CHAPTER VIII 

 CULTIVATION IN DRY AREAS - 



Cultivation in the broad sense includes all the various 

 processes of tillage. In the discussion that follows it 

 will include virtually all of these processes as applicable 

 to dry areas except plowing, which was discussed in 

 chapter VII. These include subsurface packing, discing, 

 cultivating by implements other than the disc, harrowing, 

 including the use of the weeder, rolling, planking and 

 drilling. The discussion will also include the main- 

 tenance of the dust mulch, cultivation suitable for grow- 

 ing crops and clean tillage in the bare-fallow. 



Subsurface packer and its use. The subsurface 

 packer as ordinarily constructed consists of a series of 

 wedge shaped wheels, which revolve on a common axle. 

 They are usually about 18 inches in diameter and are 

 placed about 6 inches apart. They thus press the loose 

 soil downward and to some extent laterally when in use.- 

 The primary object sought is the firming of the land 

 that has been newly plowed toward the bottom of the 

 furrow slice and leaving it loose and friable at the .sur- 

 face. The -pressure of the soil below so compacts it that 

 moisture from the firmer subsoil may ascend into the 

 less firm soil in the lower part of the furrow slice. In 

 other words it re-establishes the capillary connection 

 broken by plowing "the land. The moisture which thus 

 ascends is largely prevented from escaping by using the 

 harrow after the packer. This implement also aids ma- 

 terially in crushing lumps in cloddy soils. 



The subsurface packer may be used with advantage : 

 (1) On spring plowed lands that are loose and lacking 

 in moisture-holding power. (2) On lands that contain 

 more or less trash, the bulk of which in plowing is placed 

 between the furrow slice and the unbroken soil below, 



