PLOWING IN DRY AREAS 133 



course, cannot be sharpened. Because of the extensive 

 areas that are cultivated in dry regions, the sulky, that 

 is, the riding plow, is most commonly used. The mold- 

 board plow will do better work than the disc where the 

 conditions are favorable for using it, but the disc plow 

 has also an important place. 



The disc plow consists of one or more large discs set 

 at an angle that will turn over the furrow slice, but less 

 perfectly than the mold-board plow. It has been found 

 preferable to the mold-board plow under the following 

 conditions: (1) In heavy clay soils that are hard to 

 plow and that are more or less liable to become sticky. 

 (2) In plowing land baked so hard with the sun that it 

 is difficult to keep the mold-board plow in the soil. (3) 

 In the first plowing of sage brush land when the brush 

 is strong. (4) In plowing stony land which could not 

 be plowed with the mold-board plow without much diffi- 

 culty. The disc plow is frequently used when plowing 

 stubble land and old land generally. It is lighter of 

 draught than the mold-board plow. It does not bury 

 grass or weeds so completely as the latter. The deep 

 tilling machine is a plow with two discs. The one in 

 front cuts down to a certain depth and turns the soil. 

 The one in the rear cuts down more deeply and turns 

 the soil from a lower stratum, inverting it, in part at least, 

 above the furrow slice first inverted. Among the 

 advantages of this plow are the following: (1) It is 

 light of draught relatively in proportion to the depth 

 to which it will plow. (2) It may be used in plow- 

 ing ground when it is so dry that it could not be 

 plowed with the moldboard plow. (3) It makes it pos- 

 sible to plow the soil to any reasonable depth. (4) It 

 aids materially in pulverizing the soil which it plows. 

 This plow will probably render most excellent service in 

 much of the dry area, but its introduction is too recent 



