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Too Much of a Good Thing? Parts of the Upper Midwest Swamped by Rain

Mary Kennedy
By  Mary Kennedy , DTN Basis Analyst
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Soybeans sitting in a flooded field west of I29 at Spink, SD. (Photo by Brett Scholting, Dakota Dunes, South Dakota)

In the past week, portions of southern Minnesota experienced 72-hour rainfall totals of 3 inches to over 5 inches. According to Minnesota Public Radio, heavy rain last Saturday (June 16) into early Sunday (June 17) was in excess of a half-foot in places. That led to flash flooding, washing out highways in parts of northeastern Minnesota and northwestern Wisconsin. Then midweek, heavy rain soaked parts of northern and central Iowa and southern Minnesota.

Sioux Falls South Dakota newspaper, Argus Leader, reported that as of June 20, rainfall totals in the Sioux Falls region was 3.35 inches, breaking the record of 2.09 inches set in 2011, according to the National Weather Service. At the Sioux Falls airport, 4.69 inches of rain was reported, while Rock Valley, Iowa, received 6.43 inches of rain; Marion, South Dakota, received 4.62 inches and Luverne, Minnesota received 5.11 inches of rain.

Social media is full of pictures of flooded fields in northern Iowa and southern Minnesota, and those areas were hit with more rain again Sunday night (June 24), causing flash flood emergencies to be posted by local weather media.

Many farmers have expressed concern that there would be yield loss, especially in soybeans. Beans don't like wet feet. If you aren't familiar with this age old saying, it means that soybeans sitting in water for an extended period of time will turn yellow, suffer reduction of nitrogen and may not recover enough to reach full yield potential.

Angie Setzer, Vice President of Grain Citizens LLC Algona, Iowa, told me on June 24 that there is still a lot of water standing. "Many spots have been stunted because of the rain," she said. "There are definitely a lot of beans underwater and with the slower pace to planting this spring, not all of the corn is tall enough to handle it." Setzer noted that there is concern these issues could be compounded as hotter temperatures are expected to set in by the end of the week.

Alden, Minnesota, which is in the southern part of the state, has been more fortunate than the towns to the west, said Chad Schmidt. "We have minimal drowned out areas, but the ground is very saturated and we need to get soybeans sprayed and finish side dressing as soon as possible! I could've gotten into the field Monday, but we just got 1.5 inches and it looks to me more is on the way tonight (June 24) in to Tuesday."

Adam Ramthun, a corn and soybean farmer from Manson, Iowa, told me on June 21 that, "There is still plenty of standing water around Manson and Pomeroy, Iowa. Dredge ditches are finally going down from the high marks, so the field tiles are starting to work.

"I think most of the spots where water stood in the beans has killed them. The rest of the beans aren't too happy sitting in saturated ground, but will be okay. Far from ideal conditions, but beans are goofy so you never know until the combine runs."

Brett Scholting, BBH Territory Manager DuPont Pioneer, who lives in Dakota Dunes, South Dakota, told me that, "With much of southeast South Dakota, northeast Iowa, and southwest Minnesota getting rains that totaled over 12 inches the last week -- we are soaked. Most of us got 6-plus inches Wednesday (June 20) to Thursday (June 21) alone."

Can the Crops Recover?

In the Minnesota Crop News Blog on June 22, various crop specialists from the University of Minnesota Extension Regional Office discussed agronomic and disease issues for corn and soybean exposed to prolonged periods of high soil moisture. They noted that to date, much of southern Minnesota has experienced one of the wettest growing seasons on record. The continued rainfall has made it difficult to implement post-emergence weed control and has now created concerns about crop health due to saturated soils and flooded field conditions in some locations.

Given the June 22 calendar date, replanting corn is not an option, noted the article. "We will have to wait and see how soil flooding affects corn mortality. Completely submerged plants are at higher risk of mortality than partially submerged plants. Survivability is impacted by how fast the water recedes and temperatures during the flooded conditions. Cooler temperatures (mid-70s or cooler) are generally better for crop survivability.

"Generally corn should be able to survive a couple days of flooded conditions, but this is complicated by the fact that many spots have flooded multiple times this season. Some root death is likely in flooded soils, and new root growth will be hindered until the soil adequately dries. Affected plants could be subject to drought stress if dry conditions follow."

As for the soybean crop, the article stated that, although soybeans are generally sensitive to excess water, they can survive underwater for a week or more under ideal conditions. "Typically soybeans tolerate 48 hours under water quite well, but flooding for four to six days can reduce stands, vigor and eventually yield. Many factors determine how well a soybean crop will tolerate flooding. The most important factors that determine the fate of flooded soybean fields are: 1) duration of the flooding, 2) temperature during the flooding, 3) rate of drying after the flooding event, and 4) growth stage of the crop during the flooding. Some of the main indirect effects of flooding on soybean yields are: 1) root diseases, 2) N deficiency, and 3) other plant nutrient imbalances."

Here is a link to the entire article, which also includes the names of the extension specialists who contributed to the article:…

A farmer on social media said that while he hates to complain about too much rain, he is going to complain about too much rain. That's likely the sentiment of any farmer who has watched their fields turn in to swampland the past week.

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