14 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 



practicaUv failed to nitrify/ although the two plats appear to be very 



similar. 



Figure 5 shows the relative nitrifying power of good and poor soils 

 collected from adjoining plats. Plat 160 has a loose sandy soil to a 



DEPTH ^T W/Y/CH S/IMPLE5 \/^£R£ r^^K^N. 

 ,0to6" 6rol2" l2rol8" I8':^24" 24^36' 



^ 



Fig. 5.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 

 from plats U;0 and 170, Truckee-Carson Experiment Farm. Original nitrate present in samples from 

 plat lUO: Depth, to G inches, 8.64 parts per million; to 12 inches, 2.88;-12 to 18 inches, 4.8; IS to 24 inches, 

 O; 24 to 30 inches, 4.8. From plat 170: Depth, to (i inches, 4.32 parts per million; to 12 inches, (i; 12 to 

 18 inches, 3.84; 18 to 24 inches, 3.0: 24 to 30 inches, 3. 



depth of 18 inches; below this it is very heavy, but below 26 and 30 

 inches it is again lighter in texture. At the time of sampling, this 

 plat was supporting a fine growth of alfalfa. Plat 170 is in the north- 

 east corner of tlie same field, and was very similar except that the 



1 This field had been irrigated a .^liorl lime l)ef()re ihe .saniple.s were eollected. 

 211 



