120 DRY LAND FARMING 



tivation. But the summer-fallow even will not be effec- 

 tive in destroying volunteer grain, because of its deep 

 rooting, unless some implement is used with sufficient 

 frequency that will cut off the plants below the surface of 

 the ground. The reasons that relate to the frequency with 

 which the land should be summer-fallowed to destroy 

 such grain will apply equally to the growing of cultivated 

 crops. But when growing the latter, some hand work 

 may be necessary to complete the work. The less fre- 

 quently that the same varieties are grown in succession, 

 the less will be the 'tendency to admixing in the grains. 

 The harm from volunteering may be much lessened by 

 observing such practise in the absence of the summer- 

 fallow and also of the cultivated crop, when alfalfa is one 

 of the crops that is introduced into the rotation. When 

 the summer-fallow or the cultivated crop or the two in 

 conjunction, that is in alternation, are brought between 

 each two grain crops, the harm from grains volunteer- 

 ing may be entirely prevented. 



