FERTILITY IN SOILS 



359 



ammonia and nitrate in the untreated soil. The total nitrogen 

 as ammonia and nitrate found at the beginning of an experiment, 



200 



150 



100 



50 



N' 



P 2 5 



K a O 



□ 



Soil untreated 



m 



Soil treated withCHCL, 



Soil treated with CS 2 



Soil Jreated with toluene 



Fig. 2. — Relative amounts of plant food taken by buckwheat from variously treated soils. 



and after the soil had been kept twenty-three days at about 

 15° C. in a moist condition was : 



The results are expressed as parts per million of dry soil. 



The accumulation of ammonia might be due either to an 

 increased production in the treated soils or to the removal 

 by the treatment of some agent, other than the nitrifying 

 organisms, which is always consuming ammonia. The second 



