232 



NITRIFICATION 



the water that may be supposed to pass into the subsoil at the 

 depth of the drain. The resuh-s, however, are probably com- 

 paratively true from plot to plot. 



Table LXXXII. shoAvs the average concentration of the 

 nitrates in the drainage water from four of the wheat plots, and 



Table LXXXII. 



-Xitrogen 2)61' million i^cirts of Broadhalk Drainage 

 Water 



Table LXXXIII. the average number of days in each month 

 on which the drains of the same plots run. 



Table LXXXIII. — Xumbcr of Days with Drainage, Broadhalk Field. 

 Average over 36 years. 



Considering first the unmanured plot, Init Httle drainage 

 takes place dtmng the summer months, May to August, because 

 of the drying action of the crop upon the land. At the same 

 time the concentration of such water as does find its way 



