Dry Soybeans With Natural Air Or Should You Add Some Heat?

As weather has improved, natural air can dry beans in bin down to safe moisture content.

Published on: Nov 7, 2009

This week, more days have had sun than rain and harvest is progressing, but harvesting wet beans in November 2009 is creating challenges not seen since the early 1970s.


"The weather the past few days has improved so conditions will allow you to dry beans in a bin by running unheated natural air through them," says Iowa State University grain quality specialist Charles Hurburgh.


"The drying of soybeans has become extremely critical and it's a huge cost. Farmers are used to drying corn, but not beans," he notes. "This week we've had good weather for a change. We've had a lot of wet beans this fall—above the preferred 13% moisture content. Processors can't handle soybeans above 15% moisture content, and really not much above 13%. But the air we've had the past few days is capable of drying beans to 13% or less."


Give priority to harvesting, drying beans


You need to give soybeans priority now for drying beans and aeration. Get the beans out of the field and get into your grain drying system, urges Hurburgh.


Farmers have been lamenting how much it will cost to dry soybeans--or how much price dockage they'll get if they take them to the elevator. Drying beans is the better option. With this better weather, would just running some air through them be enough or are you going to have to put some heat on them?


"This week we've made a lot of progress just by running air on the beans," says Hurburgh. "If you can put a little bit of heat on the beans, make sure it's only a little bit. Even in a normally high temperature dryer don't try to go over 120 degrees F or preferably 100 degrees. You won't need it. The beans are going to dry pretty rapidly with the natural air conditions we have now. The beans should end up somewhere around 13% moisture."


If you harvest beans from the field today and put them in a bin and get them dried down to 13%, and you want to hold them in storage for awhile, do you have the potential for keeping that crop until mid-summer without damage? "Yes," he answers. "A moisture content of 13% is certainly dry enough to hold the beans in cold weather and in fact is dry enough with normal aeration to be able to hold them into next summer."


How should farmers handle mold issues on corn? 


Hurburgh is still getting questions about mold showing up on corn ears in some fields in Iowa. "It's predictable that we are having some issues with mold, because grain moisture is extremely high this fall, even into he 30% range in some fields in eastern Iowa," he says.


Farmers are typically seeing a mold called Cladisporium, says Hurburgh. On the corn kernels it looks like a green dot. It is not a toxin producing fungus generally. It's more of a grain grading issue than it is an animal health issue. But the longer the corn stands in the field in reasonably warm weather, until the weather turns cold, you'll probably see more of it.


But there can be other molds and mycotoxins produced. So far, only samples from corn fields that were damaged by hail this past August in Iowa have shown toxin levels high enough to affect swine and poultry—but not feed lot cattle.


What do you recommend when harvesting this corn?


"If you've got some corn with mold on it, there are precautions you should take when you harvest and store it," says Hurburgh.


"First, before you harvest any corn this fall, you should scout the field so you will know if you are coming into a field with mold or not," he advises. "Don't put corn that has mold on the surface of the kernels in a bin with clean corn. Don't mix the moldy corn with the clean corn. Isolate the two types of corn in separate storage bins so that the moldy corn can be dried perhaps a little drier and you can deal with it better after harvest than during harvest. It's very difficult for grain elevators to deal with moldy corn during the harvest period."


So if we do segregate the moldy corn and dry it down more, what are we looking at down the road in terms of selling that corn? Once it is dried and delivered, the corn will get graded for damage according to the regular standards.


If corn is coming out of the field with mold, save a sample


Visible mold on corn does not necessarily produce toxins at significant levels—testing is required to determine if there are mycotoxins present with the mold.


The feed industry and also the ethanol industry are concerned about moldy corn, as the distillers grains could have a higher concentration of toxins in them. "The total extent of the issue and whether there are feed and animal health issues will be better known later into harvest. But we can manage that and work within the system without causing alarm," says Hurburgh.


That's why the corn should be tested, to try to isolate this corn that shows mold on ears in fields, and not put it in the system right at harvest.


"Another point about scouting and letting corn stand in the fields," says Hurburgh, "is that we've noticed that corn that has ears upright tends to trap a bit more moisture and those ears are a little higher candidates for having field molds than if the ear is hanging down with the husks open. So pay attention and look before harvesting as to what some of these issues with molds might be."


SUMMING UP: Many soybeans have come out of the field at 15% or higher moisture content this fall in Iowa. But the weather has improved this week—the first week of November--so you can dry down your wet soybeans in the bin now, and do it by running only natural air on them. Or if you add some heat, don't use temperatures any higher than 120 degrees F; preferably 100 degrees. Soybeans dry quicker than corn and you can damage them by adding too much heat.


Even if you use the unheated natural air, thanks this better drying weather such as we've had this week, eventually you'll get the beans down to 13% moisture content--which is safe for storage through winter and into next summer.


There is mold showing up on corn ears in a number of fields in Iowa this fall. Scout all your fields first before you harvest them and make sure you don't mix moldy corn with corn that's not moldy.