Note on the Behaviour of Hippuric Acid in Soils. 



BY 



K. Yoshimura, Ndgakushi. 



The manurial effect of urine stands among other things in a 

 certain ratio to its amount of nitrogenous compounds, and to 

 the readiness with which these are converted into ammonia. 



Kcllncr has shown that urea as such is not absorbed by 

 the soil and that surface soil more readily converts it into am- 

 monium carbonate than soil from a certain depth. Uric acid 

 can also readily undergo fermentation, with the production of 

 ammonia and carbon dioxide, and with simultaneous oxidation/ 1 ' 



C 5 H 4 N + 0 3 + 8H 2 0 + 30=4NH 3 + 5C0 2 + 4lI 2 0. 



But there exists a considerable amount of nitrogen in still 

 another form in the urine of cattle and horses, viz., as hippuric 

 acid. 



About 10 % of the total nitrogen of cattle-urine and about 

 2 % of thai of horse-urine are present in this form. As hippuric 

 acid evidently resists the fermentative action of microbes more 

 than urea or uric acid, it seemed to me of interest to observe the 

 behaviour of hippuric acid in soils. 



At first, however, I tested soil in regard to its absorptive 

 power for this compound. 



It seemed to me possible that soil rich in hydrated oxide of 

 iron might show some absorptive power, ferric hippurate being 

 insoluble. Two kinds of soils were tested ; one, from the farm 

 of this College in Komaba, near Tokyo, consists of volcanic 

 ashes and loam, and contains about 8% of humus and 8-i i % 

 of oxide of iron ; it has a high absorptive power for ammonia 

 and phosphoric acid. The "other, from Tochigi, is of clayey 

 nature; both soils are almost free from calcium carbonate. 



( i) Sestini. Landw. Vers. Stat., 38., 157. 



