No. 6. 



DEPARTMENT OF AGRICULTURE. 



815 



In order to present ao idea of the amount of exhaustion of phos- 

 phoric acid by crop in a little different way from the above, calcula- 

 tions have been made of the quantity removed from one acre by a 

 fair yieAd of some of the commoner products. These figures are 

 presented in Table 3. 



TABLE 3. 

 Approximate Quantity of Phosphoric Acid in the Product of One Acre of Sun- 

 dry Farm Crops. 



Estimated Crop. 



J3 >.ij 



o a I 

 en 3 .o 



mod 



o, .2 



m t^ t. 



^ u o. 



%-i 03 



o d o 



3 ^ 



Corn, 50 bushels 



Oats. 40 bushels 



Wheat, 25 bushels 



Potatoes, 150 bushels 



Tomatoes, 10 tons, 



Clover hay. 2 tons 



Timothy hay, 2 tons 



Wheat straw, 1% tons 



Green fodder corn, 15 tons, 



115 

 74 

 86 



103 



to 



160 



147 



40 



214 



*Calculated on the basis of 14 per cent, available phosphoric acid. 



The figures given in Table 3 are not intended to show the amount 

 of phosphoric acid needed for the growth of the whole plant or 

 crop, but simply what would be removed in the parts which are 

 generally sold. 



The quantities of phosphoric acid which are removed by one bushel 

 of product or even by a crop from one acre as exhibited by the figures 

 in the preceding table, in most cases seem to be very small and, 

 indeed, almost insignificant, yet, when the fact is considered that 

 most of the lands have been under cultivation for a considerable 

 length of time, it will be seen that even these small amounts repre- 

 sent considerable when muUiplied by 10, 20, 50 and even 100 or 

 more crops. The figures which have been given in Tables 1, 2 and 

 3 will serve the purpose for each person to gain some idea of 

 what is taking place in individual cases, but give little conception 

 of the vastness of what is taking place in the State as a whole. 



The annual drain of phosphoric acid from the farms of Pennsyl- 

 vania, by the principal crops, is shown by the figures in Table 4. 

 Though large as these figures seem, jet they represent but a part 

 of what is taking place. The amount removed by over one million 



