corn quality can deteriorate when corn is wet and warm, even when it is first coming out of the field,” says Hurburgh. “If you leave a load of wet, warm corn sitting in a wagon overnight, you can lose half of its storage life right there.”
Pay attention to corn hybrid maturity, says Maier. Grain moisture at harvest will be higher for corn that didn’t reach maturity as soon as other hybrids before a killing frost occurs. “If you have more than one wet holding bin ahead of the dryer, try to keep the wetter grain together to run it through the dryer,” he says. “If you have some fields with drier corn, you can harvest them a little later, assuming stalk health is good. You can hold the drier corn in the fields a little longer before you have to run the corn through your grain drying system.”
Watch corn test weight, too. Test weight is an indicator of storability. “If you have a choice, and you have a hybrid coming out of a field that is low test weight, don’t store it,” advises Hurburgh. “You’ll eventually have problems if you do. If you are going to sell some of your corn anyway, the low test-weight corn is the best to sell first. Get your light corn out of the way. Take it to the elevator. Keep your highest test-weight corn for long-term storage.”
For more information, visit the Iowa Grain Quality website at extension.iastate.edu/grain.
• Be careful with warm grain coming out of the field on hot days. The storage life of grain starts immediately after harvest and is shortened significantly by periods of storage at warm temperatures. The table below is the generally accepted storage life of corn and soybeans at various temperatures and moistures. One day of holding warm, wet corn before drying can use as much as 50% of the storage life, which means storage problems will be likely next spring and summer. Holding wet corn can also result in blue-eye mold.
• Soybeans are often overlooked in the need to cool grain immediately; yet soybeans are more often harvested in warm weather compared to corn.
• Expect slower drydown in the field, slower drying in dryers and more grain breakage if test weights have been reduced. Expect backups at the dryer, either on-farm or at the elevator. Storage time is also shorter than given in the table if test weights are below average. In 2009, when average corn test weight was about 52 pounds per bushel, the storage life was about 50% of that given in the table for the same temperature and moisture conditions.
• Carryover grain stocks from 2014 are larger than carryover from the 2013 crop for both corn and soybeans. It’s likely some corn will be stored in outdoor piles for a month or two this fall, until demand can use up supply. A rush to commercial storage is likely in the second half of harvest with this year’s large crops.
• Potential exists for fungi on corn in the field. Some fungi, notably fusarium and gibberella, can produce vomitoxin and zearalenone, two mycotoxins harmful to animal and human health. Expect mills and ethanol plants to screen early-harvest samples for these toxins.
• Pay attention to test weight as an indicator of which corn to deliberately assign to long-term storage (greater than nine months). Considerable 2015 corn is expected to be on hand in 2017.
• Don’t mix old- and new-crop grain in the same bin. There will be increased spoilage risks, because the old crop has used much of its storage time and the new crop is still balancing its moisture. Rotate stocks if you can, keep old stocks and new stocks separate. Be sure to separate the two crop years and draw the center cores out of all bins, corn and beans alike.
• Temporary outdoor piles are best handled by a commercial elevator. Management of piled grain is labor-intensive, and often requires quick decisions about moving the grain. Larger piles are also easier to aerate.
• Nothing is worth taking shortcuts on safety. High volumes and wetter corn are common ingredients for grain handling accidents, both entanglements and engulfments.
This article published in the October, 2015 edition of WALLACES FARMER.
All rights reserved. Copyright Farm Progress Cos. 2015.