334 



SOIL PHYSICS AND MANAGEMENT. 



The bar in front, if properly adjusted, crushes clods, whife the 

 twisted blades stir the soil and destroy any weeds that may have 

 started. For this purpose it is better than the spike-tooth harrow. 



ia. 149. The-cut away disk. 



Fia. 150. The spading disk harrow. 



The disk harrow (Figs. 148, 149 and 150) is made in three 

 forms the solid disk, the cut-away, and the spading disk. The first 

 two act somewhat the same as the disk plow, hut do not turn the 

 dirt so thoroughly, yet are very effective in stirring the soil. The 



