112 DRY FARMING 



In some sticky soils the ordinary mouldboard plow 

 will not "clean", and in breaking the prairie, plows hav- 

 ing rods (Fig. 37) instead of sheet mouldboards are 

 used. These clean better and result in less friction and 

 therefore lighter draft than the sheet mouldboard type 

 and are the best to use in breaking "loose top" and some 

 other sticky soils. 



83. The Disc Plow. On stubble fields in heavy land 

 where the mouldboard plow will not clean, the disc plow 

 (Fig. 37 A) is used. This does not cut grass roots nor 

 cover weeds, nor pulverize the soil as well as a mould- 

 board plow where the latter will clean. Where a mould- 

 board plow will not clean it is not satisfactory for any 

 of these purposes. It requires more frequent sharpen- 

 ing than the disc, and it pulls harder ; but where it can 

 be used at all satisfactorily the mouldboard type is gen- 

 erally to be preferred over a disc plow. 



84. Coulters. Coulters are used on mouldboard plows 

 to cut the edge of the furrow, thus at once lessening the 

 draft and making it possible to do a better job of cutting 

 roots and covering rubbish. There are different kinds of 

 coulters such as "fin", "knife", "rolling coulter" and 

 "skim coulter" or "jointer". The rolling coulter is 

 mostly used in the "West. It should be set about half 

 an inch outside the line of the landside and should cut 

 at least one-third the depth of the furrow. In trashy 

 ground it should be set well forward to give more clear- 

 ance, while in stony ground it should be set well down 

 as well as ahead. The skim coulter does good work under 

 some conditions in helping to cover weeds. Combination 

 skim and rolling coulters are very common as are also 

 those of the fin and knife type. (Fig. 37C). 



