714 SOILS: PBOP^BTIES AND MANAGEMENT 



the substratum as much as possible by tillage in order to 

 increase its capillary capacity. The need of this treat- 

 ment, of course, depends on the nature of the soil, and 

 is not always the most favorable. It is undesirable that 

 this packing should extend to the surface. Following the 

 plow, the land is frequently worked down with a subsur- 

 face packer, an implement of considerable weight, made 

 up of openwork rims that press the soil together and at 

 the same time leave a mulch on the surface. By acting 

 on the lower part of the furrow instead of on the surface, 

 the packer brings it into closer contact with the subsoil 

 and thereby establishes better capillary connection. 



After thorough packing of the main part of the furrow, 

 a dust mulch is maintained on the surface. This should 

 be of medium depth in the season when rains are likely 

 to occur, and of somewhat greater depth during the 

 dry period. Two or three inches is usually a sufficient 

 depth. 



Various applications of the principle of mulching may be 

 employed. Land may be disked before plowing in fall or 

 spring, to hold moisture until the plowing can be done. 

 As soon as a crop is removed, the land should be plowed 

 or fitted and worked down to a good mulched surface. 

 Land should not be alloived to stand unworked for any 

 considerable time after harvest. All rowed crops should 

 be kept thoroughly mulched. Much may be done to 

 conserve water in grain and hayfields by tillage. The 

 same principles apply to the practices that are used on 

 irrigated land. Special revolving toothed implements 

 have been devised to loosen up the surface soil under 

 such conditions. 



613. Alternate cropping. — Where the rainfall is too 

 light in a single season to permit the production of a profit- 



