20 



Maine Agricultural Experiment Station. 1919. 



THE MINERAL MATTERS OF MAINE GROWN 

 POTATOES 



The' ash of potatoes as shown by analysis is about .9 per 

 cent . But part of this will be certain impurities chiefly un- 

 burned carbon, and sand and silica that is not removed even by 

 careful washing. In the analysis made by the Maine Station 

 the potato ash has carried about 10 per cent of these impurities. 

 And hence the pure ash of potatoes is about .8 instead of .9 per 

 cent as shown in the table above. The pure ash in the few 

 samples examined at 'the Maine Station run pretty uniform and 

 carry about 56 per cent potash, 1.8 per cent soda, 1.2 per cent 

 lime, 3.8 per cent magnesia, 14.6 per cent phosphoric acid and 

 6.2 per cent sulphuric acid. The high potash content of the 

 ash probably explains one of the important functions of pota- 

 toes as a food. While the ash functions of food are not clearly 

 known, it is known that potash salts are of high nutritive value, 

 particularly in organic combination. 



These mineral matters also have a value in considering the 

 fertilizer needs of the potato plant. The results of the analysis 

 calculated to the water content of the fresh potato are given in 

 the table that follows : 



Table Showing the Fertilizer Constituents of Maine Grown 

 Potatoes Calculated to Water Content of Fresh Potatoes 



Ammonia 



Phosphoric Acid 



Potash 



Lime 



% 

 .37 



% 

 .13 



% 

 .48 



% 

 .01 



If the figures cited from the results of the analysis of 

 Maine grown potatoes are fairly representative, a crop of 250 

 bushels (about 90 barrels), weighing 150 hundredweight would 

 remove 56 pounds of amonia, 20 pounds of phosphoric acid, 72 

 pounds of potash, iy 2 pounds of lime from the soil. 



