DETAILia) STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 



31 



determinations were niaile. Yet these results show conckisively that 

 in both good and poor soils there are large numbers of ammonifiers 

 which are i)hysiologically active if proper conditions are provided for 

 them to develop. The relative dillerences in their ammonifying 

 power and whether or not there are conditions in the soil to i)revent 

 their normal activities remain to be shown by further experiment. 



Denitrification is of two kinds : The reduction of nitrates to lower 

 forms or transformation into organic form, and the complete breaking 

 down of the nitrogenous substance with the evolution of free nitrogen 

 as a gas. Either of these processes could be a source of infertility. 



^|l200 



NJ^IIOO 



^oooo 



A 



...„_^^ /SDa ySj: _ 6ooop °lL^ 



DEPT^ /^T IVMC^/ S/JMP^£S lV£^P£r 7?JK£:A/. 



Sto^' 



€to\Z' 



I2toI8" 



I8to24-" 



aood5oi>_ 

 /SDoys- Poor So//. 



Fig. 20.— Diagram showing the ainmonifiuatioii of peptone in 15 days in samples of soil from plat 350 (good 

 soil) and from plats 330 and 3-40 (poor soil), Truckee-Carson Experiment Farm. 



The evolution of free nitrogen was determined by measuring the 

 nitrogen gas produced from ])eptone-nitrate solutions at intervals of 

 7 and 1-5 days. The results are rather erratic, as is shown in Table 

 VIIT. 



Table \'III. — Denitrijkation hi/ samples of soil, from plats 330, 340, and 350, Truckee- 

 Carson Experiment Farm. 



211 



