I)ar loads — namely: Ihs.. 650 Ihs., 1250 ll)s., 1800 Ihs., with the 

 new tires; and Ih.. 500 lbs., 1100 lbs., 1500 lbs., with the 

 smooth tires — (effected a ranjre of wbeel slipjjago and weight 

 transf<'r. A mower operatinji, iin<l(M' average field conditions has 

 a draft re<|uirenient ranging from 60-100 pounds per foot of 

 width. The percent slippage of a tractor wheel was calculated 

 In tlie follovvint!;: 



"» ' 



advance per \sh<'el achance per wheel 



I'er teiil slip ^ revolution witli no pull revolution with pull 



Advance per wheel revolution with no pull 



Two tractors were used to obtain the drawbar load. The 

 tractor apjdying the basic treatment pulled another tractor 

 in gear, with the engine shut off. The different transmission 

 gears — 1st. 2nd. and 3rd in the pidled tractor — {)rovided the 

 range of drawbar loads indicated. B) drawing the pulled tractor 

 a little to one side, it was possible to avoid running on the 

 tracks made by the pulling tractor. 



A treated plot consisted of two tractor wheel tracks. After 

 the treatments were imposed, the area between the wheel 

 tracks was kept mown: consequently, only those plants which 

 had been subject to traffic were allowed to grow. (Figure 2). 



When the recovery growth in the check area was in bloom, 

 yield samples, were taken. Four samples were taken for each 



k ♦- 



■^, 



Figure 2. Areas between treated plots were kept cleanly mown during 

 the growing season. Tall row left center is a coMlr«>l row. 

 the two rows to the rifjhl show retarding i'(T«'«'t of smooth 

 tires with I5UU Ihs. <irawhar loud. 



