2 8o 



Journal of Agriculture, Victoria. [lo May, 1912. 



Table IV 



Water iu Soil as- 



iS'itrate Nitrogen per 1,000,000 Parts Dry Soil. 



Percentage of 



added Ammonia 



Nitrified. 



-141 

 9-52 

 44-69 

 59-14 

 68-36 

 63-29 

 65- 15 



Between 40 and 70 per cent, of the water-holding capacity, rate of 

 nitrification did not vary in any important degree. At the variou.s steps 

 below 40, there w-as a notable falling away ; 10 per cent, practically 

 stopped nitrification, and at 20 the rate was only one-seventh of the best 

 case. Another duplicate .set of bottles set up at the same time, but 

 analyzed one week earlier, showed results on a lower plane for each degree 

 of moistness, but placed them in the same order of merit. 



Results of the Second Experiments. 

 Here two classes of soil were used — -the one a fresh sample from tiie 

 same spot as in the first experiments, the other a medium clay. The water 

 added to the sandy soil formed as before a percentage of its saturation capa- 

 city ; the clay soil was brought up to the same content of water without 

 reference to its water-holding capacity. Ammonia added=o.i gram, per 

 300 grams 8011 = 333.33 parts per million. Length of incubation period, 

 42 days. Mean temperature taken from bi-dailv readings, 68.=; deg. F. 



Table V. 



{a) Sandv Soil. 



Nitrate Nitrogen per 1.000.000 Parts Dry Scil. 



C'outro 

 Blanks 



8-33 

 16-30 

 19-25 

 21-71 

 19-18 



9- lie?) 



Excess with 

 Ammonia. 



1-70 

 43-82 

 63-54 



88-64 

 98-47 



18-57 (?; 



The results here agree with those of Tabk^ TIL. and indicate that for 

 this soil there is a long range in the medium degrees of moistness which 

 are about equally favorable for nitrification. This sandv soil contained .86 

 per cent, moisture (see analyses) in the air-dry condition; when exposed 

 in a thin layer for four days in a saturated atmosphere at the temperature 



