186 



Fruit-growing in Arid Regions 



desert land, and in most cases the land was cleared of the 

 native growth and planted directly to trees. Thus there 

 was little or no vegetable matter in the ground; and since 

 our growers have been very insistent on clean cultivation 

 and stable manure is scarce, little has been added. Does 

 it not stand to reason that continued cropping to apples 

 or to peaches will bring the same disastrous results that 

 befell the wheat-growers ? 



The following information compiled by Roberts 1 is 

 valuable in this connection. Table IV shows the amounts 

 of plant-food that are removed in the grain and straw in 

 twenty years of continuous cropping to wheat. It is as- 

 sumed that an average of 15 bushels of grain and 35 pounds 

 of straw are removed from an acre each year : 



TABLE IV. AMOUNTS OF PLANT-FOOD REMOVED FROM AN ACRE 

 IN TWENTY YEARS' CONTINUOUS CROPPING TO WHEAT 



In contrast with this, the same author gives similar 

 figures of the plant-food that may be expected to be carried 

 away in 20 years in fruit and leaves from an acre of bear- 

 ing apple orchard. The figures represent 20 years of the 

 productive life of a New York apple orchard between the 

 ages of 1 3 and 33 years, and does not include the materials 

 stored in the wood of the tree. 



1 Roberts, I. P., Cornell Exp. Sta. Bui. 103. 



