Tillage to Modify Soil Texture. 



237 



In all of these cases weight is one of the essential 

 ures of the tool. A roller for tillage should have, n weight 

 of about 100 Ibs. to the running foot and a diameter of 

 about 2 feet. 



FIG. 75. Two types of rollers. 



Two types of rollers are represented in Fig. 75, the one 

 made of bars being designed to crush clods more completely 

 and to leave the surface ridaed so as to be less likely to be 

 influenced by the wind drifting the surface soil. 



292. The Harrow Should Follow the Roller. In most 

 cases when it has been desirable to use the roller to smooth 

 or firm the surface a light harrow should follow it quickly 

 in order to prevent unnecessary loss of soil moisture, be- 

 cause the firming draws the deeper water to the surface, 

 the surface temperature becomes higher in the sunshine 

 and the wind velocity near the smooth surface is greater; 

 each of which favors the rapid loss of water. 



293. Danger in the Use of the Roller. On heavy soils, 

 when they are a little wet, injurious result? nuiy follow the 

 use of the roller just after planting or seeding on account 

 of the close packing, excluding the air from the seed, whiVh 



