Surface sealing due to soil aggregation degradation from rainfall impact and tillage.
Surface sealing due to soil aggregation degradation from rainfall impact and tillage.

The effects of too much tillage are again seen in the state with stark evidence of gullies, rill erosion, surface crusting, sealing of soil over trying-to-emerge germinating seedlings, and flooded field areas.

There are several reasons for these effects:

  1. When there is little residue at the soil surface, there is nothing to absorb the energy of rain drops except the soil itself. What little aggregation is left after tillage is destroyed in minutes by rainfall and the soil is separated into a suspension of clay particles, with silt and sand particles separated. The soil becomes ‘smooth’ as water seeks its own level, then the water begins to flow with gravity, carrying along separated particles, along with the organic matter, to some other place. In my travels, the Jamestown area and land to its south seem particularly affected. At Extension conference call this morning, nearly every region of the state with the exception of the southwest, had periods of intense rainfall that resulted in some kind of soil water erosion.
  2. Even if soil loss is not present due to relative flatness of the field, the separated particles reform into an amorphous mass that requires wetting and drying cycles to restore some natural plant-friendly aggregation. When dry, soil particles are not buffered by organic material, and tend to cement to each other and prevent seedling emergence. The amorphous mass also serves as a ‘pan’ to keep soil from percolating as it should during rainfall.
  3. There are many areas that are farming subsoil, or at least subsoil is incorporated into the surface layer. These parent materials are not as plant friendly as the original topsoil, and crust far more easily than soils in intimate contact and matrix with true soil organic matter.