HARROWING CORN 179 



The Objects of Tillage. The chief objects of tillage are: (i) To 

 stir and loosen the entire soil to a sufficient depth for the roots of the 

 plants to freely extend themselves. 



(2) To pulverize the soil and mix thoroughly its constituent 

 parts. 



(3) To develop various degrees of openness of structure and uni- 

 formity of soil conditions suitable to the planting of seeds and the 

 setting of plants. 



(4) To place beneath the surface manure, stubble, stalks and 

 other organic matter, where it will not be in the way, and where it 

 may be converted rapidly into humus. 



(5) To destroy or prevent the growth of weeds. 



(6) To start other weed seeds which have been dormant in the 

 soil. 



(7) To modify the movements of soil moisture and soil air. 



(8) To assist in controlling soil temperature. 



Harrowing Corn. The reasons for using a harrow or weeder before 

 the first cultivation of corn are to kill newly germinated weed seeds; 

 to start other weed seeds by warming the soil and admitting the air; 

 to prevent the formation 01 a crust ; to produce a loose surface mulch ; 

 and to get over a large area in a short time. 



When and how often to harrow depends upon : first, the physical 

 condition of the soil and seedbed. 



A soil which has been plowed early and is naturally of a close 

 grained structure, and which cements together because of beating 

 rains, will bear a harrow without having its surface loosened at all. 

 The harrow teeth will not move enough dirt to cover the weeds. Soil 

 of a loose, sandy formation, the surface of which seems to break open 

 rather than bake, can be harrowed to good advantage. The roots of 

 the small grass around the hills of corn are soon freed so that the 

 sun dries them out. A seed bed covered with clods or trash cannot 

 be properly harrowed because the teeth either roll the clods on the 

 hills or dig up lumps which tear up young plants. Old root stubs 

 which have not been well buried in plowing, often catch in the harrow 

 teeth and drag hills of corn out with them. The surface of sod corn 

 land cannot be harrowed because of the loose lying pieces of turf. 

 As a rule, however, corn on new land is comparatively free from 

 grass the first year. 



In the second place, when harrowing, the amount of rainfall and 

 sunshine during the germination and early growing period must be 

 considered. 



