METHODS OF SOIL MANAGEMENT 147 



when being prepared for medium to late planted crops, should generally 

 be gone over once or twice with the disk. 



A large portion of the spring oats in the Central States are seeded 

 on land prepared by the use of the disk and harrow, and without plowing. 

 The disk is the most effective implement in the preparation of the seed- 

 bed for oats. This method of preparing the land enables farmers to 

 accomplish early seeding on a large scale. Early seeding of oats is impor- 

 tant in connection with good yields. 



Harrowing. — There are many forms of harrows varying in style of 

 teeth, number of teeth, weight and adjustment. The steel frame harrow 

 with levers to adjust the teeth, built in sections that are joined together, 

 is generally preferred. The size or width of the harrow is usually deter- 

 mined by the number of sections it has. It is an implement of light draft, 

 and to be effective should be used in the nick of time. Repeated harrow- 

 ing is often advised (1) for the purpose of maintaining a surface mulch 

 to conserve moisture, and (2) to destroy weeds just as they start growth. 

 The spring-toothed harrow is effective in stony and gravelly soil, and 

 tends to loosen the soil more than the spike-toothed harrow. The former 

 is best for destroying weeds and loosening the soil, while the latter is 

 preferable for soil pulverization and for covering small seeds that are 

 broadcasted, such as clovers, grass seeds and the millets. While the 

 harrow is generally used just prior to seeding and planting, it is found 

 to be a good practice to harrow such crops as corn and potatoes after 

 planting, and sometimes even after they are up. Such harrowing is often 

 fully as effective in destroying weeds and pulverizing the soil as a good 

 cultivation would be. It is much more rapidly and cheaply done than 

 cultivating. 



Planking or Dragging. — The plank drag is a cheap implement con- 

 sisting of three or four two-inch planks fastened securely together with 

 the edges overlapping. These may be eight to twelve feet in length. 

 It is used for pulverizing clods and smoothing the surface of the ground. 

 It is an effective implement to use where fine pulverization of the surface 

 is desired, and works satisfactorily when the soil is rather dry. 



Rolling. — The roller serves two chief purposes: (1) to compact the 

 soil, and (2) to pulverize clods. The weight and size of the roller are 

 important in this connection. Soil compacting calls for considerable 

 weight, while pulverization demands a roller of comparatively small 

 diameter. In recent years the corrugated roller with a discontinuous 

 surface has come into use and is thought to be superior to the old style. 

 It compacts the soil and yet leaves some loose soil at the surface, thus 

 lessening direct evaporation. The roller should be used only when the 

 soil is in dry condition and when it is desirable to encourage capillary 

 rise of water and establish conditions favorable for the germination of 

 seeds that lie near the surface of the soil. Rolling is most frequently 

 resorted to in preparing the seed-bed for winter wheat. This crop calls 



