THE TILLAGE OF THE SOIL 71 



3c. By compacting tools 



102. The compacting tools are rollers, and 

 the implements known as plankers or floats. 

 The objects of rolling 'are : (a) to crash clods, 



(b) to smoothen the ground for the seed-bed, 



(c) to hasten germination of seeds, (d) to com- 

 pact and , solidify soils which are otherwise too 

 loose and open, (e) to put the land in such 

 condition that other tools can act efficiently, 

 (/) to facilitate the marking- out of land. 



103. By compacting the surface soil, the 

 roller re-establishes the capillary connection be- 

 tween the under -soil and the air : that is, it 

 destroys the earth -mulch. In its passage up- 

 wards, the soil moisture supplies the seeds with 

 water ; and the particles of the soil are in 

 intimate contact with the seeds, and, therefore, 

 with the soil moisture. If the surface of rolled 

 lands is moister than loose-tilled lands, there- 

 fore, it is because the moisture is passing off into 

 the air and is being lost. 



104. The rolling of lands, then, sacrifices 

 soil moisture. The rolled or compacted surface 

 should not be allowed to remain, but the earth- 

 mulch should be quickly restored, to prevent 

 evaporation, particularly in dry weather. When 

 the object of rolling is to hasten germination, 

 however, the surface cannot be tilled at once ; 



