222 
Journal of Agricultural Research 
Vol. IX, No. 7 
inches the variation was from o.n to 4.08 mgm. The next depth shows 
a variation from 0.11 to 3.75 mgm.; and even then at a depth of 30 to 
42 inches the variation during the season was from 0.18 to 2.14 mgm. 
sorTUAfcrswx&v 9" mow /a”mcwmmotv 
o~-G” 
■ JlB-J 
/sr /5 r 3*0 <0??* 
M2 CV^Z/tt/Grtr/OM 
Fig. 8.—Diagram showing the distribution of nitrates in plot H before and after irrigations. Season of 1916. 
Plot M has never received any nitrogenous fertilizers; consequently 
the nitrate content of the soil is extremely low. Even the upper 6 inches 
showed a nitrate content of only 0.55 mgm. at the time of the first irri- 
