112 THE HANDBOOK FOR PRACTICAL FARMERS 



Rotations vary greatly under different soil, fertilizer and 

 climatic conditions. It is desirable that the crop or crops pre- 

 ceding the potato should never rob the soil of the necessary 

 fertilizer to support a maximum yield. Do not grow potatoes 

 on the same soil year after year. 



Fig. 32. — Map showing the potato-producing areas of the United States in 1909. 

 —After U. S. D A. 



FERTILIZERS FOR POTATOES 



By C. W. Ward, B.S.* 



Stable manure is the most satisfactory fertilizer for potatoes. 

 It is, however, not ahvays available in sufficient quantity to 

 supply the required amount of plant food. Land on which a 

 good crop of clover or alfalfa grew the previous season may 

 produce a satisfactory yield of potatoes without the application 

 of fertilizer in any form. The yield will, as a rule, be profitably 

 increased on such land if stable manure is applied at the rate 

 of eight to ten tons per acre. On grass land or cultivated land 

 the application of manure should be much heavier, fifteen to 

 twenty tons per acre being desirable under these conditions. 



When the supply of stable manure is not sufficient, commercial 

 fertilizer may be used to furnish needed plant food. Some form 

 of commercial fertilizer may be used profitably on nearly all 

 soils in which potatoes are grown. On clover or alfalfa sod-land 

 two hundred fifty to five hundred pounds of acid phosphate per 



' Extension Specialist, Michigan Agricultural College. 



