FEU IT GROWING 79 



bad pruning, or to a lack of potash or iron in 

 the soil. Fertility is not always a determining 

 factor of color in fruit weather conditions, 

 altitude, and soil all play a part in determining 

 the intensity of the color of a variety. 



The maintenance of the fertility in the or- 

 chard is accomplished more easily than in the 

 culture of exacting farm crops. In general 

 agriculture the rotation must be so planned as 

 to permit the use of a soil-enriching crop at 

 more or less frequent intervals. In the orchard 

 the trees are perennial and when no other de- 

 mand is made upon the soil it is a simple prob- 

 lem to maintain an abundant supply of organic 

 matter and nitrogen in the soil by the use of 

 appropriate cover crops. Upon strong soils 

 phosphoric acid and potash only will be required 

 in limited quantities. Of these, phosphoric acid 

 will be required more often than potash. The 

 nitrogen can be secured by the use of crimson 

 clover, vetch, and common clover as a winter 

 cover, and by the use of Canada peas, cow peas, 

 or clover as a summer cover. The mineral ele- 

 ments must be obtained as a commercial ma- 

 nure. Potash in the form of sulphate is as a 

 rule more desirable in fruit growing than muri- 

 ate, unless for some reason it is desirable to 

 shorten the growing season. 



Phosphoric acid can be applied in fine ground 



