By Paul Gross, Michigan State University Extension
Heavy rains and flooding have left many farm fields in need of physical repair before spring planting and full production. Flood waters erode exposed soils, leaving deep gully's, drifted crop residue, brush and building materials, as well an assortment of other types of debris. In addition, this debris may be plugging your drainage systems. Along with debris, the flood waters may have deposited sand and silt drifts that could vary from just a few inches to nearly a foot deep.
The first step is to assess damages and prioritize repairs. Evaluate field conditions for moisture before you start. Flooded soils can be slow to dry out. When field conditions allow:
•Remove the larger debris.
•Check tile outlets and tubes for obstructions.
•Check for plugged risers and breathers.
•Check for holes or broken tiles.
Drifted crop residue that is greater than 4 inches should be spread in a thin layer before incorporating. Residue less than 4 inches can be incorporated with tillage. When incorporating large amounts of plant material, consider the additional nitrogen demand that will be caused by decomposing plant materials in those areas.
In areas where the flood water left sand and silt, drifts that are less than 2 inches may be successfully mixed into the soil with normal tillage. Deposits 2 to 8 inches can be incorporated with a chisel plow, moldboard plow or other aggressive tillage tool. When deposits are deeper than 8 inches, other types of earth moving equipment may be necessary to uniformly spread soil across the field.
In areas where the running water caused gully erosion, repair will be necessary. Shallow erosion may be repaired with tillage. Deeper erosion may require some type of earth moving equipment for proper land leveling. Be cautious using the drifted sand and silt when filling the eroded gully's unless you can place topsoil over the top. The sand has very little water-holding capacity and is very likely to erode quickly in another severe rain event.
Fertility and soil health are also a concern when areas of fields are flooded. Soil microbiology can change as a result of flooding. Consider soil testing and proper fertilization in these areas, especially if the areas are a larger percentage of the field. If these areas are consistently subject to this type of erosion, consider grass waterways and cover crops for a long-term solution.
Patience will be critical this spring. Taking the time to properly repair any flood damage that occurred might just be what is needed to keep everyone out of the fields and allow them to dry out enough for optimal planting. Michigan State University Extension
is an excellent resource for information on soil testing