THE NITROGEN CYCLE 



451 



position of the manure but without any corresponding 

 increase in nitrates. On the other hand, under field con- 

 ditions, manure used in relatively small amounts does 

 not undergo this serious loss. 



The application of twenty tons of farm manure to the 

 acre to sod on a clay loam soil for three consecutive years, 

 at Cornell University, resulted in a larger production 

 of nitrates on the manured soil than on a contiguous plat 

 of similar soil left unmanured. This was true during the 

 third year of the applications, when the land was in sod, 

 and also during the fourth year, when no manure was 

 applied to either plat and when both plats were planted 

 to corn, as may be seen from the following table : 



NITRATES PRODUCED ON HEAVILY MANURED AND ON UN- 

 MANURED SOIL 



