PLANT-FOOD ELEMENTS REMOVED 



69 



preceding paragraphs the importance of plant study is emphasized. 

 If anyone wishes to grow any kind of a crop most successfully 

 he should become familiar not only with the best cultural methods 

 in growing it, but, as far as possible, with all its habits and charac- 

 teristics as well. 



h 



Fig. 27.— The root-hair in the soil, hh, root-hair; e, portion of main root; 1, air space; 



2, soil grain; 3, water film. (After Sachs.) 



Plant-food Elements Removed by Fruit Crops. — It is of interest 

 to note the amounts of elements removed from the soil by some 

 of the common fruit crops. The following table has been prepared 

 from all available data : 



Plant-food Elements Removed hy Fruit Crops 

 (Pounds per acre) 



Fruits 



Average 



annual yield 



per acre 



Number 



trees 

 per acre 



Nitrogen 



(N) 



Phosphorus 



(P) 



Potassium 



(K) 



Calcium 



(Ca) 



Apples 



Cherries 



Peaches 



Pears 



Plums 



Raspberries. . . 

 Strawberries . . 



100 bbis. 

 (300 bu.) 

 300 cases 

 (150 bu.) 



450 bu. 



500 bu. 



250 bu. 

 3000 qts. 

 6000 qts. 



50-100 



108 



100 



75 



100 



13.8 



16.0 



19.2 

 10.2 

 21.7 

 10.0 

 13.5 



2.0 



2.6 



4.1 

 1.6 

 3.6 

 1.7 

 4.5 



14.5 



16.6 



32.7 

 19.1 

 25.7 

 10.0 

 22.5 



1.0 



1.0 



1.7 

 1.8 

 2.0 



0.6* 



* strawberries need but little calcium, even in leaf and stem development. 



