THE TILLAGE OF THE SOIL 71 



3c. B[i compact inij tools 



lOJ. Th»> ('< impacting tools are rollers, an<l 

 tlit> implements known as plankers or floats. 

 The objects of rolling are : {a) to crush clods, 

 (//) to snioothen the ground for the seed-bed, 

 {(') to hasten germination of seeds, (d) to com- 

 part and solitlify soils which are otherwise too 

 loose and open, (c) to jiut the land in such 

 condition that other tools can act efficiently, 

 if) 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-nmlch. In its passage u}>- 

 wanls, the soil moisture supj)lies the seeds with 

 water ; and the particles of the soil are in 

 intimate contact with the seeds, and, therefore, 

 with the soil moisture. It" the smt'ace of rolled 

 lands is moister than loose-tilled lands, there- 

 fore, it is be«'ause the moisture is ]»assing otT into 

 the air and is l)eing lost. 



1(>4. The rolling of lands, then, sacrifices 

 soil moisture. The rolled or compacted surface 

 should not be allowed to remain, but tlie earth- 

 rauleh 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 ; 



