146 SUCCESSFUL FARMING 



for deeper plowing than shallow-rooted ones. For corn, potatoes and 

 heavy truck crops, deep plowing is generally advised. For oats, barley, 

 flax, millet and other spring annuals, shallow plowing generally gives as 

 good results as deep plowing, and at a less cost. In the long run, deep 

 plowing for most soils is to be recommended. Deep plowing increases 

 the depth of soil from which the mass of plant roots draw moisture and 

 plant food; it increases the water-holding capacity of the soil; it incor- 

 porates the organic matter to a greater depth in the soil; it enables the 

 soil to receive and hold the rainfall, thus reducing erosion. 



Where shallow plowing has been the practice, the depth of plowing 

 should be increased gradually, one-half inch to one inch each year, until 

 the desired depth has been obtained. This gives better results than 

 increasing to the full depth at once. On virgin land with deep soil shallow 

 plowing during the early years of cultivation may give as good results 

 as deep plowing. Much depends on the nature of the soil, and wherever 

 the soil at the depth of six to ten inches is compact, deep plowing and the 

 incorporation of organic matter will improve it. 



Subsoiling. — Subsoiling pertains to loosening the subsoil below the 

 usual depth of plowing. Subsoil plows are constructed to run to a depth 

 of sixteen to eighteen inches, with a view of loosening and slightly lifting the 

 subsoil. It is neither turned nor brought to the surface. Such a practice 

 is even more expensive than plowing and, consequently, more than doubles 

 the cost of the preparation of the land for crops. While it may prove 

 beneficial, many tests indicate that, ihe practice does not generally pay 

 for the expense involved. Doubtless much will depend upon the value 

 of the land, the character of subsoil and the nature of the crops to be 

 grown. On valuable land having impervious subsoil, and for high- 

 priced crops, it may frequently pay. How long the benefits from sub- 

 soiling will last is determined by the rapidity with which the soil returns 

 to its former compact condition. Heavy rains and thorough saturation 

 with water often soon overcomes the benefits of subsoiling. As a general 

 practice, subsoiling is not to be recommended. It might prove beneficial 

 in semi-arid regions as a means of increasing the water storage capacity 

 of the soil to tide over long periods of drought. In such regions the bene- 

 ficial results are likely to be more lasting than where the rainfall is heavy. 

 Both in practice and theory deep plowing is preferable to subsoiling. 



Disking.— There are two forms of disk harrows: (1) having a solid 

 disk, and (2) having a serrated disk and known as the cutaway disk. 

 The latter is generally lighter than the former, is adapted to stony and 

 gravelly soil and for light work. The full disk is more generally used, 

 although in double disks both the full disk and the cutaway disk are 

 sometimes combined in the same implement. The disk harrow stirs 

 the soil to a greater depth than do most other forms of harrows. It is 

 especially useful on land that has been plowed for some time and has 

 become somewhat compacted. Fall plowing and early spring plowing, 



