172 DRY LAND FARMING 



vation should be both shallow and deep. The necessity 

 for this arises, at least on many soils, from the tendency 

 in them to encrust below the shallow cultivation, as pre- 

 viously intimated. If cultivation reasonably deep is 

 given at the first, while lateral root growth is yet limited, 

 the time of such encrustations will be deferred. When 

 it does occur some implement must be used to break it 

 up, even at the risk of breaking some of the roots of the 

 plants, as to do this may be the lesser of the two evils. 

 The breaking of this crust under the soil mulch is a mat- 

 ter of much moment when growing such cultivated crops. 

 The extent of the cultivation will vary with the 

 different crops and classes of crops. Grains are seldom 

 harrowed beyond the time when there are indications 

 of jointing, and not very frequently for so long a period. 

 Some crops grown in rows, as alfalfa for seed, and peas, 

 cannot be cultivated to a late stage of growth because 

 of the recumbent character of the growth. Those of 

 upright growth, however, should be given cultivation 

 until and in some instances beyond the time for begin- 

 ning seed formation. 



