ROLLING, PLANKING, AND HOEING 177 



roller to the first purpose on light soils, where firm- 

 ing the soil is the chief result sought; and to use the 

 planker for the latter purpose on heavy soils, 

 where fining the soil is the end desired. More 

 rolling is done on spring sown grain after the seed 

 is harrowed in than for any other purpose. . If the 

 season is dry this gives excellent results; if it is 

 \vet and the soil is somewhat clayey the texture of 

 the soil may be injured and a crust formed. If a 

 cloddy clay soil is rolled after having been plowed 

 when it is too wet the clods are likely to be pushed 

 into the ground instead of being pulverised. In 

 rolling, as in plowing, everything depends upon 

 *' catching the soil at the right time." 



THE KINDS OF ROLLERS 



When the main reason for rolling is to compact 

 the soil, the roller should be as heavy as is ex- 

 pedient. The larger it is in diameter the heavier 

 it should be. It is well to have a roller of large 

 diameter for it pulls easier in proportion to its 

 weight. For ordinary purposes a roller should weigh 

 at least 1,500 Ibs. Wooden rollers, which are 

 usually made in one, two or three sections, are 

 cheap and quite effective, although many of them 

 are light. Their rolling surface soon becomes 

 rough, thus increasing the draft. Iron or steel 

 rollers, which are usually in more than two sections, 

 last longer, do better work and pull easier. The 

 more sections a roller has the less it furrows the 

 ground in turning around. Some iron rollers are 

 made with teeth or with corrugated surfaces or 

 blades; these are claimed to be more effective in 

 breaking lumps, but they often clog badly, thus in- 

 creasing the draft and decreasing the effectiveness. 



