58 



BULLETIN "E. 



INFLUENCE OF MANURE UPON THE AMOUNTS OF NITRIC AND 

 PHOSPHORIC ACIDS RECOVERED FROM SOILS BY PLANTS. 



Determining the mean values for the nitric acid and phos- 

 phoric acid recovered from the plants grown upon the manured 

 and unmanured soils the values stand' as given in the next 

 table: 



Mean amounts of nitric acid and of phosphoric acid recovered from 

 corn and potatoes grown upon manured and unmanured ground. 



This table shows no such sharp percentage differences as 

 stand out clear and strong with the three bases. With the 

 nitrates from both corn and potatoes, except on the poorer soils, 

 t l he relation holds which occurred with the lime and magnesia, 

 namely, a smaller relative amount in the plants which have 

 made the most vigorous growth ; and, with the nitric acid being 

 transformed into organic nitrogen, this relation is what should 

 be expected. With the phosphoric acid there is less indication 

 of the manure having had any effect upon the percentage 

 amounts recovered by the treatment of the plant samples with 

 distilled water. 



Comparing the absolute amounts of these two ingredients, 

 which had been recovered from the soils by the plants at the 

 time the samples were taken and which still remained in solu- 

 ble form in their tissues, the relations will, of course, be quite 

 different from those shown by the table. The relative amounts 

 of dry matter existing in the crops under comparison at the 

 time of observation are not known, but it is likely that the 



