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Farming after a flood
Gene Stevens stood on the front line to help farmers after the floods of 2011 inundated hundreds of farms and hundreds of thousands of acres of cropland up and down the major Midwest waterways. He's a crop specialist with the University of Missouri Commercial Agriculture Program at the Fisher Delta Center in Missouri's far southeast bootheel.
As the water piled up around Cairo, Illinois, the Army Corps of Engineers regretfully blew sections of the levees at the Bird's Point-New Madrid Floodway to pour river water onto 130,000 acres of farmland in this fertile region to save bigger population areas.
Stevens lives and works in the area. Like many other Missouri Bootheel residents, for awhile he feared for the safety of his own home and family. “When they blew holes in the levee at about 10 o'clock one evening, the windows of my house shook like an earthquake had hit,” he remembers.
Fortunately for farmers in that area, the floodwaters also drained off fairly quickly. By late May and early June, farmers in the northern end of the floodway got into fields, assessed damage, and began to think about planting a crop.
That's when Stevens' phone started ringing and callers wanted to know what to do to bring waterlogged fields back into production.
Stevens went to work to find answers to the soil problems. He called upon his expertise in soil chemistry with rice production and on his contacts in that industry, where fields are intentionally flooded three to four months each year.
“The most noticeable issues to fields in the Bird's Point Floodway were rapidly moving water causing gully erosion, sand depositions, road gravel carried into fields, damaged and toppled irrigation pivots, and stray metal in fields,” he says.
Possibly the most severe issue on these fields is sand deposition that can pile up like drifts on top of the soil. “In our area, it was a huge volume of moving water, like the whole Mississippi River coming over the fields,” he says. “It left behind these huge sand deposits. Some of them were as much as 6 feet deep, but most were less than 1 foot.”
The Corps moved some of that sand and used it to fill in holes near the levee breaks. But there's really no way to move and use the volume of sand left behind. So where it is possible, farmers will have to move in with plows and earthmovers to level out the biggest piles and blend it in with the soil underneath. “You have to mix it in; you can't plant a crop in pure sand,” says Stevens.
Of course, while that may make a field plantable, one of the problems in this altered soil is higher sand content with less water-holding capacity. Where the crops are irrigated, it likely will shorten irrigation intervals to only three days, or half of normal on typical silt loam soils.
Plowing may also be needed on these fields to fix another problem – erosion that stripped some soils to the compacted plow pan layer, 6 to 8 inches down.
“Farmers did a lot of fall tillage the previous fall because it was dry, so the loose topsoil was easily stripped away,” says Stevens. “No one anticipated that a major flood was coming.”
Upstream in northwest Missouri, Kansas, Iowa, Nebraska, and the Dakotas, some fields along the Missouri River had standing water on them for several months. When this happens, oxygen in the soil declines, which causes part of the soil phosphorus (P) to convert to an unavailable form.
“The P is still there, but it may not be available to the next crop for a while,” Stevens says. “If you're going to plant corn after a flood, you'll want to put on a starter fertilizer with phosphorus to avoid purple-stunted plants. If possible, I would band P at planting to get the corn up. Fortunately, the P still in the soil will become available over the growing season.”
Stevens uses the analogy of a person undergoing surgery. The first thing therapists will do is get you up and walking. “After a flood, the best thing you can do for the soil is get something growing in it again. Get some roots growing with a cover crop of some kind if you've got time.”
Almost any crop will help. The plants wake the soil back up by beginning the process of replenishing soil bacteria and microorganisms.
For farmers who couldn't plant a cover crop last fall, it might be possible to plant a small grain in the spring, provided fields are dry enough then. That could be followed with a late-planted soybean crop in 2012.
You can also quicken the soil recovery process by putting some organic fertilizer on the dried ground. There's limited data on this, but chicken manure or litter is favored by some farmers and soil scientists to jump-start the reestablishment of beneficial soil microbes. It may aid in bringing earthworms back as well as beneficial nematodes.
Those who favor poultry as the manure of choice think it has more microbes that benefit soils for an after-flood revitalization. It was used effectively in flood zones after previous floods. But if you're in an area where only other types of manure are available, use them for the benefits of organic matter and nitrogen availability.
Soybean nodulation may also be a problem after a flood. Stevens recommends inoculating soybean seed with a rhizobium bacteria to ensure nitrogen fixation on a first crop after a flood.
“This might be a bigger problem after very long-term flooding,” he says. “If the soil is underwater a few weeks, it's probably not an issue. But if fields were flooded for more than three months, it's a good policy to inoculate.
“If there was anything positive about the flood in southeast Missouri, it was that the water came quickly, then left quickly, too,” says Stevens. “It happened at the end of April. And by the end of May and into June, we were able to get back into some fields and plant a crop.
“The soybeans ended up yielding about 20 to 25 bushels an acre below what farmers normally produce,” says Stevens. “But we had such a hot, dry period in August, it would be hard to blame it on the flood. One day we reached 103°F. The low yields were probably caused by a combination of the flood and heat, causing sterile pollen.”
Throughout the floods in southeast Missouri, some organizations promoted the idea that the levees should not be repaired, and the area should be made into a permanent wetland for wildlife. Stevens disagrees, saying this productive farmland is very important to providing grain for use in the U.S. and around the world.
“Only 11% of the world land area is Class I, II, and III soils,” he says. “It's still a delicate balance between farm production and population. We need this land to grow crops.” That view has prevailed, and southeast Missouri's Bootheel region will grow crops again.
Iowa State University and University of Nebraska-Lincoln Extension produced fact sheets on how to recover cropland from extensive summer flooding. Find them at http://flood.unl.edu/.
Private Pilot Puts Photos Online
Larry Geiger, a private pilot from Lincoln, Nebraska, took the aerial photograph of a farmstead near the Missouri River north of Omaha in mid-June 2011, while the flood was still building momentum. It's one of hundreds he took in some 20 flights over the following six weeks.
Geiger made the first flight out of curiosity and didn't take any photos. He made the remaining flights with camera in-hand because he felt it was important “to bring attention to the flood so that people would understand what farmers were going through.”
He usually flew from Hamburg, Iowa, to Gavins Point Dam on the border between Nebraska and South Dakota. The plane he flew is a Van's Aircraft RV-12, a kit plane he built after he began flying a dozen years ago.
You can see this aerial photo and 150 more at http:/picasaweb.google.com/104592539075472798431/TheGreatMissouriRiverFloodOf2011. (Or just Google Larry Geiger flood photos).
If you have information about any of the photographs, email Geiger at firstname.lastname@example.org. ● –Rich Fee