THE SUMMER FALLOW 171 



Under the last mentioned condition packing is de- 

 sirable on soils that are (1) too loose to insure rapid 

 germination, (2) too loose to prevent excessive drying 

 around the plant roots in a season of drought, and (3) 

 not firm enough to aid in the rise of moisture from the 

 subsoil. Packing is to be preferred on late plowed fal- 



Fig. 67. Potatoes Under Irrigation North of Brooks, Alberta. 

 Inter-tilled crops make fallowing unnecessary on irrigated land. 



lows and in dry years. It is most objectionable when 

 practised on soils that bake. A fallow that is plowed 

 early may become sufficiently firm as a result of neces- 

 sary surface tillage to make packing unnecessary. 



The surface cultivation of the fallow may be by 

 harrows, discs or cultivators. The more soddy the land 

 is the more the discs will be needed; the more grass 

 there is and the greater the development of annual 

 weeds, particularly on soils that drift, the more desirable 

 the cultivator is, while on land that seldom or never 

 blows the harrows will prove the more efficient imple- 



