NITRIFYTNG POWER OF SOILS AT DIFFERENT DEPTHS. 



15 



surface was a little more compact and the alfalfa was practically a 

 failure. The nitrification curves show the same general variations, but 

 the one of the poor soil is consistently below that of the productive soil. 



DEPTH /IT WH/CH S/JMPLES WEPE T/IKEN. 

 ,0ro6" 6'^ 12" 12rol8" I8'^24" 24';-o36" 



Fig. 6.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 

 from plat ISO (poor soil) and plat 190 (good soil), Truckee-Carson Experiment Farm. Original uitrale 

 present in samples from plat 180: Depth, to 6 inches, 2 parts per million; 6 to 12 inches, 3.5; 12 to 18 

 inches, 8.25; 18 to 24 Inches, 4.5; 24 to 30 inches, 25.75. From plat 190: Depth, to 6 inches, 4.o parts per 

 million; G to 12 inches, 15.75; 12 to 18 inches, 11.25; 18 to 24 Inches, 20.75; 24 to 36 inches, 21.75. 



Plats 180 and 190 are located upon poor and good spots. The 

 texture of the samples Is very similar, both being sandy, but the 

 surface of plat 180, the unproductive soil, is hard and compact as if 



211 



