PREPARING THE SEED-BED FOR CORN 233 



plowing is to cover weeds, stubble and rubbish of all kinds. 

 This work may be greatly facilitated by the use of various 

 kinds of attachments, the most common of which are: 

 (1) coulters; (2) jointers; and (3) drag-chains. Coulters 

 are of two general types: (a) blade coulters and (b) fin 

 coulters. Blade coulters are attached to the beam or share 

 and adjusted so as to cut the furrow-slice free from the 

 side after the soil has been raised somewhat by the mold- 

 board. The roots are then most easily severed. A fin 

 coulter is merely a knife edge attached to the share. The 

 jointer is used chiefly in plowing sod land. It consists of 

 a miniature mold-board attached to the beam and adjusted 

 so as to cut and turn under the top part of the furrow- 

 slice. The result is that the plow turns a neat clean furrow 

 without leaving a portion of the rubbish exposed. The 

 drag-chain is used primarily in turning under heavy 

 growths of weeds or green-manure crops. It consists of a 

 heavy chain, one end of which is attached to the central 

 part of the beam, the other end being fastened to the 

 double-tree on the furrow side with slack enough to drag 

 down the vegetation on the furrow-slice just ahead of the 

 turning point. 



283. Subsoiling. This operation is defined and the 

 precautions to be taken in connection with the practice 

 are outlined in paragraph 119. A number of experiments 

 have been conducted by southern experiment stations 

 to determine the effects of subsoiling land for corn. Many 

 of these experiments have shown no beneficial effects. 

 In some cases negative effects have been noticed. How- 

 ever, where subsoiling has been practiced in the fall on 

 lands underlain near the surface with an impervious 

 clay subsoil, beneficial results have usually been sfe- 

 cured. 



