232 



NITRIFICATION 



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

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

 paratively true from plot to plot. 



Table LXXXII. shows the average concentration of the 

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



TABLE LXXXII. Nitrogen per million parts of BroadbalTc Drainage 



Water. 



Table LXXXIII. the average number of days in each month 

 on which the drains of the same plots run. 



TABLE LXXXIII. Number of Days with Drainage, Broadbalk Field. 

 Average over 36 years. 



Considering first the unmanured plot, but little drainage 

 takes place during 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 



