SHALLOW SURFACE CULTIVATION 31 



published must, of necessity, vary with the nature of the 

 soil. If a harrow is used, the pulverization should be 

 complete. If a disk is used, the teeth should be set at 

 an angle, and not perpendicularly, so as to prevent, as 

 suggested by King, 13 the formation of hard ridges 

 which hasten evaporation. When the disk is set at an 

 angle, a layer of soil is completely cut off, and the 

 capillary connection with the subsoil is broken. Sur- 

 face cultivation should be from two to three inches 



Fig. 14. Soil without surface cultivation. 



deep, and the finer the condition in which the surface 

 soil is left the better. 



Shallow surface cultivation is an effectual means of 

 conserving soil moisture. It can be practiced in con- 

 nection with deep plowing, shallow plowing, subsoil- 

 ing, or rolling ; in fact, it can be combined with any 

 method of treating the land. Shallow surface cultiva- 

 tion does not mean that the soil should not be pre- 

 viously well prepared by thorough cultivation. The 

 following example shows the extent to which shallow 

 surface cultivation may conserve the soil water. 14 



Per cent, of water in cornfield. 



With shallow sur- 

 face cultivation. 



Soil, depth 3 to 9 inches 14.12 



Soil, depth 9 to 15 inches 17.21 



Without shallow 

 surface cultivation. 



8.02 

 12.38 



