144 



SOIL MANAGEMENT 



than necessary ; and, second, the ground will not pul- 

 verize well. It is better to have each furrow slice lap 

 slightly upon the preceding one. 



95. The Harrow. The first harrow was probably a tree 

 limb with projecting branches. The purpose of the har- 

 row is to crumble the soil and to give it good tilth, or fine- 

 ness. After plowing, 

 the surface of the 

 ground should not be 

 allowed to dry out be- 

 fore harrowing, since it 

 is then more difficult to 

 break up the clods. 



There are three com- 

 mon types of harrows : 



a. The spike-toothed 

 harrow is made of spikes 

 fastened in a wooden or 

 iron frame. This type 

 is especially useful in 

 forming a dry-dust 

 mulch. It is used to 

 follow the plow, and 

 sometimes, again, with 

 crops like corn and po- 

 tatoes, after planting 



SPRING-TOOTH HARROW. 



This is especially effective in leveling 

 and breaking up the surface soil. 



but before the plants 



sprout. In this second case, the teeth are slanted back, 

 so as to stir the soil very lightly. 



b. Each tooth of the spring-toothed harrow is a broad 

 spur extending from a strong half coil of steel. When 

 these teeth strike an obstruction that they cannot tear up, 

 they " spring " back and release themselves. This kind of 

 harrow, therefore, is suited to stony fields and to orchards 



