Iowa State University agronomists share possible post-flood scenarios

As of now, no one can precisely tell these farmers what they’re in for once waters do finally recede. Iowa State University (ISU) agronomists say some likely scenarios to consider include managing sediment, possible tillage and fallow syndrome.

This, however, depends on whether flood waters recede by the early spring thaw, which will be necessary for farmers to get in the field and begin repairs. Mahdi Al-Kaisi, agronomist with ISU, says the effect of water staying over the winter will depend on several factors, including how much water is on the soil and how long it stands.

“This will be a function of soil drainage,” Al-Kaisi explains. “The effect of freezing water over the winter will also be dictated by what kind of spring we have, which will most likely be a wet one, given the recent history. The effect will be how we deal with wet soil and delay in getting to the fields.”

If the soil is dry, ISU Extension Agronomist Clarke McGrath says farmers will have to clear fields before planting.

“There may be sediment, mostly likely from sand and debris to move out of fields,” McGrath explains. “Management of the deposits is a long and complex discussion that involves how much is left, where it is, how deep it is, access to equipment to move it, cost of fuel and time.”

McGrath says to make it even more complicated, there’s the issue of ownership versus rental of the land.

“If a farmer is renting, then there is a serious discussion to be had with the landowner. And, as a landowner, the amount of sediment left could have a significant impact on land values and rental income.”

McGrath emphasizes this is all a huge unknown since water is still present on much of the land and there will likely be many variables once farmers see the extent of the sediment.

Even if the field is somehow clear of sand, silt and debris, McGrath says the few inches of soil may need tillage to break up any layer of “crust” that formed while the water sat on the field and degraded the upper few inches of soil structure.

“We hope it just takes light tillage to break up the crust,” he says. “That is our best guess, but it’s impossible to say for sure until the water is gone and the field is dry enough to inspect.”

After tillage, the question of fallow syndrome remains. McGrath explains that when fields do not have something growing in them for a season, or even a significant part of a season, crops do not grow well due to the loss of soil microorganisms that cannot survive in the absence of plant roots and oxygen.

“We often recommend growers plant a cover crop in the summer or fall after a flood so the soil microbes can make a comeback prior to planting high value cash crops, like soybeans or corn.”

But, he says, if growers can’t even get into the fields until next spring, this isn’t a practical idea. “They may just have to roll the dice and plant without having had time to plant a cover crop. A lot of hard decisions will be made this fall and spring, depending on when fields can be entered.”

Though agronomists can look back at previous floods for management and repair strategies, Jorgenson and Ettleman say there’s no comparison.

“They always compare all floods to the great flood of 1952,” Ettleman notes. “There are a lot of houses that are inundated this year that were dry in 1952, as well as 1993. This is by far worse than either of those floods.”

Jorgenson stresses that part of the story often gets left out. “The situation isn’t going to change. We have to deal with this for a long time to come.” He adds he isn’t sure what has been ruined by the floods or what will remain after the water is gone, including farm ground. “Nobody knows. We haven’t seen anything like what we’re dealing with.”

Though doubt and frustration have wracked the community, Ettleman has no intention of leaving. “We’re just going to keep up the fight and keep going. We’re not going anywhere.”