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Managing Crops Damaged by Mid-to-late Season Flooding

What to expect and what to do after flooding.

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Updated:

September 3, 2024

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Flooded field in Tioga County.

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Flooding (i.e., partial or complete submergence) events occurring in the mid-to-late growing season can result in significant yield and crop quality losses. Plant death of soybeans and corn typically does not happen if the soil is drained within 96 hours of the flooding event. However, significant lodging may prevent the crop from being harvested. Further, crop quality issues such as soil deposition on the grain, sprouting, and mycotoxin contamination can make harvesting challenging and even render the crop unfit for animal feed. After a flooding event, the following steps are to: (1) assess the damage, (2) document any damage with pictures, and (3) contact your crop insurance adjuster to report the event and seek advice specific to your situation.

Below are general farm-level recommendations for managing crops after a mid-to-late season flooding event.

Corn for Silage

Corn destined for silage will be more at risk for fungal and bacterial contamination. Take steps to promote good fermentation, such as heavy inoculation and extra packing in the silos. A good fermentation will kill many (but not necessarily all) pathogens in the silage.
Target the least affected fields for silage and increase harvest (stubble) height to ensure the harvested crop is clean and dust-free.
Do not chop corn for silage with considerable dirt or silt on it.
Segregate any corn chopped for silage to be evaluated before feeding. Forage should be tested before feeding, paying particular attention to dry matter percent, starch, ash, mycotoxins, and fermentation profile.
Silage and high moisture corn from these fields should be evaluated at feed-out, and animal health should be closely monitored. Soil contamination alone may not be a serious animal health factor. Still, contamination from manure, sewage treatment plants, and other chemicals is unknown and could vary from one situation to another.

Silt line can be seen below the ears in this corn field in Tioga County. Photo credit: Craig Williams.

Corn for Grain

Harvesting for grain is likely a better option than for silage when flooding has occurred.
Monitor for stalk rots. Fields that remained flooded for over 12 hours are most at risk for stalk rots.
The crop may mature more rapidly under these conditions since corn that has been stressed when near maturity often seems to dry down fast.
Monitor for sprouting. Some river bottom fields are prone to bird damage and often have some sprouting risk. The flood may exacerbate the problem. Try to adjust the combine to remove most of the sprouted grain.
Monitor for molds. Corn from flood-damaged fields should be evaluated for grain quality and kept separate if there are indications of molds. Mold and mycotoxin levels can be determined by most feed testing laboratories and used as guidance in marketing.
The risk of molds and sprouting is likely a function of the exposure to the water and stage of growth. Corn under water will have an increased risk of molds and bacterial rotting. This may be more pronounced in corn that is already drying down (less than 40% grain moisture) and then taking on moisture during the flood.
The expected quality of grain is uncertain and should be monitored since crop contamination by flood waters could affect marketability. Check with the crop insurer for specific advice.
Combine air filters should be changed more frequently to ensure the harvested grain is clean. Operators should take steps to avoid breathing the dust.
Harvesting high-moisture corn at the drier range of acceptable levels could improve grain cleanliness.

Soybeans

Soybeans are typically more affected than corn because they are more susceptible to lodging, and the lower pods are easily exposed to flood waters.
Monitor grain quality before harvest. Soybean crops will likely experience increased harvest losses and machinery problems during harvest. Many soybeans may be impossible to harvest due to lodging and debris.
Harvest and, if possible, store soybeans from flooded areas separately from areas that were not flooded.
Monitor grain moisture. Due to stress-induced senescence, flooded soybeans may mature earlier than non-flooded ones.

Soybean plant covered in soil. — Soybean plant in a field in Tioga County completely covered in soil. Photo credit: Craig Williams.

Hay and Pasture Crops

Soil and organic matter on forage crops can also lead to fermentation issues, increased ash, decreased digestibility, and animal health problems, especially for horses.
Do not pasture or harvest silt-laden forage crops.
It might be best to mow the previously flooded pastures and wait for them to regrow before grazing.
Mowed forage lying in the field for more than one week should be chopped and blown back onto the field, particularly if it shows signs of molding.
Roots in soil flooded for 2 to 3 weeks may die from suffocation (no oxygen available for the roots to respire).
Root diseases such as Rhizoctonia or Phytophthora can increase in wet soils and lead to thinned stands next year.

Round Bales of Hay or Baleage

Forage harvested in large bales (round or square) as hay or fermented as baleage and exposed to flooding can drastically alter nutrient content and increase disease risk.
Flood waters can potentially contain pathogenic bacteria and contaminate the forage. Soil bacteria such as Listeria and Clostridium can cause disease once the contaminated forage is consumed.
Botulism (Clostridium botulinum) is always a potential concern in moist large-baled hay, but this risk increases with flood water contamination. Horses are particularly sensitive to this disease and should be vaccinated.
Listeriosis (Listeria monocytogenes), commonly termed “circling disease”, is a high-risk disease for sheep and goats. This organism grows in poorly fermented forage with a pH above 5.
Water-soaked bales will leech soluble sugars and proteins, reducing forage quality. Hay or baleage may undergo a fermentation process resulting in increased temperature with a potential risk for spontaneous combustion. Do not stack these affected bales with unaffected bales. A compost thermometer can be used to determine any increase in temperature. Temperatures exceeding 80 degrees Fahrenheit would be of concern.
Before feeding any affected bales, representative core samples should be collected and submitted to a forage testing laboratory for analysis. Wet chemistry methods are suggested as this will more accurately assess an altered forage. Look for elevated values of ash (>10%) and iron (>1000 ppm) for indication of soil contamination. Review sugar, starch, and soluble protein values relative to fiber (NDF and ADF) to assess the loss of available nutrients. Request a pH and fermentation profile for any ensiled forages to further evaluate forage quality and aerobic stability.