by Wayne Flanary Regional Agronomist, CPAg, CCA
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The common question coming into the Holt County Extension office is "Should I be tilling my fields that were flooded?" Before anyone conducts any tillage on the Missouri river bottom, they should consider the possibility of the Corp releasing water next year. As of this date, the Corp of Engineers policy is to release water again in 2012. Hopefully, this policy may change.
Another concern is broken levees. What is the risk of flood to my farm with broken levees? Resources to repair levees may be limited with Federal levees receiving aid first. Also, if they are repaired, they will be weaker than a levee that has the tops and sides seeded. Water hitting a levee can erode soil easily.
If you decide to conduct tillage, here are some general guidelines. Water saturated soils will break down soil structure causing soils to be "run-together." It will seem like the soils are compacted, but it is a different process where the structure breaks down, as would be the bottom of a farm pond. When a farm pond is drained, it resembles some of the same issues that you will find in long-term flooded soils. Saturated soils filled with water do not compact because the pore space if filled with water.
Soil particles during a flood can be deposited, scalped or no change. The best way to make the appropriate decision is to use a tile spade and look at the profile. Take some time and make comparisons between various areas of the fields.
Sand deposits are the worse issue to resolve. If the sand is too deep, it is best to focus on other field areas because of the expense of sand removal. Also, if you are going to deep plow, look at a soil map and determine the texture of the original soil so one can determine if there will be any benefit by diluting the sand with other soil textures.
If you have silt deposits, there can be a distinct and abrupt change in textures. It is generally preferable to mix these abrupt changes which will ease water movement downward and also crop rooting. Also, breaking the surface of deposits that do not have any structure will help get oxygen moved into the soil and thereby dry.
Before conducting deep tillage, check soils with a tile spade. Soils that are too wet will ribbon and not fracture.
As we have looked at the Heitman side of the Graves Chapple Farm, the soils still have structure. We are planning on leaving the plots as is. This area has been no-tilled for a number of years and upon examination, you can see a tremendous difference among the tillage plots at this site. Again, take a spade and look at the soils.
For more information, contact Wayne Flanary at 660-446-3724 or Heather Benedict at 660-425-6434, Regional Agronomists, University of Missouri Extension.