Flooding and Stored Grain March 20, 2019
The following article from Iowa State University is by Charles Hurburgh, ISU Department of Agricultural and Biosystems Engineering, and Dan Loy, ISU Department of Animal Science, and was published in the ISU Integrated Crop Management News, Iowa State University Extension and Outreach. (This article replaces the author's 2011 article by the same title.)
The rapid snowmelt in Spring 2019 has caused instances of stored grain being inundated with floodwater. By current Food and Drug Administration (FDA) policy, flood-soaked grain is considered adulterated and must be destroyed. As shown by the example of the inundated Omaha sewage treatment plant, floodwaters can bring in many hazards and create very rapid grain spoilage.
Flooding affects both the stored grain and the storage structures. Try to move the grain before the flood reaches the bin, but stop using underfloor conveyors and legs once the water starts entering the pits.
Grain and Grain Products
Flood damaged grain is adulterated grain because of the potential for many contaminants to enter through the water. This grain should be destroyed, never blended. Contact local public health and sanitation officials for the best disposal process in your area. The recent Food Safety Modernization Act has increased public awareness of food and feed related hazards.
Water coming up from tiles and pits is just as suspect because storm and sanitary sewers are usually compromised in floods. Even field tile water may contain animal waste products, high chemical levels and other contaminants.
Corn will stay at about 30 percent moisture after the water drains off; soybeans about 25 percent moisture. When stored grain is flooded, the moisture won't travel more than a foot above the flood water line. There may be opportunity to remove the good grain on top of the flooded grain either from the top or side, not down through the damaged grain. The reclaim conveyors and pits under bins contain flood water as well. Remove all the good grain before doing anything with the bad portion. Do not start aeration fans on flooded bins. Take care not to track or mix mud or gravel from flooded grounds into good grain during salvage operations. These materials are potentially toxic for the same reasons as the floodwaters. Have the entire structure and related electrical components inspected by a qualified electrician, to verify that nothing is still energized, before taking action to salvage the grain. Use professional salvage operators that will take correct safety precautions for bin entry.
Mold toxins are likely in rewetted grain. Warm wet conditions are ideal for mold growth and moldy grain is a safety hazard. Use precaution and wear protective equipment when working with moldy grain. Grain will be moldy by the time the water has receded.
The FDA allows for reconditioning (washing and drying at high temperatures) in cases where it is known that the water did not contain contaminants. This situation would be very rare, to know that floodwater was clean. In past flooding situations, the water was determined to be contaminated; expect that to be true in 2019 as well.
Grains swell when wet so bin damage is likely; more so with soybeans. Bolts can shear or holes can elongate. Look for signs such as stretched caulking seals, doors misaligned or similar structural problems. Farm bins typically have lighter-grade steel and fasteners than commercial bins. Be aware of signs of failure when working around bins containing wetted grain. Check bins with stirring devices carefully. The bin must be perfectly round for them to work correctly. Wood structures will be hard hit and may retain mold and contaminants. Bin foundations can shift, float or deteriorate from flooding. Inspect structures and foundations carefully, and have an engineering evaluation for larger bins.
Expect electric wiring, controls, motors and fans to be ruined. Do not energize wet components. Be sure the power is off and locked out before touching any electrical components of flooded systems.
Clean and disinfect facilities and grounds completely. Then do a careful food safety inspection before returning facilities to operation. A third party inspection is recommended. Maintain records of cleaning.
- Cut all power and professionally verify that all structures are not energized.
- Determine where the water line was, and therefore the extent of adulterated grain.
- Consult your insurance carrier before moving any grain.
- Remove good grain from the top, have it graded by an official grader, and tested for mycotoxins.
- In Nebraska, for information on disposal of adulterated grain, please see this Nebraska Department of Environmental Quality resource, Flood Damaged Grain and Hay Disposal.
- Clean and disinfect storage structures. Replace electrical components.
- Feed the good grain in consultation with a veterinarian who may ask for additional tests.
In the rare situations where the water was not contaminated, the grain may be reconditioned. If the grain is sold, reconditioning has to be done with the written consent of the FDA. For feed on site, producers have three alternatives.
- Dry the grain
- Feed it immediately to their livestock
- Ensile the grain for future livestock feed, in bunkers or bags
Feeding must be done under the supervision of a veterinarian. Ensiling may be the best way of protecting quality and palatability. There is no problem, other than spoilage within a day or two, with using uncontaminated soaked corn as a livestock feed. Just replace the corn in the animals' current diet with the wet corn. Remember to adjust amounts fed for moisture.
Wet, whole soybeans can be fed to cattle if the soybeans are limited to 10-12 percent of the ration's dry matter. Soybeans substitute well for the protein in soybean meal, but they need to be fed with a vitamin-mineral-additive premix if substituted for a complete protein supplement. It is not necessary to heat-treat the soybeans for cattle. Also, if adding whole soybeans to diets high in distillers' grains, watch the total ration fat content. For hogs, raw soybeans can only be fed to mature sows. The soybeans need to be heat treated if fed to younger pigs.
Decisions need to be made quickly. The good grain should be removed immediately, again not down through the soaked grain. No flooded grain can be sold to any market without approval of the FDA, to document its exposure only to uncontaminated water, with subsequent reconditioning and intended use. The spring flooding of 2019 is not likely to create many salvageable situations. Localized flooding not originating from stream or river flow might be a salvage case.