WHEEL TRAFFIC IN ALFALFA – WHAT DO WE KNOW? WHAT CAN WE DO ABOUT IT?

Alfalfa yield is reduced by the damage that is caused by the normal hay harvest operations. This yield reduction is mainly due to physical damage to new shoots re-growing after cutting. There is a subsequent reduction in root stored carbohydrates and reduced plant vigor. Soil Compaction can be a contributing factor to reduced yield. Compaction is especially evident under irrigated sandy loam soils and on heavy soils that are driven upon when wet. Crown rot diseases increase when there is damage to plants such as the mechanical damage caused by wheel traffic. Historic and recent traffic x variety trials have documented a range of yield reduction (16-26%) when traffic treatments were applied at 5 to 7 days following cutting. Earlier traffic treatments resulted in much less damage (5-8%). New “grazing and wheel traffic resistant ” varieties that were selected by testing under wheel traffic conditions have less traffic caused yield reduction than many of the standard varieties. The percentage of field area exposed to harvest traffic varies with the type and size of equipment, the need for extra trips to turn hay in wet conditions, and the configuration of the equipment to track over previous equipment tracks. There is a difference when the traffic occurs, traffic imposed soon after cutting being less damaging as compared t