Tillage and Its Purposes 141 



teeth. This implement takes a wide space of soil and 

 during the earlier stages of the crop can be used to great 

 advantage since its small teeth can work right up to and 

 among the growing plants and thus keep down the yoimg 

 starting weeds. By taking care to have com rows run 

 very straight, the weeder can be used through the whole 

 cultivation of the crop by taking out the teeth that strike 

 two rows and thus enabling the operator to cultivate the 

 whole of one row and the halves of the others at once pass- 

 ing, and by thus rapidly going over the ground the work 

 can be repeated more frequently, and when rains are fre- 

 quent advantage can be taken of the short intervals to keep 

 the forming crust broken until the corn gets so tall that the 

 final cultivation must be done with the single cultivator. 

 No matter what sort of a plow is used 

 HsSowine^ the preparation of a proper seed bed de- 

 mands that the upper surface of the soil be 

 made fine. For this purpose we use a harrow. Harrows 

 are made in a legion of forms, every one of which has some 

 advantages for special work. Most of the older forms 

 of harrows depended for the pulverization of the soil on 

 an array of projecting spikes in a heavy V-shaped frame. 

 In the further development of the spike harrow the teeth 

 were made of steel instead of iron and of a smaller size, 

 and the frame is so contrived that the teeth can be made 

 to slant backward making what is known as the smooth- 

 ing harrow, an implement of much value for the final 

 smoothing of the surface or the breaking of a forming 

 crust before the plants are above the ground, or for cov- 

 ering grass and clover seed. 

 The various forms in which the spike harrow has been 



