208 



THE PRINCIPLES OF SOIL MANAGEMENT 



portions of the plots bearing no crop, but otherwise 

 receiving the same treatment as the remainder of the 

 plot. The table thus shows the moisture conserved 

 or lost by treatment, entirely aside from that transpired 

 by the crop. 



Table XXXVII 



Increased (+) 



or 



decreased ( ) 



yield 



Check plot 



Weeds removed, but not 

 cultivated 



Mulched with straw 



( 'heck plot 



No cultivation; weeds al- 

 lowed to grow 



One cultivation; weeds al- 

 lowed to grow 



Check plot 



Pounds 



-157 



+ 873 



-2,888 

 109 



Compari- 

 son soil 

 moisture 

 basis of 100 

 on check 

 plots 



100 



90 

 130 

 100 



54 



95 

 100 



The application of the dust mulch is not confined 

 to inter-tilled crops like maize, potatoes, vineyards, 

 fallow, etc. Under some conditions, it may be applied 

 to grain fields with good results. In those sections of 

 the country where "dry farming" is practiced, it is not 

 uncommon to drag the grain field with a sharp-toothed 

 harrow, the teeth pointing very slightly backward. 

 This is begun when the plants are small, and may be kept 

 up until they attain a considerable size or until they 

 sufficiently shade the ground to greatly reduce surface 

 evaporation. The surface soil between the plants is 

 broken up and converted into a mulch. Similar to this 



