194 DRY FARMING 



potatoes and roots. The most suitable legume crops are 

 alfalfa, sweet clover (red clover in some areas) and peas, 

 while Western rye grass, brome grass and timothy are 

 the best grasses. 



The grain crops lessen plant food and organic matter, 

 return nothing to the soil and permit annual weeds to 

 flourish. The intertilled crops remove plant food and 

 very greatly lessen organic matter but the intertillage 

 they require conserves moisture, develops available plant 

 food and aids in weed control. The legume crops feed 

 heavily upon mineral plant food elements but will main- 

 tain or increase the nitrogen supply if grown frequently 

 enough. The grass crops use up plant food but increase 

 the root fiber or organic matter in the soil, and by oc- 

 cupying it for a year or more tend to smother out 

 annual weeds. 



150. Planning a Rotation. The establishing of suit- 

 able rotations in all new agricultural countries has been 

 a slow process. So many different factors enter into the 

 problem that the conservative farmer prefers to let some 

 one else do the testing, at least so long as his present 

 methods are profitable. Chief among the .factors that 

 must be considered when one is planning a rotation 

 are: 



1. The need that exists for improving one's own soil 

 conditions and controlling weeds. 



2. The future requirements of the soil from the fer- 

 tility standpoint. 



3. The particular effect of different classes of crops on 

 the land. 



4. The relative suitability of different classes of crops 

 to the climatic and soil conditions that obtain in 

 the district. 



