390 DRY LAND FARMING 



transportation as to one more limited in use and of 

 costly transportation, because of its bulkiness. It may 

 not be easy to glut the wheat market, but the potato 

 market, for instance, may be glutted in a single season. 

 The same is true of the market for certain kinds of per- 

 ishable fruits. When all the people center on the pro- 

 duction of one commodity, the tendency in the outcome 

 is to disturb the market and adversely to the interests 

 of the farmer. The equilibrium in marketing is also 

 disturbed. 



Additional reasons for rotation in dry areas. In dry 

 areas the reasons for rotating the crops in addition to 

 those given include the following: (1) to prevent the 

 loss of moisture that does not enter the soil ; (2) to pre- 

 vent the loss of moisture in the soil ; (3) to increase the 

 moisture content in the same, and (4) to make farming 

 possible and profitable. 



In such areas it is greatly important, as previously 

 shown, that the precipitation which comes, whether in 

 the form of snow or rain, shall in due time enter the soil 

 rather than run away over . the surface. The various 

 methods which may be resorted to in order to accomplish 

 this have already been discussed (see p. 123). The great 

 importance of preventing waste from this source is 

 emphasized at this time. All the operations relating to 

 tillage should, therefore, be conducted with this thought 

 in mind. In humid areas it is different. In these there 

 are times when the removal of the waters of precipita- 

 tion is more important than their retention, as, for in- 

 stance, when they are present in excess, but even when 

 thus present removal through drainage beneath the sur- 

 face is much preferable to removal through open drains. 

 Rotation facilitates the entrance of water into the soil 

 in dry areas by the necessity which exists for intro- 

 ducing into it frequently crops that call for frequent 

 stirring of the surface soil, and an occasional deep stir- 



