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The Cornell Reading-Courses 



Fourth, when the soil is either too wet or too dry the draft is increased 

 over that for the soil in good plowing condition. 



The draft of the plow will ordinarily be five to nine pounds per 

 square inch of cross section for the stubble type and four to eight pounds 

 for the sod type. For a six-by-fourteen-inch furrow the total draft would 

 therefore be four to five hundred pounds in a soil in good condition. 

 Attachments, dull edges, and stones in the soil increase the draft. 



Plow attachments. — - Several attachments are used on the plow for special 

 conditions of the soil. (Fig. 94.) On sod land the jointer much improves 

 the result. This is a miniature plow which cuts the surface roots and 

 turns under the edge of the furrow, giving a smoother appearance. It 

 tends also to prevent grass from growing along the soil line of each furrow. 



Several types of colter are used on sod or rooty ground for cutting the 

 furrow from the landside. All these should be placed a little back of the 



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Fig. 97. — A heavy chain attached to the whiffle-tree and the beam of the plow, as 

 shown in the illustration, is very useful for turning under a heavy growth of vege- 

 tation on the soil — as, for example, a green manure crop 



plow point and slightly outside the line of the landside, so as to cut a 

 clear course at the moment when the roots are drawn taut over the 

 point. The rolling and blade colters are attached to the beam. The 

 rolling colter adds less to the draft, and is more satisfactory than the 

 blade colter where there is much surface rubbish. Occasionally, a small 

 fin colter is attached to the share. When the shin of the plow is sharp, 

 especially on fallow ground in good condition, colters arc of little service, 

 and the jointer in particular is objectionable owing to the increase in 

 draft. 



Moldboard versus disk plows. — There are two types of turning plow, 

 the moldboard and the disk. The former is in most general use and is 

 adapted to the widest range of soil conditions. The disk plow is especially 

 suited to hard, dry soil and docs particularly well where there is much 

 rubbish or vegetation to be turned under. It is not adapted to sod land 

 or to soil that is very stony. On stony land the cut-out disk is preferred 



