All this wheel traffic has to cause some damage, but how much? When fields are dry, studies from multiple states consistently show that yields are reduced 5 to 8 percent within the wheel tracks at the next cutting if wheel tracks occur within a couple days of cutting and before new regrowth occurs.

Emeritus Professor / Extension Forage Specialist / University of Nebraska – Lincoln

But driving on these plants just five to seven days after cutting, when regrowth shoots have started to grow, reduces yield 15 to 25 percent or more. Furthermore, survival of these plants is reduced. However, driving over the same plants a second or third time on the same day caused about the same change in survival or yield as driving over them just once.

This research shows that the major cause of reduced yield due to wheel traffic is the breaking off of new regrowth stems. However, when fields are wet, wheel traffic causes much more compaction. When this happens, yield loss typically exceeds 30 percent.

To reduce yield losses caused by wheel traffic:

  1. Harvest as quickly as possible after cutting.
    • Make silage or wrapped bales instead of dry hay.
    • Use conditioners and make wide swaths for faster drying.
    • Rake within two days of cutting and merge swaths into large windrows.
  2. Minimize trips across the field.
    • Mow and condition in one trip.
    • Collect and drop bales at field edges.
    • Drive on same path and remove bales as soon as possible.
    • Do not drive on field between harvests.
  3. Plant alfalfa varieties that are more traffic tolerant.
  4. Avoid dual wheels.
  5. Consider using larger equipment if it will reduce trips over the field.
  6. Use the lightest equipment (like tractors) needed to complete the job.
  7. Adjust equipment so wheels trail one another.

Alfalfa fields must be driven on during harvest, but you can lessen the damage by controlling where, when and how often you drive.  FG


Bruce Anderson, Ph.D., is an agronomy and forage specialist for the University of Nebraska – Lincoln.

Excessive wheel traffic on alfalfa regrowth can reduce yield by 25 percent or more. Photo by FG staff.