DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 29 



Fig. 18.— Diagram showing the effect of calcium sulphate upon nitrification of ammonium sulphate in 

 samples of soil from plat 300, Truckee-Carson Experiment Farm, representing poor soil "A "; plat 310, 

 representing poor soil " B"; and plat 320, representing good soil. 



Table Yll.— Nitrate formed from nitrite by samples of soil from plats 330 and 350, 

 Truckee-Carson Irrigation Project, in medium for nitrate bacteria. Incubated at 28° C. 



211 



