70 



AGRICULTURE. 



and heat to enter. The same plan is beneficial 

 if the plowing is clone in the fall, as the rains 



FIG. 22. A PLANK HARROW. 



will percolate through the soil instead of run- 

 ning off of the surface. 



2. Surface Tillage. Plowing should be fol- 

 lowed by surface-working tools, to pulverize the 



FIG. 23. A ROLLING CPTTF.R HARROW 



the ground and to prepare an earth mulch. 

 The first surface tillage to follow the plowing 

 should be done before the ground becomes too 

 hard and dry with a heavy, coarse tool to crush 



