In 1960. as in 1959. l)oth sett* of tires inflicted significant dam- 

 age when compared to the control plots. On hoth alfalfa and 

 red clover the smooth tires inflicted more damage than the 

 new tires. The major <lamage was inflicted hy tractor traffic 

 without drive wheel slippage. (Figures 1. 5. and 6k Increas- 



Figure 8. Alfalfa Crown Damage — showing (top) the whole crown 

 and (hotloni) the same roots sliced longitudinally left 

 to right. Control — New tire — smooth lire. 



Ill 



