f« n I lie Bchaviiti- of Xitrate in Paddy Suil. j c 



a). Bact. denitrificans I. ] 

 b). „ „ II. J 



c). „ nitrovorum. 



One hundred g of soil from our Experiment Station were kept in an 

 Erlenmeyer's flask of ca. 300 cc. capacity with 100 cc. of nitrate solution as 

 in Expt. Ill, (a). After repeated sterilization the denitrifying organisms 

 were inoculated on Aug. 16, 1905, and kept at room temperature. Of the 

 supernatant solutions small doses were withdrawn from time to time with 

 a sterilized pipette, and tested for nitrate, nitrite and ammonia with the 

 following results : 



(a). Bact. denitrificans I. Much nitrite was found after 24 hours and 

 after 6 days the amount of nitrite reached the maximum (0,125^ KNO^). 

 But even after 2 months later both nitrate and nitrite were still present. 



(b). Bact. denitrificans II. The nitrite reaction was observed after 

 2 days from the start and after 9 days this reaction showed the maximum. 

 All the nitrate and nitrite were reduced after 1 3 days from the start. 



(c). Bact. nitrovorum. Nitrite was observed also after two days, the 

 maximum point of the nitrite reaction after 6 days, and the disappearance of 

 both nitrate and nitrite after 16 days from the start. 



A moderate ammonia reaction was obtained in each mixture after 3 

 days, (a) yielded much, (b) and (c) a weak ammoniacal reaction after 5-10 

 days, and still a moderate reaction after 2 weeks. 



Further with the flask (a) much pasty film was noticed on the surface 

 of the soil, but with flasks (b) and (c) this was not the case ; the liquids 

 became gradually turbid and of a light reddish-brown color. 



LABORATORY EXPERIMENT. V. 



To observe the influence of starch, compost, straw and rape cake upon 

 the reduction of nitrate in paddy soil and to determine the loss of nitrogen 

 by denitrification the following experiment was made. 



On Sept. 18, 1905, 28 Erlenmeyer's flasks of ca. 300 cc. capacity were 



i). These two organisms were isolated from the soil in the field of this Station by S. Machida. 

 Burri and Stutzer were the first to isolate denitrifying bacteria in pure culture. 



